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NEET levelSingle correct optionDifficulty 1 of 3g3011

In the acid-catalysed dehydration of an alcohol that proceeds through a carbocation, the first step is:

Aattack of $H X^{-}$ on the carbon bearing OH
Bprotonation of the hydroxyl oxygen to give $R - OH X_{2} X^{+}$
Closs of $OH X^{-}$ directly to give $R X^{+}$
Dremoval of a beta hydrogen by a base

Answer: B

OH X^{-}

is a poor leaving group, so the acid first protonates it to

ROH X_{2} X^{+}

. Water then leaves to give the carbocation, followed by loss of a proton to form the alkene.

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