ORGANIC NOMENCLATURE 1
1) Some nomenclature rules
• The name is based around the name of the longest carbon chain (which contains the functional group):
number of C atoms 1C 2C 3C 4C 5C 6C 7C 8C 9C 10 C
stem meth eth prop but pent hex hept oct non dec
• The functional group
roup is indicated by a prefix or suffix. e.g. chloroethane
• The position of the functional group is given by a number – counting from the end that gives the functional group the
lowest number.
• We only include numbers if they are needed.
• Where there are two or more of the same groups, di-, tri-, tetra, penta-, hexa-, etc. are used.
• If there is more than one functional group/subsitutent, numbers are se separated
parated by commas and the groups are listed in
alphabetical order (ignoring nay di, tri
tri, etc.). e.g. 3-bromo-1-chlorobutane, 2,2-dibromo-1-chlorobutane
chlorobutane.
• The suffix for alkenes can go in front of other suffixes, e.g. 2-chlorobut-3-enal.
2) Alkanes
displayed
isplayed formula structural formula skeletal formula
methane
CH4
ethane
C2H6
propane
C3H8
butane
C4H10
pentane
C5H12
hexane
C6H14
© www.CHEMSHEETS.co.uk 11-December-2015 Chemsheets AS 1072
3) Alkyl groups
The following groups are often attached to organic molecules – these groups are derived from alkanes with an H missing.
They are called alkyl groups.
methyl ethyl propyl butyl
H H H H H H H H H H
H C H C C H C C C H C C C C
H H H H H H H H H H
CH3- CH3CH2- CH3CH2CH2- CH3CH2CH2CH2-
4) AS functional groups
prefix / suffix
homologous series functional group example
(* = usual use)
H H
suffix -ene
alkenes C C ethene
C C
H H
H H
suffix* -ol
alcohols C OH H C C OH ethanol
prefix hydroxy-
H H
H H H
prefix chloro-
haloalkanes C halogen bromo- H C C C Cl 1-chloropropane
iodo-
H H H
H O
O suffix -al
aldehydes H C C H ethanal
C H
H
H O H H
O suffix* - one
H C C C C H butanone
ketones
C prefix oxo-
H H H
H O
O suffix -oic acid
carboxylic acids H C C OH ethanoic acid
C OH
H
H
suffix -nitrile
H C C N ethanenitrile
nitriles C N
H
H H H
suffix* - amine
amines C NH2 H C C C NH2 propylamine
prefix amino-
H H H
© www.CHEMSHEETS.co.uk 11-December-2015 Chemsheets AS 1072
ALKANES
Structural CH3CH2CH(CH3)CH3 (C2H5)2CHCH(CH3)CH(CH3)2
formula
Displayed
formula
Skeletal
formula
Name
ALKENES
Structural
(CH3)2C=CHCH3
formula
Displayed
formula
Skeletal
formula
Name
HALOALKANES
Structural
CH3CH2Br CH3CH2CH(CH3)CH2CHFCH3
formula
Displayed
formula
Skeletal
formula
Name
© www.CHEMSHEETS.co.uk 11-December-2015 Chemsheets AS 1072
ALCOHOLS
Structural
(CH3)3COH
formula
Displayed
formula
Skeletal
formula
Name
ALDEHYDES
Structural CH3CH2CH2CH2CHO (CH3)2CHCHO
formula
Displayed
formula
Skeletal
formula
Name
KETONES
Structural
CH3COCH(CH3)2
formula
Displayed
formula
Skeletal
formula
Name
© www.CHEMSHEETS.co.uk 11-December-2015 Chemsheets AS 1072
CARBOXYLIC ACIDS
Structural
CH3CH2COOH (CH3)3CCH2COOH
formula
Displayed
formula
Skeletal
formula
Name
AMINES
Structural CH3NH2
formula
Displayed
formula
Skeletal
formula
Name
NITRILES
Structural
CH3CH(CH3)CH2CN
formula
Displayed
formula
Skeletal
formula
Name
© www.CHEMSHEETS.co.uk 11-December-2015 Chemsheets AS 1072
