Carboxylic acids containing an amino group `(-NH_(2))` as a substituent are called amino acids. When this amino group substitution is at `alpha` position with respect to carboxylic group, the aminoacid is called `alpha`-amino acid. The aminoacids with two carboxylic acids are called acidic amino acids whereas aminoacids with two amino group are called basic amino acids Amino acids show amphoteric character. Ali chiral natural amino acids exist in L-form. :
Which of the following is not an `alpha`-amino acid?

Options

A.
B.
C.
D.

Answer

To determine which of the given options is not an alpha-amino acid, we need to analyze each option based on the definition of alpha-amino acids. An alpha-amino acid is characterized by having an amino group (-NH₂) attached to the carbon atom that is adjacent (alpha position) to the carboxylic acid group (-COOH).

### Step-by-Step Solution:

1. **Understand the Structure of Alpha-Amino Acids**:
- An alpha-amino acid has the general structure where the amino group is on the carbon next to the carboxylic acid group. This carbon is referred to as the alpha carbon.

2. **Analyze Each Option**:
- **Option 1**: Check if the amino group is at the alpha position relative to the carboxylic acid group.
- If the amino group is present at the alpha position, it is an alpha-amino acid.
- **Option 2**: Again, check the position of the amino group.
- If the amino group is at the alpha position of a carboxylic acid, it qualifies as an alpha-amino acid.
- **Option 3**: Examine this option closely.
- If there is no amino group at the alpha carbon of the carboxylic acid, then it is not an alpha-amino acid.
- **Option 4**: Finally, check this option.
- If the amino group is at the alpha position, it is an alpha-amino acid.

3. **Identify the Correct Answer**:
- After analyzing all options, identify which option does not have the amino group at the alpha position. This option is the one that is not an alpha-amino acid.

### Conclusion:
- The answer is **Option 3**, as it does not have an amino group at the alpha position relative to the carboxylic acid group.