Question

Predict the alkene formed by dehydrohalogenation of 1-Bromo-1-methylcyclohexane.

Hint:

Zaitsev's rule: Elimination gives the more substituted (more stable) alkene as the major product.

Answer 1

Step 1: Concept
Dehydrohalogenation is an elimination reaction ($E2$ or $E1$) following Zaitsev's rule: the more substituted (more stable) alkene is the major product.

Step 2: Analysis
1-Bromo-1-methylcyclohexane has the bromine on the quaternary carbon of the ring. Elimination can occur by removing H from C2 (ring carbon) to give methylenecyclohexane (exocyclic double bond) or 1-methylcyclohex-1-ene (endocyclic double bond). The endocyclic double bond is trisubstituted and more stable.

Step 3: Conclusion
By Zaitsev's rule, the major product is

1-methylcyclohex-1-ene (the more substituted, endocyclic alkene).

Final Answer: Major product: 1-Methylcyclohex-1-ene (endocyclic, more substituted double bond, preferred by Zaitsev's rule).