How many structural isomers can be obtained by the replacement of one hydrogen atom of propene with chlorine?

Options

A. 4
B. 3
C. 2
D. 5

Answer

To determine how many structural isomers can be obtained by replacing one hydrogen atom of propene (C3H6) with chlorine (Cl), we can follow these steps:

### Step 1: Identify the structure of propene.
Propene is an alkene with the molecular formula C3H6. Its structure can be represented as:
- CH2=CH-CH3

### Step 2: Understand the concept of structural isomers.
Structural isomers are compounds that have the same molecular formula but different structural arrangements of atoms. In this case, we will replace one hydrogen atom in propene with a chlorine atom.

### Step 3: Identify the positions for chlorine substitution.
In propene, we can replace one of the hydrogen atoms at different positions:
1. Replace a hydrogen on the first carbon (C1).
2. Replace a hydrogen on the second carbon (C2).
3. Replace a hydrogen on the third carbon (C3).

### Step 4: Draw the possible isomers.
1. **Chlorine on C1**:
- Structure: CHCl=CH-CH3
- IUPAC Name: 1-Chloropropene

2. **Chlorine on C2**:
- Structure: CH2=CH-CH2Cl
- IUPAC Name: 2-Chloropropene

3. **Chlorine on C3**:
- Structure: CH2=CHCl-CH3
- IUPAC Name: 3-Chloropropene

### Step 5: Count the structural isomers.
From the above structures, we can see that there are three distinct structural isomers:
1. 1-Chloropropene
2. 2-Chloropropene
3. 3-Chloropropene

### Conclusion:
Thus, the total number of structural isomers that can be obtained by replacing one hydrogen atom of propene with chlorine is **3**.