Illustrated Glossary of Organic Chemistry

Ester: A molecule or functional group derived by condensation of an alcohol and an acid with simultaneous loss of water. The most common type of ester is carboxylic ester (also called a carboxylate ester; frequently just called an ester), derived from a carboxylic acid. A carboxylic ester is sometimes abbreviated as RCOOR or RCO2R.


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Carboxylic acid
Alcohol
General carboxylate ester structure.

Representative Carboxylate Esters



Ethyl acetate, a common solvent.   
Methyl salicylate (oil of wintergreen).   
Nepetalactone, the active substance in catnip.


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Methanol
Sulfuric acid
Dimethyl sulfate, a sulfate ester.
Condensation of an alcohol with sulfuric acid produces a sulfate ester. In this example, sulfuric acid condenses with two equivalents of methanol to produce dimethyl sulfate.


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 A nucleoside
Phosphoric acid
A nucleotide
Condensation of an alcohol with a phosphoric acid produces a phosphate ester. In this example, phosphoric acid condenses with a nucleoside to produce a nucleotide.