Which of the following compounds is a tertiary amine?

• A. ${\mathrm{CH}}_3$$\mathrm{NH}$$2$
• B. ${\mathrm{CH}}_3$$\mathrm{NH}$${\mathrm{CH}}_3$
• C. ${\mathrm{CH}}_3$$\mathrm{NH}$${\mathrm{CH}}_2$${\mathrm{CH}}_3$
• D. ${\mathrm{CH}}_3$${\mathrm{CH}}_2$$N$${\mathrm{CH}}_3$${\mathrm{CH}}_3$

Answer: (D)

Verified step by step guidance

1. Recall the definition of primary, secondary, and tertiary amines: a primary amine has one alkyl or aryl group attached to the nitrogen, a secondary amine has two, and a tertiary amine has three.
2. Identify the nitrogen atom in each compound and count how many carbon-containing groups (alkyl groups) are directly bonded to it.
3. For example, in methylamine (CH\_3NH\_2), the nitrogen is bonded to one methyl group and two hydrogens, so it is a primary amine.
4. In dimethylamine (CH\_3NHCH\_3), the nitrogen is bonded to two methyl groups and one hydrogen, making it a secondary amine.
5. In the compound where nitrogen is bonded to three alkyl groups (such as CH\_3CH\_2NCH\_3CH\_3), the nitrogen has three carbon substituents, which classifies it as a tertiary amine.