The compound `C_5 H_(13) N` is optically active and reacts with HONO to give `C_5 H_(11) OH`. The compound is

Options

A. 2-amino pentane
B. N-methyl butanamine
C. N,N-Dimethyl propanamine
D. 1- amino pentane

Answer

To solve the problem, we need to determine the compound with the molecular formula \( C_5H_{13}N \) that is optically active and reacts with nitrous acid \( HONO \) to yield \( C_5H_{11}OH \).

### Step 1: Identify the type of amine
The compound \( C_5H_{13}N \) is an amine. Given that it is optically active, it must have a chiral center. A chiral center is typically a carbon atom bonded to four different groups.

### Step 2: Determine possible structures
We need to consider the possible structures of \( C_5H_{13}N \) that could contain a chiral carbon. The options provided are:
1. 2-Aminopentane
2. N-Methylbutanamine
3. N,N-Dimethylpropanamine
4. 1-Aminopentane

### Step 3: Analyze each option for chirality
1. **2-Aminopentane**: The structure is:
\[ CH_3-CH(NH_2)-CH_2-CH_2-CH_3 \]
The carbon atom at position 2 is bonded to \( NH_2 \), \( CH_3 \), \( CH_2-CH_2-CH_3 \) (the rest of the pentane chain), and \( H \). This carbon is chiral.

2. **N-Methylbutanamine**: The structure is:
\[ CH_3-CH_2-CH(NH_2)-CH_3 \]
The nitrogen is bonded to a methyl group and the butane chain, but the carbon with the amine group is not chiral.

3. **N,N-Dimethylpropanamine**: The structure is:
\[ CH_3-CH(N(CH_3)_2)-CH_2-CH_3 \]
The carbon with the amine group is not chiral since it has two identical methyl groups attached.

4. **1-Aminopentane**: The structure is:
\[ NH_2-CH_2-CH_2-CH_2-CH_3 \]
The amine is at the terminal position, and there is no chiral center.

### Step 4: Determine the reaction with nitrous acid
The reaction of a primary amine with nitrous acid \( HONO \) typically yields an alcohol. Since 2-aminopentane is a primary amine, it will react with \( HONO \) to form 2-hydroxypentane:
\[ C_5H_{13}N + HONO \rightarrow C_5H_{11}OH + N_2 + H_2O \]

### Conclusion
The only compound that meets all the criteria (optically active, primary amine, and reacts with nitrous acid to form an alcohol) is **2-aminopentane**.

### Final Answer
The compound is **2-aminopentane**.

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