Isobutyric acid Property

Melting point:

-47 °C (lit.)

Boiling point:

153-154 °C (lit.)

Density 

0.95 g/mL at 25 °C (lit.)

vapor density 

3.04 (vs air)

vapor pressure 

1.5 mm Hg ( 20 °C)

refractive index 

n20/D 1.393(lit.)

FEMA 

2222 | ISOBUTYRIC ACID

Flash point:

132 °F

storage temp. 

Store below +30°C.

solubility 

618g/l

form 

Liquid

pka

4.84(at 20℃)

color 

Clear colorless

PH

3.96(1 mM solution);3.44(10 mM solution);2.93(100 mM solution);

Odor

at 1.00 % in propylene glycol. acidic sour cheese dairy buttery rancid

Odor Type

acidic

Odor Threshold

0.0015ppm

explosive limit

1.6-7.3%(V)

Water Solubility 

210 g/L (20 ºC)

Merck 

14,5155

JECFA Number

253

BRN 

635770

Dielectric constant

2.6（Ambient）

InChIKey

KQNPFQTWMSNSAP-UHFFFAOYSA-N

LogP

1.1 at 25℃

CAS DataBase Reference

79-31-2(CAS DataBase Reference)

NIST Chemistry Reference

Propanoic acid, 2-methyl-(79-31-2)

EPA Substance Registry System

Isobutyric acid (79-31-2)

Safety

Hazard Codes 

Xn

Risk Statements 

21/22

Safety Statements 

23-36/37/39-24/25

RIDADR 

UN 2529 3/PG 3

WGK Germany 

1

RTECS 

NQ4375000

F 

13

Autoignition Temperature

824 °F

TSCA 

Yes

HazardClass 

3

PackingGroup 

III

HS Code 

29156000

Hazardous Substances Data

79-31-2(Hazardous Substances Data)

Toxicity

LD50 orally in Rabbit: 266 mg/kg LD50 dermal Rabbit 475 mg/kg

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H226Flammable liquid and vapour

H302Harmful if swallowed

H311Toxic in contact with skin

H314Causes severe skin burns and eye damage

Precautionary statements

P210Keep away from heat/sparks/open flames/hot surfaces. — No smoking.

P233Keep container tightly closed.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P301+P312IF SWALLOWED: call a POISON CENTER or doctor/physician IF you feel unwell.

P303+P361+P353IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

Isobutyric acid Chemical Properties,Usage,Production

Chemical Properties

Isobutyric acid is a clear colorless oily liquid with an odor and flavor similar to n-butyric acid. Miscible with water, soluble in ethanol and ether. Prepared via oxidation of isobutyl alcohol.

Physical properties

Isobutyric Acid is a flavoring agent that is a colorless liquid with a strong, penetrating odor, resembling butter. it is miscible in alcohol, propylene glycol, glycerin, mineral oil, and most fixed oils and soluble in water. it is obtained by chemical synthesis. it is also termed isopropylformic acid.

Occurrence

Isobutyric acid occurs naturally in Ceratonia siliqua L. The gum obtained from the kernels of this species is used as a thickener in the food industry. Reported found in several essential oils: Arnica montana, Roman chamomile, Laurus nobilis, imperatoria, and in carob fruits (Siliqua dulcis); also identified in the essence of Seseli tortuosum, Artemisia transiliensis.

Uses

Isobutyric acid is used to prepare esters for flavors and perfumes. It is also used as a disinfecting agent, preservative and tanning agent. It finds applications in textile, varnish and the leather industry. Further, it is used as a lactation stimulant in dairy cattle. In addition to this, it is used in the preparation of tetramethylsuccinic acid and diisopropyl ketone.

Preparation

Isobutyric acid is prepared in a similar way to butyric acid, mainly by direct oxidation of isobutanol and isobutyraldehyde, which is obtained by a direct oxidation reaction with air or oxygen.

Application

Isobutyric acid is mainly used in the synthesis of isobutyric acid esters, such as methyl isobutyrate, propyl ester, isoamyl ester and benzyl ester. It can also be used manufacture of esters for solvents, flavors and perfume bases, disinfecting agent, varnish, plasticizers, deliming hides, tanning agent and used in pharmaceutical. Isobutyric acid has some important derivatives that, in the industry, is actually used for the production of isobutyronitrile intermediates, and then converted to isobutylamidine hydrochloride that is the raw materials of pesticide diazinon.

Definition

ChEBI: Isobutyric acid is a branched fatty acid comprising propanoic acid carrying a methyl branch at C-2. It has a role as a volatile oil component, a plant metabolite and a Daphnia magna metabolite. It is a branched-chain saturated fatty acid, a methyl-branched fatty acid and a fatty acid 4:0. It is a conjugate acid of an isobutyrate.

Aroma threshold values

Detection: 10 ppb to 9.5 ppm; aroma characteristics at 10 ppm: acidic pungent, dairy buttery and cheesy with fruity undertones.

Taste threshold values

Taste characteristics at 15 ppm: acidic, sour dairy, creamy, cheese, cultured dairy nuance.

General Description

Isobutyric acid appears as a colorless liquid with a light odor of rancid butter. Flash point 132°F. Density 7.9 lb / gal. Corrosive to metals and tissue.

Air & Water Reactions

Flammable. Water soluble

Reactivity Profile

Isobutyric acid corrodes aluminum and other metals. Flammable hydrogen gas may accumulate in enclosed spaces in which this reaction has taken place [USCG, 1999].

Hazard

Toxic by ingestion, strong irritant to tissue.

Health Hazard

Inhalation causes irritation of nose and throat. Ingestion causes irritation of mouth and stomach. Contact with eyes or skin causes irritation.

Fire Hazard

Flammable/combustible material. May be ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

Biochem/physiol Actions

Odor at 10 ppm

Synthesis

The preparation of isobutyric acid is similar with butyric acid, which is performed by the direct oxidation of isobutyl alcohol and isobutyraldehyde. Isobutyric acid can be directly generated from the oxidation of isobutyraldehyde in air or oxygen. Other manufacturing methods have isobutyronitrile hydrolysis and methacrylic acid hydrogenation. The oxidation of 2-methyl-1-nitropropane to prepare isobutyric acid can also obtain a higher yield. The purification of Isobutyric acid can be realized by azeotropic distillation with water, and anhydrous isobutyric acid can be obtained by the extractive distillation from carbon tetrachloride. Propylene and formic acid ester can react at 50 °C with the catalysis of hydrofluoric acid to generate methyl isobutyrate and propyl isobutyrate.

Purification Methods

Distil the acid from KMnO4, then redistil it from P2O5. [Beilstein 2 H 288, 2 I 126, 2 II 257, 2 III 637, 2 IV 843.]