Naming Esters

Definition of Esters:

Esters are organic chemical compounds whose structure has the general form:

general molecular structure of an ester (class of organic compounds)

where the symbols R1 and R2 represent organic radicals.

  • R1 and R2 are often carbon chains that can be either linear or branched and might also have other functional groups attached.
  • R1 and R2 are not necessarily the same as each other, hence the 1 and 2 to distinguish them in the general definition of an ester. However, they can be the same, e.g. methyl ethanoate, ethyl propanoate, propyl butanoate and so on.
  • R2 is not a hydrogen atom because if it were, the molecule would be a carboxylic acid rather than an ester.

The simplest esters 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.

Names of Esters in General

Esters are named according to the standard system of naming organic compunds. As for other types of organic compounds, there are also some non-standard names for esters. 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 heading 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.

This is shown using the example of ethyl propanoate:

The diagram above 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:

  1. Recognise that the molecule is an ester because it has the general form:
  2. 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.

Ease of naming esters and drawing the molecular structures of esters comes with experience. It helps to consider a series of simple examples in order to recognise patterns in the naming of esters that can then be applied to similar and larger and more complicated examples.

Names and Structures of simple Linear Esters
in which R2 = CH3, which is known as a "-methyl group"

The following table shows the first six members of 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 is easier to follow when viewing the molecular structures in the table:

  • methyl formate (C2H4O2)
    Simple Structure:
    molecular structure of methyl formate
    *Examples of other / previous names:
  • methyl ethanoate (C3H6O2)
    Simple Structure:
    molecular structure of methyl ethanoate
    *Examples of other / previous names:
  • methyl propanoate (C4H8O2)
    Simple Structure:
    molecular structure of methyl propanoate
    *Examples of other / previous names:
  • methyl butanoate (C5H10O2)
    Simple Structure:
    molecular structure of methyl butanoate
    *Examples of other / previous names:
  • methyl pentanoate (C6H12O2)
    Simple Structure:
    molecular structure of methyl pentanoate
    *Examples of other / previous names:
  • methyl hexanoate (C7H14O2)
    Simple Structure:
    molecular structure of methyl hexanoate
    *Examples of other / previous names:

Names and Structures of simple Linear Esters
in which R2 = CH2CH3, which is known as an "-ethyl group"

The following table shows the first six members of 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.

  • ethyl formate (C3H6O2)
    Simple Structure:
    molecular structure of ethyl formate
    *Examples of other / previous names:
  • ethyl ethanoate (C4H8O2)
    Simple Structure:
    molecular structure of ethyl ethanoate
    *Examples of other / previous names:
  • ethyl propanoate (C5H10O2)
    Simple Structure:
    molecular structure of ethyl propanoate
    *Examples of other / previous names:
  • ethyl butanoate (C6H12O2)
    Simple Structure:
    molecular structure of ethyl butanoate
    *Examples of other / previous names:
  • ethyl pentanoate (C7146O2)
    Simple Structure:
    molecular structure of ethyl pentanoate
    *Examples of other / previous names:
  • ethyl hexanoate (C8H16O2)
    Simple Structure:
    molecular structure of ethyl hexanoate
    *Examples of other / previous names:

Names and Structures of simple Linear Esters
in which R2 = CH2CH2CH3, which is known as an "-propyl group"

The following table shows the first six members of the homologous series of linear esters that include a -propyl group attached (via a single covalent bond) to the oxygen atom in the chain of the ester molecule.

  • propyl formate (C4H8O2)
    Simple Structure:
    molecular structure of propyl formate
    *Examples of other / previous names:
  • propyl ethanoate (C5H10O2)
    Simple Structure:
    molecular structure of propyl ethanoate
    *Examples of other / previous names:
  • propyl propanoate (C6H12O2)
    Simple Structure:
    molecular structure of propyl propanoate
    *Examples of other / previous names:
  • propyl butanoate (C7H14O2)
    Simple Structure:
    molecular structure of propyl butanoate
    *Examples of other / previous names:
  • propyl pentanoate (C8H16O2)
    Simple Structure:
    molecular structure of propyl
    *Examples of other / previous names:
  • propyl hexanoate (C9H18O2)
    Simple Structure:
    molecular structure of propyl hexanoate
    *Examples of other / previous names:

Why stop at six carbon atoms (before the -O- ) ? It doesn't. There are more linear esters.

* The synonyms indicated for compounds listed above are just some examples of alternative names found online and believed to have been used to refer to the compound indicated. They have not all been verified and may include common (non-scientific) names and trade names specific to particular suppliers. The purpose of these lists is to give a general indication of the range of names by which these linear esters are, or have been, known.

See also the related page about functional groups in organic molecules.

In the News:

Packaged food healthiest in the UK, USA, Australia and Canada - 22 Aug '19

Garlic and Artichoke adopted through ABC's Adopt-an-Herb Program - 14 Jun '19

Cranberry Harvest underway in USA - 5 Oct '18

By 2043 obesity might exceed smoking as the largest preventable cause of cancer in women - 25 Sep '18

Total retail sales of herbal supplements in the USA exceeded $8 Billion in 2017 - 13 Sep '18

It's a bumper blueberry season - 13 Jul '18

Heat-related health concerns for older adults increase during the summer - 28 Jun '18

U.S. FDA takes steps to advance health through improvements in nutrition - 27 Jun '18

Pope St Gregory I (c.540-604 CE) stated that there were nine ranks of angels in Heaven.

Although care has been taken when compiling this page, the information contained might not be completely up to date. Accuracy cannot be guaranteed. This material is copyright. See terms of use.

IvyRose Holistic 2003-2019.