[Federal Register Volume 90, Number 147 (Monday, August 4, 2025)]
[Notices]
[Pages 36520-36534]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-14705]


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DEPARTMENT OF THE TREASURY

Internal Revenue Service


Superfund Tax on Chemical Substances; Notice of Determinations To 
Add Substances to List of Taxable Substances; Corrected Name and Tax 
Rate for Sodium Nitrilotriacetate Monohydrate

AGENCY: Internal Revenue Service (IRS), Treasury.

ACTION: Notice of determinations.

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SUMMARY: This notice of determinations modifies the list of taxable 
substances to include the following 21 substances: polyphenylene 
sulfide, cellulose acetate (degree of substitution = 1.5-2.0), 4,4'-
isopropylidenediphenol-epichlorohydrin copolymer, nylon 6, caprolactam, 
methyl ethyl ketoxime, iso-butanol, diethylene glycol monomethyl ether, 
ethylene glycol phenyl ether, methoxytriglycol, propylene glycol methyl 
ether acetate, propylene glycol methyl ether, propylene glycol n-propyl 
ether, propylene glycol phenyl ether, di-isobutyl carbinol, di-isobutyl 
ketone, methyl isobutyl carbinol, cyanuric acid, potassium bicarbonate, 
potassium carbonate, and sodium chlorite. This notice also modifies the 
list included in Notice 2021-66 by correcting a typographical error in 
the spelling of the name of the taxable substance sodium 
nitrilotriacetate monohydrate and prescribing a tax rate for sodium 
nitrilotriacetate monohydrate.

DATES: The effective date for purposes of the tax under section 4671 of 
the Internal Revenue Code (Code) for the taxable substances added to 
the list is January 1, 2026. For the effective date for purposes of 
refund claims under section 4662(e) of the Code for the taxable 
substances added to the list, see the determination for each substance. 
The tax rate for sodium nitrilotriacetate monohydrate is effective July 
1, 2022.

FOR FURTHER INFORMATION CONTACT: Andrew Clark or Jacob Peeples at (202) 
317-6855 (not a toll-free number).

SUPPLEMENTARY INFORMATION:

Background

    Section 4671(a) of the Code imposes an excise tax on the sale or 
use of a taxable substance by the importer thereof. Section 4672(a)(1) 
of the Code defines the term taxable substance as any substance which, 
at the time of sale or use by the importer, is listed as a taxable 
substance by the Secretary of the Treasury or the Secretary's delegate 
(Secretary) on the list of taxable substances under section 4672(a) 
(List).
    Under section 4672(a)(2), an importer or exporter of any substance 
may request that the Secretary determine whether such substance should 
be added to the List as a taxable substance or should be removed from 
the List. Under section 4672(a)(2)(B) and (4) and (b)(2), the Secretary 
is required to add a substance to the List if the Secretary determines 
that any taxable chemicals that are listed in section 4661(b) of the 
Code constitute more than 20 percent of the weight, or more than 20 
percent of the value, of the materials used to produce such substance, 
which determination is required under section 4672(a)(2)(B) and (a)(4) 
to be made based on the predominant method of production (weight or 
value test). Section 4672(a)(4) authorizes the Secretary to remove a 
substance from the List only if such substance meets

[[Page 36521]]

neither the weight nor the value test of section 4672(a)(2)(B).
    Section 4672(a)(3) includes an initial list of taxable substances. 
Section 4 of Notice 2021-66 (2021-52 I.R.B. 901) provides the list of 
101 substances that the Secretary added to the List before November 15, 
2021. Rev. Proc. 2022-26 (2022-29 I.R.B. 90), as modified by Rev. Proc. 
2023-20 (2023-15 I.R.B. 636), provides the exclusive procedures by 
which an importer, exporter, or interested person may request a 
determination that a particular substance be added to or removed from 
the List.
    Section 4671(b)(3) authorizes the Secretary to prescribe a tax rate 
for taxable substances in lieu of the tax rate specified in section 
4671(b)(2). The tax rate prescribed by the Secretary for a substance 
added to the List is calculated by multiplying the conversion factor 
for each taxable chemical used in the production of the substance by 
the corresponding tax rate for that taxable chemical under section 
4661(b), and adding those results together. Conversion factors are 
determined based on the predominant method of production of the 
substance. See sections 8 and 10.04(8) of Rev. Proc. 2022-26. Importers 
are not required to use the prescribed tax rate for a taxable substance 
and may calculate their own rate under section 4671(b)(1).
    Pursuant to section 4672(a)(4), this notice of determination 
modifies the List to include the 21 additional taxable substances 
listed in the Summary of Determinations section of this notice, as 
explained in the Requests to Add Substances to the List and General 
Explanation of Determinations sections of this notice. The 
determination for each specific substance added to the List is 
explained in parts I through XXI of the Modifications to the List of 
Taxable Substances section of this notice.
    In June 2022, the Secretary prescribed rates for some of the 
substances listed in section 4672(a)(3) and Notice 2021-66.\1\ The 
Correction to the List of Taxable Substances section of this notice 
modifies Notice 2021-66 by correcting a typographical error in the 
spelling of sodium nitrilotriacetate monohydrate and prescribing a tax 
rate for the substance. The updated List and prescribed tax rates for 
taxable substances will be included in the instructions to Form 6627, 
Environmental Taxes.
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    \1\ Available at https://www.irs.gov/newsroom/irs-issues-superfund-chemical-excise-tax-rates.
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Summary of Determinations

    On August 1, 2025, the Secretary determined to add the following 
substances to the List:

I. Polyphenylene sulfide
II. Cellulose acetate (degree of substitution = 1.5-2.0)
III. 4,4'-isopropylidenediphenol-epichlorohydrin copolymer
IV. Nylon 6
V. Caprolactam
VI. Methyl ethyl ketoxime
VII. Iso-butanol
VIII. Diethylene glycol monomethyl ether
IX. Ethylene glycol phenyl ether
X. Methoxytriglycol
XI. Propylene glycol methyl ether acetate
XII. Propylene glycol methyl ether
XIII. Propylene glycol n-propyl ether
XIV. Propylene glycol phenyl ether
XV. Di-isobutyl carbinol
XVI. Di-isobutyl ketone
XVII. Methyl isobutyl carbinol
XVIII. Cyanuric acid
XIX. Potassium bicarbonate
XX. Potassium carbonate
XXI. Sodium chlorite

Requests To Add Substances to the List

    For each of the substances listed in the Summary of Determinations 
section of this notice, an importer, an exporter, or an interested 
person submitted a petition to the IRS in accordance with Rev. Proc. 
2022-26 requesting a determination under section 4672(a)(2) to add the 
substance to the List. For each substance, the petition represented 
that the taxable chemicals constitute more than 20 percent of the 
weight of materials used to produce the substance, based on the 
predominant method of production.

General Explanation of Determinations

    After reviewing the petitions for each of the substances listed in 
the Summary of Determinations section of this notice, the Secretary 
determined that taxable chemicals constitute more than 20 percent by 
weight of the materials used to produce the substance, based on the 
predominant method of production. Therefore, each of the substances is 
added to the List as required under section 4672(a)(2) and (4). The 
Secretary made the determinations to add these substances to the List 
in accordance with the requirements of section 4672(a)(2) and (4), and 
pursuant to the procedures set forth in Rev. Proc. 2022-26, as modified 
by Rev. Proc. 2023-20.
    The relevant information for each taxable substance is provided in 
the specific determinations included in parts I through XXI of the 
Modification to the List of Taxable Substances section of this notice. 
The tax rate for each taxable substance, as prescribed by the 
Secretary, is provided in paragraph (a)(6) of each specific 
determination.
    Classification numbers proposed by each petitioner are included in 
paragraph (b) of each part, after each specific determination. The 
classification numbers provided with respect to a taxable substance are 
not part of the determination of whether it is added to the List and do 
not impact whether such substance is a taxable substance. Taxpayers may 
not rely on classification numbers for any purpose under sections 4661, 
4662, 4671, and 4672, including (but not limited to) identification of 
a substance as a taxable substance on the List. Classification numbers 
may change over time. The Department of the Treasury (Treasury 
Department) and the IRS do not anticipate updating this document to 
reflect any such changes.
    For purposes of the section 4671 tax, all the modifications in 
parts I through XXI of the Modification to the List of Taxable 
Substances section of this notice are effective on and after January 1, 
2026. For purposes of refund claims under section 4662(e), see the 
effective date for each specific determination in paragraph (a)(5)(ii) 
of each of parts I through XXI of the Modification to the List of 
Taxable Substances section of this notice. The tax rate for sodium 
nitrilotriacetate monohydrate in the Correction to the List of Taxable 
Substances section of this notice is effective July 1, 2022.

