QuestionOrganic / dehydration with rearrangement
The major product formed in the following reaction is:
- (a) 3,3-Dimethylcyclohexene
- (b) 1-Methylcyclohexene
- (c) 1,2-Dimethylcyclohexene
- (d) Isopropylidenecyclopentane
Answer: (c)
2,2-Dimethylcyclohexanol + H₂SO₄: 2° cation forms, then 1,2-methyl shift gives a 3° cation; loss of H⁺ gives the most substituted alkene, 1,2-dimethylcyclohexene (tetrasubstituted, Saytzeff) → (c). Ring contraction to (d) is minor.