The treatment of alkyl chloride with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH, alkenes are the major products. Explain why?

Answer : In aqueous solution, KOH is ionised into K+ and OH. OH being a nucleophile leads to nucleophilic substitution reaction with alkyl chlorides to form alcohols. Moreover, the OH ions in aqueous solution are highly hydrated. This reduces the basic character of OH ions which, therefore, fail to remove hydrogen from β-carbon to form an alkene.

An alcoholic solution of KOH, on the other hand, contains alkoxide (RO) ions that are much stronger base than OH ions; hence, alcoholic solution of KOH preferentially eliminates a molecule of HCl from an alkyl chloride to form an alkene.

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