Functional group

In organic chemistry, functional groups (or moieties) are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of.

Combining the names of functional groups with the names of the parent alkanes generates a powerful systematic nomenclature for naming organic compounds.


The non-hydrogen atoms of functional groups are always associated with each other and with the rest of the molecule by covalent bonds. When the group of atoms is associated with the rest of the molecule primarily by ionic forces, the group is referred to more properly as a polyatomic ion or complex ion—all of these are called radicals, by a meaning of the term radical that predates the free radical.

The first carbon atom after the carbon that attaches to the functional group is called the alpha carbon.

Functional groups are attached to the carbon backbone of organic molecules. They determine the characteristics and chemical reactivity of molecules. Functional groups are far less stable than the carbon backbone and are likely to participate in chemical reactions.

Table of common functional groups

The following is a list of common functional groups. In the formulas, the symbols R and R' usually denotes an attached hydrogen, or a hydrocarbon side chain of any length, but may sometimes refer to any group of atoms. Below is an image of multiple functional groups found in organic chemistry.

(For convenience, see basic functional groups covered in General Biology)

Chemical class Group Formula Structural Formula Prefix Suffix Example
Acyl halide Haloformyl RCOX Acyl halide haloformyl- -oyl halide Acetyl chloride
Acetyl chloride
(Ethanoyl chloride)
Alcohol Hydroxyl ROH Hydroxyl hydroxy- -ol methanol
Aldehyde Aldehyde RCHO Aldehyde aldo- -al acetaldehyde
Alkane Alkyl RH Alkyl alkyl- -ane methane
Alkene Alkenyl R2C=CR2 Alkene alkenyl- -ene ethylene
Alkyne Alkynyl RC≡CR' Alkyne alkynyl- -yne acetylene
Amide Carboxamide RCONR2 Amide carboxamido- -amide acetamide
Amines Primary amine RNH2 Primary amine amino- -amine methylamine
Secondary amine R2NH Secondary amine amino- -amine dimethylamine
Tertiary amine R3N Tertiary amine amino- -amine trimethylamine
4° ammonium ion R4N+ Quaternary ammonium cation ammonio- -ammonium choline
Azide Azide RN3 Organoazide azido- alkyl azide Phenyl azide
Phenyl azide
Azo compound Azo
RN2R' Azo.pngl azo- -diazene Methyl orange
Methyl orange
(p-dimethylamino-azobenzenesulfonic acid)
Toluene derivative Benzyl RCH2C6H5
Benzyl benzyl- 1-(substituent)toluene Benzyl bromide
Benzyl bromide
Carbonate Carbonate ester ROCOOR Carbonate alkyl carbonate
Carboxylate Carboxylate RCOO Carboxylate


carboxy- -oate Sodium acetate
Sodium acetate
(Sodium ethanoate)
Carboxylic acid Carboxyl RCOOH Carboxylic acid carboxy- -oic acid Acetic acid
Acetic acid
(Ethanoic acid)
Cyanates Cyanate ROCN Cyanate cyanato- alkyl cyanate
Thiocyanate RSCN Thiocyanate thiocyanato- alkyl thiocyanate
Disulfide Disulfide RSSR' Disulfide alkyl alkyl disulfide File:Cystamine.svg
Ether Ether ROR' Ether alkoxy- alkyl alkyl ether Diethyl ether
Diethyl ether
Ester Ester RCOOR' Ester alkyl alkanoate Ethyl butyrate
Ethyl butyrate
(Ethyl butanoate)
Haloalkane Halo RX Halide group halo- alkyl halide Chloroethane
(Ethyl chloride)
Hydroperoxide Hydroperoxy ROOH Hydroperoxy hydroperoxy- alkyl hydroperoxide Methyl ethyl ketone peroxide
Methyl ethyl ketone peroxide
Imine Primary ketimine RC(=NH)R' Imine imino- -imine
Secondary ketimine RC(=NR)R' Imine imino- -imine
Primary aldimine RC(=NH)H Imine imino- -imine
Secondary aldimine RC(=NR')H Imine imino- -imine
Imide Imide RC(=O)NC(=O)R' Imide imido- -imide
Isocyanide Isocyanide RNC Isocyanide isocyano- alkyl isocyanide
Isocyanates Isocyanate RNCO Isocyanate isocyanato- alkyl isocyanate Methyl isocyanate
Methyl isocyanate
Isothiocyanate RNCS Isothiocyanate isothiocyanato- alkyl isothiocyanate Allyl isothiocyanate
Allyl isothiocyanate
Ketone Carbonyl RCOR' Ketone keto-, oxo- -one Butanone
Methyl ethyl ketone
Nitrate Nitrate RONO2 Nitrate nitrooxy-, nitroxy-

