Which reagent can be used to convert a carboxylic acid chloride into a ketone ?

Options

A. Chromic acid
B. PCP
C. Diborane , hydrogen peroxide
D. An organolithium compound

Answer

To convert a carboxylic acid chloride into a ketone, we can use an organolithium compound, specifically a Gilman reagent (R2CuLi). Here is a step-by-step breakdown of the process:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We start with a carboxylic acid chloride, which has the general structure R-C(=O)-Cl, where R is an alkyl group.
- We need to introduce another alkyl group (R') to form a ketone, which has the structure R-C(=O)-R'.

2. **Choose the Reagent**:
- The reagent we will use is an organolithium compound, specifically a Gilman reagent (R2CuLi). This reagent contains two alkyl groups (R) and lithium (Li) combined with copper (Cu).

3. **Mechanism of Reaction**:
- The organolithium compound (R2CuLi) acts as a nucleophile. The alkyl group (R') from the Gilman reagent will attack the carbonyl carbon of the acid chloride.
- This attack results in the formation of a tetrahedral intermediate where the carbonyl bond (C=O) breaks, and the oxygen becomes negatively charged (an oxyanion).

4. **Formation of the Ketone**:
- The negatively charged oxygen can stabilize itself by forming a bond with another atom or by expelling the chloride ion (Cl-) as a good leaving group.
- The lithium ion (Li+) stabilizes the negative charge during the reaction.
- After the chloride ion is expelled, we are left with the ketone product, which has the structure R-C(=O)-R'.

5. **Final Product**:
- The final product of this reaction is a ketone, which is formed by the combination of the original alkyl group (R) from the acid chloride and the new alkyl group (R') from the Gilman reagent.

### Conclusion:
Thus, the correct reagent to convert a carboxylic acid chloride into a ketone is an organolithium compound, specifically a Gilman reagent (R2CuLi).