Out of all isomers of C_4H_11N . How many are primary structures?

The correct answer is option 2. 4.

The molecular formula \(C_4H_{11}N\) represents different isomers of amines. To determine how many of these isomers are primary amines, let's first understand what primary amines are:

Primary Amines:

In a primary amine, the nitrogen atom is attached to one alkyl group and two hydrogen atoms, with the general formula \(RNH_2\). For \(C_4H_{11}N\), \(R\) represents different possible alkyl chains of four carbon atoms.

List all possible alkyl groups with four carbon atoms that can be attached to the nitrogen:

Butyl group (Straight chain): \(C_4H_9\) attached to \(NH_2\).

Isobutyl group: A branched isomer with the formula \(CH_3CH(CH_3)CH_2\).

Sec-butyl group: A secondary butyl group with the formula \(CH_3CH_2CH(CH_3)\).

Tert-butyl group: A tertiary butyl group with the formula \(C(CH_3)_3\).

List the Primary Structures:

n-Butylamine: \(CH_3CH_2CH_2CH_2NH_2\)

Isobutylamine: \(CH_3CH(CH_3)CH_2NH_2\)

Sec-butylamine: \(CH_3CH_2CH(NH_2)CH_3\)

Isopropylmethylamine: \(CH_3CH_2(CH_3)NH_2\)

These four structures correspond to primary amines, where the nitrogen is attached to one alkyl group and two hydrogen atoms.

There are 4 primary amines with the molecular formula \(C_4H_{11}N\), so the correct answer is option 2: 4.