alkyl nitrate

Amyl nitrate
Amyl nitrate
Nitrile Nitrile RCN Nitrile cyano-

alkyl cyanide

(Phenyl cyanide)
Nitrite Nitrosooxy RONO Nitrite nitrosooxy-

alkyl nitrite

Amyl nitrite
Amyl nitrite
Nitro compound Nitro RNO2 Nitro nitro-   Nitromethane
Nitroso compound Nitroso RNO Nitroso nitroso-   Nitrosobenzene
Peroxide Peroxy ROOR Peroxy peroxy- alkyl peroxide Di-tert-butyl peroxide
Di-tert-butyl peroxide
Benzene derivative Phenyl RC6H5 Phenyl phenyl- -benzene Cumene
Phosphine Phosphino R3P A tertiary phosphine phosphino- -phosphane Methylpropylphosphane
Phosphodiester Phosphate HOPO(OR)2 Phosphodiester phosphoric acid di(substituent) ester di(substituent) hydrogenphosphate DNA
Phosphonic acid Phosphono RP(=O)(OH)2 Phosphono group phosphono- substituent phosphonic acid Benzylphosphonic acid
Benzylphosphonic acid
Phosphate Phosphate ROP(=O)(OH)2 Phosphate group phospho- Glyceraldehyde 3-phosphate
Glyceraldehyde 3-phosphate
Pyridine derivative Pyridyl RC5H4N

4-pyridyl group
3-pyridyl group
2-pyridyl group




-pyridine Nicotine
Sulfide RSR' Sulfide group di(substituent) sulfide Dimethyl sulfide
Dimethyl sulfide
Sulfone Sulfonyl RSO2R' Sulfonyl group sulfonyl- di(substituent) sulfone Dimethyl sulfone
Dimethyl sulfone
Sulfonic acid Sulfo RSO3H Sulfonyl group sulfo- substituent sulfonic acid Benzenesulfonic acid
Benzenesulfonic acid
Sulfoxide Sulfinyl RSOR' Sulfinyl group sulfinyl- di(substituent) sulfoxide Diphenyl sulfoxide
Diphenyl sulfoxide
Thiol Sulfhydryl RSH Sulfhydryl mercapto-, sulfanyl- -thiol Ethanethiol
(Ethyl mercaptan)

See also


  • McMurry, John. Organic Chemistry. 6th ed. Belmont, CA: Brooks/Cole, 2004. ISBN 0534420052
  • Morrison, Robert T., and Robert N. Boyd. Organic Chemistry. 6th ed. Englewood Cliffs, NJ: Prentice Hall, 1992. ISBN 0-13-643669-2
  • Solomons, T.W. Graham, and Fryhle, Craig B. Organic Chemistry. 8th ed. Hoboken, NJ: John Wiley, 2004. ISBN 0471417998

External links

All links retrieved May 16, 2017.

Topics in organic chemistry

Aromaticity | Covalent bonding | Functional groups | Nomenclature | Organic compounds | Organic reactions | Organic synthesis | Publications | Spectroscopy | Stereochemistry

List of organic compounds


New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

Note: Some restrictions may apply to use of individual images which are separately licensed.