Question

The good method for converting benzene into propyl benzene is:

• A. $C_6{H}_6+C{H}_{3}C{H}_{2}C{H}_{2}Cl+$Anhyd. $AlC{l}_3$
• B. $C_6{H}_6+C{H}_{3}C{H}_{3}C{H}_{2}COCl+$Anhyd. $AlC{l}_3$ and then treatment with $Zn/Hg/HCl$
• C. $C_6{H}_6+C{H}_{3}C{H}_{3}C{H}_{2}COCl+$Anhyd. $AlC{l}_3$ and then treatment with $H_{2}Ni$
• D. $C_6{H}_6+$ Anhyd. $AlC{l}_3$ + cyclopropane

Answer 1

Answer: (B), (D)

The correct options are
B $C_6{H}_6+C{H}_{3}C{H}_{3}C{H}_{2}COCl+$Anhyd. $AlC{l}_3$ and then treatment with $Zn/Hg/HCl$
D $C_6{H}_6+$ Anhyd. $AlC{l}_3$ + cyclopropane

The replacement of a hydrogen atom in benzene by acyl group can be brought about with alkyl chloride in presence of anhydrous aluminum chloride. The reaction is known as Friedel craft's acylation reaction.
Thus benzene is treated with propionyl chloride in presence of anhydrous aluminum chloride to obtain propiophenone.
The carbonyl group is then reduced to methylene group by using zinc amalgam in presence of conc. HCl to obtain propylbenzene.
Propylbenzene can also be obtained by the reaction of benzene with cyclopropane in presence of anhydrous aluminium chloride.