Modifications to the List of Taxable Substances

I. Determination To Add Polyphenylene Sulfide to the List

    Celanese Ltd., an exporter of polyphenylene sulfide, submitted a 
petition in accordance with Rev. Proc. 2022-26 requesting to add 
polyphenylene sulfide to the List. According to the petition, the 
taxable chemicals sodium hydroxide, benzene, and chlorine constitute 
90.00 percent by weight of the materials used to produce polyphenylene 
sulfide, based on the predominant method of production.
    (a) Determination. Polyphenylene sulfide is added to the list of 
taxable substances under section 4672(a). Other pertinent information 
is as follows:
    (1) Predominant method of production: The process involves three 
separate reactions:
    (i) 1,4 dichlorobenzene is made from the reaction of benzene with 2 
equivalents of chlorine;

[[Page 36522]]

    (ii) Sodium hydrogen sulfide is made from the reaction of hydrogen 
sulfide with sodium hydroxide; and
    (iii) 1,4-dichlorobenzene (p-dichlorobenzene, p-DCB), sodium 
hydrosulfide (NaSH), and sodium hydroxide (NaOH) are reacted at high 
temperature and high pressure to form polyphenylene sulfide and 
byproduct sodium chloride.
    (2) Stoichiometric material consumption equation:

n [2 NaOH + C6H6 + 2 Cl2 + 
H2S] [rarr] [C6H4S]n + 2n 
H2O + 2n NaCl + 2n HCl

    (3) Reasons for the determination: The polyphenylene sulfide 
petition was filed on December 20, 2022. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (87 FR 80579) on December 30, 2022. A supplemental 
notice of filing announcing a corrected petition and correction to the 
stoichiometric material consumption equation in the original notice of 
filing and requesting comments was published in the Federal Register 
(89 FR 11941) on February 15, 2024. The Treasury Department and the IRS 
received no written comments in response to the original notice of 
filing or the supplemental notice of filing. A public hearing was 
neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation in the corrected petition, as provided in the 
supplemental notice of filing, and other information in the petition 
shows that the taxable chemicals sodium hydroxide, benzene, and 
chlorine constitute more than 20 percent by weight of the materials 
used in the production of polyphenylene sulfide, based on the 
predominant method of production. Therefore, the test in section 
4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of polyphenylene sulfide to the 
List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $14.50 per ton. The 
conversion factors for the taxable chemicals used in the production of 
polyphenylene sulfide are 0.74 for sodium hydroxide, 0.72 for benzene, 
and 1.31 for chlorine. The tax rate is calculated by adding the 
products of the conversion factor for each taxable chemical and the tax 
rate for that taxable chemical: ((0.74 x $0.56) + (0.72 x $9.74) + 
(1.31 x $5.40) = $14.50).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 3911.90.2500.
    (ii) Schedule B number: 3911.90.6100.
    (iii) CAS numbers: 25212-74-2, 26125-40-6.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

II. Determination To Add Cellulose Acetate (Degree of Substitution = 
1.5-2.0) to the List

    Celanese Ltd., an exporter of cellulose acetate (degree of 
substitution = 1.5-2.0), submitted a petition in accordance with Rev. 
Proc. 2022-26 requesting to add cellulose acetate (degree of 
substitution = 1.5-2.0) to the List. According to the petition, the 
taxable chemical methane constitutes greater than 20 percent \2\ by 
weight, of the materials used to produce cellulose acetate (degree of 
substitution = 1.5-2.0), based on the predominant method of production.
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    \2\ The petition covers cellulose acetate (degree of 
substitution = 1.5-2.0), commonly referred to as cellulose 
diacetate. Cellulose acetate in this range generally has similar 
properties. The petition uses the lowest end of the range cellulose 
acetate (degree of substitution = 1.5) (21 percent taxable 
chemicals) to demonstrate that >20% of the substance is made from 
taxable chemicals, and the midpoint cellulose acetate (degree of 
substitution = 1.75) (24 percent taxable chemicals) to calculate the 
tax rate for the entire range.
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    (a) Determination. Cellulose acetate (degree of substitution = 1.5-
2.0) is added to the list of taxable substances under section 4672(a). 
Other pertinent information is as follows:
    (1) Predominant method of production: Cellulose acetate is derived 
from cellulose by deconstructing wood pulp into a purified cellulose. 
The cellulose is reacted with acetic acid and acetic anhydride in the 
presence of sulfuric acid. It is subjected to a controlled, partial 
hydrolysis to remove the sulfate and a sufficient number of acetate 
groups to give the product the desired degree of substitution. The 
polymer unit is the fundamental repeating structure of cellulose and 
has three hydroxyl groups which can react to form acetate esters. The 
most common form of cellulose acetate fiber has an acetate group on 
approximately two of every three hydroxyls, referred to as cellulose 
diacetate. In this petitioner's cellulose acetate, the actual 
substitution is 1.674 acetate/cellulose, a degree of substitution 
commonly used in U.S. cellulose acetate production.
    (2) Stoichiometric material consumption equation:

3.5 CH4 + 1.75 O2 + 
C6H10O5 [rarr] 
C9.5H13.5O6.75 + 3.50 
H2 + 1.75 H2O

    (3) Reasons for the determination: The cellulose acetate (degree of 
substitution = 1.5-2.0) petition was filed on December 20, 2022. The 
notice of filing summarizing the petition and requesting comments was 
published in the Federal Register (88 FR 16307) on March 16, 2023. The 
Treasury Department and the IRS received no written comments in 
response to the notice of filing. A public hearing was neither 
requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemical methane constitutes more than 20 percent by weight 
of the materials used in the production of cellulose acetate (degree of 
substitution = 1.5-2.0), based on the predominant method of production. 
Therefore, the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of cellulose acetate (degree of 
substitution = 1.5-2.0) to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $1.65 per ton. The 
conversion factor for the methane used in the production of cellulose 
acetate (degree of substitution = 1.5-2.0) is 0.24. The tax rate is 
calculated by multiplying the conversion factor by the tax rate for 
methane: (0.24 x $6.88 = $1.65).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification number: CAS number: 9035-69-2.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers:
    (i) HTSUS numbers: 5502.10.0000, 5403.33.0020.
    (ii) Schedule B numbers: 5502.10.0000, 5403.33.0000.

[[Page 36523]]

III. Determination To Add 4,4'-Isopropylidenediphenol-Epichlorohydrin 
Copolymer to the List

    Westlake Epoxy Inc., an exporter of 4,4'-isopropylidenediphenol-
epichlorohydrin copolymer, also known as ``bisphenol A epoxy resin,'' 
submitted a petition in accordance with Rev. Proc. 2022-26 requesting 
to add 4,4'-isopropylidenediphenol-epichlorohydrin copolymer to the 
List. According to the petition, the taxable chemicals benzene, 
propylene, chlorine, and sodium hydroxide constitute 92.98 percent by 
weight of the materials used to produce 4,4'-isopropylidenediphenol-
epichlorohydrin copolymer, based on the predominant method of 
production.
    (a) Determination. 4,4'-isopropylidenediphenol-epichlorohydrin 
copolymer, also known as ``bisphenol A epoxy resin,'' is added to the 
list of taxable substances under section 4672(a). Other pertinent 
information is as follows:
    (1) Predominant method of production: 4,4'-isopropylidenediphenol-
epichlorohydrin copolymer is produced from epichlorohydrin and 
bisphenol-A via a two-step glycidation reaction sequence. 
Epichlorohydrin is typically produced via an addition reaction of 
chlorine to propylene that yields allyl chloride and subsequently 
dichlorohydrin isomers, followed by a dehydrochlorination step in the 
presence of sodium hydroxide to yield epichlorohydrin. Bisphenol A is 
typically produced from the reaction of benzene and propylene that 
yields phenol and acetone. Under acidic conditions and with an 
appropriate catalyst, two units of phenol can react with one unit of 
acetone to yield Bisphenol A. With available epichlorohydrin and 
Bisphenol A, 4,4'-isopropylidenediphenol-epichlorohydrin copolymer can 
be obtained through a two-step glycidation reaction sequence where 
epichlorohydrin is added to Bisphenol A (deprotonated with sodium 
hydroxide) and then water, sodium hydroxide, and sodium chloride are 
removed in a dehydrochlorination step.
    (2) Stoichiometric material consumption equation:

2 C6H6 (benzene) + 4 C3H6 
(propylene) + 4 Cl2 (chlorine) + 6 NaOH (sodium hydroxide) + 
2 O2 (oxygen) [rarr] 
(CH3)2C(C6H4OC3H5
O)2 (4,4'-isopropylidenediphenol-epichlorohydrin copolymer) 
+ CH3COCH3 (acetone) + 2 HCl (hydrogen chloride) 
+ 6 NaCl (sodium chloride) + 5 H2O (water)

    (3) Reasons for the determination: The 4,4'-isopropylidenediphenol-
epichlorohydrin copolymer petition was filed on December 20, 2022. The 
notice of filing summarizing the petition and requesting comments was 
published in the Federal Register (88 FR 3478) on January 19, 2023. The 
Treasury Department and the IRS received no written comments in 
response to the notice of filing. A public hearing was neither 
requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals benzene, propylene, chlorine, and sodium 
hydroxide constitute more than 20 percent by weight of the materials 
used in the production of 4,4'-isopropylidenediphenol-epichlorohydrin 
copolymer, based on the predominant method of production. Therefore, 
the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of 4,4'-isopropylidenediphenol-
epichlorohydrin copolymer to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $14.13 per ton. The 
conversion factors for the taxable chemicals used in the production of 
4,4'-isopropylidenediphenol-epichlorohydrin copolymer are 0.46 for 
benzene, 0.49 for propylene, 0.83 for chlorine, and 0.71 for sodium 
hydroxide. The tax rate is calculated by adding the products of the 
conversion factor for each taxable chemical and the tax rate for that 
taxable chemical: ((0.46 x $9.74) + (0.49 x $9.74) + (0.83 x $5.40) + 
(0.71 x $0.56) = $14.13).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 3907.30.0000.
    (ii) Schedule B number: 3907.30.0000.
    (iii) CAS number: 25068-38-6.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

