Which of the following will not exist in zwitter ionic form at pH=7?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds will not exist in zwitterionic form at pH 7, we need to understand the concept of zwitterions and the nature of the functional groups present in the compounds.

### Step-by-Step Solution:

1. **Understanding Zwitterions**:
- A zwitterion is a molecule that has both a positive and a negative charge but is overall electrically neutral. This typically occurs in amino acids where the amino group (-NH2) can accept a proton (H+) to become (-NH3+), and the carboxylic acid group (-COOH) can lose a proton to become (-COO-).

2. **Identifying Functional Groups**:
- We need to analyze the functional groups in each option provided. A zwitterion requires the presence of both a basic group (which can accept a proton) and an acidic group (which can donate a proton).

3. **Analyzing Each Option**:
- **Option 1**: Contains an amino group (-NH2) and a carboxylic acid group (-COOH).
- At pH 7, the amino group will become -NH3+ and the carboxylic acid will become -COO-. This will form a zwitterion.

- **Option 2**: Contains an amide group (-C(=O)NH2) and a carboxylic acid group (-COOH).
- The amide nitrogen is not basic because its lone pair is involved in resonance with the carbonyl group, thus it cannot accept a proton. Therefore, there is no basic group present, and this compound cannot form a zwitterion.

- **Option 3**: Contains an amino group (-NH2) and a sulfonic acid group (-SO3H).
- The amino group will become -NH3+ and the sulfonic acid will become -SO3-. This will form a zwitterion.

- **Option 4**: Contains an amino group (-NH2) and a sulfonic acid group (-SO3H) in a cyclic structure.
- Similar to option 3, the amino group will become -NH3+ and the sulfonic acid will become -SO3-. This will also form a zwitterion.

4. **Conclusion**:
- The only option that does not form a zwitterion at pH 7 is **Option 2**, which contains an amide group and a carboxylic acid group.

### Final Answer:
**Option 2** will not exist in zwitterionic form at pH 7.