Notice2025-08329
Superfund Tax on Chemical Substances; Request To Modify List of Taxable Substances; Notice of Filing for Chlorobutyl Isobutylene Isoprene Rubber (x = 7036, y = 88, z = 70)
Primary source
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Published
May 13, 2025
Issuing agencies
Treasury DepartmentInternal Revenue Service
Abstract
This notice of filing announces that a petition has been filed requesting that chlorobutyl isobutylene isoprene rubber (((C<INF>4</INF>H<INF>8</INF>)<INF>x</INF>(C<INF>5</INF>H<INF>8</INF>)<INF>y</INF> (Cl<INF>2</INF>)<INF>z</INF>; x = 7036, y = 88, z = 70)), also known as CIIR, be added to the list of taxable substances. This notice of filing also requests comments on the petition. This notice of filing is not a determination that the list of taxable substances is modified.
Full Text
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<title>Federal Register, Volume 90 Issue 91 (Tuesday, May 13, 2025)</title>
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[Federal Register Volume 90, Number 91 (Tuesday, May 13, 2025)]
[Notices]
[Page 20350]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-08329]
[[Page 20350]]
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DEPARTMENT OF THE TREASURY
Internal Revenue Service
Superfund Tax on Chemical Substances; Request To Modify List of
Taxable Substances; Notice of Filing for Chlorobutyl Isobutylene
Isoprene Rubber (x = 7036, y = 88, z = 70)
AGENCY: Internal Revenue Service (IRS), Treasury.
ACTION: Notice of filing and request for comments.
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SUMMARY: This notice of filing announces that a petition has been filed
requesting that chlorobutyl isobutylene isoprene rubber
(((C<INF>4</INF>H<INF>8</INF>)<INF>x</INF>(C<INF>5</INF>H<INF>8</INF>)<INF>y</INF>
(Cl<INF>2</INF>)<INF>z</INF>; x = 7036, y = 88, z = 70)), also known as
CIIR, be added to the list of taxable substances. This notice of filing
also requests comments on the petition. This notice of filing is not a
determination that the list of taxable substances is modified.
DATES: Written comments and requests for a public hearing must be
received on or before July 14, 2025.
ADDRESSES: Commenters are encouraged to submit public comments or
requests for a public hearing relating to this petition electronically
via the Federal eRulemaking Portal at <a href="https://www.regulations.gov">https://www.regulations.gov</a>
(indicate public docket number IRS-2025-0043 or CIIR
(((C<INF>4</INF>H<INF>8</INF>)<INF>x</INF>(C<INF>5</INF>H<INF>8</INF>)<INF>y</INF>
(Cl<INF>2</INF>)<INF>z</INF>; x = 7036, y = 88, z = 70)) by following
the online instructions for submitting comments. Comments cannot be
edited or withdrawn once submitted to the Federal eRulemaking Portal.
Alternatively, comments and requests for a public hearing may be mailed
to: Internal Revenue Service, Attn: CC:PA:01:PR (Notice of Filing for
CIIR
(((C<INF>4</INF>H<INF>8</INF>)<INF>x</INF>(C<INF>5</INF>H<INF>8</INF>)<INF>y</INF>
(Cl<INF>2</INF>)<INF>z</INF>; x = 7036, y = 88, z = 70)), Room 5203,
P.O. Box 7604, Ben Franklin Station, Washington, DC 20044. All comments
received are part of the public record and subject to public
disclosure. All comments received will be posted without change to
<a href="https://www.regulations.gov">https://www.regulations.gov</a>, including any personal information
provided. You should submit only information that you wish to make
publicly available. If a public hearing is scheduled, notice of the
time and place for the hearing will be published in the Federal
Register.
FOR FURTHER INFORMATION CONTACT: Andrew Clark at (202) 317-6855 (not a
toll-free number).
SUPPLEMENTARY INFORMATION:
Request To Add Substance to the List
(a) Overview. A petition was filed pursuant to Rev. Proc. 2022-26
(2022-29 I.R.B. 90), as modified by Rev. Proc. 2023-20 (2023-15 I.R.B.
