If acetylene is reacted with an excess of sodium metal in hexane
and the reaction product is treated with 1-bromopropane ,
the final product will be

Options

A. 3-octene
B. 4-octyne
C. 8-octane
D. none of the above

Explanation

To solve the problem step by step, we will analyze the reaction of acetylene with sodium metal in hexane and the subsequent reaction with 1-bromopropane.

### Step 1: Reaction of Acetylene with Sodium Metal
Acetylene (C₂H₂) reacts with sodium metal (Na) in the presence of hexane. This reaction leads to the formation of a compound known as disodium acetylide.

**Reaction:**
\[ 2 \, \text{C}_2\text{H}_2 + 2 \, \text{Na} \rightarrow \text{Na}_2\text{C}_2 + 2 \, \text{H}_2 \]

Here, disodium acetylide (\(\text{Na}_2\text{C}_2\)) is formed.

### Step 2: Reaction of Disodium Acetylide with 1-Bromopropane
Next, the disodium acetylide reacts with 1-bromopropane (C₃H₇Br). In this reaction, the sodium atoms in the disodium acetylide are replaced by the propyl groups from 1-bromopropane through a nucleophilic substitution reaction.

**Reaction:**
\[ \text{Na}_2\text{C}_2 + 2 \, \text{C}_3\text{H}_7\text{Br} \rightarrow \text{C}_2\text{C}(\text{C}_3\text{H}_7)_2 + 2 \, \text{NaBr} \]

### Step 3: Structure of the Final Product
The resulting product from this reaction is 4-octyne. The structure can be visualized as follows:

- The original acetylene has two carbon atoms, and each sodium atom is replaced by a propyl group (C₃H₇).
- The final structure will have a total of 8 carbon atoms, with a triple bond between the second and third carbon atoms.

### Final Product
Thus, the final product of the reaction is **4-octyne**.

### Summary of the Steps:
1. Acetylene reacts with sodium to form disodium acetylide.
2. Disodium acetylide reacts with 1-bromopropane, leading to the substitution of sodium with propyl groups.
3. The final product is 4-octyne.