Alkylation of benzene can be accomplished by treating benzene with haloalkane (RX) in the presence of AlCl₃. The reaction is known as a Friedel–Crafts alkylation reaction. (The reaction is named after Charles Friedel, a French chemist, and James M. Crafts, an American chemist, who discovered this method of making alkylbenzenes in 1877.) An example of a Friedel–Crafts alkylation reaction is shown below:

The mechanism for this reaction involves the following steps. First, (CH₃)₂CHCl and AlCl₃ react in a Lewis acid–base reaction to form an adduct, (CH₃)₂CH—Cl—AlCl₃, in which a chlorine atom is bonded to both carbon and aluminum. The adduct then dissociates to (CH₃)₂CH⁺ a carbocation, and AlCl₄^–.The carbocation acts as an electrophile in a reaction with benzene, forming an arenium ion. Finally, a proton is removed from the arenium ion by AlCl₄^–, yielding an alkylbenzene, HCl, and AlCl₃. Write chemical equations for the elementary processes involved in forming cumene and HCl from  (CH₃)₂CHCl and benzene. Use curved arrows to show the movement of electrons.

Transcribed Image Text:

+ (CH3)2CHCI AICI 3 CH(CH3)2 Cumene + HCI