If 1,3–dibromopropane reacts with zinc dust, the product obtained is:

Options

A. Propene
B. Propane
C. Cyclopropane
D. Hexane

Answer

To determine the product obtained when 1,3-dibromopropane reacts with zinc dust, we can follow these steps:

### Step 1: Identify the structure of 1,3-dibromopropane
1,3-dibromopropane has the following structure:
- It consists of a three-carbon chain (propane) with bromine atoms attached to the first and third carbon atoms.
- The molecular formula can be represented as CH2Br-CH2-CH2Br.

### Step 2: Understand the reaction conditions
The reaction involves zinc dust and typically occurs in the presence of an ether solvent. Zinc acts as a reducing agent, donating electrons.

### Step 3: Electron donation by zinc
Zinc will donate electrons to one of the carbon atoms bonded to bromine because bromine is more electronegative and will stabilize the negative charge. Let’s say zinc donates electrons to the carbon at position 1:
- The carbon at position 1 becomes negatively charged (delta negative) after receiving the electrons.

### Step 4: Formation of a carbanion
After the electron donation, we have:
- CH2Br-CH2-CH2 (with a negative charge on the first carbon).
- This carbanion is highly reactive and will seek to stabilize itself.

### Step 5: Elimination reaction
The negatively charged carbon (from step 4) will attack the carbon at position 3 (which has a bromine atom). This leads to an elimination reaction:
- The bromine atom at position 3 is eliminated along with the zinc bromide (ZnBr2) formed during the reaction.

### Step 6: Formation of cyclopropane
The elimination of ZnBr2 results in the formation of a cyclic compound:
- The three carbon atoms (from the original chain) will form a cyclopropane ring.
- The final product is cyclopropane.

### Final Answer
The product obtained from the reaction of 1,3-dibromopropane with zinc dust is **cyclopropane**.

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