Introduction to Organic Nomenclature: Alkanamines

Basic Organic Nomenclature

An Introduction

Dave Woodcock,
Associate Professor Emeritus UBC (Okanagan)
©1996,2000, 2008

5. Functional Groups
with Suffix or Prefix
II Alkanamines
(Amines)

Index

Atomic grouping
Suffix	-amine
Prefix	amino
Position in chain	anywhere
General formula	C_nH_2n+3N

Note: since the suffix (-amine) has an initial vowel, the terminal -e of the alkane name is dropped before the suffix is added, even if a locant is placed immediately before the suffix.

One other point about amines: replacing the H atoms in the -NH₂ group with other carbon groups does not significantly change the chemistry of the compounds (it is the strong C-N bond and the nitrogen lone pair of electrons which are mainly responsible for the chemistry). Consequently compounds with one, two or three carbon groups attached to nitrogen are all classified as amines. Historically, the designation primary, secondary, and tertiary amine has refered to the number of carbon atoms connected to the nitrogen. Take care to distinguish between a secondary amine (two carbons attached to nitrogen) and secondary alkanol (the OH group is attached to a carbon which itself is attached to two other carbons.

Finally, there are a number of acceptable ways of naming amines. The one given here is the one I prefer.

Examples : Primary Amines

Structure	IUPAC Name	Model
	methanamine
	ethanamine
	propan-1-amine
	propan-2-amine
	ethane-1,2-diamine *
	cyclopentanamine

* Because the suffix here is -diamine which starts with a consonant, the terminal -e of the alkane name is retained.

Examples : Secondary Amines

The longest chain of carbons takes the root name (alkanamine) and the other chain becomes a substituent with the locant N (italicised). The N is considered to be a lower locant than numerical locants, and so is placed ahead of them.

Structure	IUPAC Name	Model
	N-methylmethanamine
	N-methylethanamine
	N-ethylethanamine
	N-methylpentan-3-amine
	N,3-dimethylbutan-2-amine

Examples : Tertiary Amines

The longest chain of carbons takes the root name (alkanamine) and the other chains become a substituents with the locant N (italicised). The N is considered to be a lower locant than numerical locants, and so is placed ahead of them.