The halide which will not react with benzene in presence of anhydrous `AlCl_(3)` is

Options

A. `CH_(3)CHClCH_(3)`
B. `C_(6)H_(5)CH_(2)Cl`
C. `C_(6)H_(5)Cl`
D. `CH_(3)" "CH_(2)CH_(2)Cl`

Answer

To determine which halide will not react with benzene in the presence of anhydrous AlCl₃, we need to analyze the behavior of different halides under Friedel-Crafts reactions.

### Step-by-Step Solution:

1. **Understanding Friedel-Crafts Reaction**:
The Friedel-Crafts reaction involves the electrophilic substitution of an aromatic compound (like benzene) using an alkyl or acyl halide in the presence of a Lewis acid catalyst, such as AlCl₃. The halide reacts with AlCl₃ to generate a more reactive electrophile.

2. **Analyzing Different Halides**:
- **Methyl Chloride (CH₃Cl)**:
- In the presence of AlCl₃, CH₃Cl loses Cl to form CH₃⁺ (methyl cation), which can react with benzene.
- **Ethyl Chloride (C₂H₅Cl)**:
- Similarly, C₂H₅Cl will also lose Cl in the presence of AlCl₃ to form C₂H₅⁺ (ethyl cation), which can react with benzene.
- **Chlorobenzene (C₆H₅Cl)**:
- Chlorobenzene, however, has a C-Cl bond that exhibits partial double bond character due to resonance. The lone pair of electrons on the chlorine atom can delocalize into the aromatic ring, stabilizing the C-Cl bond and making it less reactive. Thus, the bond does not break easily in the presence of AlCl₃, and therefore chlorobenzene will not react with benzene.

3. **Conclusion**:
The halide that will not react with benzene in the presence of anhydrous AlCl₃ is **Chlorobenzene (C₆H₅Cl)**.