Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Aldehydes, Ketones and Carboxylic Acids

Question:

Case: Read the passage and answer the following questions

Aldehydes and ketones are generally prepared by oxidation of primary and secondary alcohols. Dehydrogenation of alcohols gives aldehydes and ketones. Ozonolysis alkenes give aldehydes ketones or a mixture of both depending on the substitution pattern of the alkene. Aldehydes are prepared from acyl chloride, nitrile, esters and even from hydrocarbons by different kinds of oxidation. Ketones are prepared from benzene or its derivatives through Friedel-Crafts acylation reaction. Carboxylic acids are prepared from aldehydes and ketones on oxidation. Nitriles are hydrolysed to amides and then to carboxylic acids. It is even prepared using Grignard’s reagent.

Acyl chloride (acid chloride) is hydrogenated over a catalyst, palladium on barium sulphate. What is the name of the reaction?

Options:

Wurtz reaction

Rosenmund reduction.

Sandmeyers reaction

None of these

Correct Answer:

Rosenmund reduction.

Explanation:

The correct answer is option 2. Rosenmund reduction.

Acyl chloride (acid chloride) is hydrogenated over a catalyst, palladium on barium sulphate. This reaction is called Rosenmund reduction.

  • Wurtz reaction: This is used to prepare higher alkanes by reacting alkyl halides with metallic sodium in dry ether ($2RX + 2Na \rightarrow R - R + 2NaX$).
  • Sandmeyer's reaction: This involves the replacement of a diazonium group in an aromatic diazonium salt with a nucleophile like $Cl^{-}$, $Br^{-}$, or $CN^{-}$ using cuprous salts ($Cu_{2}X_{2}$).