Naming Esters
Definition of Esters:
Esters are organic chemical compounds whose structure has the general form:
where the symbols "R1" and "R2" represent organic radicals, usually carbon chains. |
[Symbols such "R","R' ", "R1", "R2", "R1" and "R2" and similar are often used to represent organic radicals in general, which are frequently (linear or branched) carbon chains that may or may not have addtional functional groups attached, or can alternatively be hydrogen atoms or halogen atoms, e.g. flourine (F), chlorine (Cl), bromine (Br).] |
In the case of esters, "R1" and "R2" are often carbon chains that may be either linear or branched and may also have other functional groups attached.
"R2" is not a hydrogen atom because if it were, the molecule would be a carboxylic acid rather than an ester.
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The simplest esters to describe are those where both R1 and R2 are "an alkane less the hydrogen atom at the end of the chain", and hence where the hydrogen atom at the end of the corresponding alkane is replaced by the carbon or oxygen atom to which that "R" (so, R1 or R2 in the diagram above) is attached.
R1 and R2 are not necessarily the same (hence the "1" and "2" to distinguish them in the general definition of an ester).
However, they may be the same.
Names of Esters in General
Esters are named according to the standard system of naming organic compunds. As true for other types of organic compounds, there are also some non-standard names for esters in common usage. Some of the alternative names used for the simple esters shown in the tables of examples on this page are listed in the column under the header "synonyms".
The standard system for naming esters uses the suffix -oate to indicate that a molecule is an ester.
The two organic radicals (which are often carbon chains) labelled
"R1" and "R2" in the diagram at the top of this page are also identified in the name of the compound, or molecule drawn-out to represent the compound.
This may be explained using a diagram of the simple example of ethyl propanoate:
This shows that esters consist of two parts (often carbon chains), as labelled
"R1" and "R2" at the top of this page.
When working-out the name of an ester given its molecular structure the first steps are:
- Recognise that the molecule is an ester because it has the general form:
- Identify the parts labelled
"R1" and "R2".
To do this
recall the standard system of labelling carbon chains as used for alkanes.
Also take care to distinguish
"R1" and "R2" by noticing which "R" the oxygen atom is attached to by a double bond.
Note that
"R1" and "R2" may be linear charbon chains (which are simpler to name) or they may be branched, and they may even have other functional groups (e.g. halogens, see haloalkanes) attached as well.
Familiarity with naming esters and, conversely, with drawing the molecular structures of esters given their names, comes with experience.
It is helpful to begin by viewing a series of simple examples in order to recognise patterns in the process of naming esters that can then be applied to similar and more complex cases.
Some of the simplest esters are named and their structures drawn in the following tables:
Names and Structures of simple Linear Esters
in which R2 = CH3, which is known as a "-methyl group"
The homologous series of linear esters that include a -methyl group attached (via a single covalent bond) to the oxygen atom in the chain of the ester molecule. This description is easier to follow in conjunction with viewing the molecular structures in the table:
Number carbons in the chain R1 |
Name |
Simple Structure |
Other Names = Synonyns
(*Examples not complete lists) |
and simple formula |
showing bond types but not accurate bond angles |
 |
1 |
methyl formate
(C2H4O2)
|
 |
- methyl formate
- methyl methanoate
- formic acid, methyl ester
|
2 |
methyl ethanoate
(C3H6O2) |
 |
- methyl acetate
- methylacetate
- methyl acetic ester
- acetic acid, methyl ester
- devoton
- tereton
|
3 |
methyl propanoate
(C4H8O2) |
 |
- methyl propanoate
- methyl propionate
- methyl propylate
- propanoic acid, methyl ester
- propionic acid, methyl ester
|
4 |
methyl butanoate
(C5H10O2) |
 |
- methyl butanoate
- methyl n-butanoate
- methyl butyrate
- butanoic acid, methyl ester
- butyric acid, methyl ester
- methyl n-butyrate
- methyl-n-butyrate
- methyl n-butanoate
- 2-methyl butyric acid
|
5 |
methyl pentanoate
(C6H12O2) |
 |
- methyl pentanoate
- methyl valerate
- valeric acid, methyl ester
- pentanoic acid, methyl ester
- methyl n-valerate
- methyl valerianate
|
6 |
methyl hexanoate
(C7H14O2) |
 |
- methyl hexanoate
- methyl caproate
- hexanoic acid, methyl ester
- methyl hexoate
- methyl capronate
- methyl n-hexanoate
- methyl hexylate
- caproic acid methyl ester
- hexanoic acid methyl ester
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Why stop at six carbon atoms (in the chain) ? It doesn't. There are more similar linear esters. We stopped here due to page width. |
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Important Note: *The synonyms indicated for compounds listed above are just examples of alternative names found online and believed to have been used to refer to the substance indicated. They have not all been verified and may include common (non-scientific) names, trade names specific to particular suppliers, and perhaps errors. The purpose of these lists is to give a general indication of the range of names by which esters are known - both generally, and specifically. |
