Question

Draw structural formulas for the three secondary amines with the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{11} \mathrm{~N}\).

Short answer

Answer: The three secondary amines are: 1. \(\mathrm{CH}_{3} \mathrm{N} \mathrm{C}_{3} \mathrm{H}_{7}\) or H3C-N-CH2-CH2-CH3 2. \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{N} \mathrm{C}_{2} \mathrm{H}_{5}\) or CH3-CH2-N-CH2-CH3 3. \(\mathrm{CH}_{3} \mathrm{N} \mathrm{C}( \mathrm{C}_{3} \mathrm{H}_{7})_{2}\) or H3C-N-CH(CH3)2

Step-by-step solution

Understand the structure of secondary amines

In secondary amines, the nitrogen atom is bonded to two carbon atoms and one hydrogen atom. The general formula for a secondary amine is R1-NR2-H, where R1 and R2 are carbon chains that can be the same or different.

Identify the carbon chains in the molecular formula

In the given molecular formula \(\mathrm{C}_{4} \mathrm{H}_{11} \mathrm{~N}\), there are four carbon atoms. To find the isomers for secondary amines, we need to distribute the carbon atoms into different groups bonded to the nitrogen atom.

First Secondary Amine

Divide the four carbon atoms into two groups: one group with three carbon atoms (propyl group) and one group with one carbon atom (methyl group). The first secondary amine will have the structure \(\mathrm{CH}_{3} \mathrm{N} \mathrm{C}_{3} \mathrm{H}_{7}\), which can also be drawn as: ``` H | H3C-N-CH2-CH2-CH3 ```

Second Secondary Amine

Divide the four carbon atoms into two groups: one group with two carbon atoms (ethyl group) and another group with two carbon atoms (ethyl group). The second secondary amine will have the structure \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{N} \mathrm{C}_{2} \mathrm{H}_{5}\), which can also be drawn as: ``` H | CH3-CH2-N-CH2-CH3 ```

Third Secondary Amine

Divide the four carbon atoms into two groups: one group with one carbon atom (methyl group) and another group with three carbon atoms (isopropyl group). The third secondary amine will have the structure \(\mathrm{CH}_{3} \mathrm{N} \mathrm{C}( \mathrm{C}_{3} \mathrm{H}_{7})_{2}\), which can also be drawn as: ``` H | H3C-N-CH(CH3)2 ``` These are the three secondary amines with the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{11} \mathrm{~N}\).