IV. Determination To Add Nylon 6 to the List

    AdvanSix Inc., an exporter of nylon 6, submitted a petition in 
accordance with Rev. Proc. 2022-26 requesting to add nylon 6 to the 
List. According to the petition, nylon 6 is made from the taxable 
chemicals benzene, propylene, ammonia, methane, and sulfuric acid; 
however, sulfuric acid is cancelled from the stoichiometric material 
consumption equation due to no net consumption/production. The petition 
further represented that the benzene, propylene, ammonia, and methane 
constitute 46.64 percent by weight of the materials used to produce 
nylon 6, based on the predominant method of production.
    (a) Determination. Nylon 6 is added to the list of taxable 
substances under section 4672(a). Other pertinent information is as 
follows:
    (1) Predominant method of production: The predominant method of 
production of nylon 6 is the ``hydrolytically initiated ring-opening 
polymerization of caprolactam'' which is also referred to in industry 
literature as the ``hydrolytic polymerization of nylon 6.'' This 
process is termed ``hydrolytic'' because water plays a key role in the 
chemical mechanism. Nylon 6 is produced almost exclusively through this 
method because it is easier to control and better adapted for large-
scale operations.
    The hydrolytic polymerization of nylon 6 generally entails heating 
a mixture of caprolactam and water to ~270 [deg]C in an inert 
atmosphere of nitrogen and holding until equilibrium conditions are 
achieved. The three principal reactions in this process are summarized 
below:
    (i) In the initiation step of the process, the caprolactam ring is 
hydrolyzed via ring opening with the addition of one water molecule to 
become amino-caproic acid.
    (ii) In the next step of the mechanism, the amino-caproic acid acts 
as the initiating species to begin the addition polymerization by ring-
opening of caprolactam.
    (iii) The last major mechanism step of the hydrolytic 
polymerization of nylon 6 is the condensation of primary amine and 
carboxylic acid chain-ends to form an amide linkage in the now higher 
molecular weight polyamide with the simultaneous loss of a water 
molecule.
    (2) Stoichiometric material consumption equation:

nC6H6 (benzene) + nC3H6 
(propylene) + 2.5nO2 (oxygen) + 0.5nCH4 (methane) 
+ 5nNH3 (ammonia) + 2nH2O (water) + 
2nSO2 (sulfur dioxide) [rarr] 
(C6H11NO)n (nylon 6) + 
nC3H6O (acetone) + 
2n(NH4)2SO4 (ammonium sulfate) + 
0.5nCO2 (carbon dioxide)


[[Page 36524]]


    (3) Reasons for the determination: The nylon 6 petition was filed 
on November 8, 2023. The notice of filing summarizing the petition and 
requesting comments was published in the Federal Register on February 
22, 2024 (89 FR 13399). A supplemental notice of filing announcing a 
corrected petition, correction to the stoichiometric material 
consumption equation in the original notice of filing, and requesting 
comments was published in the Federal Register (89 FR 66175) on August 
14, 2024. The Treasury Department and the IRS received no written 
comments in response to the notice of filing and received one written 
comment in response to the supplemental notice of filing, discussed 
below. A public hearing was neither requested nor held.
    The public comment submitted in response to the supplemental notice 
of filing generally wrote in support of adding nylon 6 to the list of 
taxable substances. However, the commenter requested that the Treasury 
Department and the IRS add to the list of taxable substances the 
categories `nylon resins' or `polyamides' rather than merely the single 
taxable substance nylon 6. The commenter asserts that nylon 6 is one of 
the many grades of nylons or polyamides which contain more than 20 
percent of taxable chemicals.
    At this time, the Treasury Department and the IRS decline to add 
the additional categories of nylon resins and polyamides to the List, 
as suggested by the commenter. The filed petition that is the subject 
of this determination requested only to add the substance nylon 6 to 
the List, so a comment that the Treasury Department and the IRS should 
add additional substances to the List is outside the scope of the 
determination for nylon 6. To request to add nylon resins and 
polyamides to the List, an importer, exporter, or interested person 
must follow the determination procedures provided under Rev. Proc. 
2022-26, including submitting a petition for each substance with the 
required information. See sections 4 and 6 of Rev. Proc. 2022-26.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making the determination to add nylon 6 to the List. A review of the 
stoichiometric material consumption equation in the corrected petition, 
as provided in the supplemental notice of filing, and other information 
in the petition shows that the taxable chemicals benzene, propylene, 
ammonia, and methane constitute more than 20 percent by weight of the 
materials used in the production of nylon 6, based on the predominant 
method of production. Therefore, the test in section 4672(a)(2)(B) is 
satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of nylon 6 to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $14.77 per ton. The 
conversion factors for the taxable chemicals used in the production of 
nylon 6 are 0.69 for benzene, 0.37 for propylene, 0.75 for ammonia, and 
0.07 for methane. The tax rate is calculated by adding the products of 
the conversion factor for each taxable chemical and the tax rate for 
that taxable chemical: ((0.69 x $9.74) + (0.37 x $9.74) + (0.75 x 
$5.28) + (0.07 x $6.88) = $14.77).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 3908.10.00.
    (ii) Schedule B number: 3908.10.0000.
    (iii) CAS number: 25038-54-4.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

V. Determination To Add Caprolactam to the List

    AdvanSix Inc., an exporter of caprolactam, submitted a petition in 
accordance with Rev. Proc. 2022-26 requesting to add caprolactam to the 
List. According to the petition, caprolactam is made from the taxable 
chemicals benzene, propylene, ammonia, methane, and sulfuric acid; 
however, sulfuric acid is cancelled from the stoichiometric material 
consumption equation due to no net consumption/production. The petition 
also represented that the benzene, propylene, ammonia, and methane 
constitute 46.64 percent by weight of the materials used to produce 
caprolactam, based on the predominant method of production.
    (a) Determination. Caprolactam is added to the list of taxable 
substances under section 4672(a). Other pertinent information is as 
follows:
    (1) Predominant method of production: Caprolactam is produced by 
first oxidizing cumene to yield phenol, which is then partially reduced 
with hydrogen to yield cyclohexanone. Cyclohexanone is then reacted 
with Raschig hydroxylamine to generate cyclohexanone oxime. The 
cyclohexanone oxime undergoes Beckmann rearrangement in the presence of 
fuming sulfuric acid (oleum) to give an intermediate material known as 
rearrangement mass, which is subsequently hydrolyzed and then 
neutralized with ammonia to yield [egr]-caprolactam.
    (2) Stoichiometric material consumption equation:

C6H6 (benzene) + C3H6 
(propylene) + 2.5 O2 (oxygen) + 0.5 CH4 (methane) 
+ 5 NH3 (ammonia) + 2 H2O (water) + 2 
SO2 (sulfur dioxide) [rarr] C6H11ON 
([egr]- caprolactam) + C3H6O (acetone) + 
2(NH4)2SO4 (ammonium sulfate) + 0.5 
CO2 (carbon dioxide)

    (3) Reasons for the determination: The caprolactam petition was 
filed on November 8, 2023. The notice of filing summarizing the 
petition and requesting comments was published in the Federal Register 
(89 FR 13400) on February 22, 2024. The Treasury Department and the IRS 
received no written comments in response to the notice of filing. A 
public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals benzene, propylene, ammonia, and methane 
constitute more than 20 percent by weight of the materials used in the 
production of caprolactam, based on the predominant method of 
production. Therefore, the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of caprolactam to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): January 1, 2023.
    (6) Tax rate prescribed by the Secretary: $14.77 per ton. The 
conversion factors for the taxable chemicals used in the production of 
caprolactam are 0.69 for benzene, 0.37 for propylene, 0.75 for ammonia, 
and 0.07 for methane. The tax rate is calculated by adding the products 
of the conversion factor for each taxable chemical and the tax rate for 
that taxable chemical: ((0.69 x $9.74) + (0.37 x $9.74) + (0.75 x 
$5.28) + (0.07 x $6.88) = $14.77).
    (b) Classification numbers.

[[Page 36525]]

    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2933.71.00.
    (ii) Schedule B number: 2933.71.0000.
    (iii) CAS number: 105-60-2.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

VI. Determination To Add Methyl Ethyl Ketoxime to the List

    AdvanSix Inc., an exporter of methyl ethyl ketoxime (commonly 
referred to as MEKO), submitted a petition in accordance with Rev. 
Proc. 2022-26 requesting to add methyl ethyl ketoxime to the List. 
According to the petition, methyl ethyl ketoxime is made from the 
taxable chemicals ammonia, sulfuric acid, and butylene; however, 
sulfuric acid is cancelled from the stoichiometric material consumption 
equation due to no net consumption/production. The petition further 
represented that ammonia and butylene constitute 39.97 percent by 
weight of the materials used to produce methyl ethyl ketoxime, based on 
the predominant method of production.
    (a) Determination. Methyl ethyl ketoxime is added to the list of 
taxable substances under section 4672(a). Other pertinent information 
is as follows:
    (1) Predominant method of production: The conventional method was 
developed in the late 1960s via a route that involves condensation of 
methyl ethyl ketone with a hydroxylamine salt in the presence of a 
base. More specifically, methyl ethyl ketone is oximated with Raschig 
hydroxylamine to yield methyl ethyl ketoxime.
    (2) Stoichiometric material consumption equation:

C4H8 (butylene) + 5 NH3 (ammonia) + 2 
H2O (water) + 1.5 O2 (oxygen) + 2 SO2 
(sulfur dioxide) [rarr] C4H9ON (methyl ethyl 
ketoxime) + 2 (NH4)2SO4 (ammonium 
sulfate) + H2 (hydrogen)

