Class 12 Chemistry - Chapter Alcohols Phenols and Ethers NCERT Solutions | Illustrate with examples the limitations
Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers.
The reaction of Williamson synthesis involves SN2 attack of an alkoxide ion on a primary alkyl halide.
But if secondary or tertiary alkyl halides are taken in place of primary alkyl halides, then elimination would compete over substitution. As a result, alkenes would be produced. This is because alkoxides are nucleophiles as well as strong bases. Hence, they react with alkyl halides, which results in an elimination reaction.
More Questions From Class 12 Chemistry - Chapter Alcohols Phenols and Ethers
- Q:-
Explain the following with an example.
(i) Kolbe's reaction.
(ii) Reimer-Tiemann reaction.
(iii) Williamson ether synthesis.
(iv) Unsymmetrical ether.
- Q:-
How are the following conversions carried out?
(i) Propene → Propan-2-ol
(ii) Benzyl chloride → Benzyl alcohol
(iii) Ethyl magnesium chloride → Propan-1-ol.
(iv) Methyl magnesium bromide → 2-Methylpropan-2-ol.
- Q:-
Write the mechanism of acid-catalysed dehydration of ethanol to yield ethene.
- Q:-
Give the equations of reactions for the preparation of phenol from cumene.
- Q:-
Write equations of the following reactions:
(i) Friedel-Crafts reaction-alkylation of anisole.
(ii) Nitration of anisole.
(iii) Bromination of anisole in ethanoic acid medium.
(iv) Friedel-Craft's acetylation of anisole.
- Q:-
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- Q:-
Show how are the following alcohols prepared by the reaction of a suitable
Grignard reagent on methanal?
(i)
(ii)
- Q:-
Give two reactions that show the acidic nature of phenol. Compare acidity of phenol with that of ethanol.
- Q:-
Write the reactions of Williamson synthesis of 2-ethoxy-3-methylpentane starting from ethanol and 3-methylpentan-2-ol.
- Q:-
What is meant by hydroboration-oxidation reaction? Illustrate it with an example.
Popular Questions of Class 12 Chemistry
- Q:-
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- Q:-
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- Q:-
(i) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N
(ii) Write IUPAC names of all the isomers.
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- Q:-
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- Q:-
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- Q:-
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(iii) 2-Hydroxycyclopentane carbaldehyde
(iv) 4-Oxopentanal
(v) Di-sec-butyl ketone
(vi) 4-Fluoroacetophenone
- Q:-
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- Q:-
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- Q:-
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- Q:-
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(v) Perfluorobenzene
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- Q:-
Write the IUPAC names of the following ketones and aldehydes. Wherever possible, give also common names.
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(iii) CH3(CH2)5CHO (iv) Ph-CH=CH-CHO
(v)
(vi) PhCOPh - Q:-
Comment on the nature of two S-O bonds formed in SO2 molecule. Are the two S-O bonds in this molecule equal?
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