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JEE Main levelSingle correct optionDifficulty 2 of 3g3014

2,2-Dimethylpropyl (neopentyl) cation, $(CH X_{3}) X_{3} C - CH X_{2} X^{+}$ , rearranges to the more stable cation by:

Aa 1,2-hydride shift giving 2,2-dimethylpropan-1-yl cation
Bno rearrangement, because primary cations are the most stable
Ca 1,2-methyl shift giving 2-methylbutan-2-yl cation
Da 1,2-hydride shift giving 2-methylbutan-2-yl cation

Answer: C

The neighbouring carbon is quaternary and has no hydrogen, so only a methyl group can migrate. Methyl shift gives the tertiary

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

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