    (3) Reasons for the determination: The methyl ethyl ketoxime 
petition was filed on July 10, 2023. The notice of filing summarizing 
the petition and requesting comments was published in the Federal 
Register (88 FR 45454) on July 17, 2023. The Treasury Department and 
the IRS received no written comments in response to the notice of 
filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals ammonia and butylene constitute more than 20 
percent by weight of the materials used in the production of methyl 
ethyl ketoxime, based on the predominant method of production. 
Therefore, the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of methyl ethyl ketoxime to the 
List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): January 1, 2023.
    (6) Tax rate prescribed by the Secretary: $11.41 per ton. The 
conversion factors for the taxable chemicals used in the production of 
methyl ethyl ketoxime are 0.98 for ammonia and 0.64 for butylene. The 
tax rate is calculated by adding the products of the conversion factor 
for each taxable chemical and the tax rate for that taxable chemical: 
((0.98 x $5.28) + (0.64 x $9.74) = $11.41).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2928.00.10.
    (ii) Schedule B number: 2928.00.1000.
    (iii) CAS number: 96-29-7.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

VII. Determination To Add Iso-Butanol to the List

    OQ Chemicals Corporation, an exporter of iso-butanol, submitted a 
petition in accordance with Rev. Proc. 2022-26 requesting to add iso-
butanol to the List. According to the petition, the taxable chemicals 
methane and propylene constitute 78.41 percent by weight of the 
materials used to produce iso-butanol, based on the predominant method 
of production.
    (a) Determination. Iso-butanol is added to the list of taxable 
substances under section 4672(a). Other pertinent information is as 
follows:
    (1) Predominant method of production: Iso-butanol is co-produced by 
hydroformylation of propylene to produce both iso-butyraldehyde and n-
butyraldehyde followed by hydrogenation of the aldehyde intermediates 
to the corresponding iso-butanol and n-butanol. The predominant method 
of production is as follows:
    (i) Partial oxidation of methane with oxygen to produce synthesis 
gas, a mixture of carbon monoxide and hydrogen. This petitioner uses a 
Partial Oxidation (POX) process that is non catalytic but operates at 
>1300 deg C and >40 atm pressure. Thus, synthesis gas is produced from 
methane and oxygen:

CH4 + \1/2\ O2 [rarr] CO + 2H2

    (ii) Oxo process: Hydroformylation of propylene with carbon 
monoxide and hydrogen over a catalyst to produce iso-butyraldehyde. The 
reaction also produces normal butyraldehyde simultaneously; the 
stoichiometry is the same for either the iso or the normal aldehyde. 
Thus, iso-butyraldehyde is produced from propylene and syngas.

CO + H2 + CH2 =CH-CH3 [rarr] 
(CH3)2-CH-CHO

    (iii) Iso-butyraldehyde is hydrogenated with hydrogen over a 
catalyst. Thus, iso-butanol is produced from iso-butyraldehyde and 
hydrogen.

(CH3)2-CH-CHO + H2 [rarr] 
(CH3)2CHCH2OH

    (2) Stoichiometric material consumption equation:

CH4 (methane) + \1/2\ O2 + CH2 = CH-
CH3 (propylene) [rarr] 
(CH3)2CHCH2OH (iso-butanol)

    (3) Reasons for the determination: The iso-butanol petition was 
filed on January 25, 2024. The notice of filing summarizing the 
petition and requesting comments was published in the Federal Register 
(89 FR 14558) on February 27, 2024. The Treasury Department and the IRS 
received no written comments in response to the notice of filing. A 
public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals methane and propylene constitute more than 20 
percent by weight of the materials used in the production of iso-
butanol, based on the predominant method of production. Therefore, the 
test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of iso-butanol to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): April 1, 2023.
    (6) Tax rate prescribed by the Secretary: $7.07 per ton. The 
conversion

[[Page 36526]]

factors for the taxable chemicals used in the production of iso-butanol 
are 0.22 for methane and 0.57 for propylene. The tax rate is calculated 
by adding the products of the conversion factor for each taxable 
chemical and the tax rate for that taxable chemical: ((0.22 x $6.88) + 
(0.57 x $9.74) = $7.07).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2905.14.50.10.
    (ii) Schedule B number: 2905.14.5010.
    (iii) CAS number: 78-83-1.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

VIII. Determination To Add Diethylene Glycol Monomethyl Ether to the 
List

    The Dow Chemical Company, an exporter of diethylene glycol 
monomethyl ether, submitted a petition in accordance with Rev. Proc. 
2022-26 requesting to add diethylene glycol monomethyl ether to the 
List. According to the petition, the taxable chemicals ethylene and 
methane constitute 59.00 percent by weight of the materials used to 
produce diethylene glycol monomethyl ether, based on the predominant 
method of production.
    (a) Determination. Diethylene glycol monomethyl ether is added to 
the list of taxable substances under section 4672(a). Other pertinent 
information is as follows:
    (1) Predominant method of production: Glycol ethers are 
predominantly produced by reacting an epoxide (typically ethylene oxide 
or propylene oxide) with an alcohol; this reaction process is referred 
to as alkoxylation. Diethylene glycol monomethyl ether 
(C5H12O3) is produced by the 
alkoxylation process using methanol (CH3OH) and 2 
equivalents of ethylene oxide (C2H4O). Methanol 
is made from syngas (carbon monoxide and dihydrogen). Carbon monoxide 
(CO) and dihydrogen (H2) are made by steam-methane reforming 
(CH4 and H2O). Ethylene oxide (EO) is made from 
oxidizing ethylene (C2H4). Additional information 
on the production process is as follows:
    (i) The diethylene glycol monomethyl ether reaction (methanol + EO) 
is base catalyzed, using a small amount of metal hydroxide to produce 
methoxide. Since the amount of metal hydroxide used to produce 
diethylene glycol monomethyl ether \3\ is very small, the metal 
hydroxide has been excluded from the stoichiometric material 
consumption equation; including the metal hydroxide would lead to a 
distorted conversion factor.
---------------------------------------------------------------------------

    \3\ The Notice of Filing erroneously stated, ``Since the amount 
of metal hydroxide used to produce propylene glycol methyl ether . . 
.'' This error is corrected here.
---------------------------------------------------------------------------

    (ii) Once methoxide is made, it is regenerated following conversion 
to the product in the presence of EO as follows:
    (A) Methoxide + 2 EO [rarr] diethylene glycol monomethyl ether-
alkoxide.
    (B) Diethylene glycol monomethyl ether-alkoxide + methanol [rarr] 
diethylene glycol monomethyl ether + methoxide (goes back to 
participate in the reaction above).
    (iii) Regenerated methoxide in the presence of EO will perpetually 
react until all EO is consumed or the reaction is halted through the 
use of controls.
    (2) Stoichiometric material consumption equation:

2 C2H4 (ethylene) + O2 (oxygen) + 
CH4 (methane) + H2O (water) [rarr] H2 
(hydrogen) + C5H12O3 (diethylene 
glycol monomethyl ether)

    (3) Reasons for the determination: The diethylene glycol monomethyl 
ether petition was filed on June 13, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (89 FR 71788) on September 3, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals ethylene and methane constitute more than 20 
percent by weight of the materials used in the production of diethylene 
glycol monomethyl ether, based on the predominant method of production. 
Therefore, the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of diethylene glycol monomethyl 
ether to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $5.47 per ton. The 
conversion factors for the taxable chemicals used in the production of 
diethylene glycol monomethyl ether are 0.47 for ethylene and 0.13 for 
methane. The tax rate is calculated by adding the products of the 
conversion factor for each taxable chemical and the tax rate for that 
taxable chemical: ((0.47 x $9.74) + (0.13 x $6.88) = $5.47).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2909.44.01.10.
    (ii) Schedule B number: 2909.49.0000.
    (iii) CAS number: 111-77-3.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

IX. Determination To Add Ethylene Glycol Phenyl Ether to the List

    The Dow Chemical Company, an exporter of ethylene glycol phenyl 
ether, submitted a petition in accordance with Rev. Proc. 2022-26 
requesting to add ethylene glycol phenyl ether to the List. According 
to the petition, the taxable chemicals ethylene, benzene, and propylene 
constitute 76.00 percent by weight of the materials used to produce 
ethylene glycol phenyl ether, based on the predominant method of 
production.
    (a) Determination. Ethylene glycol phenyl ether is added to the 
list of taxable substances under section 4672(a). Other pertinent 
information is as follows:
    (1) Predominant method of production: Glycol ethers are 
predominantly produced by reacting an epoxide (typically ethylene oxide 
or propylene oxide) with an alcohol; this reaction process is referred 
to as alkoxylation. Ethylene glycol phenyl ether 
(C8H10O2) is produced by the 
alkoxylation process using phenol (CH3OH) and ethylene oxide 
(C2H4O). Ethylene oxide is made by oxidizing 
ethylene (C2H4). Phenol is made via the Hock 
process (sometimes called the cumene process). The Hock process has two 
stages. In stage 1, benzene (C6H6) is alkylated 
with propylene (C3H6) to make cumene (isopropyl 
benzene). In stage 2, cumene 
(C6H5(C3H7)) is partially 
oxidized to make phenol (C6H5OH) and side product 
dimethyl ketone ((CH3)2CHO)).

