Chlorination of toluene in the presence of light and heat followed by treatment with aqueous NaOH gives

Options

A. o - Cresol
B. p - Cresol
C. 2, 4- Dihydroxytoluene
D. Benzoic acid

Answer

To solve the problem of what product is formed from the chlorination of toluene in the presence of light and heat, followed by treatment with aqueous NaOH, we can break it down into a series of steps:

### Step 1: Understand the structure of Toluene
Toluene is a methyl-substituted benzene, with the molecular formula C7H8. Its structure can be represented as follows:

```
CH3
|
C6H5
```

### Step 2: Chlorination of Toluene
When toluene is treated with chlorine (Cl2) in the presence of light and heat, a free radical substitution reaction occurs. The hydrogen atoms on the aromatic ring can be substituted by chlorine atoms.

- The reaction can proceed with the substitution of one hydrogen atom at a time.
- Chlorination can occur at different positions on the benzene ring, leading to ortho and para products.

For example:
1. First substitution: Toluene (C7H8) → Chlorotoluene (C7H7Cl) + HCl
2. Second substitution: Chlorotoluene → Dichlorotoluene (C7H6Cl2) + HCl
3. Third substitution: Dichlorotoluene → Trichlorotoluene (C7H5Cl3) + HCl

### Step 3: Treatment with Aqueous NaOH
After chlorination, the product (trichlorotoluene) is treated with aqueous NaOH. This will lead to a nucleophilic substitution reaction where the chlorine atoms are replaced by hydroxyl (OH) groups.

- The reaction can be summarized as:
- Trichlorotoluene (C7H5Cl3) + 3 NaOH → Toluene-3,4-diol (C7H5(OH)3) + 3 NaCl

### Step 4: Dehydration of the Intermediate
The product formed (toluene-3,4-diol) is unstable due to the presence of three hydroxyl groups on the same carbon. It will lose a water molecule (dehydration) to form benzoic acid.

- The reaction can be summarized as:
- Toluene-3,4-diol → Benzoic acid (C7H6O2) + H2O

### Final Product
The final product of the reaction is benzoic acid (C7H6O2).

### Conclusion
Thus, the chlorination of toluene in the presence of light and heat followed by treatment with aqueous NaOH gives benzoic acid.

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