Isocrotonic acid explained

Isocrotonic acid (also known as quartenylic acid; formally named (Z)-2-butenoic acid) is the cis isomer of crotonic acid. It is an oil, possessing an odor similar to that of brown sugar. At its boiling point of 171.9 °C, it converts into crotonic acid. The compound can be prepared from 1,3dibromo-2butanone via the Favorskii rearrangement.^[1]

Related compounds

Ethyl isocrotonate can be prepared by semihydrogenation of ethyl tetrolate.^[2]

Rudolph Fittig and Hugo Erdmann showed that the γ-phenyl structural analog of isocrotonic acid forms α-naphthol when dehydrated, an observation that provided useful evidence in understanding the nature of naphthalene.^[3]

(Z)-(C₆H₅)CH=CHCH₂COOH   →   α-naphthol   +   H₂O

References

1. 10.15227/orgsyn.053.0123 . cis-a,b-Unsaturated Acids: Isocrotonic Acid . Organic Syntheses . 1973 . 53 . 123. C. Rappe .
2. 10.15227/orgsyn.064.0108 . Ethyl Isocrotonate . Organic Syntheses . 1986 . 64 . 108. Michael J. Taschner, Terry Rosen, Clayton H. Heathcock.
3. Rudolph. Fittig. Hugo. Erdmann. Rudolph Fittig. Hugo Erdmann. Ber. Dtsch. Chem. Ges.. 1883. 16. 1. 43–44. German. Synthese des α-Naphtols. Synthesis of α-Naphtol. 10.1002/cber.18830160115.