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JEE Advanced levelSingle correct optionDifficulty 3 of 3o2042

2-Methylbut-2-ene is to be converted into 3-methylbutan-2-ol. Which sequence is suitable?

A $HBr$ (no peroxide), then aqueous $KOH$
B $BH X_{3} \cdot THF$ , then $H X_{2} O X_{2} / NaOH$
Cdilute $H X_{2} SO X_{4}$ , $H X_{2} O$
D $Hg (OAc) X_{2} / H X_{2} O$ , then $NaBH X_{4}$

Answer: B

Boron adds to the less substituted carbon, C-3, and H to the tertiary C-2; oxidation gives 3-methylbutan-2-ol. The other three Markovnikov routes put OH on the tertiary carbon, giving 2-methylbutan-2-ol.

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