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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ap016

Which of the following methods give 2-methylpropan-2-ol (tert-butyl alcohol) as the major product?

APropanone with $CH X_{3} MgBr$ , then $H X_{3} O X^{+}$
BEthyl ethanoate with excess $CH X_{3} MgBr$ , then $H X_{3} O X^{+}$
C2-Methylpropene with dilute $H X_{2} SO X_{4}$ and water
D2-Methylpropene with $BH X_{3}$ /THF, then $H X_{2} O X_{2}$ / $NaOH$

Answer: A, B, C

Propanone plus methyl Grignard gives

(CH X_{3}) X_{3} C - OH

. An ester adds two

CH X_{3} X^{-}

groups to the acyl carbon, again giving

(CH X_{3}) X_{3} C - OH

(plus ethanol). Markovnikov hydration of 2-methylpropene gives the tertiary alcohol. Hydroboration is anti-Markovnikov and gives 2-methylpropan-1-ol.

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