    (2) Stoichiometric material consumption equation:

C2H4 (ethylene) + 1.5 O2 (oxygen) + 
C6H6 (benzene) + C3H6 
(propylene) [rarr] C3H6O (dimethyl ketone) + 
C8H10O2 (ethylene glycol phenyl ether)

    (3) Reasons for the determination: The ethylene glycol phenyl ether 
petition was filed on June 13, 2024. The notice of filing summarizing 
the petition and requesting comments was published in

[[Page 36527]]

the Federal Register (89 FR 71785) on September 3, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals ethylene, benzene, and propylene constitute more 
than 20 percent by weight of the materials used in the production of 
ethylene glycol phenyl ether, based on the predominant method of 
production. Therefore, the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of ethylene glycol phenyl ether to 
the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $10.42 per ton. The 
conversion factors for the taxable chemicals used in the production of 
ethylene glycol phenyl ether are 0.20 for ethylene, 0.57 for benzene, 
and 0.30 for propylene. The tax rate is calculated by adding the 
products of the conversion factor for each taxable chemical and the tax 
rate for that taxable chemical: ((0.20 x $9.74) + (0.57 x $9.74) + 
(0.30 7 x $9.74) = $10.42).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) Schedule B number: 2909.49.0000.
    (ii) CAS number: 122-99-6
    (2) The Secretary is unable to confirm the following proposed 
classification number:
    HTSUS number: 2909.49.60.00.

X. Determination To Add Methoxytriglycol to the List

    The Dow Chemical Company, an exporter of methoxytriglycol, 
submitted a petition in accordance with Rev. Proc. 2022-26 requesting 
to add methoxytriglycol to the List. According to the petition, the 
taxable chemicals ethylene and methane constitute 60.00 percent by 
weight of the materials used to produce methoxytriglycol, based on the 
predominant method of production.
    (a) Determination. Methoxytriglycol is added to the list of taxable 
substances under section 4672(a). Other pertinent information is as 
follows:
    (1) Predominant method of production: Glycol ethers are 
predominantly produced by reacting an epoxide (typically ethylene oxide 
or propylene oxide) with an alcohol; this reaction process is referred 
to as alkoxylation. Methoxytriglycol 
(C7H16O4) is produced by the 
alkoxylation process using methanol (CH3OH) and 3 
equivalents of ethylene oxide (C2H4O). Methanol 
is made from syngas (carbon monoxide and dihydrogen). Carbon monoxide 
(CO) and dihydrogen (H2) are made by steam-methane reforming 
(CH4 and H2O). Ethylene oxide (EO) is made from 
oxidizing ethylene (C2H4). Additional information 
on the production process is as follows:
    (i) The methoxytriglycol reaction (methanol + EO) is base 
catalyzed, using a small amount of metal hydroxide to produce 
methoxide. Since the amount of metal hydroxide used to produce 
methoxytriglycol \4\ is very small, the metal hydroxide has been 
excluded from the stoichiometric material consumption equation; 
including the metal hydroxide would lead to a distorted conversion 
factor.
---------------------------------------------------------------------------

    \4\ The Notice of Filing erroneously stated, ``Since the amount 
of metal hydroxide used to produce propylene glycol methyl ether. . 
.'' This error is corrected here.
---------------------------------------------------------------------------

    (ii) Once methoxide is made, it is regenerated following conversion 
to the product in the presence of EO as follows:
    (A) Methoxide + 3 EO [rarr] methoxytriglycol-alkoxide.
    (B) Methoxytriglycol-alkoxide + methanol [rarr] methoxytriglycol + 
methoxide (goes back to participate in the reaction above).
    (iii) Regenerated methoxide in the presence of EO will perpetually 
react until all EO is consumed or the reaction is halted through the 
use of controls.
    (2) Stoichiometric material consumption equation:

3 C2H4 (ethylene) + 1.5 O2 (oxygen) + 
CH4 (methane) + H2O (water) [rarr] H2 
(hydrogen) + C7H16O4 
(methoxytriglycol)

    (3) Reasons for the determination: The methoxytriglycol petition 
was filed on June 13, 2024. The notice of filing summarizing the 
petition and requesting comments was published in the Federal Register 
(89 FR 71789) on September 3, 2024. The Treasury Department and the IRS 
received no written comments in response to the notice of filing. A 
public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals ethylene and methane constitute more than 20 
percent by weight of the materials used in the production of 
methoxytriglycol, based on the predominant method of production. 
Therefore, the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of methoxytriglycol to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $5.66 per ton. The 
conversion factors for the taxable chemicals used in the production of 
methoxytriglycol are 0.51 for ethylene and 0.10 for methane. The tax 
rate is calculated by adding the products of the conversion factor for 
each taxable chemical and the tax rate for that taxable chemical: 
((0.51 x $9.74) + (0.10 x $6.88) = $5.66).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2909.49.6000.
    (ii) Schedule B number: 2922.17.0000.
    (iii) CAS number: 112-35-6.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XI. Determination To Add Propylene Glycol Methyl Ether Acetate to the 
List

    The Dow Chemical Company, an importer and exporter of propylene 
glycol methyl ether acetate, submitted a petition in accordance with 
Rev. Proc. 2022-26 requesting to add propylene glycol methyl ether 
acetate to the List. According to the petition, the taxable chemicals 
propylene, chlorine, sodium hydroxide, and methane constitute 93.00 
percent by weight of the materials used to produce propylene glycol 
methyl ether acetate, based on the predominant method of production.
    (a) Determination. Propylene glycol methyl ether acetate is added 
to the list of taxable substances under section 4672(a). Other 
pertinent information is as follows:
    (1) Predominant method of production: Glycol ethers are 
predominantly produced by reacting an epoxide (typically ethylene oxide 
or propylene oxide) with an alcohol; this

[[Page 36528]]

reaction process is referred to as alkoxylation. Propylene glycol 
methyl ether acetate is made by esterification of propylene glycol 
methyl ether and acetic acid. Propylene glycol methyl ether is made via 
the alkoxylation process (also known as ring opening of an epoxide) 
using methanol and propylene oxide. Methanol is made from syngas 
(carbon monoxide and dihydrogen). Carbon monoxide (CO) and dihydrogen 
(H2) are made by steam-methane reforming (CH4 and 
H2O). Propylene oxide is made by hydrochlorination (chlorine 
(Cl2), propylene (C3H6), and sodium 
hydroxide (NaOH)). Acetic acid is made via the carbonylation of 
methanol with carbon monoxide. Additional information on the production 
process is as follows:
    (i) The propylene glycol methyl ether alkoxylation reaction 
(methanol + propylene oxide) is base catalyzed, using a small amount of 
metal hydroxide to produce methoxide. Once methoxide is made, it is 
regenerated following conversion to the product in the presence of 
propylene oxide. Regenerated methoxide in the presence of propylene 
oxide will perpetually react until all propylene oxide is consumed or 
the reaction is halted through the use of controls. Since the amount of 
metal hydroxide used to produce propylene glycol methyl ether acetate 
\5\ is very small, the metal hydroxide has been excluded from the 
stoichiometric material consumption equation; including the metal 
hydroxide would lead to a distorted conversion factor.
---------------------------------------------------------------------------

    \5\ The Notice of Filing erroneously stated, ``Since the amount 
of metal hydroxide used to produce propylene glycol methyl ether is 
very small . . .'' This error is corrected here.
---------------------------------------------------------------------------

    (ii) After the production of methanol from syngas, methanol is 
reacted with CO to produce acetic acid. This process is commonly 
referred to as carbonylation. The reaction is typically catalyzed by 
either a rhodium or iridium-based catalyst and involves iodomethane as 
a key intermediate.
    (iii) Acetic acid when combined with propylene glycol methyl under 
specific conditions (temperature, pressure, pH, etc.) produces 
propylene glycol methyl ether acetate. This reaction is commonly known 
as esterification (or Fischer esterification). Esterification typically 
involves a basic or acid catalytic species and can generate water or an 
aqueous hydroxide as byproduct depending on the pH. Once the final 
reaction contents are dehydrated and separated, commercial grade 
propylene glycol methyl ether acetate is obtained.
    (2) Stoichiometric material consumption equation:

C3H6 (propylene) + Cl2 (chlorine) + 2 
NaOH (sodium hydroxide) + 3 CH4 (methane) + H2O 
(water) [rarr] 2 NaCl (sodium chloride) + 5 H2 (hydrogen) + 
C6H12O3 (propylene glycol methyl ether 
acetate)

    (3) Reasons for the determination: The propylene glycol methyl 
ether acetate petition was filed on June 13, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (89 FR 71789) on September 3, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals propylene, chlorine, sodium hydroxide, and 
methane constitute more than 20 percent by weight of the materials used 
in the production of propylene glycol methyl ether acetate, based on 
the predominant method of production. Therefore, the test in section 
4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of propylene glycol methyl ether 
acetate to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $8.85 per ton. The 
conversion factors for the taxable chemicals used in the production of 
propylene glycol methyl ether acetate are 0.32 for propylene, 0.54 for 
chlorine, 0.61 for sodium hydroxide, and 0.36 for methane. The tax rate 
is calculated by adding the products of the conversion factor for each 
taxable chemical and the tax rate for that taxable chemical: ((0.32 x 
$9.74) + (0.54 x $5.40) + (0.61 x $0.56) + (0.36 x $6.88) = $8.85).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2915.39.90.00.
    (ii) Schedule B number: 2915.39.9500.
    (iii) CAS number: 108-65-6.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XII. Determination To Add Propylene Glycol Methyl Ether to the List

