Question

Consider the addition of $HBr$ to 3,3-dimethylbut-1-ene as shown below :


Which of the following represents correct mechanistic explanation for the formation of above product?

• A. Protonation of alkene followed by a hydride shift and addition of bromide to the carbocation.
• B. Double bond shift in the alkene followed by protonation and addition of bromide to the carbocation.
• C. Addition of bromide to the alkene followed by a double bond shift and protonation.
• D. Protonation of alkene followed by a methyl shift and addition of bromide to the carbocation.

Answer 1

The correct option is D Protonation of alkene followed by a methyl shift and addition of bromide to the carbocation.

The reaction takes place by protonation of alkene followed by methyl shift making a more stable tertiary carbocation , and then addition of bromide is there as shown :