Three molecules of acetone in the presence of dry HCl form `:`

Options

A. Mesitylene
B. Phorone
C. Glyoxal
D. Mesity oxide

Answer

To solve the problem of what three molecules of acetone in the presence of dry HCl form, we can break it down step by step.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactant is acetone, which has the chemical formula \( \text{CH}_3\text{COCH}_3 \).

2. **Understand the Reaction Conditions**:
- The presence of dry HCl indicates that we are likely dealing with a condensation reaction where HCl acts as a catalyst.

3. **Determine the Reaction Type**:
- In the presence of HCl, acetone can undergo a reaction known as aldol condensation. However, since we are using three molecules, we should consider a more complex reaction that leads to the formation of a larger molecule.

4. **Write the Reaction**:
- When three molecules of acetone react, they can form a compound through a series of reactions. The reaction can be represented as:
\[ 3 \text{CH}_3\text{COCH}_3 \xrightarrow{\text{dry HCl}} \text{CH}_3\text{C}=\text{C}(\text{CH}_3)\text{C}=\text{C}(\text{CH}_3)\text{CO} \]

5. **Identify the Product**:
- The product formed from this reaction is a compound known as "foron" or "foronone", which has the structure:
\[ \text{CH}_3\text{C}=\text{C}(\text{CH}_3)\text{C}=\text{C}(\text{CH}_3)\text{CO} \]
- This compound features multiple double bonds and a carbonyl group.

6. **Conclusion**:
- Therefore, the final product formed from three molecules of acetone in the presence of dry HCl is foron.

### Final Answer:
Three molecules of acetone in the presence of dry HCl form foron.

---