Isobutyric acid

Isobutyric acid[1]
IUPAC name	2-Methylpropanoic acid
Other names	Isobutyric acid 2-Methylpropionic acid Valerianic acid
Identifiers
CAS number	79-31-2 Y
SMILES	CC(C)C(=O)O
Properties
Molecular formula	C4H8O2
Molar mass	88.11 g/mol
Density	0.9697 g/cm3 at 0 °C
Melting point	-47 °C, 226 K, -53 °F
Boiling point	155 °C, 428 K, 311 °F
Acidity (pKa)	4.84 at 20 °C
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Isobutyric acid, also known as 2-methylpropanoic acid, is a carboxylic acid with structural formula (CH₃)₂-CH-COOH. It is found in the free state in carobs (Ceratonia siliqua) and in the root of Arnica dulcis, and as an ethyl ester in croton oil.

Isobutyric acid is an isomer of n-butyric acid; they have the same chemical formula C₄H₈ O₂ but a different structure.

Isobutyric acid may be artificially prepared by the hydrolysis of isobutyronitrile with alkalis, by the oxidation of isobutanol with potassium dichromate and sulfuric acid,^[2] or by the action of sodium amalgam on methacrylic acid. It is a liquid of somewhat unpleasant smell, boiling at 155 °C. Its specific gravity is 0.9697 (0 °C) and pKa is 4.84 (20 °C). Heated with chromic acid solution to 140 °C, it gives carbon dioxide and acetone. Alkaline potassium permanganate oxidizes it to α-hydroxyisobutyric acid, (CH₃)₂-C(OH)-COOH. Its salts are more soluble in water than those of butyric acid.

References

This article incorporates text from the Encyclopædia Britannica, Eleventh Edition, a publication now in the public domain.