    The Dow Chemical Company, an importer and exporter of propylene 
glycol methyl ether, submitted a petition in accordance with Rev. Proc. 
2022-26 requesting to add propylene glycol methyl ether to the List. 
According to the petition, the taxable chemicals propylene, chlorine, 
sodium hydroxide, and methane constitute 100.00 percent by weight of 
the materials used to produce propylene glycol methyl ether, based on 
the predominant method of production.
    (a) Determination. Propylene glycol methyl ether is added to the 
list of taxable substances under section 4672(a). Other pertinent 
information is as follows:
    (1) Predominant method of production: Glycol ethers are 
predominantly produced by reacting an epoxide (typically ethylene oxide 
or propylene oxide) with an alcohol; this reaction process is referred 
to as alkoxylation. Propylene glycol methyl ether is made via the 
alkoxylation process (also known as ring opening of an epoxide) using 
methanol and propylene oxide. Methanol is made from syngas (carbon 
monoxide and dihydrogen). Carbon monoxide (CO) and dihydrogen 
(H2) are made by steam-methane reforming (CH4 and 
H2O). Propylene oxide is made by hydrochlorination (chlorine 
(Cl2), propylene (C3H6), and sodium 
hydroxide (NaOH)). Additional information on the production process is 
as follows:
    (i) The propylene glycol methyl ether alkoxylation reaction 
(methanol + propylene oxide) is base catalyzed, using a small amount of 
metal hydroxide to produce methoxide. Once methoxide is made, it is 
regenerated following conversion to the product in the presence of 
propylene oxide. Regenerated methoxide in the presence of propylene 
oxide will perpetually react until all propylene oxide is consumed or 
the reaction is halted through the use of controls.
    (ii) Since the amount of metal hydroxide used to produce propylene 
glycol methyl ether is very small, the metal hydroxide has been 
excluded from the stoichiometric material consumption equation; 
including the metal hydroxide would lead to a distorted conversion 
factor.
    (2) Stoichiometric material consumption equation:

C3H6 (propylene) + Cl2 (chlorine) + 2 
NaOH (sodium hydroxide) + CH4 (methane) [rarr] 
C4H10O2 (propylene

[[Page 36529]]

glycol methyl ether) + 2 NaCl (sodium chloride) + H2 
(hydrogen)

    (3) Reasons for the determination: The propylene glycol methyl 
ether petition was filed on June 13, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (89 FR 71784) on September 3, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals propylene, chlorine, sodium hydroxide, and 
methane constitute more than 20 percent by weight of the materials used 
in the production of propylene glycol methyl ether, based on the 
predominant method of production. Therefore, the test in section 
4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of propylene glycol methyl ether 
to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $10.58 per ton. The 
conversion factors for the taxable chemicals used in the production of 
propylene glycol methyl ether are for 0.47 for propylene, 0.79 for 
chlorine, 0.89 for sodium hydroxide, and 0.18 for methane. The tax rate 
is calculated by adding the products of the conversion factor for each 
taxable chemical and the tax rate for that taxable chemical: ((0.47 x 
$9.74) + (0.79 x $5.40) + (0.89 x $0.56) + (0.18 x $6.88) = $10.58).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2909.49.6000.
    (ii) Schedule B number: 2909.49.0000.
    (iii) CAS number: 107-98-2.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XIII. Determination To Add Propylene Glycol N-Propyl Ether to the List

    The Dow Chemical Company, an importer and exporter of propylene 
glycol n-propyl ether, submitted a petition in accordance with Rev. 
Proc. 2022-26 requesting to add propylene glycol n-propyl ether to the 
List. According to the petition, the taxable chemicals propylene, 
chlorine, sodium hydroxide, ethylene, and methane constitute 100.00 
percent by weight of the materials used to produce propylene glycol n-
propyl ether, based on the predominant method of production.
    (a) Determination. Propylene glycol n-propyl ether is added to the 
list of taxable substances under section 4672(a). Other pertinent 
information is as follows:
    (1) Predominant method of production: Glycol ethers are 
predominantly produced by reacting an epoxide (typically ethylene oxide 
or propylene oxide) with an alcohol; this reaction process is referred 
to as alkoxylation. Propylene glycol n-propyl ether is produced via the 
alkoxylation process (also known as ring opening of an epoxide) using 
n-propylene and propylene oxide. Propylene oxide is made by 
hydrochlorination (chlorine, propylene, NaOH). The n-propanol is 
manufactured by catalytic hydrogenation of propionaldehyde (hydrogen 
(H2) + propionaldehyde (CH3CH2CHO)). 
Propionaldehyde is produced by hydroformulation of ethylene 
(C2H4) using carbon monoxide (CO). The n-propanol 
is made by hydrogenating propionaldehyde in the presence of a catalyst. 
Additional information on the production process is as follows:
    (i) The propylene glycol n-propyl ether alkoxylation reaction (n-
propanol + propylene oxide) is base catalyzed, using a small amount of 
metal hydroxide to produce methoxide. Once propoxide is made, it is 
regenerated following conversion to the product in the presence of 
propylene oxide. Regenerated propoxide in the presence of propylene 
oxide will perpetually react until all propylene oxide is consumed or 
the reaction is halted through the use of controls.
    (ii) Since the amount of metal hydroxide used to produce propylene 
glycol n-propyl ether is very small, the metal hydroxide has been 
excluded from the stoichiometric material consumption equation; 
including the metal hydroxide would lead to a distorted conversion 
factor.
    (2) Stoichiometric material consumption equation:

C3H6 (propylene) + Cl2 (chlorine) + 2 
NaOH (sodium hydroxide) + C2H4 (ethylene) + 
CH4 (methane) [rarr] 2 NaCl (sodium chloride) + 
H2 (hydrogen) + C6H14O2 
(propylene glycol n-propyl ether)

    (3) Reasons for the determination: The propylene glycol n-propyl 
ether petition was filed on June 13, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (89 FR 71791) on September 3, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals propylene, chlorine, sodium hydroxide, ethylene, 
and methane constitute more than 20 percent by weight of the materials 
used in the production of propylene glycol n-propyl ether, based on the 
predominant method of production. Therefore, the test in section 
4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of propylene glycol n-propyl ether 
to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $10.43 per ton. The 
conversion factors for the taxable chemicals used in the production of 
propylene glycol n-propyl ether are for 0.36 for propylene, 0.60 for 
chlorine, 0.68 for sodium hydroxide, 0.24 for ethylene, and 0.14 for 
methane. The tax rate is calculated by adding the products of the 
conversion factor for each taxable chemical and the tax rate for that 
taxable chemical: ((0.36 x $9.74) + (0.60 x $5.40) + (0.68 x $0.56) + 
(0.24 x $9.74) + (0.14 x $6.88) = $10.43).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2909.49.60.00.
    (ii) Schedule B number: 2909.49.0000.
    (iii) CAS number: 1569-01-3.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XIV. Determination To Add Propylene Glycol Phenyl Ether to the List

    The Dow Chemical Company, an importer and exporter of propylene 
glycol phenyl ether, submitted a petition in accordance with Rev. Proc.

[[Page 36530]]

2022-26 requesting to add propylene glycol phenyl ether to the List. 
According to the petition, the taxable chemicals propylene, chlorine, 
sodium hydroxide, and benzene constitute 91.00 percent by weight of the 
materials used to produce propylene glycol phenyl ether, based on the 
predominant method of production.
    (a) Determination. Propylene glycol phenyl ether is added to the 
list of taxable substances under section 4672(a). Other pertinent 
information is as follows:
    (1) Predominant method of production: Glycol ethers are 
predominantly produced by reacting an epoxide (typically ethylene oxide 
or propylene oxide) with an alcohol; this reaction process is referred 
to as alkoxylation. Propylene glycol phenyl ether is made via the 
alkoxylation process (also known as ring opening of an epoxide) using 
phenol and propylene oxide. Propylene oxide is made by 
hydrochlorination (chlorine (Cl2), propylene 
(C3H6), and sodium hydroxide (NaOH)). Phenol is 
made via the Hock process (sometimes called the cumene process). The 
Hock process has two stages. In stage 1, benzene 
(C6H6) is alkylated with propylene 
(C3H6) to make cumene (isopropyl benzene). In 
stage 2, cumene 
(C6H5(C3H7)) is partially 
oxidized to make phenol (C6H5OH) and side product 
dimethyl ketone ((CH3)2CHO). Additional 
information on the production process is as follows:
    (i) The propylene glycol phenyl ether alkoxylation reaction (phenol 
+ propylene oxide) is base catalyzed, using a small amount of metal 
hydroxide. Once phenoxide is made, it is regenerated following 
conversion to the product in the presence of propylene oxide. 
Regenerated phenoxide in the presence of propylene oxide will 
perpetually react until all propylene oxide is consumed or the reaction 
is halted through the use of controls.
    (ii) Since the amount of metal hydroxide used to produce propylene 
glycol phenyl ether is very small, the metal hydroxide has been 
excluded from the stoichiometric material consumption equation; 
including the metal hydroxide would lead to a distorted conversion 
factor.
    (2) Stoichiometric material consumption equation:

2 C3H6 (propylene) + Cl2 (chlorine) + 
2 NaOH (sodium hydroxide) + C6H6 (benzene) + 
O2 (oxygen) [rarr] 2 NaCl (sodium chloride) + H2O 
(water) + (CH3)2CO (dimethyl ketone) + 
C9H12O2 (propylene glycol phenyl 
ether)

    (3) Reasons for the determination: The propylene glycol phenyl 
ether petition was filed on June 13, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (89 FR 71786) on September 3, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals propylene, chlorine, sodium hydroxide, and 
benzene constitute more than 20 percent by weight of the materials used 
in the production of propylene glycol phenyl ether, based on the 
predominant method of production. Therefore, the test in section 
4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of propylene glycol phenyl ether 
to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $13.16 per ton. The 
conversion factors for the taxable chemicals used in the production of 
propylene glycol phenyl ether are 0.55 for propylene, 0.47 for 
chlorine, 0.53 for sodium hydroxide, and 0.51 for benzene. The tax rate 
is calculated by adding the products of the conversion factor for each 
taxable chemical and the tax rate for that taxable chemical: ((0.55 x 
$9.74) + (0.47 x $5.40) + (0.53 x $0.56) + (0.51 x $9.74) = $13.16).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2909.49.15.00.
    (ii) Schedule B number: 2909.49.0000.
    (iii) CAS number: 770-35-4.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XV. Determination To Add Di-Isobutyl Carbinol to the List

