In which of the following can peroxide effect operate ?

Options

A. `CH_3CH_2CH=CH_2+HCl`
B. `CH_3CH_2CH=CH_2+HBr`
C. `CH_3CH=CHCH_3+HBr`
D. `CH_3CH_2CH=CH_2+HI`

Explanation

To determine in which of the given options the peroxide effect can operate, we need to analyze the conditions required for the peroxide effect to take place. The peroxide effect, also known as the Kharasch effect, typically occurs during the addition of hydrogen halides (like HBr) to alkenes in the presence of peroxides. Here are the steps to solve the problem:

### Step-by-Step Solution:

1. **Identify the Peroxide Effect Conditions**:
- The peroxide effect requires the presence of peroxides (ROOR).
- It is most commonly observed with hydrogen bromide (HBr).
- The alkene must be unsymmetrical for the peroxide effect to operate, leading to anti-Markovnikov addition.

2. **Analyze the Given Options**:
- Let's assume the options are:
1. HCl
2. HBr (unsymmetrical alkene)
3. HBr (symmetrical alkene)
4. HI

3. **Evaluate Each Option**:
- **Option 1: HCl** - The peroxide effect does not operate with HCl, so this option is not valid.
- **Option 2: HBr (unsymmetrical alkene)** - This option satisfies both conditions (presence of HBr and unsymmetrical alkene), so the peroxide effect can operate here.
- **Option 3: HBr (symmetrical alkene)** - While HBr is present, the alkene is symmetrical, which does not satisfy the requirement for the peroxide effect, so this option is not valid.
- **Option 4: HI** - The peroxide effect does not operate with HI, so this option is not valid.

4. **Conclusion**:
- The only option where the peroxide effect can operate is **Option 2** (HBr with an unsymmetrical alkene).

### Final Answer:
The peroxide effect can operate in **Option 2** (HBr with an unsymmetrical alkene).

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