Class 12 Chemistry Notes – Electronic Structure & Prepration of Alcohols

Electronic structure of Alcohols:-

(i) In alcohols both oxygen and the carbon attached to it are sp³ hybridized

(ii) Two of the four sp3 hybridized orbitals of oxygen overlaps separately with l₀ orbital of H and an sp₃ orbital of carbon of alkyl group to form OH and C – O bond

Methods of preparation of alcohols:-

From Haloalkanes:- when HaloAlkanes (alkyl halides) are heated with aqueous sodium or Potassium Hydroxide, they forms alcohols

From Alkenes:- Alcohols can be produced from Alkenes by their Hydration, by passing alkenes through concentrated H₂SO₄ and then hydrolysis with boiling water gives alcohols.
Mechanism: – it involves following steps

(i) Electrophilic attack by hydroxyl union on alkenes gives a carbocation intermediate :-

(ii) Nucleophilic attack by water on 2⁰ carbocation

(iii) Deprotonation or loss of proton to form alcohol

Hydroboration – oxidation :- B₂H₆ (Diborane) if C- deficient molecule it acts as an electrophilic and react with alkenes to form trialkylborates  which on subsequent oxidation with alkaline H₂O₂ gives alcohols

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