Which is the most suitable reagent for the following conversion?
`CH_3-CH=CH-CH_2-overset(O) overset(||)C-CH_3 to CH_3 -CH=CH-CH_4- overset(O) overset(||)C-OH `

Options

A. Tollen's reagent
B. `I_2` and NaOH solution
C. Benzoyl peroxide
D. Sn and NaOH solution

Explanation

To solve the conversion of the compound \( CH_3-CH=CH-CH_2-C(=O)-CH_3 \) to \( CH_3-CH=CH-CH_2-C(=O)-OH \), we need to identify the most suitable reagent for this transformation. The first compound is an enone (which has a double bond and a ketone group), and the target compound is a carboxylic acid with the same double bond intact.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- The starting compound has a ketone functional group (C=O) and an alkene (C=C) functional group.
- The target compound has a carboxylic acid (C(=O)OH) and retains the alkene.

2. **Determine the Required Reaction**:
- We need to convert the ketone to a carboxylic acid while maintaining the alkene. This indicates that we need an oxidation reaction.

3. **Select the Appropriate Reagent**:
- The reagent must be capable of oxidizing the ketone to a carboxylic acid without affecting the double bond.
- One suitable reagent for this transformation is iodine (I2) in the presence of sodium hydroxide (NaOH). This is known as the haloform reaction, which can convert methyl ketones to carboxylic acids.

4. **Write the Reaction**:
- The reaction can be represented as follows:
\[ CH_3-CH=CH-CH_2-C(=O)-CH_3 + I_2 + NaOH \rightarrow CH_3-CH=CH-CH_2-C(=O)-OH + CHI_3 + Na^+ \]
- Here, the ketone is oxidized to a carboxylic acid, and a haloform (CHI3) is produced.

5. **Final Product**:
- The final product is \( CH_3-CH=CH-CH_2-C(=O)-OH \), which is the desired carboxylic acid.

### Conclusion:
The most suitable reagent for the conversion of \( CH_3-CH=CH-CH_2-C(=O)-CH_3 \) to \( CH_3-CH=CH-CH_2-C(=O)-OH \) is **I2 in NaOH**.

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