Which of the following nitoalkane will not show tautomerism ?

Options

A. `CH_3CH_2CH_2CH_2NO_2`
B. `CH_3-CH-underset(CH_3)underset(|)(CH_2)-CH_2NO_2`
C. `CH_3-underset(NO_2)underset(|)(CH)-CH_2-CH_3`
D.

Answer

To determine which nitroalkane will not show tautomerism, we need to understand the concept of tautomerism and the role of alpha hydrogens in this process.

### Step-by-Step Solution:

1. **Understanding Tautomerism**: Tautomerism is a type of structural isomerism where isomers (tautomers) can readily interconvert, typically involving the migration of a hydrogen atom and a shift in the position of a double bond. For tautomerism to occur, at least one alpha hydrogen must be present.

2. **Identifying Alpha Hydrogens**: Alpha hydrogens are the hydrogen atoms attached to the carbon atom adjacent to the functional group (in this case, the nitro group). We need to analyze each option given in the question to check for the presence of alpha hydrogens.

3. **Analyzing Each Option**:
- **Option A**: Check the structure for alpha hydrogens. If it has at least one alpha hydrogen, it can show tautomerism.
- **Option B**: Check the structure for alpha hydrogens. If it has at least one alpha hydrogen, it can show tautomerism.
- **Option C**: Check the structure for alpha hydrogens. If it has at least one alpha hydrogen, it can show tautomerism.
- **Option D**: Check the structure for alpha hydrogens. If it has zero alpha hydrogens, it cannot show tautomerism.

4. **Conclusion**: After analyzing the options:
- Option A has 2 alpha hydrogens.
- Option B has 0 alpha hydrogens.
- Option C has 1 alpha hydrogen.
- Option D has 0 alpha hydrogens.

Since tautomerism requires at least one alpha hydrogen, the nitroalkane that will not show tautomerism is **Option B** (and also Option D, if both are considered).

5. **Final Answer**: The nitroalkane that will not show tautomerism is **Option B**.