    ALTIVIA Ketones & Additives, LLC, an exporter of di-isobutyl 
carbinol, submitted a petition in accordance with Rev. Proc. 2022-26 
requesting to add di-isobutyl carbinol to the List. According to the 
petition, the taxable chemical propylene constitutes 87.51 percent by 
weight of the materials used to produce di-isobutyl carbinol, based on 
the predominant method of production.
    (a) Determination. Di-isobutyl carbinol is added to the list of 
taxable substances under section 4672(a). Other pertinent information 
is as follows:
    (1) Predominant method of production: The predominant method of 
production is aldol condensation of acetone. Aldol condensation is a 
two-step process in which an aldol reaction forms an aldol product and 
a dehydration reaction removes water to form the final product. The 
process uses acetone in condensation, dehydration, and hydrogenation 
steps. Acetone is passed over a strong base catalyst to form diacetone 
alcohol, then dehydrated to mesityl oxide, and subsequently 
hydrogenated to methyl isobutyl ketone. Generally, the process forms 
co-produced methyl isobutyl ketone, methyl isobutyl carbinol, di-
isobutyl ketone and, to a lesser extent, di-isobutyl carbinol.
    (2) Stoichiometric material consumption equation:

3(C3H6 (propylene)) + H2O [rarr] 
C9H20O (di-isobutyl carbinol)

    (3) Reasons for the determination: The di-isobutyl carbinol 
petition was filed on September 23, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (89 FR 94878) on November 29, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemical propylene constitutes more than 20 percent by 
weight of the materials used in the production of di-isobutyl carbinol, 
based on the predominant method of production. Therefore, the test in 
section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of di-isobutyl carbinol to the 
List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): January 1, 2024.
    (6) Tax rate prescribed by the Secretary: $8.57 per ton. The 
conversion

[[Page 36531]]

factor for the propylene used in the production of di-isobutyl carbinol 
is 0.88. The tax rate is calculated by multiplying the conversion 
factor by the tax rate for propylene (0.88 x $9.74 = $8.57).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2905.19.9090.
    (ii) Schedule B number: 2905.19.9095.
    (iii) CAS number: 108-82-7.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XVI. Determination To Add Di-Isobutyl Ketone to the List

    ALTIVIA Ketones & Additives, LLC, an exporter of di-isobutyl 
ketone, submitted a petition in accordance with Rev. Proc. 2022-26 
requesting to add di-isobutyl ketone to the List. According to the 
petition, the taxable chemical propylene constitutes 87.51 percent by 
weight of the materials used to produce di-isobutyl ketone, based on 
the predominant method of production.
    (a) Determination. Di-isobutyl ketone is added to the list of 
taxable substances under section 4672(a). Other pertinent information 
is as follows:
    (1) Predominant method of production: The predominant method of 
production is aldol condensation of acetone. Aldol condensation is a 
two-step process in which an aldol reaction forms an aldol product and 
a dehydration reaction removes water to form the final product. The 
process uses acetone in condensation, dehydration, and hydrogenation 
steps. Acetone is passed over a strong base catalyst to form diacetone 
alcohol, then dehydrated to mesityl oxide, and subsequently 
hydrogenated to methyl isobutyl ketone. Generally, the process forms 
co-produced methyl isobutyl ketone, methyl isobutyl carbinol, di-
isobutyl ketone and, to a lesser extent, di-isobutyl carbinol.
    (2) Stoichiometric material consumption equation:

3(C3H6 (propylene)) + H2O [rarr] 
C9H18O (di-isobutyl ketone) + H2

    (3) Reasons for the determination: The di-isobutyl ketone petition 
was filed on September 23, 2024. The notice of filing summarizing the 
petition and requesting comments was published in the Federal Register 
(89 FR 94879) on November 29, 2024. The Treasury Department and the IRS 
received no written comments in response to the notice of filing. A 
public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemical propylene constitutes more than 20 percent by 
weight of the materials used in the production of di-isobutyl ketone, 
based on the predominant method of production. Therefore, the test in 
section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of di-isobutyl ketone to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): January 1, 2024.
    (6) Tax rate prescribed by the Secretary: $8.67 per ton. The 
conversion factor for the propylene used in the production of di-
isobutyl ketone is 0.89. The tax rate is calculated by multiplying the 
conversion factor by the tax rate for propylene: (0.89 x $9.74 = 
$8.67).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2914.19.0000.
    (ii) Schedule B number: 2914.19.0000.
    (iii) CAS number: 108-83-8.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XVII. Determination To Add Methyl Isobutyl Carbinol to the List

    ALTIVIA Ketones & Additives, LLC, an exporter of methyl isobutyl 
carbinol, submitted a petition in accordance with Rev. Proc. 2022-26 
requesting to add methyl isobutyl carbinol to the List. According to 
the petition, the taxable chemical propylene constitutes 82.36 percent 
by weight of the materials used to produce methyl isobutyl carbinol, 
based on the predominant method of production.
    (a) Determination. Methyl isobutyl carbinol is added to the list of 
taxable substances under section 4672(a). Other pertinent information 
is as follows:
    (1) Predominant method of production: The predominant method of 
production is aldol condensation of acetone. Aldol condensation is a 
two-step process in which an aldol reaction forms an aldol product and 
a dehydration reaction removes water to form the final product. The 
process uses acetone in condensation, dehydration, and hydrogenation 
steps. Acetone is passed over a strong base catalyst to form diacetone 
alcohol, then dehydrated to mesityl oxide, and subsequently 
hydrogenated to methyl isobutyl ketone. Generally, the process forms 
co-produced methyl isobutyl ketone, methyl isobutyl carbinol, di-
isobutyl ketone and, to a lesser extent, di-isobutyl carbinol.
    (2) Stoichiometric material consumption equation:

2(C3H6 (propylene)) + H2O [rarr] 
C6H14O (methyl isobutyl carbinol)

    (3) Reasons for the determination: The methyl isobutyl carbinol 
petition was filed on September 23, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (89 FR 94877) on November 29, 2024. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemical propylene constitutes more than 20 percent by 
weight of the materials used in the production of methyl isobutyl 
carbinol, based on the predominant method of production. Therefore, the 
test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of methyl isobutyl carbinol to the 
List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): January 1, 2024
    (6) Tax rate prescribed by the Secretary: $7.99 per ton. The 
conversion factor for the propylene used in the production of methyl 
isobutyl carbinol is 0.82. The tax rate is calculated by multiplying 
the conversion factor by the tax rate for propylene: (0.82 x $9.74 = 
$7.99).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2905.19.9090.
    (ii) Schedule B number: 2905.19.9095.
    (iii) CAS number: 108-11-2.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XVIII. Determination To Add Cyanuric Acid to the List

    Occidental Chemical Corporation, an interested person in cyanuric 
acid,

[[Page 36532]]

submitted a petition in accordance with Rev. Proc. 2022-26 requesting 
to add cyanuric acid to the List. According to the petition, the 
taxable chemical ammonia constitutes 27.90 percent by weight of the 
materials used to produce cyanuric acid, based on the predominant 
method of production.
    (a) Determination. Cyanuric acid is added to the list of taxable 
substances under section 4672(a). Other pertinent information is as 
follows:
    (1) Predominant method of production: The predominant process for 
the manufacture of cyanuric acid is using urea thermal decomposition to 
produce cyanuric acid.
    (2) Stoichiometric material consumption equation:

3 NH3 (ammonia) + 3 CO2 (carbon dioxide) [rarr] 
C3N3O3H3 (cyanuric acid) + 
3 H2O (water)

    (3) Reasons for the determination: The cyanuric acid petition was 
filed on November 25, 2024. The notice of filing summarizing the 
petition and requesting comments was published in the Federal Register 
(90 FR 7246) on January 21, 2025. The Treasury Department and the IRS 
received one written comment, discussed below, in response to the 
notice of filing. A public hearing was neither requested nor held.
    The commenter asserts that the notice did not give a reason to add 
the substance to the List and inquires ``[w]hy would a long-term 
product be added . . . if it's already in production at a chemical 
plant for distribution.'' It is not clear to the Treasury Department 
and the IRS what is the significance of a ``long-term product.'' 
Regardless, the commenter did not demonstrate that cyanuric acid does 
not meet the weight or value test under section 4672(a)(2)(B). Under 
section 4672(a)(2)(b) and (4) and (b)(2), the Secretary is required to 
add a substance to the List if the Secretary determines that any 
taxable chemicals used to produce the substance meet the weight or 
value test. The petition represented and the Secretary determined that 
a taxable chemical constitutes more than 20 percent by weight of the 
materials used in the production of cyanuric acid, based on the 
predominant method of production. For this reason, the Treasury 
Department and the IRS decline to adopt any change to this 
determination based on the public comment.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemical ammonia constitutes more than 20 percent by weight 
of the materials used in the production of cyanuric acid, based on the 
predominant method of production. Therefore, the test in section 
4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of cyanuric acid to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): October 1, 2024.
    (6) Tax rate prescribed by the Secretary: $2.11 per ton. The 
conversion factor for the ammonia used in the production of cyanuric 
acid is 0.40. The tax rate is calculated by multiplying the conversion 
factor by the tax rate for ammonia: (0.40 x $5.28 = $2.11).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2933.69.6050.
    (ii) Schedule B number: 2933.69.0000.
    (iii) CAS number: 108-80-5.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XIX. Determination To Add Potassium Bicarbonate to the List

