In the reaction sequence `CH_3CHOoverset(NH_2OH//overset(o+)H)rarr(A)overset(P_2O_5//Delta)rarr(B)`, B will be

Options

A. `CH_3CH=NOH`
B. `H_2C=NOH`
C. `CH_3CN`
D. `CH_3CH_2NH_2`

Answer

To solve the problem, we will analyze the reaction sequence step by step.

1. **Identify the starting compound**: The starting compound is CH₃CHO, which is acetaldehyde.

2. **First reaction with NH₂OH**: When acetaldehyde (CH₃CHO) reacts with hydroxylamine (NH₂OH) in the presence of an acid (H⁺), it forms an oxime. The reaction can be represented as:
\[ \text{CH}_3\text{CHO} + \text{NH}_2\text{OH} \rightarrow \text{CH}_3\text{C}=\text{N-OH} + \text{H}_2\text{O} \]
The product formed is CH₃C=N-OH, which is called acetaldehyde oxime (compound A).

3. **Second reaction with P₂O₅ and heating**: The next step involves treating the oxime (compound A) with phosphorus pentoxide (P₂O₅) and heating it. P₂O₅ acts as a dehydrating agent, removing a water molecule from the oxime. The reaction can be represented as:
\[ \text{CH}_3\text{C}=\text{N-OH} \xrightarrow{\text{P}_2\text{O}_5, \Delta} \text{CH}_3\text{C} \equiv \text{N} + \text{H}_2\text{O} \]
The product formed is CH₃C≡N, which is called propionitrile (compound B).

4. **Final product**: Therefore, the final product B is CH₃C≡N (propionitrile).

### Summary of the Steps:
- Step 1: Start with CH₃CHO (acetaldehyde).
- Step 2: React with NH₂OH to form CH₃C=N-OH (acetaldehyde oxime).
- Step 3: Treat with P₂O₅ and heat to remove water and form CH₃C≡N (propionitrile).

### Final Answer:
The compound B formed in the reaction sequence is CH₃C≡N (propionitrile).