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.