Acid can be reduced into ketone by -

Concept:

• Reduction of Carboxylic Acids: Carboxylic acids can be reduced to alcohols or ketones using different reagents.

  • NaBH₄ (Sodium Borohydride): This reagent is typically used to reduce aldehydes and ketones to alcohols. It is not effective for reducing carboxylic acids.

  • LiAlH₄ (Lithium Aluminium Hydride): This is a strong reducing agent that can reduce carboxylic acids to primary alcohols, but it is not used to reduce carboxylic acids to ketones.

  • R₂CuLi (Diorganocopper Reagents): These reagents, also known as Gilman reagents, are used to couple with epoxides, alkyl iodides, and certain other electrophiles, but they are not typically used for the reduction of carboxylic acids to ketones.

  • R-Li (Organolithium Reagents): Organolithium reagents can reduce carboxylic acids to ketones by first converting the carboxylic acid to a lithium carboxylate and then reacting with another equivalent of the organolithium reagent to form a ketone.

Explanation:

• NaBH₄:

  • Sodium borohydride is not effective for reducing carboxylic acids to ketones.

• LiAlH₄:

  • Lithium aluminium hydride reduces carboxylic acids to primary alcohols, not ketones.

• R₂CuLi:

  • Diorganocopper reagents are not typically used to reduce carboxylic acids to ketones.

• R-Li:

  • Organolithium reagents can reduce carboxylic acids to ketones through the formation of a lithium carboxylate intermediate, which then reacts with another equivalent of the organolithium reagent to form the ketone.

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Conclusion:

The correct reagent to reduce a carboxylic acid to a ketone is: R-Li