. Illustrate the following name reactions giving suitable example in each case


(a) Illustrate the following name reactions giving suitable example in each case:

(i) Clemmensen reduction

(ii) Hell-Volhard-Zelinsky reaction

(b) How are the following conversions carried out?

(i) Ethylcyanide to ethanoic acid

(ii) Butan-1-ol to butanoic acid

(iii) Benzoic acid to m-bromobenzoic acid

                                                            OR

(a) Illustrate the following reactions giving a suitable example for each:

(i) Cross aldol condensation

(ii) Decarboxylation

(b) Give simple tests to distinguish between the following pairs of compounds

(i) Pentan-2-one and Pentan-3-one

(ii) Benzaldehyde and Acetophenone

(iii) Phenol and Benzoic acid

Best Answer

(a) (i) The carbonyl group of aldehydes and ketones is reduced to CH2 group on treatment with zinc-amalgam and concentrated hydrochloric acid. The reaction is known as Clemmensen reduction

carbonyl group

(ii) Carboxylic acids having an hydrogen-hydrogen are halogenated at the position-position on treatment with chlorine or bromine in the presence of small amount of red phosphorus to give halocarboxylic-halocarboxylic acids. This reaction is called Hell–Volhard–Zelinsky reaction.

-Halocarboxylic acid

Illustrate , compounds

Talk to Our counsellor