Functional group

In ecology functional groups are collections of organisms based on morphological, physiological, behavioral, biochemical, or environmental responses or on trophic criteria.

In organic chemistry functional groups are submolecular structural motifs, characterized by specific elemental composition and connectivity, that confer reactivity upon the molecule that contains them.

The following is a list of common functional groups. In the formulas, the symbols R and R' denote any group of atoms.

Chemical class Group Formula Prefix Suffix
Alcohol Hydroxyl R−OH hydroxy- -ol
Alkanes Methyl R−CH3 methyl- (similarly for higher alkyl substituents: ethyl, propyl, butyl, etc.)  
Alkenes Alkene R−CH=CH−R' convert the part substituting for alk in the name of the alkane into the alk of the word alkene: ethane/ethene, propane/propene, butane/butene, etc. -ene
Alkynes Alkyne R−C≡C−R' convert the part substituting for alk in the name of the alkane into the alk of the word alkyne: ethane/ethyne, propane/propyne, butane/butyne, etc. -yne
Amide Amide R−C(=O)N(−H)−R' name according to the parent amine and acid, respectively: alkyl alkanamide  
Amines primary Amine R−NH2 amino- -amine
secondary Amine R−N(−H)−R' amino- -amine
tertiary Amine R−N(−R')−R amino- -amine
Azo Azo R-N=N-R'    
  Nitrile R−C≡N cyano-  
  Pyridyl R−C5H4N    
Carboxylic acid Carboxyl R−C(=O)OH



carboxy- -oic acid
Carbonyl Aldehyde R−C(=O)H   -al
Ketone R−C(=O)−R' keto- -one
Imines primary Imine R−C(=NH)−R' imino- -imine
secondary Imine R−C(−H)=N−R' imino- -imine
Ether Ether R−O−R' named according to the parent alcohols, respectively: alkylalkylether  
Ester Ester R−C(=O)O−R' named according to the parent alcohol and acid, respectively: alkyl alkanoate  
Halogens Halogen F,Cl,Br,etc.    
Isocyanates Isocyanate R−N=C=O alkyl isocyanate  
Isothiocyanate R−N=C=S alkyl isothiocyanate  
Phenyl Phenyl R−C6H5    
Benzyl Benzyl R−CH2−C6H5 benzyl  
  Phosphodiester R−OP(=O)2O−R'    
Thiol sulfhydryl group R−SH   -thiol
  Thioether R−S−R'    

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 funcional de:Funktionelle Gruppe es:Grupo funcional eo:Funkcia grupo fr:Groupe fonctionnel it:Gruppo funzionale nl:Functionele groep ja:基 pl:Grupa funkcyjna pt:Grupo funcional vi:Nhóm chức


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