Isobutyric acid is a carboxylic acid with structural formula (CH3)2-CH-COOH. It is found in the free state in carobs (Ceratonia siliqua), in vanilla 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, or by the action of sodium amalgam on methacrylic acid. 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. Isobutyric acid can also be manufactured commercially using engineered bacteria using a sugar feedstock. Isobutyric acid is a retained trivial name under the IUPAC rules.
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