process3

cis-2-butenoic acid and trans-2-butenoic acid

cis-crotonic acid,trans-crotonic acid
cis-2-butenoic acid trans-2-butenoic acid

If cis-2-butenoic acid is heated at 180 ^oC,
it is converted to trans-2-butenoic acid.

cis-2-butenoic acid can be prepared by distilling
b-hydroxyglutaric acid under reduced pressure.

trans-2-butenoic acid may be formed by oxidation of 2-butenal.
CH₃-CH=CH-CHO CH₃-CH=CH-COOH

Potassium permanganate oxidises
trans-2-butenoic acid to 2,3-dihydroxybutanoic acid
CH₃-CH=CH-COOH CH₃-CHOH-CHOH-COOH

Chlorine adds to trans-2-butenoic acid forming 2,3-dichlorobutanoic acid.
CH₃-CH=CH-COOH + Cl2 CH₃-CHCl-CHCl-COOH

Hydrogen bromide reacts with trans-2-butenoic acid to form 3-bromobutanoic acid .
CH₃-CH=CH-COOH + HBr CH₃-CHBr-CH2-COOH