Oxygen Containing Compounds

Question 1

Explain preparation of alcohol by hydrolysis of alkyl halides

Answer 1

There are two processes
A. Treatment of haloalkane with alkali (NaOH/KOH)
When a haloalkane is warmed with aqueous sodium or potassium hydroxide, the covalently bonded halogen in haloalkane is converted to halide ion and alcohol is formed.
R-X + OH→ R-OH + X

B. Treatment of haloalkane with moist silver oxide: Moist silver on treatment with Alkyl halide gives precipitate of silver halide and alcohol.
R-X + AgOH →R-OH +AgX↓

Question 2

Explain preparation of alcohol by acid catalyzed hydration of alkenes

Answer 2

hydration of alkenes using concentrated H2SO4 : Alkene reacts with sulphuric acid to produce alkyl hydrogen sulfate, which on hydrolysis gives alcohol. This follows Markownikoff’s rule.

Alkene+sulphuric acid→hydrogen sulfate +H-OH (hydrolysis) →alcohol

Question 3

Explain preparation of alcohol by Hydroboration -oxidation of alkenes

Answer 3

With diborane (B2H6). alkene undergoes addition reaction (Hydroboration) to give trialkylborane (R3B) which on oxidation with hydrogen peroxide in alkaline medium gives alcohol. This antimarkownikoff hydration of alkenes.

Question 4

How is phenol converted into Benzoquinone.

Answer 4

When phenol is oxidised with chromic anhydride Or sodium dichromate in presence of H2SO4, p-benzoquinone is formed.

Question 5

How is phenol concert into benzene

Answer 5

When phenol is treated with zinc dust, it gets reduced to zinc dust.

Question 6

Write action of Cu on primary, secondary and tertiary alcohol

Answer 6

Primary alcohol turns to aldehyde
Secondary alcohol turns into ketone
And tertiary alcohol turns into alkene