Question

How will you prepare benzoic acid from benzene, with the help of Friedel-Craft reaction? Also write any two chemical properties of Benzoic acid?

Answer 1

Benzoic acid is prepared from benzene, with the help of Friedel-Craft reaction followed by hydrolysis.
$\underset{\text{Benzene}}{C_6{H}_6}+\underset{\text{Carbonyl chloride}}{CO{Cl}_2}\underset{Al{Cl}_3}{\overset{\text{Anhy.}}{\to }}\underset{\text{Benzoyl chloride}}{C_6{H}_{5}COCl}\underset{-HCl}{\overset{H_{2}O}{\to }}\underset{\text{Benzoic Acid}}{C_6{H}_{5}COOH}$

Chemical properties of Benzoic acid:

1) Benzoic acid is reduced to benzyl alcohol by reduction with $LiAl{H}_4$.
$C_6{H}_5-COOH\stackrel{LiAl{H}_4}{\to }{C}_6{H}_5-C{H}_2-OH$
2) Benzoic acid reacts with thionyl chloride ( in presence of pyridine ) to form benzoyl chloride.
$C_6{H}_5-COOH+SOC{l}_2\stackrel{\text{pyridine}}{\to }{C}_6{H}_5-COCl+S{O}_2+HCl$