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		haloformyl-	-oyl halide	Acetyl chloride (Ethanoyl chloride)
Alcohol	Hydroxyl	ROH		hydroxy-	-ol	Methanol
Aldehyde	Aldehyde	RCHO		aldo-	-al	Acetaldehyde (Ethanal)
Alkane	Alkyl	RH		alkyl-	-ane	Methane
Alkene	Alkenyl	R2C=CR2		alkenyl-	-ene	Ethylene (Ethene)
Alkyne	Alkynyl	RC≡CR'		alkynyl-	-yne
Amide	Carboxamide	RCONR2		carboxamido-	-amide
Amines	Primary amine	RNH2		amino-	-amine	Methylamine (Methanamine)
	Secondary amine	R2NH		amino-	-amine	Dimethylamine
	Tertiary amine	R3N		amino-	-amine	Trimethylamine
	4° ammonium ion	R4N+		ammonio-	-ammonium	Choline
Azide	Azide	RN3		azido-	alkyl azide	Phenyl azide (Azidobenzene)
Azo compound	Azo (Diimide)	RN2R'		azo-	-diazene	Methyl orange (p-dimethylamino-azobenzenesulfonic acid)
Toluene derivative	Benzyl	RCH2C6H5 RBn		benzyl-	1-(substituent)toluene	Benzyl bromide (1-Bromotoluene)
Carbonate	Carbonate ester	ROCOOR			alkyl carbonate
Carboxylate	Carboxylate	RCOO−		carboxy-	-oate	Sodium acetate (Sodium ethanoate)
Carboxylic acid	Carboxyl	RCOOH		carboxy-	-oic acid
Cyanates	Cyanate	ROCN		cyanato-	alkyl cyanate
	Thiocyanate	RSCN		thiocyanato-	alkyl thiocyanate
Disulfide	Disulfide	RSSR'			alkyl alkyl disulfide	Cystamine (2,2'-Dithiobis(ethylamine))
Ether	Ether	ROR'		alkoxy-	alkyl alkyl ether	Diethyl ether (Ethoxyethane)
Ester	Ester	RCOOR'			alkyl alkanoate	Ethyl butyrate (Ethyl butanoate)
Haloalkane	Halo	RX		halo-	alkyl halide	Chloroethane (Ethyl chloride)
Hydroperoxide	Hydroperoxy	ROOH		hydroperoxy-	alkyl hydroperoxide	Methyl ethyl ketone peroxide
Imine	Primary ketimine	RC(=NH)R'		imino-	-imine
	Secondary ketimine	RC(=NR)R'		imino-	-imine
	Primary aldimine	RC(=NH)H		imino-	-imine
	Secondary aldimine	RC(=NR')H		imino-	-imine
Imide	Imide	RC(=O)NC(=O)R'		imido-	-imide
Isocyanide	Isocyanide	RNC		isocyano-	alkyl isocyanide
Isocyanates	Isocyanate	RNCO		isocyanato-	alkyl isocyanate	Methyl isocyanate
	Isothiocyanate	RNCS		isothiocyanato-	alkyl isothiocyanate	Allyl isothiocyanate
Ketone	Carbonyl	RCOR'		keto-, oxo-	-one	Methyl ethyl ketone (Butanone)
Nitrate	Nitrate	RONO2		nitrooxy-, nitroxy-	alkyl nitrate	Amyl nitrate (1-nitrooxypentane)
Nitrile	Nitrile	RCN		cyano-	alkanenitrile alkyl cyanide	Benzonitrile (Phenyl cyanide)
Nitrite	Nitrosooxy	RONO		nitrosooxy-	alkyl nitrite	Amyl nitrite (3-methyl-1-nitrosooxybutane)
Nitro compound	Nitro	RNO2		nitro-		Nitromethane
Nitroso compound	Nitroso	RNO		nitroso-		Nitrosobenzene
Peroxide	Peroxy	ROOR		peroxy-	alkyl peroxide	Di-tert-butyl peroxide
Benzene derivative	Phenyl	RC6H5		phenyl-	-benzene	Cumene (2-phenylpropane)
Phosphine	Phosphino	R3P		phosphino-	-phosphane	Methylpropylphosphane
Phosphodiester	Phosphate	HOPO(OR)2		phosphoric acid di(substituent) ester	di(substituent) hydrogenphosphate	DNA
Phosphonic acid	Phosphono	RP(=O)(OH)2		phosphono-	substituent phosphonic acid	Benzylphosphonic acid
Phosphate	Phosphate	ROP(=O)(OH)2		phospho-		Glyceraldehyde 3-phosphate
Pyridine derivative	Pyridyl	RC5H4N		4-pyridyl (pyridin-4-yl) 3-pyridyl (pyridin-3-yl) 2-pyridyl (pyridin-2-yl)	-pyridine	Nicotine
Sulfide		RSR'			di(substituent) sulfide	Dimethyl sulfide
Sulfone	Sulfonyl	RSO2R'		sulfonyl-	di(substituent) sulfone	Dimethyl sulfone (Methylsulfonylmethane)
Sulfonic acid	Sulfo	RSO3H		sulfo-	substituent sulfonic acid	Benzenesulfonic acid
Sulfoxide	Sulfinyl	RSOR'		sulfinyl-	di(substituent) sulfoxide	Diphenyl sulfoxide
Thiol	Sulfhydryl	RSH		mercapto-, sulfanyl-	-thiol	Ethanethiol (Ethyl mercaptan)

See also

• Chemical classification
• Organic chemistry

References

ISBN links support NWE through referral fees

• 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 April 15, 2024.

• IUPAC Compendium of Chemical Terminology - the Gold Book International Union of Pure and Applied Chemistry.

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