Question

Which of the following is a $3^{\circ }$ amine?

• A. 1-methylcyclohexylamine
• B. tert-butylamine
• C. N-methylaniline
• D. Triethylamine

Answer 1

The correct option is D Triethylamine

Classification of amines

Amines are classified as primary$\left(1^{\circ }\right)$, secondary$\left(2^{\circ }\right)$ and tertiary $\left(3^{\circ }\right)$ depending upon the number of hydrogen atoms replaced by alkyl groups in ammonia molecules.

• If one hydrogen atom of ammonia is replaced by R or Ar, we get $R-N{H}_{2}orAr-N{H}_2$, i.e. a primary amine $\left(1^{\circ }\right)$.
• If two hydrogen atoms of ammonia are replaced by another alkyl/aryl$\left(R^{\prime }/Ar\text{'}\right)$ group, we get $R-NH{R}^{\prime }$ or $R-NHA{r}^{\prime }$, i.e. secondary amine $\left(2^{\circ }\right)$.
• If all the three hydrogen atoms are replaced by alkyl/aryl group, it leads to the formation of tertiary amine$(3^{\circ }$) like $R_{2}N-R$ or $R_{2}N-Ar.$

Hence, the correct option is (B).