Propyne on passing through red hot copper tube forms

Options

A. benzene
B. 1,3,5 - trimethylbezene
C. toluene
D. hexamethylbenzene

Answer

To solve the question regarding the reaction of propyne when passed through a red hot copper tube, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactant**:
Propyne is an alkyne with the chemical formula C₃H₄. Its structure can be represented as CH₃C≡CH.

2. **Understand the Reaction Conditions**:
When propyne is passed through a red hot copper tube, it undergoes a process known as pyrolysis or cracking. This process involves breaking the triple bond in propyne due to the high temperature.

3. **Predict the Products**:
The thermal decomposition of propyne can lead to various products, including smaller hydrocarbons and aromatic compounds. In this case, the reaction can lead to the formation of benzene derivatives.

4. **Formation of Methylstyrene**:
One of the products formed is methylstyrene (C₈H₈), which can be represented as a benzene ring with a methyl group attached to it. The structure can be drawn as follows:
- A benzene ring (C₆H₆) with one methyl group (CH₃) attached, resulting in C₇H₈.

5. **Identify the Final Product**:
The specific product formed from propyne under these conditions is 1,3,5-trimethylbenzene (also known as pseudocumene). This compound has three methyl groups attached to the benzene ring at the 1, 3, and 5 positions.

6. **Conclusion**:
Therefore, when propyne is passed through a red hot copper tube, it forms 1,3,5-trimethylbenzene (methylstyrene).

### Final Answer:
The correct answer is **1,3,5-trimethylbenzene**.