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The treatment of alkyl chlorides with aq...

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.

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

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

Knowledge Check

  • Haloalkane in the presence of alcoholic KOH undergoes

    A
    elimination
    B
    polymerization
    C
    substitution
    D
    dimerization
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    A
    B
    C
    D
  • 2-Chlorobutane on treatment with alcoholic KOH/ Delta gives major product :

    A
    2-Butene
    B
    1-Butene
    C
    2-Butanol
    D
    1-Butyne
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