Exams › JEE Advanced › Chemistry
Consider the compound CH3-CH2-CH(X)-CH3, where X is a halogen. When treated with alcoholic KOH and heated, it undergoes elimination to give alkene products. For which choice of X will the proportion of the Hofmann (less substituted) alkene product be the greatest?
- X = I
- X = Br
- X = Cl
- X = F
Correct answer: X = F
Solution
Fluorine is the poorest leaving group among halogens; the E2 transition state with C-F bond breaking is early and reactant-like, reducing the preference for the more substituted (Saytzeff) product and maximising the proportion of the Hofmann (less substituted) alkene.
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