What reagent is commonly used to dehydrate an Alcohol to form an Alkene?

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Multiple Choice

What reagent is commonly used to dehydrate an Alcohol to form an Alkene?

Dehydration of an alcohol to an alkene happens fastest under strong acid catalysis, where the hydroxyl group is turned into a good leaving group and water is removed to form a double bond. Concentrated sulfuric acid serves as the acid catalyst and dehydrating agent: it protonates the OH group, converting it to water, which then leaves to give a carbocation (especially for secondary or tertiary alcohols). A base (often the conjugate base of the acid or the surrounding alcohol) removes a proton adjacent to the carbocation, yielding the alkene. The strong acid also helps pull the water off, pushing the equilibrium toward alkene formation. Bromine wouldn’t remove water to form an alkene; it’s used for halogenation or addition to double bonds. Ammonia isn’t the dehydrating agent you need here, and hydrogen on a metal surface would hydrogenate rather than dehydrate.

Dehydration of an alcohol to an alkene happens fastest under strong acid catalysis, where the hydroxyl group is turned into a good leaving group and water is removed to form a double bond. Concentrated sulfuric acid serves as the acid catalyst and dehydrating agent: it protonates the OH group, converting it to water, which then leaves to give a carbocation (especially for secondary or tertiary alcohols). A base (often the conjugate base of the acid or the surrounding alcohol) removes a proton adjacent to the carbocation, yielding the alkene. The strong acid also helps pull the water off, pushing the equilibrium toward alkene formation.

Bromine wouldn’t remove water to form an alkene; it’s used for halogenation or addition to double bonds. Ammonia isn’t the dehydrating agent you need here, and hydrogen on a metal surface would hydrogenate rather than dehydrate.

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