636), requesting that CIIR be added to the list of taxable substances
under section 4672(a) of the Internal Revenue Code (List). The petition
requesting the addition of CIIR to the List is based on weight and
contains the information detailed in paragraph (b) of this document.
The information is provided for public notice and comment pursuant to
section 9 of Rev. Proc. 2022-26. The publication of petition
information in this notice of filing is not a determination and does
not constitute Treasury Department or IRS confirmation of the accuracy
of the information published.
(b) Petition Content.
(1) Substance name: Chlorobutyl isobutylene isoprene rubber
((C<INF>4</INF>H<INF>8</INF>)<INF>x</INF>(C<INF>5</INF>H<INF>8</INF>)<INF>y</INF>
(Cl<INF>2</INF>)<INF>z</INF>); x = 7036, y = 88, z = 70).
The substance is also known as CIIR.
(2) Petitioner: Exxon Mobil Corporation, an exporter of CIIR.
(3) Proposed classification numbers:
(i) HTSUS number: 4002.39.00.
(ii) Schedule B number: 4002.39.00.
(iii) CA S number: 68081-82-3.
(4) Petition filing dates:
(i) Petition filing date for purposes of making a determination:
April 8, 2025.
(ii) Petition filing date for purposes of section 11.02 of Rev.
Proc. 2022-26, as modified by section 3 of Rev. Proc. 2023-20: July 1,
2022.
(5) Description from petition: CIIR is a synthetic rubber commonly
used for the inner liner of tubeless tires.
CIIR is made from butylene and chlorine. Taxable chemicals
constitute 98.50 percent by weight of the materials used to produce
this substance.
(6) Process identified in petition as predominant method of
production of substance: The predominant method of production of
regular butyl rubber is using a carbocationic polymerization reaction
of isobutylene and a comonomer of isoprene. The catalyst system used is
typically composed of aluminum chloride, boron trifluoride or similar
with an initiator dissolved in a methyl chloride solvent. Monomer feed
of isobutylene and isoprene dissolved in a methyl chloride solvent are
fed to a reactor operated at approximately -100 [deg]C to control the
rapid exothermic polymerization reaction generating a high molecular
weight regular butyl rubber polymer. To obtain this high molecular
weight polymer it is necessary for the feed monomers to be as pure as
possible as well as ensuring that the feed system stays as dry as
possible. The methyl chloride and unreacted monomers are flashed
overhead and recycled back to the feed system while the polymer is
precipitated out as a solid which is then baled and packaged.
The polymerization process for CIIR starts with the exact same
process for regular butyl rubber outlined above. A subsequent
halogenation step is then carried out in a well agitated vessel to
ionically substitute a chlorine molecule to the polymer backbone while
the polymer is dissolved in an appropriate solvent. The solvent is then
flashed precipitating out a solid which is then baled and packaged.
(7) Stoichiometric material consumption equation, based on process
identified as predominant method of production:
7036 C<INF>4</INF>H<INF>8</INF> (Isobutylene) + 88
C<INF>5</INF>H<INF>8</INF> (Isoprene) + 70 Cl<INF>2</INF> (Chlorine)
[rarr] [7036 C<INF>4</INF>H<INF>8</INF> + 88
C<INF>5</INF>H<INF>8 +</INF> 70 Cl<INF>2</INF>] (CIIR)
(8) Tax rate calculated by Petitioner, based on Petitioner's
conversion factors for taxable chemicals used in production of
substance:
(i) Tax rate: $9.50 per ton.
(ii) Conversion factors: 0.97 for butylene, 0.01 for chlorine.
(9) Public docket number: IRS-2025-0043.
Michael Beker,
Senior Counsel (Energy, Credits, and Excise Tax), IRS Office of Chief
Counsel.
[FR Doc. 2025-08329 Filed 5-12-25; 8:45 am]
BILLING CODE P
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