2 and 1.6 compounds were identical, then we should expect the two well-known crotonic acids, CH 3 CH: CH COOH and CH 2: CH CH 2 000H, to be identical.
Crotonic acid >>
CROTONIC ACID (C 4 H 6 0 2).
Crotonic acid, isocrotonic acid and methacrylic acid; the constitutional formulae are HC CO 2 H HC C02H HC CH3 CH3 CH Crotonic Acid.
The isomerism of crotonic and isocrotonic acids is to be explained on the assumption of a different spatial arrangement of the atoms in the molecule (see Stereochemistry).
Crotonic acid, so named from the fact that it was erroneously supposed to be a saponification product of croton oil, may be prepared by the oxidation of croton-aldehyde, CH3 CH:CH CHO, obtained by dehydrating aldol, or by treating acetylene successively with sulphuric acid and water; by boiling allyl cyanide with caustic potash; by the distillation of 0-oxybutyric acid; by heating paraldehyde with malonic acid and acetic acid to, oo C. (T.
It boils at 171.9° C., with partial conversion into crotonic acid; the transformation is complete when the acid is heated to 170-180° C. in a sealed tube.
Heated with sulphur it forms benzoic acid and stilbene: 2C 7 H 6 0+S = C6HS000H+C6H5CHS, 2C 6 H 5 CHS =2S +C14H12 Its addition compound with hydrocyanic acid gives mandelic acid C 6 H 5 CH(OH) COOH on hydrolysis; when heated with sodium succinate and acetic anhydride, phenyl-iso-crotonic acid C 6 H 5 CH: CH CH 2 000H is produced, which on boiling is converted into a-naphthol C 10 H 7 0H.