The reaction of `RCONH_(2)` with a mixture of `Br_(2)` and aqueous `KOH` gives `RNH_(2)` as the main product The intermediate (s) involved in this reation is (are) .

Options

A. `RCONHBr`
B. `RCON^(-)BrK^(+)`
C. `R-N=C=O`
D. `RCONBr_(2)`

Answer

To solve the question regarding the reaction of `RCONH2` with a mixture of `Br2` and aqueous `KOH`, we will analyze the reaction step by step and identify the intermediates involved.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
The reaction in question is known as the Hofmann bromamide degradation reaction. It involves the conversion of a primary amide (`RCONH2`) into a primary amine (`RNH2`) using bromine (`Br2`) and a strong base like potassium hydroxide (`KOH`).

2. **Initial Reaction**:
The primary amide (`RCONH2`) reacts with bromine in the presence of KOH. The hydroxide ion (OH-) from KOH abstracts a hydrogen atom from the amide nitrogen, leading to the formation of an intermediate:
\[ RCONH2 + OH^- \rightarrow RCONH^- + H2O \]
Here, `RCONH^-` is the negatively charged intermediate formed.

3. **Formation of N-bromoamide**:
The negatively charged nitrogen in the intermediate attacks the bromine molecule, resulting in the formation of N-bromoamide:
\[ RCONH^- + Br2 \rightarrow RCONHBr + Br^- \]
This intermediate is called N-bromoamide (`RCONHBr`).

4. **Second Reaction with Hydroxide Ion**:
The N-bromoamide then reacts with another hydroxide ion from the KOH solution:
\[ RCONHBr + OH^- \rightarrow RCO^- + HBr + H2O \]
This leads to the formation of another intermediate, which can be represented as an anion of bromamide.

5. **Rearrangement to Isocyanide**:
The next step involves the rearrangement of the intermediate, breaking the carbon-nitrogen bond and forming isocyanide:
\[ RCO^- \rightarrow RNC \text{ (isocyanide)} \]

6. **Hydrolysis of Isocyanide**:
The isocyanide undergoes hydrolysis when water is added, leading to the formation of a carboxylic acid and the primary amine:
\[ RNC + H2O \rightarrow RNH2 + CO2 \]

7. **Final Product**:
The final product of the reaction is the primary amine (`RNH2`), and the intermediates involved are `N-bromoamide` and `isocyanide`.

### Conclusion:
The intermediates involved in the reaction of `RCONH2` with `Br2` and `KOH` are:
1. N-bromoamide (`RCONHBr`)
2. Isocyanide (`RNC`)