3-Methylbut-1-ene, (CH3)2CH-CH=CH2, reacts with HBr in the absence of peroxide. The major product is

JEE Main levelSingle correct optionDifficulty 2 of 3o2014

3-Methylbut-1-ene, $(CH X_{3}) X_{2} CH - CH = CH X_{2}$ , reacts with HBr in the absence of peroxide. The major product is

Protonation gives the secondary cation

(CH X_{3}) X_{2} CH - CH X^{+} - CH X_{3}

. A 1,2-hydride shift converts it to the more stable tertiary cation

(CH X_{3}) X_{2} C X^{+} - CH X_{2} CH X_{3}

. Capture by

Br X^{-}

gives 2-bromo-2-methylbutane as the major product.