Question

What product is formed by $HBr$ addition to $2-cyclobutylpropene$?

• A. $2-bromo-2-cyclobutyl-propane$
• B. $1,2-dimethyl-1-bromocyclopentane$
• C. $2-bromo-2-cyclopropyl-butane$
• D. $1-bromo-2-cyclobutyl-propane$

Answer 1

The correct option is B $1,2-dimethyl-1-bromocyclopentane$

Markownikoff's rule can be stated that the hydrogen atom is added to the carbon with the greater number of hydrogen atoms while the X component is added to the carbon with the fewer number of hydrogen atoms.

$HBr$ is added to $2-cyclobutyl$ propene and tertiary carbocation is formed. Ring expansion results in a more stable compound.