Systematic Nomenclature of Organic Compounds
1. Find the longest continuous carbon chain (parent chain).
a. If there is a functional group (double or triple bond, alcohol etc) it must be
on or part of the parent chain.
b. If there is a ring in the compound either the ring itself or the non-ringed
chain will be the parent chain but never both combined.
c. If there are two or more chains of equal length, pick the one with the
greatest number of substituents.
2. Number the carbons in the parent chain.
a. If there is a functional group, assign it the lowest possible position. If the
functional group gets the same position from either end then consider the
lowest number for the substituents. If there is a functional group on a ring,
assign it position 1. Double bonds in a ring are at positions 1 and 2.
b. If there is multiple functional groups the priority is carbonyls > alcohols >
carbon-carbon multiple bonds > amines. If you have a carbon-carbon
double bond and a carbon-carbon triple bond, go in the directions that
gives the lowest possible positions. If both directions give the same
numbers, the double bond will take priority.
c. If there are no functional groups, give the substituents the lowest possible
numbers. If you get the same numbers from either end assign the
alphabetically first substituent the lowest number.
3. Naming your compound.
a. If the compound has a specific configuration or geometry (cis/trans, E/Z
or R/S) indicate this first.
b. The first name is the substituents in alphabetical order. Prefixes that
denote a number (di, tri, sec, tert etc.) are not alphabetized. List the
position(s) on the parent chain and denote how many with a Greek prefix.
If a substituent is on a nitrogen the letter N is used to denote the position
in lieu of a number. Hyphens are placed between letters and number
whereas commas between two numbers.
c. The last name of the compound is the parent chain. The stem of the name
indicates the length of the parent chain and the suffix reflects the type of
compound. If your parent chain is a ring add the prefix cyclo. If your
parent chain had a functional group indicate the position if it’s not
obvious.
# of
C’s
1
2
3
4
5
6
7
8
9
10
11
12
Stem
meth
eth
prop
but
pent
hex
hept
oct
non
dec
undec
dodec
Type of
Compound
Alkane
Alkene
Alkyne
Alcohol
Amine
Suffix
ane
ene, adiene,
atriene etc.
yne, adiyne,
atriyne etc.
anol, enol,
ynol, anediol,
anetriol etc.
anamine,
enamine,
ynamine
Type of
Compound
Aldehyde
Ketone
Carboxylic acid
Ester
Suffix
anal
enal
ynal
anone
enone
ynone
anoic acid
enoic acid
ynoic acid
anoate
cyclopropane
cyclobutane
cyclopentane
cyclohexane
benzene
Substituent Names
CH3
H3C
H3C
CH3
methyl
CH3
ethyl
propyl
CH3
butyl
H3C
CH3
pentyl
H3C
H3C
hexyl
CH3
CH3
CH3
isopropyl
H3C
CH3
H3C
CH3
CH3
CH3
isobutyl
sec-butyl
tert-butyl
Common Functional Groups
Structure
Functional
Group
Systematic
suffix
alkene
-ene
1-butene
alkyne
-yne
2-pentyne
alkyl halide
N/A
alcohol
-ol
ether
N/A
amine
N/A
aldehyde
-al
Example
Name
1-bromobutane
Br
OH
C-O-C
2-pentanol
O
isopropyl
propyl ether
secbutylethylamine
HN
H
propanal
O
ketone
-one
carboxylic acid
-oic acid
O
2-pentanone
O
butanoic acid
OH
O
ester
-oate
O
amide
NH2
-amide
O
methyl
butanoate
propanamide
Subclasses of Alcohols and Amines
For alcohols look at how many carbons are bonded to the carbon with the OH
For amines look at how many carbons are bonded to the nitrogen
Degrees of Unsaturation
Pi bonds and ring structures are degrees of unsaturation. By adding a pi and/or ring it
causes the molecule to lose 2 hydrogens.
For example look at these three molecules that contain 3 carbons but with varying
hydrogens due to the varying number of pi bonds
CH3–CH2–CH3 (C3H8) vs. CH2=CH–CH3 (C3H6) vs. HC≡C–CH3 (C3H4)
For example compare hexane to benzene
CH3–CH2– CH2– CH2– CH2– CH3 (C6H14)
vs.
(C6H6)
The general formula to determine the number of degrees of unsaturation:
CnH2n+2-2(ring + π)