NEET 2016 Phase 2 · ChemistryPrevious Year Question
Which of the following can be used as the halide component for a Friedel-Crafts (alkylation) reaction?
Answer: (D) (D) Isopropyl chloride. Friedel-Crafts alkylation needs a halide whose bond can heterolyse (with ) to give a carbocation electrophile.
- A.(A) Chlorobenzene
- B.(B) Bromobenzene
- C.(C) Chloroethene
- D.(D) Isopropyl chloride✓
Correct Answer
(D) (D) Isopropyl chloride
Solution & Explanation
Friedel-Crafts alkylation needs a halide whose bond can heterolyse (with ) to give a carbocation electrophile. Isopropyl chloride, , gives a stable secondary carbocation. In aryl halides (chlorobenzene, bromobenzene) and the vinyl halide (chloroethene) the bond has partial double-bond character due to resonance, so it is strong and does not ionise — these cannot serve as the halide component.
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