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

Explanation

If aqueous solution, KOH is almost completely ionized to give `OH^(-)` ions which being a strong nucleophile brings about a substitution reaction on alkyl halides to form alcohols. Further in the aqueous solution, `OH^(-)`ions are highly solvated (hydrated). This solvation reduces the basic character of `OH^(-)` ions which, therefore, fails to abstract a hydrogen from the p-carbon of the alkyl chloride to form alkenes. ln contrast, an alcoholic solution of KOH contains alkoxide `(RO^(-))` ion which being a much stronger base than `OH^(-)` ions perferentially eliminates of HCl from an alkyl chloride to form alkenes.