Benzenediazonium chloride on reaction with aniline in weakly basic medium gives

Options

A. diphenyl ether
B. p-aminoazobenzene
C. Chlorobenzene
D. benzene

Answer

To solve the question regarding the reaction of benzenediazonium chloride with aniline in a weakly basic medium, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are benzenediazonium chloride (C6H5N2Cl) and aniline (C6H5NH2).

2. **Understand the Medium**:
- The reaction occurs in a weakly basic medium, typically with a pH range of 4 to 5. This means that the medium is not strongly acidic or basic, which allows for the reaction to proceed without excessive protonation of the reactants.

3. **Recognize the Reaction Type**:
- This reaction is an example of an electrophilic substitution reaction. In this case, the diazonium cation acts as the electrophile, while aniline acts as the nucleophile.

4. **Mechanism of the Reaction**:
- The diazonium cation (C6H5N2^+) has a positively charged nitrogen that is highly electrophilic. The lone pair of electrons on the amino group (NH2) of aniline attacks the electrophilic nitrogen of the diazonium ion.
- This results in the formation of a new bond and the release of HCl as a byproduct.

5. **Formation of the Product**:
- The product formed from this reaction is para-amino-azo-benzene (C6H5-N=N-C6H4-NH2). The amino group (NH2) on aniline directs the substitution to the para position due to its electron-donating nature, which increases electron density at the ortho and para positions of the aromatic ring.

6. **Final Product**:
- The final product of the reaction is para-amino-azo-benzene, which is characterized by the azo (-N=N-) linkage between the two aromatic rings.

### Conclusion:
The reaction of benzenediazonium chloride with aniline in a weakly basic medium gives **para-amino-azo-benzene**.