Functional group

In organic chemistry functional groups 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.

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, the basic functional groups covered in General Biology are also listed here)

Chemical class	Group	Formula	Graphical Formula	Prefix	Suffix	Example
Acyl halide	Haloformyl	RCOX	Acyl halide	haloformyl-	-oyl halide	Acetyl chloride Acetyl chloride
Alcohol	Hydroxyl	ROH	Hydroxyl	hydroxy-	-ol	methanol Methanol
Aldehyde	Aldehyde	RCHO	Aldehyde	oxo-	-al	acetaldehyde Acetaldehyde
Alkane	Alkyl	RH	Alkyl	alkyl-	-ane	methane Methane
Alkene	Alkenyl	R2C=CR2	Alkene	alkenyl-	-ene	ethylene Ethylene
Alkyne	Alkynyl	RC≡CR'	Alkyne	alkynyl-	-yne	acetylene Acetylene
Amide	Carboxamide	RCONR2	Amide	carboxamido-	-amide	acetamide Acetamide
Amines	Primary amine	RNH2	Primary amine	amino-	-amine	methylamine Methylamine
	Secondary amine	R2NH	Secondary amine	amino-	-amine	dimethylamine Dimethylamine
	Tertiary amine	R3N	Tertiary amine	amino-	-amine	trimethylamine Trimethylamine
	4° ammonium ion	R4N+	Quaternary ammonium cation	ammonio-	-ammonium	choline Choline
Azo compound	Azo (Diimide)	RN2R'	Azo.pngl	azo-	-diazene
Toluene derivative	Benzyl	RCH2C6H5 RBn	Benzyl	benzyl-	1-(substituent)toluene	Benzyl bromide Benzyl bromide (1-bromotoluene)
Carbonate	Carbonate ester	ROCOOR	Carbonate		alkyl carbonate
Carboxylate	Carboxylate	RCOOâˆ'	Carboxylate Carboxylate	carboxy-	-oate
Carboxylic acid	Carboxyl	RCOOH	Carboxylic acid	carboxy-	-oic acid
Cyanates	Cyanate	ROCN	Cyanate	cyanato-	alkyl cyanate
	Thiocyanate	RSCN	Thiocyanate	thiocyanato-	alkyl thiocyanate
Ether	Ether	ROR'	Ether	alkoxy-	alkyl alkyl ether
Ester	Ester	RCOOR'			-oate
Haloalkane	Halo	RX	Halide group	halo-	alkyl halide
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
Isocyanide	Isocyanide	RNC	Isocyanide	isocyano-	alkyl isocyanide
Isocyanates	Isocyanate	RNCO	Isocyanate	isocyanato-	alkyl isocyanate
	Isothiocyanate	RNCS	Isothiocyanate	isothiocyanato-	alkyl isothiocyanate
Ketone	Ketone	RCOR'		keto-, oxo-	-one
Nitrile	Nitrile	RCN	Nitrile	cyano-	alkanenitrile alkyl cyanide
Nitro compound	Nitro	RNO2	Nitro	nitro-
Nitroso compound	Nitroso	RNO	Nitroso	nitroso-
Peroxide	Peroxy	ROOR	Peroxy	peroxy-	alkyl peroxide
Benzene derivative	Phenyl	RC6H5	Phenyl	phenyl-	-benzene
Phosphine	Phosphino	R3P	A tertiary phosphine	phosphino-	-phosphane	Methylpropylphosphane Methylpropylphosphane
Phosphodiester	Phosphate	HOPO(OR)2	Phosphodiester	phosphoric acid di(substituent) ester	di(substituent) hydrogenphosphate
Phosphonic acid	Phosphono	RP(=O)(OH)2	Phosphono group	phosphono-	substituent phosphonic acid
Phosphate	Phosphate	ROP(=O)(OH)2	Phosphate group	phospho-
Pyridine derivative	Pyridyl	RC5H4N	4-pyridyl group 3-pyridyl group 2-pyridyl group	4-pyridyl / pyridin-4-yl 3-pyridyl / pyridin-3-yl 2-pyridyl / pyridin-2-yl	-pyridine
Sulfone	Sulfonyl	RSO2R'	Sulfonyl group	sulfonyl-	di(substituent) sulfone
Sulfonic acid	Sulfo	RSO3H	Sulfonyl group	sulfo-	substituent sulfonic acid
Sulfoxide	Sulfinyl	RSOR'	Sulfinyl group	sulfinyl-	di(substituent) sulfoxide	Diphenyl sulfoxide Diphenyl sulfoxide
Thiol	Sulfhydryl	RSH	Sulfhydryl	mercapto-, sulfanyl-	-thiol

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. And all of these are called radicals, by a meaning of the term radical that predates the free radical.

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

External links

* IUPAC ligand abbreviations (pdf)
* IUPAC Gold Book (Compendium of Chemical Terminology)
* IUPAC Blue Book (organic nomenclature)

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