Question

Question #bbbea

Answer 1

Aqueous KOH gives alcohols because of substitution reaction. While alcoholic KOH gives alkenes due to elimination reaction.

Explanation:

Alkyl chlorides with Aq.KOH :--
When an alkyl chlorides treated with Aq.KOH in solution KOH is almost ionized to give OH— ions which being a strong nucleophile, brings about a substitution reaction and give alcohols.

Ex. `"R"-"Cl" +"K"OH"`(Aq) =`"R"-"OH" +"K"Cl"`

Alkyl chlorides with alco.KOH :--
In contrast,an alcoholic solution of KOH contains alkoxide (RO–) ions which being a much stronger base than OH- ions eliminates a mol ecule of HCl from an alkyl chlorides to form alkenes.

Ex. `"CH"_3 "CH"_2"CH"_2"Cl"+"KOH"`(alc.) = `"CH"_3"CH"="CH"_2` +`"H"Cl"`