The good method for converting benzene into propyl benzene is:

In the second alternative, a -R group can attach to the benzene ring and form a stable carbocation, giving us a ketone attached to the ring. The ketone is then reduced by the reagents Zn, Hg, and HCl to give us a hydrocarbon, and as a result, propyl benzene. The reaction can be expressed as:

The final option includes cyclopropane that has been alkylated using anhydrous aluminium chloride. The response is readable as