Question:

Name the reagents used in the following reactions:

(i)Oxidation of a primary alcohol to carboxylic acid. 

(ii)Oxidation of a primary alcohol to aldehyde.

(iii)Bromination of phenol to 2,4,6-tribromophenol.

(iv)Benzyl alcohol to benzoic acid.

(v)Dehydration of propan-2-ol to propane.

(vi)Butan-2-one to butan-2-ol.

Updated On: Dec 11, 2023
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Solution and Explanation

(i)Acidified potassium permanganate 

potassium permanganate

(ii)Pyridinium chlorochromate(PCC) 

Pyridinium chlorochromate

(iii) Bromine water 

Bromine water

(iv)Acidified potassium permanganate 

Acidified potassium permanganate

(v)85% phosphoric acid 

85% phosphoric acid

(vi)NaBH4 or LiAlH4

NaBH4 or LiAlH4

 

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Notes on Alcohols, Phenols And Ethers

Concepts Used:

Preparation - Alcohols, Phenols and Ethers

Alcohols, phenols, and ethers are organic compounds that can be prepared by various methods.

Preparation of Alcohols:

  1. Direct hydration of alkenes: Alcohols can be prepared by the addition of water to an alkene in the presence of a strong acid catalyst.
  2. Reduction of carbonyl compounds: Alcohols can be prepared by the reduction of aldehydes, ketones, or carboxylic acids using reducing agents like NaBH4 or LiAlH4.
  3. Grignard reaction: Alcohols can be prepared by reacting Grignard reagents with carbonyl compounds.
  4. Hydroboration-oxidation: Alcohols can be prepared by the hydroboration of alkenes followed by oxidation with an oxidizing agent like H2O2.

Preparation of Phenols:

  1. Hydrolysis of diazonium salts: Phenols can be prepared by the hydrolysis of diazonium salts, which are formed by the reaction of aniline with nitrous acid.
  2. Oxidation of sulfonic acids: Phenols can be prepared by the oxidation of sulfonic acids using strong oxidizing agents like potassium permanganate or chromic acid.

Preparation of Ethers:

  1. Williamson synthesis: Ethers can be prepared by the reaction of an alkoxide ion with a primary alkyl halide or tosylate in the presence of a strong base like NaOH or KOH.
  2. Dehydration of alcohols: Ethers can be prepared by the dehydration of alcohols in the presence of a strong acid catalyst like H2SO4.

In summary, alcohols, phenols, and ethers can be prepared by a variety of methods, including hydration, reduction, Grignard reaction, hydroboration-oxidation, hydrolysis, oxidation, Williamson synthesis, and dehydration. The choice of the method depends on the availability of starting materials, the desired product, and the conditions of the reaction.

Also Read: Classification of Alcohols, Phenols and Ethers