Nomenclature for esters
R is H or an alkyl or aryl group
R' is either an alkyl or aryl group
Esters are organic compounds containing the functional group shown at the right.
Esters are referred to as carboxylic acid derivatives.Reaction of a carboxylic acid (RCO2H) and an alcohol (R'OH) gives an ester and H2O.
Naming esters All esters have two words in their name.
One describes RCO2 portion of the molecule.
Because this includes the functional group, it is the second word in the name.
The other describes the R' portion of the molecule.
R' as a substituent on the O of the functional group. Thus this is the first word in the name.
The RCO2 portion takes priority and determines the ending on the name.
The second word ends in -oate, the functional group ending for esters.
For saturated esters the -oate is preceded by -an-.
The -anoate is preceding by a prefix indicating the number of carbons in the longest chain of RCO2 including the CO carbon.
If the R chain has substituents on it, the C=O is number 1.
For saturated esters the -oate is preceded by -an-.
The -anoate is preceding by a prefix indicating the number of carbons in the longest chain of RCO2 including the CO carbon.
If R = CH3 the ester is an ethanoate (see example at right).
If the R chain has substituents on it, the C=O is number 1.
methyl ethanoate
The word describing this part is the first word in the ester name.
This word is derived from the corresponding hydrocarbon name with a -yl ending.
This word is derived from the corresponding hydrocarbon name with a -yl ending.
If R' is CH3 the compound is a methyl ester
If R' is CH2CH3 the compound is an ethyl ester
If R' is CH2CH3 the compound is an ethyl ester