Which is the major product formed when acetone is heated with iodine and potassium hydroxide ?

Options

A. Acetophenone
B. Iodoform
C. lodoacetone
D. Acetic acid

Answer

To determine the major product formed when acetone is heated with iodine and potassium hydroxide, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants are acetone (CH₃COCH₃), iodine (I₂), and potassium hydroxide (KOH).

2. **Understand the Reaction Mechanism**: The reaction involves the halogenation of acetone at the alpha position. Potassium hydroxide acts as a base and abstracts an alpha hydrogen from acetone.

3. **Formation of Enolate Ion**: When KOH abstracts an alpha hydrogen from acetone, it forms an enolate ion. The structure of the enolate ion can be represented as:
\[ CH₃C(=O)CH_2^- \]

4. **Resonance Stabilization**: The enolate ion can undergo resonance, where the negative charge can be delocalized. This leads to the formation of:
\[ CH₃C(=O)C^-(CH_2) \]

5. **Iodination Step**: The enolate ion reacts with iodine (I₂). The oxygen atom of the carbonyl group donates a lone pair to form a bond with iodine, leading to the formation of an iodo compound:
\[ CH₃C(=O)CH_2I \]

6. **Further Halogenation**: The presence of KOH allows for the abstraction of another alpha hydrogen from the iodo compound, leading to the formation of another enolate ion, which can again react with iodine. This results in the formation of:
\[ CH₃C(=O)C(I)₂ \]

7. **Formation of Iodoform**: The final step involves the reaction of the iodo compound with KOH, which leads to the elimination of iodoform (CHI₃) and the formation of potassium acetate (CH₃COOK):
\[ CH₃COOK + CHI₃ \]

8. **Final Product**: The major product formed is iodoform (CHI₃).

### Conclusion:
The major product formed when acetone is heated with iodine and potassium hydroxide is **iodoform (CHI₃)**.