Functional Group

A functional group is a section of a compound that is classified as a specific group of bound atoms. Functional groups help determine the reactions and connections that a compound may engage in.

Amino Acids
- - Structure and classification of amino acids
  - Properties of amino acids
  - Essential and non-essential amino acids
  - Polar and non-polar amino acids
  - Acidic and basic amino acids
  - Amino acid sequencing
  - Peptide bond formation
Protein Structure and Function
- - Primary, secondary, tertiary, and quaternary structure of proteins
  - Protein folding and stability
  - Denaturation of proteins
  - Protein-protein interactions
  - Enzymes and catalysis
  - Enzyme kinetics
  - Allosteric enzymes
  - Protein domains and motifs
Protein Synthesis
- - Transcription and translation
  - Genetic code
  - tRNA and aminoacyl-tRNA synthetases
  - Ribosomes and ribosomal RNA
  - Protein targeting and transport
  - Post-translational modifications of proteins
Proteomics
- - Proteome and proteomics
  - Two-dimensional gel electrophoresis
  - Mass spectrometry
  - Protein-protein interaction analysis
  - Structural proteomics
Protein Engineering
- - Rational protein design
  - Directed evolution
  - Protein expression systems
  - Protein purification techniques
  - Biophysical techniques for protein characterization
Diseases Related to Proteins
- - Protein misfolding diseases
  - Amyloidosis
  - Prion diseases
  - Proteopathies
  - Protein aggregation
  - Protein-losing enteropathy

Functional Groups of Organic Compounds:

Accessory molecules

Key characteristics of functional groups include: having consistent chemical properties and their atoms are linked to by covalent bonds. They behave as special accessory molecules which bind to organic compounds. The arrangement of a functional group makes it possible to predict how a new compound will react.

Characteristic Properties:

Specific groups of atoms

The bonding of other elements with carbon and hydrogen forms characteristic functional groups. Specific groups of atoms determine properties of a compound which are either chemical or physical. Chemical properties are used to characterize materials in reactions that change their identity. Physical properties are used to characterize matter and energy and their interactions.

The unique properties of an organic compound depend not only on its carbon skeleton but also on the atoms that are attached to the skeleton. In an organic molecule, the groups of atoms that usually participate in chemical reactions are called functional groups.

Functional Group Structure:

Functional Group Distinguishing Feature — GRAPHIC

Table of Functional Groups:

Hydrocarbons Functional Groups

Chemical Name	Group	Formula	Prefix	Suffix	Example	Structural Formula
Alkanes	Alkane group	R-CH3	Alkyl-	-ane	Ethane	CH3CH3
Alkenes	Alkene group	R-CH=CH2	Alkenyl-	-ene	Propene	CH3CH=CH2
Alkynes	Alkyne group	R-C≡CH	Alkynyl-	-yne	Butyne	CH3C≡CH
Cycloalkanes	Cycloalkane group	CnH2n (n = number of carbon atoms)	Cycloalkyl-	-ane	Cyclohexane	(CH2)6
Aromatic hydrocarbons	Aromatic group	Ar (Ar = aromatic ring)	Phenyl-	-	Benzene	C6H6

Oxygen Functional Groups

Chemical Name	Group	Formula	Prefix	Suffix	Example	Structural Formula
Alcohols	Hydroxyl	ROH	Hydroxy-	-ol	Ethanol	CH₃CH₂OH
Aldehydes	Aldehyde	RCHO	-	-al	Formaldehyde	HCHO
Ketones	Ketone	R₂C=O	-	-one	Acetone	CH₃COCH₃
Carboxylic acids	Carboxyl	RCOOH	-	-oic acid	Acetic acid	CH₃COOH
Esters	Carboxylate ester	RCOOR'	Alkyl/aryl-	-oate	Ethyl acetate	CH₃COOCH₂CH₃
Acid chlorides	Acyl chloride	RCOCl	-	-oyl chloride	Acetyl chloride	CH₃COCl
Acid anhydrides	Acyl anhydride	(RCO)₂O	-	-oic anhydride	Acetic anhydride	(CH₃CO)₂O
Ethers	Ether	R-O-R'	Alkoxy-	-ether	Dimethyl ether	(CH₃)₂O
Epoxides	Oxirane	O-CH₂-CH₂-O	-	-oxirane	Ethylene oxide	CH₂CH₂O
Peroxides	Peroxide	R-O-O-R'	Alkyl/aryl-	-peroxide	Hydrogen peroxide	H₂O₂
Thiols	Thiol	R-SH	Mercapto-	-thiol	Ethanethiol	CH₃CH₂SH
Sulfides	Thioether	R-S-R'	Alkyl/aryl-	-sulfide	Dimethyl sulfide	(CH₃)₂S
Sulfoxides	Sulfoxide	R-S(=O)-R'	-	-sulfoxide	Dimethyl sulfoxide	(CH₃)₂SO
Sulfones	Sulfone	R-S(=O)₂-R'	-	-sulfone	Dimethyl sulfone	(CH₃)₂SO₂
Acyl halides	Acyl halide	RCOX	-	-oyl halide	Acetyl chloride	CH₃COCl
Carboxylic acid salts	Carboxylate	RCOOR'	Alkyl/aryl-	-oate	Sodium acetate	CH₃COONa
Amides	Carboxamide	RCO-NH₂	-	-amide	Acetamide	CH₃CONH₂
Nitro compounds	Nitro	R-NO₂	Nitro-	-nitro	Nitrobenzene	C₆H₅NO₂
Phenols	Phenolic hydroxyl	Ar-OH (Ar = aromatic ring)	Hydroxy-	-ol	Phenol	C₆H₅OH

