Which one of the following will not give alkyl cyanide on treatment with `P_(2)O_(5)`

Options

A.
B. `C_(6)H_(5)-CH=NOH`
C. `C_(6)H_(5)-underset("NOH")underset("| ")"C "-CH_(3)`
D. A and C

Answer

To determine which compound will not give alkyl cyanide upon treatment with \( P_2O_5 \), we need to analyze the structures of the given compounds and their ability to lose water (H2O) to form a cyanide.

### Step-by-Step Solution:

1. **Understanding the Role of \( P_2O_5 \)**:
- \( P_2O_5 \) is a dehydrating agent that removes water from compounds. For a compound to form an alkyl cyanide, it must have a hydroxyl group (–OH) and a hydrogen atom (–H) on the carbon that is adjacent to the hydroxyl group. This allows the removal of water (H2O) to form a cyano group (–C≡N).

2. **Analyzing Each Option**:
- **Option A**: If this compound has both –OH and –H, it can lose water to form an alkyl cyanide.
- **Option B**: Similarly, if this compound has both –OH and –H, it can also lose water to form an alkyl cyanide.
- **Option C**: If this compound has an –OH group but lacks a hydrogen atom on the carbon that is bonded to the –OH, it cannot lose water and therefore cannot form an alkyl cyanide.
- **Option D**: This option will also be analyzed based on its structure.

3. **Identifying the Non-Alkyl Cyanide Formers**:
- From the analysis, if Option C has an –OH but no hydrogen on the adjacent carbon, it will not form an alkyl cyanide.
- If Option A is hydrogen cyanide (HCN), it is not considered an alkyl cyanide because it does not contain an alkyl group.

4. **Conclusion**:
- Both Option A (if it is HCN) and Option C (if it lacks a hydrogen atom adjacent to the hydroxyl group) will not form alkyl cyanides upon treatment with \( P_2O_5 \).
- Therefore, the correct answer is that both options A and C do not give alkyl cyanides.

### Final Answer:
The correct answer is **Option D (A and C)**.