Crotonic acid

Crotonic acid, or trans-2-butenoic acid, is a short-chain unsaturated carboxylic acid, described by the formula CH₃CH=CHCO₂H. Crotonic acid is so named because it was erroneously thought to be a saponification product of croton oil. It crystallizes as needles from hot water.

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Isocrotonic acid (or quartenylic acid) is the cis analogue of crotonic acid. It is an oil, possessing a smell similar to that of brown sugar. It boils at 171.9°C, concomitant with conversion into crotonic acid. Isomerizaton is complete when the cis acid is heated to 170-180°C in a sealed tube.

Racemic threonine can be prepared from crotonic acid by alpha-functionalization using mercury(II) acetate.^[1]

See also

• Crotyl
• Crotonaldehyde
• Crotyl alcohol
• Methacrylic acid

References

1. ^ Carter, H. E.; West, H. D. “dl-Threonine” Organic Syntheses, Collected Volume 3, p.813 (1955). http://www.orgsyn.org/orgsyn/pdfs/CV3P0813.pdf.

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