Chapter 10. Organic Chemistry

10.5 Nomenclature of Amines

Learning Objectives

By the end of this section, you will be able to:
  • Describe the structure and properties of an amine.
  • Distinguish between a primary, secondary and tertiary amine.
  • Name and draw structures for primary, secondary and tertiary amines.

An amine is an organic derivative of ammonia (NH3). In amines, one or more of the H atoms in NH3 is substituted with an organic group.

A primary amine has one H atom substituted with an R group: A secondary amine has two H atoms substituted with an R group: A tertiary amine has all three H atoms substituted with R groups:

 Like ammonia, amines are weak bases due to the lone pair of electrons on their nitrogen atoms:

Two reactions are shown. In the first, ammonia reacts with H superscript plus. An unshared pair of electron dots sits above the N atom. To the left, right, and bottom, H atoms are bonded. This is followed by a plus symbol and an H atom with a superscript plus symbol. To the right of the reaction arrow, ammonium ion is shown in brackets with a superscript plus symbol outside. Inside the brackets, the N atom is shown with H atoms bonded on all four sides. In a very similar second reaction, methyl amine reacts with H superscript plus to yield methyl ammonium ion. The methyl amine structure is like ammonia except a C H subscript 3 group is attached in place of the left most H atom in the structure. Similarly, the resulting methyl ammonium ion is represented in brackets with a superscript plus symbol appearing outside. Inside, the structure is similar to that of methyl amine except that an H atom appears at the top of the N atom where the unshared electron pair was previously shown.

The basicity of an amine’s nitrogen atom plays an important role in much of the compound’s chemistry.

Naming Amines

The alkyl groups connected to the nitrogen atom are named separately and followed by “amine.”  If some alkyl groups are the same, then a prefix is used (di or tri), as illustrated here for a few simple examples:

Three structures are shown, each with a red, central N atom which has a pair of electron dots indicated in red above the N atoms. The first structure is labeled methyl amine. To the left of the N, a C H subscript 3 group is bonded. H atoms are bonded to the right and bottom of the central N atom. The second structure is labeled dimethyl amine. This structure has C H subscript 3 groups bonded to the left and right of the N atom and a single H atom is bonded below. The third structure is labeled trimethyl amine, which has C H subscript 3 groups bonded to the left, right, and below the central N atom.

Example 1

Name the following organic compounds:

a) (CH3)2NCH2CH3    b) CH3CH2CH2NHCH3   c) CH3(CH3CH2)NCH2CH2CH3


a) ethyldimethylamine    b) methylpropylamine   c) ethylmethylpropylamine


Test Yourself
Give the condensed structure of the following amines:

a) butylamine   b) trihexylamine   c) methylpentylamine



a) CH3CH2CH2CH2NH2    b) (CH3CH2CH2CH2CH2CH2)3N   c) CH3(CH3CH2CH2CH2CH2)NH

Key Concepts and Summary

Compounds containing a nitrogen atom bonded in a hydrocarbon framework are classified as amines. Amines are a basic functional group. An acid-base reaction occurs when an amine is mixed with and an acid.

The systematic methods of naming amines follow a simple procedure:
primary amines: ALKYLamine  
secondary amines: ALKYLALKYLamine    or   diALKYLamine
tertiary amines: ALKYLALKYLALKYLamine    or   triALKYLamine


1. What are the structure and name of the smallest amine?

2. Identify each compound as a primary, secondary, or tertiary amine.

a)  cysteine

b)  Question 3-2

c)  ex_3c

3. Identify each compound as a primary, secondary, or tertiary amine.

a)  ex_4a

b)  Question 4-2

4. Write the chemical reaction between each amine in Exercise 2 and HCl.

5. Name each amine.

a)  ex_3c    b)  ethyldipropylamine

c)ex_8a    d) example_11



1. CH3NH2; methylamine

2. a)  primary  b)  tertiary  c)  secondary

3. a) primary  b) secondary

4. a)  C3H3CO2HSHNH2 + HCl [latex]\longrightarrow[/latex] C3H3CO2HSHNH3Cl

b)  (C6H11)(C2H5)(CH3)N + HCl [latex]\longrightarrow[/latex] (C6H11)(C2H5)(CH3)NHCl

c)  (C2H5)(CH3)NH + HCl [latex]\longrightarrow[/latex] (C2H5)(CH3)NH2Cl

5. a)  ethylmethylamine   b)  ethyldipropylamine  c) diethylmethylamine


amine: organic molecule in which a nitrogen atom is bonded to one or more alkyl group


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