Nomenclature
Nomenclature
Amines
IUPAC
To name an amine, the longest alkane chain is identified. The –e suffix is removed and is replaced with an –amine suffix.
If the amino group is not on the end, #1, carbon atom, a number needs to be used to identify the location of the amino group. The carbon chain should be numbered starting at the end closest to the amino group.
If it is secondary or tertiary, the prefix N- is used for each shorter substituent that is attached to the nitrogen (N) atom of the amine. The N- prefix tells us the shorter substituent is located on the nitrogen atom (N) instead of the longest, numbered carbon chain. The “N” prefix is written for each small alkyl substituent on the nitrogen atom.
Common names
Alkyl amines
Amines are commonly named by naming the alkyl groups on the nitrogen atom followed by the suffix -amine. If two or three identical groups are on the nitrogen atom, the prefixes di- or tri- are used.
Aryl amines
The first aryl amines that you should memorize are aniline, pyrrole, and pyridine. Purine and pyrimidine are biologically important because they are the bases that we find in DNA. There are many more common names for amine-based rings that you will learn as you progress in your study of organic chemistry, but this is a good starting point.
As a substituent
If the molecule is more complex, an –NH2 group can be named as an “amino” substituent.
Nitriles
IUPAC
We name the parent compound by counting the number of carbon atoms of the longest chain (including the carbon atom of the C≡N). The numbering for the compound starts at this nitrile carbon atom. This is followed by the word –nitrile.
As a substituent
If the molecule is more complex, the -C≡N group can be named as a substituent, a “cyano” group.
Common names
Nitrile common names are derived from taking the common name of the corresponding carboxylic acid, dropping the –ic acid suffix and adding the suffix –onitrile. Notice the carbon of the carbonyl (with three C-O bonds) is the one that becomes the carbon of the nitrile (with three C-N bonds).
1. Draw the following compounds.
a) 1,4-dicyanocyclohexane
b) 3-ethylheptanenitrile
c) 4-aminocyclohexanone
d) 3-ethylaniline
e) 2-methylpyridine
f) triethylamine
g) 2-octanamine
h) N-methyl-2-pentanamine
Answers
1.
a)
b)
c)
d)
e)
f)
g)
h)
