Question

Conversion phenyl magnesium bromide to benzoic acid reaction

Answer 1

Conversion of bromobenzene to benzoic acid involves following steps

Step -1:—Formation of toluene from chlorobenzene.

Chlorobenzene and methyl chloride are reacted with sodium metal in presence of dry ether to form toluene.

Step-2:—Oxidation of toluene to benzoic acid.

Toluene is oxidised by alkaline KMnO₄ to form potassium benzoate,which on acid hydrolysis gives benzoic acid.

Answer 2

Explanation:

1) To phenyl magnesium bromide add methanal to obtain adduct.

$Ph-Mg-Br+HCHO\rightarrow Ph-C(H_2)-OMg$

2) Now on acidic hydrolysis of the adduct we will get, benzyl alcohol as a product:

$Ph-C(H_2)-OMg+H_2O\overset{H^+}\rightarrow Ph-CH_2OH+MgBrOH$

3) On oxidation of benzyl alcohol in the presence of acidified potassium permanganate gives benzoic acid:

$Ph-CH_2OH+KMnO_4\overset{H^+}\rightarrow C_6H_5-COOH$