Hydrocarbon Prefixes in Organic Chemistry


Hydrocarbon Prefixes

Hydrocarbon prefixes and suffixes offer a lot of information about the composition and structure of organic molecules. Hydrocarbons are molecules consisting entirely of carbon and hydrogen. But, they may contain functional groups or act as substituents in other molecules. Their nomenclature indicates how many carbons are in a chain, whether the chain is linear or forms a ring, the type of bonds between the carbon atoms, and the identity and location of functional groups. Here is a list of the first 20 hydrocarbon prefixes, common suffixes, and examples of hydrocarbon names.

20 Hydrocarbon Prefixes

This table lists 20 hydrocarbon prefixes in organic chemistry for simple hydrocarbon chains.

PrefixNumber of
Carbon Atoms
Formula
meth-1C
eth-2C2
prop-3C3
but-4C4
pent-5C5
hex-6C6
hept-7C7
oct-8C8
non-9C9
dec-10C10
undec-11C11
dodec-12C12
tridec-13C13
tetradec-14C14
pentadec-15C15
hexadec-16C16
heptadec-17C17
octadec-18C18
nonadec-19C19
eicosan-20C20

Hydrocarbons With Halogen Substituents

Hydrocarbons with halogen substituents are named using prefixes, such as fluoro-, chloro-, bromo-, iodo-, and the general halo- when the element identity isn’t specified. Numbers identify the substituent position. For example, (CH3)2CHCH2CH2Br is 1-bromo-3-methylbutane.

Hydrocarbon Suffixes

The suffix or ending of a hydrocarbon name describes the type of chemical bonds between carbon atoms and functional groups attached to the chain.

  • -ane means all carbon-carbon bonds are single covalent bonds. The general formula for this type of hydrocarbon is CnH2n+2. Examples include propane and hexane.
  • -ene means the hydrocarbon contains at least one carbon-carbon double bond. The general formula is CnH2n. Examples include ethene and propene.
  • -yne means the hydrocarbon contains at least one carbon-carbon triple bond. The general formula is CnH2n-2.
  • -ol means the compound is an alcohol or contains the -OH functional group.
  • -ic acid means the compound contains the -O=C-OH carboxylic acid functional group.
  • -al means the molecule has the -O=C-H aldehyde functional group.
  • -amine means the compound has the -C-NH2 amine functional group.
  • -ate indicates an ester, which is the -O=C-O-C functional group.
  • -ether stands for an ether or the -C-O-C functional group.
  • -one stands for a ketone or the -C=O functional group.

Hydrocarbon Substituents

When hydrocarbons serve as substituents on other molecules, the number of carbon atoms is indicated by a prefix. Here are some familiar examples:

  • amyl: 5-carbon substituent
  • valeryl: 6-carbon substituent
  • lauryl: 12-carbon substituent
  • myristyl: 14-carbon substituent
  • cetyl or palmityl: 16-carbon substituent
  • stearyl: 18-carbon substituent

For example, NaC12H25SO4 is the formula for sodium lauryl sulfate.

Aromatic Hydrocarbons

Aromatic hydrocarbons or arenes are ring-shaped molecules. Aromatic alkanes are the cycloalkanes. Their names use the same prefixes and suffixes as the straight-chain alkanes. So, you get cyclopropane, cyclobutane, cyclopentane, and so on.

Naming gets more complicated once you introduce double and triple bonds. Sometimes compounds have common names that don’t conform to typical nomenclature. For example, C6H6 is benzene. The –ene ending indicates the molecule has carbon-carbon double bonds. However, the benz– prefix actually comes from “gum benzoin,” which is an aromatic resin.

References

  • Clayden, J., Greeves, N., et al. (2001) Organic Chemistry. Oxford. ISBN 0-19-850346-6.
  • Silberberg, Martin (2004). Chemistry: The Molecular Nature Of Matter and Change. New York: McGraw-Hill Companies. ISBN 0-07-310169-9.

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