Hydrohalogenation

[anthropos]

"Treatment of 3-methylcyclohexene with HCl yields 2 products, 1-chloro-3-methylcyclohexane and 1-chloro-1-methylcyclohexane. Draw a mechanism to explain the result."

 

I can't really figure out one can arrive at 1-chloro-1-methylcyclohexane, how did the positive charge manage to shift to the CH3 position?

 

Also, I read another textbook, and it features a question which states that "reaction of HBr with 3-methylcyclohexene yields a mixture of four products:

cis- and trans-1-bromo-3-methylcyclohexane and cis- and trans-1-bromo-2-methylcyclohexane". Then shouldn't the HCl reaction yield products of similar structure?

 

Thank you.

[mississippichem]

-Remember, carbocations will rearrange to obtain a more stable configuration.

 

-More electron donating groups lead to higher stability.

 

-Cl^- will attack this carbocation after rearrangement.

 

-You're starting with a secondary carbocation after the addition of H⁺. Is there any way a tertiary carbocation can arise? Maybe this will point you in the right direction.

[Horza2002]

Mississippichem has given you some great advice there.

 

And remember that bromine is a lot larger than chlorine so its nucleophilic properties are different to that of chlorine