Question

(a) Bring about the following conversions: 

(i) Propanal to 2-methyl pentanol 

(ii) Iodobenzene to benzoic acid 

(b) Though Carboxylic acids have >C=O group in their structure, but they are not prone to nucleophilic addition reactions. Why? 

(c) An organic compound A, with molecular formulae C₉H₁₂ is oxidized to monocarboxylic acid B, C₇H₆O₂ on vigorous oxidation with Potassium permanganate, whereas when oxidized in presence of air and further treated with dilute acid forms phenol. Sodium salt of B finds use as a food preservative and esters of B are used in perfumery. Identify A and B and write the reactions involved

Answer 1

(a) (i) 

(ii) 

(b) This is so because the Carbon in >C=O group in carboxylic group is less electrophilic due to the possible resonance as shown:

(c)A is oxidized to monocarboxylic acid, B indicates that the ring structure has only one side chain. Also, Phenol is formed when oxidized in the presence of air and further treatment with dil acid so A must be Cumene. 

Sodium salt of B is food preservative and esters of it is used in perfumery, confirms B to be benzoic acid.