Question

a) Among formaldehyde, acetaldehyde, benzalde hyde and formic acid, which compounds undergo Cannizzaro reaction? Give reason.

b) What is esterification?

c) Write the chemical reaction to effect the transformation of sodium acetate to ethane.

d) Write the IUPAC names of the compounds given below,

i) CH₃-CH₂-CO-CH₃

ii) HOOC-CH₂-COOH

Answer 1

a) i) Canizzaro reaction - Aldehydes which do not have an α-hydrogen atom, undergo self oxidation and reduction (disproportionation) reaction on treatment with concentrated alkali. In this reaction, one molecule of the aldehyde is reduced to alcohot while another is oxidised to carboxylic acid salt. 

e.g.

ii) Carboxylic acids react with alcohols or phenols in the presence of mineral acids such as concentrated H₂SO₄ or HCI gas as catalysts to form esters. This reaction is known as esterification.

b) Formation of ester is known as esterification. Carboxylic acid react with alcohols or phenols in presence of acids like HCI to give ester.

c) By Kolbe’s electrolytic method – An aqueous solution of sodium acetate on electrolysis gives ethane at the anode.