HazMat Tool — substance information

Isobutyric acid

HMT May 2026
UN / ID
UN 2529
Hazard class
3
Packing group
III
ERG guide
ERG 132
Special provisions
SP B1, SP IB3, SP T4, SP TP1
Source
49 CFR §172 (2026/05)

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Isobutyric acid


Isobutyric acid, also known as 2-methylpropanoic acid or isobutanoic acid, is a carboxylic acid with structural formula (CH3)2CHCOOH. It is an isomer of butyric acid. It is classified as a short-chain fatty acid. Deprotonation or esterification gives derivatives called isobutyrates. Isobutyric acid is a colorless liquid with a somewhat unpleasant odor. Wikipedia

Substance Data

Source: PubChem (HSDB, 26.11.2019)

CAS-Number

79-31-2

Flash Point

n/a

Boiling Point

n/a

Emergency Response Guide No. 132

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

(3) Hazard Class

3
Flammable liquids

(4) Identification number Help

UN 2529

(5) Packing Group Help

III

(6) Labels Help

Flammable liquids (3) Corrosive liquids (8)

(7) Special Provisions (§172.102) Help

×Note:
Special provisions may be very complex. The extracts are taken from 49 CFR §172.102. Please be careful with the information, as necessary, additional conditions may be applied that are not written here. Please check the original source and report bugs.
B1
IB3
T4
TP1

(8) Packing Authorizations (§173.***) Help

(8A) Exceptions150see 49 CFR §173.150
(8B) Non-bulk203see 49 CFR §173.203
(8C) Bulk242see 49 CFR §173.242

(9) Quantity Limits Help

(9A) Passenger aircraft/rail5 L
(9B) Cargo aircraft only60 L

(10) Vessel stowage Help

(10A) Location
(10B) Other n/a

Segregation chart for load, transport, and storage

This chart shows whether loading, transport, or storage with other hazard classes is permitted, prohibited, or restricted. Based on 49 CFR §177.848.

Prohibited Must not be loaded, transported, or stored together in the same vehicle or facility.
Permitted May be loaded, transported, or stored together.
Restricted May be loaded, transported, or stored together only with restrictions.

Similar substances

UN / IDProper shipping nameHazard class
tert-Butyl peroxyisobutyrate, with more than 77 percent in solutionForbidden
UN 2045Isobutyraldehyde or Isobutyl aldehyde3