Friedel–Crafts alkylation of benzene with tert-butyl chloride yields which major product?

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Multiple Choice

Friedel–Crafts alkylation of benzene with tert-butyl chloride yields which major product?

Friedel–Crafts alkylation creates a carbocation from the alkyl halide in the presence of a Lewis acid, and this electrophile attacks the benzene ring to form an alkylbenzene after deprotonation. With tert-butyl chloride, the tert-butyl cation forms readily because it’s very stable (a tertiary carbocation) and it doesn’t rearrange. That cation then attacks benzene to give tert-butylbenzene as the major product. The bulky tert-butyl group also discourages further alkylation, so mono-substitution tends to predominate. The other options require different carbocations or reaction pathways (isopropyl for cumene, ethyl for ethylbenzene, or formation of tert-butyl alcohol), which aren’t produced by this setup.

Friedel–Crafts alkylation creates a carbocation from the alkyl halide in the presence of a Lewis acid, and this electrophile attacks the benzene ring to form an alkylbenzene after deprotonation. With tert-butyl chloride, the tert-butyl cation forms readily because it’s very stable (a tertiary carbocation) and it doesn’t rearrange. That cation then attacks benzene to give tert-butylbenzene as the major product. The bulky tert-butyl group also discourages further alkylation, so mono-substitution tends to predominate. The other options require different carbocations or reaction pathways (isopropyl for cumene, ethyl for ethylbenzene, or formation of tert-butyl alcohol), which aren’t produced by this setup.

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