Basic Organic Nomenclature: A Short Summary

The name is composed of three sections: one or more prefixes for the substituents; a root name for the longest continuous chain or ring of carbon atoms to which the highest priority functional group is attached; and a suffix indicating what the highest priority functional group is.

Root Names: are based on the number of carbon atoms (given in parenthesis):

(1) meth, (2) eth, (3) prop, (4) but, (5) pent, (6) hex, (7) hept, (8) oct, (9) non, (10) dec, (11) undec, (12) dodec, (13) tridec, (14) tetradec, (15) pentadec, (16) hexadec, (17) heptadec, (18) octadec, (19) nonadec, (20) icos.

Note: the cyclo- prefix is added to rings (i.e. cyclobutane).

Functional Groups: Are a set of atoms arranged in a specific bonding pattern. If it is the highest priority it will appear as a suffix, otherwise as a prefix. The common functional groups are (in decreasing order of priority, names in blue are attached directly to a ring).
 
 

Functional
Group
Formula
Suffix
Prefix
Cations   R4-N+ -ammonium
-phosphoium
-sulphonium
ammonio-
phosphonio-
sulphonio-
Carboxylic Acids R-CO2H -oic acid
-carboxylic acid
carboxy-
Acid Anhydrides R-CO2-CO-R -oic anhydride
----- 
Esters R-CO2-R' (alkyl) -oate
(alkyl) -carboxylate
alkoxycarbonyl-
carbalkoxy-
Acyl Halides R-CO-X -oyl halide haloalkanoyl-
halide alkanoyl-
Amides R-CO-NH2 -amide
-carboxamide
carbamoyl-
Nitriles R-CºN -nitrile
-onitrile
cyano-
Aldehydes R-CHO -al
-carbaldehyde
alkanoyl-
-oxo-
Ketones R-CO-R' -one
alkyl alkyl ketone
-oxo-
Alcohols R-OH -ol hydroxy-
Thiols R-SH -thiol mercapto-
Amines R-NH2 -amine amino-
-aza-
Ethers R-O-R' alkyl alkyl ether -oxa-
-alkoxy-
Sulphides R-S-R' alkyl alkyl sulphide -alkylthio
-thia
Alkenes R-C=C-R' -ene alkenyl-
Alkynes R-CºC-R' -yne alkynyl-
Halides R-X -halide halo-
Nitro R-NO2
----- 
nitro-
Alkanes R -ane -yl (alkyl-)

Common substituent names: isopropyl (-CH(CH3)2), sec-butyl (-CH(CH3)CH2CH3), tert-butyl (-C(CH3)3), phenyl (-C6H5)

1) The numbering of the chain is done to give the lowest number to the highest priority functional group.

2) Substituents are listed in alphabetical order, there is no priority between substituents.

3) If there are more than one of a single type of substituent, indicate by a di-, tri-, tetra-,... prefix to the substituent name. (Note, there needs to be as many numbers locating the substituents as the prefix indicates i.e. 2,3-dimethyl).

4) Stereochemical features are indicated by a R/S or E/Z with the atom number indicating the location. The stereochemistry is indicated before the first substituent and in parenthesis (i.e. (2R,3E)- ).
 

Note: For syntax: there should be a comma between numbers; a hyphen between letters and numbers; and parenthesis around the name of a complex substituent and stereochemical indicators.

If this does not answer your questions check the textbook or web pages for the specific functional group.

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