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

In 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, fail to abstract a hydrogen from the `beta`-carbon of the alkyl chloride to form an alkene.
In contrast, an alcoholic solution of KOH contains alkoxiide `(RO^(-))` ions which being a much stronger base than `OH^(-)` ions preferentially eliminates a molecule of HCl from an alkyl chloride to form alkenes.