Which of the following compound will not show tautomerism ?

Options

A. `H_(3)C- overset(CH_(3)) overset(|) underset(CH_(3)) underset(|)(C)-N=O`
B. `CH_(3)-CH_(2)-NO_(2)`
C. `CH_(3)-NH-overset(O) overset(||)(C)-CH_(3)`
D. `CH_(3)- overset(O) overset(||)(C)-CH_(2)-overset(O) overset(||) (C)-OC_(2)H_(5)`

Explanation

To determine which compound does not show tautomerism, we need to analyze each compound based on the presence of alpha hydrogen atoms and the ability to exist in two tautomeric forms. Tautomerism typically involves the transfer of a hydrogen atom and the shift of a double bond.

### Step-by-Step Solution:

1. **Understanding Tautomerism**:
- Tautomerism is a chemical phenomenon where a compound can exist in two forms that are in equilibrium. This usually involves the migration of a hydrogen atom and a shift in the position of a double bond.

2. **Identify Alpha Hydrogen**:
- Alpha hydrogen atoms are those hydrogen atoms that are attached to the carbon adjacent to a functional group (like a carbonyl group). For a compound to exhibit tautomerism, it must have at least one alpha hydrogen.

3. **Analyze Each Option**:
- **Option 1**: CH3-N=O (with two methyl groups on the nitrogen)
- This compound has no alpha hydrogen atoms because the carbon adjacent to the nitrogen has no hydrogen atoms. Therefore, it cannot show tautomerism.

- **Option 2**: CH3-CH(NH)-C=O
- This compound has alpha hydrogen atoms on the carbon adjacent to the carbonyl group. It can undergo tautomerism by transferring one of the hydrogen atoms to form an enol.

- **Option 3**: CH3-NH-C(=O)-CH3
- This compound also has alpha hydrogen atoms on the carbon adjacent to the carbonyl group. It can similarly undergo tautomerism.

- **Option 4**: CH3-C(=O)-CH2-C(=O)-CH3
- This compound has multiple alpha hydrogen atoms and can undergo tautomerism by transferring hydrogen from the methylene group adjacent to the carbonyl.

4. **Conclusion**:
- Among the options, **Option 1 (CH3-N=O)** is the only compound that does not have any alpha hydrogen atoms and therefore does not show tautomerism.

### Final Answer:
The compound that will not show tautomerism is **Option 1 (CH3-N=O)**.

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