3-methyl-pent-2-ene on reaction with HBr in the presence of peroxide forms an addition product. The number of possible stereoisomers for the product is

Options

A. two
B. four
C. six
D. zero

Answer

To determine the number of possible stereoisomers for the addition product formed when 3-methyl-pent-2-ene reacts with HBr in the presence of peroxide, we can follow these steps:

### Step 1: Identify the structure of 3-methyl-pent-2-ene
3-methyl-pent-2-ene is an alkene with the following structure:

```
CH3
|
CH3-CH-CH=CH-CH3
```

### Step 2: Understand the reaction with HBr in the presence of peroxide
When alkenes react with HBr in the presence of peroxides, the reaction follows the anti-Markovnikov rule. This means that the bromine atom will add to the less substituted carbon of the double bond.

### Step 3: Identify the possible addition products
In the case of 3-methyl-pent-2-ene, the double bond is between the second and third carbon atoms. The addition of HBr will result in the following two possible products:

1. **Product 1**: H adds to the second carbon, and Br adds to the third carbon.
2. **Product 2**: H adds to the third carbon, and Br adds to the second carbon.

### Step 4: Determine the stereochemistry of the products
Both products can lead to stereoisomers due to the presence of a chiral center. Specifically, the carbon that is bonded to the bromine atom can have different spatial arrangements (R/S configurations).

### Step 5: Count the stereoisomers
For each product, we need to check if there are any chiral centers:

- **Product 1**: This product has one chiral center (the carbon that is bonded to Br).
- **Product 2**: This product also has one chiral center.

Each chiral center can exist in two configurations (R or S), leading to:

- For Product 1: 2 stereoisomers (R and S)
- For Product 2: 2 stereoisomers (R and S)

### Step 6: Calculate the total number of stereoisomers
Since there are two products, each with two stereoisomers, the total number of possible stereoisomers is:

Total stereoisomers = 2 (from Product 1) + 2 (from Product 2) = 4 stereoisomers.

### Final Answer
The number of possible stereoisomers for the product is **4**.

---