Total number of isomeric products(excluding stereoisomers) formed on monochlorination of 2-methylbutane are

Options

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

Answer

To determine the total number of isomeric products (excluding stereoisomers) formed on the monochlorination of 2-methylbutane, we can follow these steps:

### Step 1: Identify the Structure of 2-Methylbutane
2-Methylbutane has the following structure:
```
CH3
|
CH3 - CH - CH2 - CH3
```
This molecule has a total of 5 carbon atoms, with a methyl group attached to the second carbon.

### Step 2: Understand Monochlorination
Monochlorination involves replacing one hydrogen atom in the molecule with a chlorine atom (Cl). The different positions where chlorine can replace hydrogen will lead to different isomers.

### Step 3: Identify Possible Hydrogen Atoms for Substitution
In 2-methylbutane, we can identify the hydrogen atoms that can be replaced by chlorine:
- **From the terminal CH3 groups** (2 positions)
- **From the CH2 group** (1 position)
- **From the CH group** (1 position)

### Step 4: List the Isomeric Products
Now, we will consider the different positions where chlorine can be substituted:

1. **Substituting at the first carbon (C1)**:
- Product: 1-chloro-2-methylbutane
- Structure:
```
CH3
|
Cl - CH - CH2 - CH3
```

2. **Substituting at the second carbon (C2)**:
- Product: 2-chloro-2-methylbutane
- Structure:
```
CH3
|
CH3 - C - CH2 - CH3
|
Cl
```

3. **Substituting at the third carbon (C3)**:
- Product: 2-chloro-3-methylbutane
- Structure:
```
CH3
|
CH3 - CH - CH - CH3
|
Cl
```

4. **Substituting at the fourth carbon (C4)**:
- Product: 3-chloro-2-methylbutane
- Structure:
```
CH3
|
CH3 - CH - CH2 - CH
|
Cl
```

### Step 5: Count the Isomers
From the above substitutions, we have identified the following four isomers:
1. 1-chloro-2-methylbutane
2. 2-chloro-2-methylbutane
3. 2-chloro-3-methylbutane
4. 3-chloro-2-methylbutane

### Final Answer
The total number of isomeric products (excluding stereoisomers) formed on monochlorination of 2-methylbutane is **4**.

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