Benzene is an aromatic hydrocarbon with the molecular formula C6H6, while toluene is a compound with the molecular formula C7H8. Benzene can be converted into toluene through a process known as alkylation, specifically Friedel-Crafts alkylation. This reaction involves the substitution of a hydrogen atom on the benzene ring with an alkyl group, in this case, a methyl group (-CH3). The reaction is typically catalyzed by a Lewis acid, such as aluminum chloride (AlCl3).

The Friedel-Crafts Alkylation Reaction:
The Friedel-Crafts alkylation reaction is a powerful method for introducing alkyl groups onto aromatic compounds. Here is how benzene can be converted into toluene using this reaction:

Step 1: Activation of the Lewis Acid Catalyst:
The first step involves the activation of the Lewis acid catalyst, typically aluminum chloride (AlCl3). This is achieved by adding a small amount of the catalyst to a solvent, such as anhydrous chloroform or dichloromethane. The Lewis acid catalyst functions by coordinating with the alkyl halide, making it more reactive.

Step 2: Formation of the Carbocation:
Next, the alkyl halide, in this case, methyl chloride (CH3Cl), is added to the reaction mixture. The Lewis acid catalyst activates the alkyl halide by polarizing the carbon-halogen bond, leading to the formation of a carbocation intermediate. The carbocation is a positively charged carbon atom.

Step 3: Attack of Benzene on the Carbocation:
Once the carbocation is formed, the benzene molecule acts as a nucleophile and attacks the carbocation. The pi electrons of the benzene ring form a bond with the positively charged carbon atom of the carbocation, resulting in the substitution of a hydrogen atom on the benzene ring.

Step 4: Regeneration of the Catalyst:
Finally, the reaction mixture is quenched with water or a weak acid, which protonates the negatively charged complex formed between the catalyst and the alkyl group attached to the benzene ring. This leads to the formation of the final product, toluene, and regenerates the Lewis acid catalyst.

Overall Reaction:
The overall reaction can be represented as follows:

Benzene + Methyl Chloride (CH3Cl) + Lewis Acid Catalyst (AlCl3) → Toluene + Regenerated Catalyst

Summary:
- Benzene can be converted into toluene through Friedel-Crafts alkylation.
- The reaction involves the substitution of a hydrogen atom on the benzene ring with a methyl group.
- The process requires a Lewis acid catalyst, typically aluminum chloride (AlCl3).
- The reaction proceeds through the formation of a carbocation intermediate and the attack of benzene as a nucleophile.
- The reaction mixture is quenched to regenerate the catalyst and obtain the final product, toluene.