Which of the following compound does not show tautomerism?

Options

A. `NH_(2)-overset(O) overset(||)(C)-NH_(2)`
B. `NH_(2)-overset(S) overset(||)(C)-NH_(2)`
C. `CH_(3)- overset(O) overset(||)(C)-CH_(3)`
D.

Explanation

To determine which of the given compounds does not show tautomerism, we need to understand the concept of tautomerism and the structural requirements for it to occur.

### Step-by-Step Solution:

1. **Understanding Tautomerism**: Tautomerism is a type of isomerism where two or more compounds (tautomers) can interconvert by the movement of a hydrogen atom and a shift of a double bond. This typically requires the presence of an alpha hydrogen (a hydrogen atom attached to a carbon atom adjacent to a functional group).

2. **Identifying the Compounds**: We need to analyze the structures of the given compounds to check for the presence of alpha hydrogens.

3. **Analyzing Each Compound**:
- **Compound 1**: This compound has an -OH group and an -NH group. It has alpha hydrogens that can participate in tautomerism.
- **Compound 2**: Similar to Compound 1, it has functional groups that allow for the presence of alpha hydrogens, enabling tautomerism.
- **Compound 3**: This compound also contains alpha hydrogens and can undergo tautomerism.
- **Compound 4**: This compound lacks alpha hydrogens. The nitrogen atoms are bonded in such a way that there are no adjacent hydrogen atoms that can shift to form a tautomer.

4. **Conclusion**: Based on the analysis, the compound that does not show tautomerism is **Compound 4**, as it does not have any alpha hydrogens available for the tautomeric shift.

### Final Answer:
The compound that does not show tautomerism is **Compound 4**.

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