Question

(a) Write chemical equations to illustrate the following name bearing reactions:

(i) Cannizzaro’* reaction

(ii) ****-Volhard-Zelinsky reaction

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

(i) Propanal and Propanone

(ii) Acetophenone and Benzophenone

(iii) Phenol and Benzoic acid

Answer 1

(ii) **-Volhald-Zelinsky reaction:**

(b) ( i) Propanal and Propanone:
Tollen’* reagent test: Propanal being an aldehyde reduces Tollens reagent to silver mirror but propanone being a ketone does not.

(ii) Benzophenone and Acetophenone:
Iodoform test: Acetophenone being a methyl ketone on treatment with NaOI (I2/NaOH) gives yellow ppt of iodoform but benzophenone does not.

(iii) Phenol and Benzoic acid:
FeCl3 test: Phenol gives a violet colouration with neutral FeCl3 solution while benzoic acid gives buff **** ppt ferric benzoate.