Aldehydes, Ketones and Carboxylic Acids

In the given reaction, an aromatic aldehyde is condensed with an acid anhydride (Perkin condensation) in the presence of a base to form α,β-unsaturated acid (cinnamic acid). This gives effervescence on reaction with NaHCO3 and positive test with Bayer’s reagent (1 % alkaline KMnO4).

Ph−CHO

I

(CH3CO)2O CH3COONa

→

Ph−CH=−COOH

J(Cinnamic‌acid)

NaHCO3

→

Effervescence
Cinnamic acid

1%cold,alk;KMnO4

→

(Bayer′s‌reagent)

Positive