Which of the following is most reactive towards aqueous NaOH?

Options

A. `C_6H_5Cl`
B. `C_6H_5CH_2Cl`
C. `C_6H_5Br`
D. `BrC_6H_4Br`

Explanation

To determine which of the given compounds is most reactive towards aqueous NaOH, we need to analyze the reactivity of each compound with respect to nucleophilic substitution reactions.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- Benzyl chloride
- Benzyl methyl chloride
- Bromobenzene
- Dibromobenzene

2. **Understand the Reaction Type**: Aqueous NaOH acts as a nucleophile in a nucleophilic substitution reaction (SN1 or SN2). The reactivity of haloalkanes and haloarenes towards nucleophilic substitution varies significantly.

3. **Reactivity of Haloalkanes**:
- Haloalkanes (like benzyl chloride and benzyl methyl chloride) are generally more reactive towards nucleophiles because they have a carbon-halogen single bond that can be easily broken.
- Benzyl chloride (C6H5CH2Cl) is particularly reactive due to the stability of the benzyl cation formed during the reaction.

4. **Reactivity of Aryl Halides**:
- Aryl halides (like bromobenzene) are less reactive because the carbon-halogen bond is partially double-bonded due to resonance with the aromatic ring. This makes the bond stronger and less susceptible to nucleophilic attack.
- Dibromobenzene, being an aryl halide with two bromine atoms, is even less reactive.

5. **Compare the Reactivity**:
- Between benzyl chloride and benzyl methyl chloride, benzyl chloride is more reactive because it can form a stable benzyl cation.
- Bromobenzene and dibromobenzene are less reactive than both benzyl chloride and benzyl methyl chloride due to resonance stabilization.

6. **Conclusion**: Based on the analysis, benzyl chloride is the most reactive compound towards aqueous NaOH.

### Final Answer:
**Benzyl chloride** is the most reactive towards aqueous NaOH.

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