Asparagusic acid, S₂₂CHCO₂H is an organosulfur carboxylic acid

Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

 present in the vegetable asparagus

Asparagus

Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...

 and may be the metabolic precursor to other odorous thiol compounds. Biosynthetic studies revealed that asparagusic acid is derived from isobutyric acid

Isobutyric acid

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

. This colorless solid has a m.p. of 75.7-76.5 °C. The corresponding dithiol (m.p. 59.5-60.5 °C) is also known; it is called dihydroasparagusic acid or dimercaptoisobutyric acid.

Isolation

From 40 kg of "asparagus aroma concentrate," Jansen obtained 32 g of a compound he identified as 3,3’-dimercaptoisobutyric acid.