    Occidental Chemical Corporation, an exporter of potassium 
bicarbonate, submitted a petition in accordance with Rev. Proc. 2022-26 
requesting to add potassium bicarbonate to the List. According to the 
petition, the taxable chemical potassium hydroxide constitutes 56.04 
percent by weight of the materials used to produce potassium 
bicarbonate, based on the predominant method of production.
    (a) Determination. Potassium bicarbonate is added to the list of 
taxable substances under section 4672(a). Other pertinent information 
is as follows:

    (1) Predominant method of production: The predominant process for 
the manufacture of potassium bicarbonate is absorption of 
CO2 with potassium hydroxide. The predominant process for 
carbonate manufacture is absorption of CO2 with alkaline 
liquid. This substance is produced as a pure component, not a mixture.
    (2) Stoichiometric material consumption equation:

CO2 (carbon dioxide) + KOH (potassium hydroxide) [rarr] 
HKCO3 (potassium bicarbonate)

    (3) Reasons for the determination: The potassium bicarbonate 
petition was filed on November 25, 2024. The notice of filing 
summarizing the petition and requesting comments was published in the 
Federal Register (90 FR 7245) on January 21, 2025. The Treasury 
Department and the IRS received no written comments in response to the 
notice of filing. A public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemical potassium hydroxide constitutes more than 20 
percent by weight of the materials used in the production of potassium 
bicarbonate, based on the predominant method of production. Therefore, 
the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of potassium bicarbonate to the 
List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $0.25 per ton. The 
conversion factor for the potassium hydroxide used in the production of 
potassium bicarbonate is 0.56. The tax rate is calculated by 
multiplying the conversion factor by the tax rate for potassium 
hydroxide: (0.56 x $0.44 = $0.25).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2836.40.2000.
    (ii) Schedule B number: 2836.40.0000.
    (iii) CAS number: 298-14-6.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XX. Determination To Add Potassium Carbonate to the List

    Occidental Chemical Corporation, an exporter of potassium 
carbonate, submitted a petition in accordance with Rev. Proc. 2022-26 
requesting to add potassium carbonate to the List. According to the 
petition, the taxable chemical potassium hydroxide constitutes 71.83 
percent by weight of the materials used to produce potassium carbonate, 
based on the predominant method of production.
    (a) Determination. Potassium carbonate is added to the list of 
taxable

[[Page 36533]]

substances under section 4672(a). Other pertinent information is as 
follows:
    (1) Predominant method of production: The predominant process for 
the manufacture of potassium carbonate is absorption of CO2 
with KOH. The predominant process for carbonate manufacture is 
absorption of CO2 with alkaline liquid. This substance is 
produced as a pure component, not a mixture.
    (2) Stoichiometric material consumption equation:

    CO2 (carbon dioxide) + 2 KOH (potassium hydroxide) 
[rarr] K2CO3 (potassium carbonate) + 
H2O (water)

    (3) Reasons for the determination: The potassium carbonate petition 
was filed on November 25, 2024. The notice of filing summarizing the 
petition and requesting comments was published in the Federal Register 
(90 FR 7247) on January 21, 2025. The Treasury Department and the IRS 
received two written comments, discussed below, in response to the 
notice of filing. A public hearing was neither requested nor held.
    One public comment asserted that potassium carbonate does ``not 
pose any significant health or environmental risks,'' objected to the 
weight or value test of section 4672(a)(2)(B), and urged the Secretary 
to exercise discretion when determining whether a substance poses a 
significant danger that warrants imposing the tax under section 4671. 
Another public comment inquired about the effects of potassium 
carbonate and asserted that ``[t]he most important thing is to avoid 
any type of exposure to the chemical as it can cause severe damage.'' 
Neither comment demonstrated whether potassium carbonate meets the 
weight or value test under section 4672(a)(2)(B). Under section 
4672(a)(2)(b) and (4) and (b)(2), the Secretary is required to add a 
substance to the List if the Secretary determines that any taxable 
chemicals used to produce the substance meet the weight or value test. 
Congress did not give the Secretary discretion to determine whether a 
substance poses significant health or environmental risks or otherwise 
poses a significant danger. The petition represented and the Secretary 
determined that a taxable chemical constitutes more than 20 percent by 
weight of the materials used in the production of potassium carbonate, 
based on the predominant method of production. For this reason, the 
Treasury Department and the IRS decline to adopt the suggestions of 
these public comments.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemical potassium hydroxide constitutes more than 20 
percent by weight of the materials used in the production of potassium 
carbonate, based on the predominant method of production. Therefore, 
the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of potassium carbonate to the 
List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $0.36 per ton. The 
conversion factor for the potassium hydroxide used in the production of 
potassium carbonate is 0.81. The tax rate is calculated by multiplying 
the conversion factor by the tax rate for potassium hydroxide: (0.81 x 
$0.44 = $0.36).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2836.40.1000.
    (ii) Schedule B number: 2836.40.0000.
    (iii) CAS number: 584-08-7.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

XXI. Determination To Add Sodium Chlorite to the List

    Occidental Chemical Corporation, an exporter of sodium chlorite, 
submitted a petition in accordance with Rev. Proc. 2022-26 requesting 
to add sodium chlorite to the List. According to the petition, the 
taxable chemicals chlorine and sodium hydroxide constitute 75.87 
percent by weight of the materials used to produce sodium chlorite, 
based on the predominant method of production.
    (a) Determination. Sodium chlorite is added to the list of taxable 
substances under section 4672(a). Other pertinent information is as 
follows:
    (1) Predominant method of production: The predominant process for 
the manufacture of sodium chlorite is electrolytic production of 
NaClO3 followed by hydrochlorination with wet acid with 
byproduct chlorine and hydrogen used in the manufacture of acid. This 
substance is produced as a pure component, not a mixture, though it may 
be sold as an aqueous liquid.
    (2) Stoichiometric material consumption equation:

2 Cl2 (chlorine) + 4 NaOH (sodium hydroxide) + 3 
O2 (oxygen) [rarr] 4 NaClO2 (sodium chlorite) + 2 
H2O (water)

    (3) Reasons for the determination: The sodium chlorite petition was 
filed on November 25, 2024. The notice of filing summarizing the 
petition and requesting comments was published in the Federal Register 
(90 FR 7247) on January 21, 2025. The Treasury Department and the IRS 
received no written comments in response to the notice of filing. A 
public hearing was neither requested nor held.
    The Secretary followed the process in section 4672(a)(2)(B) in 
making this determination. A review of the stoichiometric material 
consumption equation and other information in the petition shows that 
the taxable chemicals chlorine and sodium hydroxide constitute more 
than 20 percent by weight of the materials used in the production of 
sodium chlorite, based on the predominant method of production. 
Therefore, the test in section 4672(a)(2)(B) is satisfied.
    (4) Date of determination: August 1, 2025.
    (5) Effective dates for addition of sodium chlorite to the List:
    (i) Effective date for purposes of the section 4671 tax (see 
section 11.01 of Rev. Proc. 2022-26): January 1, 2026.
    (ii) Effective date for purposes of refund claims under section 
4662(e) (see sections 11.02 and 11.03 of Rev. Proc. 2022-26, as 
modified by section 3 of Rev. Proc. 2023-20): July 1, 2022.
    (6) Tax rate prescribed by the Secretary: $2.35 per ton. The 
conversion factors for the taxable chemicals used in the production of 
sodium chlorite are 0.39 for chlorine and 0.44 for sodium hydroxide. 
The tax rate is calculated by adding the products of the conversion 
factor for each taxable chemical and the tax rate for that taxable 
chemical: (0.39 x $5.40 + 0.44 x $0.56 = $2.35).
    (b) Classification numbers.
    (1) The Secretary has no basis to object to the following proposed 
classification numbers:
    (i) HTSUS number: 2828.90.0000.
    (ii) Schedule B number: 2828.90.0000.
    (iii) CAS number: 7758-19-2.
    (2) The Secretary is unable to confirm the following proposed 
classification numbers: Not applicable.

Correction to the List of Taxable Substances

    Section 4 of Notice 2021-66 includes in the initial list of taxable 
substances the taxable substance ``sodium nitriolotriacetate 
monohydrate.'' There is a typographical error in the spelling of this 
taxable substance. The correct name of this taxable substance is

[[Page 36534]]

``sodium nitrilotriacetate monohydrate.'' The tax rate for sodium 
nitrilotriacetate monohydrate was not previously provided by the 
Secretary. The tax rate prescribed by the Secretary for sodium 
nitrilotriacetate monohydrate is $3.97 per ton. The conversion factors 
for the taxable chemicals used in the production of sodium 
nitrilotriacetate monohydrate are 0.25 for ammonia, 0.35 for methane, 
and 0.44 for sodium hydroxide. The tax rate is calculated by adding the 
products of the conversion factor for each taxable chemical and the tax 
rate for that taxable chemical: ((0.25 x $5.28) + (0.35 x $6.88) + 
(0.44 x $0.56) = $3.97). This tax rate is effective July 1, 2022.

Effect on Other Documents

    Section 4 of Notice 2021-66 is modified by replacing the name 
``sodium nitriolotriacetate monohydrate'' with ``sodium 
nitrilotriacetate monohydrate.''

Krishna P. Vallabhaneni,
Tax Legislative Counsel.
[FR Doc. 2025-14705 Filed 8-1-25; 8:45 am]
BILLING CODE 4830-01-P