Names and Structures of simple Linear Esters
in which R2 = CH2CH3, which is known as an "-ethyl group"
The homologous series of linear esters that include an -ethyl group attached (via a single covalent bond) to the oxygen atom in the chain of the ester molecule. This description is easier to follow in conjunction with viewing the molecular structures in the table:
Number carbons in the chain R1 |
Name |
Simple Structure |
Other Names = Synonyns
(*Examples not complete lists) |
and simple formula |
showing bond types but not accurate bond angles |
|
1 |
ethyl formate
(C3H6O2) |
 |
- ethyl formate
- ethyl methanoate
- ethyl formic ester
- formic acid, ethyl ester
- formic ether
- formic acid ethyl ester
- carboxylic acid oxaethane
- areginal
|
2 |
ethyl ethanoate
(C4H8O2) |
 |
- ethyl acetate
- ethylacetate
- acetoxyethane
- acetic acid, ethyl ester
- ethyl acetic ester
- vinegar naphtha
- ethylacetate
- acetidin
- acetic acid ethyl ester
- acetic ester
|
3 |
ethyl propanoate
(C5H10O2) |
 |
- ethyl propanoate
- ethyl propionate
- propanoic acid, ethyl ester
- propionic ester
|
4 |
ethyl butanoate
(C6H12O2) |
 |
- ethyl butanoate
- ethyl butyrate
- ethyl n-butyrate
- butanoic acid, ethyl ester
- butyric acid, ethyl ester
- butyric ester
- butyric acid ethyl ester
- butanoic acid ethyl ester
|
5 |
ethyl pentanoate
(C7146O2) |
 |
- ethyl pentanoate
- ethyl valerate
- valeric acid, ethyl ester
- ethyl n-valerate
- pentanoic acid, ethyl ester
- ethyl valerianate
|
6 |
ethyl hexanoate
(C8H16O2) |
 |
- ethyl hexanoate
- ethyl caproate
- ethyl hexoate
- ethyl butyl acetate
- hexanoic acid, ethyl ester
- caproic acid ethyl ester
- capronic ether absolute
- caproic acid ethylester
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Why stop at six carbon atoms (in the chain) ? It doesn't. There are more similar linear esters. We stopped here due to page width. |
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Important Note: *The synonyms indicated for compounds listed above are just examples of alternative names found online and believed to have been used to refer to the substance indicated. They have not all been verified and may include common (non-scientific) names, trade names specific to particular suppliers, and perhaps errors. The purpose of these lists is to give a general indication of the range of names by which esters are known - both generally, and specifically. |
Names and Structures of simple Linear Esters
in which R2 = CH2CH2CH3, which is known as an "-propyl group"
The homologous series of linear esters that include an -propyl group attached (via a single covalent bond) to the oxygen atom in the chain of the ester molecule. This description is easier to follow in conjunction with viewing the molecular structures in the table:
Number carbons in the chain R1 |
Name |
Simple Structure |
Other Names = Synonyns
(*Examples not complete lists) |
and simple formula |
showing bond types but not accurate bond angles |
|
1 |
propyl formate
(C4H8O2) |
 |
- propyl formate
- propyl methanoate
- n-propyl methanoate
- n-propyl formate
- formic acid, propyl ester
|
2 |
propyl ethanoate
(C5H10O2) |
 |
- propyl acetate
- n-propylacetate
- acetic acid, propyl ester
- 1-acetoxypropane
- 1-propyl acetate
- n-propyl ethanoate
- acetic acid propyl ester
- acetic acid n-propyl ester
|
3 |
propyl propanoate
(C6H12O2) |
 |
- propyl propanoate
- propyl propionate
- n-propyl propionate
- propanoic acid, propyl ester
- propionic acid, propyl ester
- propyl propanoate
- n-ropyl propanoate
|
4 |
propyl butanoate
(C7H14O2) |
 |
- propyl butanoate
- propyl butyrate
- butyric acid, propyl ester
- butanoic acid, propyl ester
- propyl butanoate
- propyl n-butyrate
- 1-propyl butyrate
- n-propyl-n-butanoate
|
5 |
propyl pentanoate
(C8H16O2) |
 |
- propyl pentanoate
- n-propyl n-valerate
- propyl valerate
- valeric acid, propyl ester
- pentanoic acid, propyl ester
|
6 |
propyl hexanoate
(C9H18O2) |
 |
- propyl hexanoate
- n-propyl hexanoate
- propyl caproate
- hexanoic acid, propyl ester
- caproic acid propyl ester
|
Why stop at six carbon atoms (in the chain) ? It doesn't. There are more similar linear esters. We stopped here due to page width.
Important Note: *The synonyms indicated for compounds listed above are just examples of alternative names found online and believed to have been used to refer to the substance indicated. They have not all been verified and may include common (non-scientific) names, trade names specific to particular suppliers, and perhaps errors. The purpose of these lists is to give a general indication of the range of names by which esters are known - both generally, and specifically.
Note:
This is one of many pages about types of organic compounds in our Organic Chemistry Section. Similar and related pages describe hydrocarbons, alkanes, haloalkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons (arenes), alcohols, esters, ethers, aldehydes, ketones, carboxylic acids, acid chlorides, acid anhydrides, azo dyes, amines, amides, nitriles, amino acids (chemistry), peptides, proteins (chemistry), polypeptides and others. If you need further information ask your chemistry tutor.
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