Nitrogen Functional Groups

Chemical Name	Group	Formula	Prefix	Suffix	Example	Structural Formula
Amines	Amino group	R-NH2	Amino-	-amine	Ethylamine	CH3CH2NH2
Amides	Carboxamide group	RCO-NH2	-	-amide	Acetamide	CH3CONH2
Nitriles	Cyanide group	RC≡N	-	-nitrile	Acetonitrile	CH3CN
Nitro compounds	Nitro group	R-NO2	Nitro-	-nitro	Nitrobenzene	C6H5NO2
Azides	Azide group	R-N3	Azido-	-azide	Phenyl azide	C6H5N3
Imines	Imine group	R2C=NR'	-	-imine	Methylamine	CH3NHCH3
Pyridines	Pyridine group	C5H5N	-	-pyridine	Pyridine	C5H5N
Quaternary ammonium salts	Quaternary ammonium group	R4N+	-	-onium	Tetraethylammonium bromide	(C2H5)4NBr
Hydrazines	Hydrazine group	N2H4	-	-hydrazine	Hydrazine	N2H4
Oximes	Oxime group	R-C=N-OH	-	-oxime	Acetoxime	CH3C=N-OH
Imides	Imide group	R-CO-NH-CO-R'	-	-imide	Succinimide	C4H5NO2
Hydrazones	Hydrazone group	R-C=N-NH-R'	-	-hydrazone	Phenylhydrazine	C6H5NHNH2
Azo compounds	Azo group	R-N=N-R'	Azo-	-azo	Azobenzene	C6H5N=NPh
Nitroso compounds	Nitroso group	R-NO	Nitroso-	-nitroso	Nitrosobenzene	C6H5NO
Isocyanates	Isocyanate group	R-N=C=O	Isocyanato-	-isocyanate	Methyl isocyanate	CH3NCO
Isocyanides	Isocyanide group	R-N≡C	-	-isocyanide	Phenyl isocyanide	C6H5NC
Pyrimidines	Pyrimidine group	C4H4N2	-	-pyrimidine	Pyrimidine	C4H4N2
Pyrazines	Pyrazine group	C4H4N2	-	-pyrazine	Pyrazine	C4H4N2
Pyridazines	Pyridazine group	C4H4N2	-	-pyridazine	Pyridazine	C4H4N2

Sulfur Functional Groups

Chemical Name	Group	Formula	Prefix	Suffix	Example	Structural Formula
Thiols	Sulfhydryl group	R-SH	Mercapto-	-thiol	Ethanethiol	CH3-CH2-SH
Sulfides	Thioether group	R-S-R'	Alkylthio-	-sulfide	Dimethyl sulfide	CH3-S-CH3
Sulfoxides	Sulfinyl group	R-S(=O)-R'	Alkylsulfinyl-	-sulfoxide	Dimethyl sulfoxide	CH3-S(=O)-CH3
Sulfones	Sulfonyl group	R-S(=O)2-R'	Alkylsulfonyl-	-sulfone	Diphenyl sulfone	C6H5-S(=O)2-C6H5
Sulfonic acids	Sulfonic acid group	R-S(=O)2-OH	Alkanesulfonyl-	-sulfonic acid	Methanesulfonic acid	CH3-S(=O)2-OH
Sulfonyl halides	Sulfonyl halide group	R-S(=O)2-X	Alkanesulfonyl-	-sulfonyl halide	Methanesulfonyl chloride	CH3-S(=O)2-Cl
Thiocyanates	Thiocyanate group	R-S-C≡N	Alkylthiocyanato-	-thiocyanate	Ethyl thiocyanate	CH3CH2-S-C≡N
Sulfonic esters	Sulfonate group	R-S(=O)2-O-R'	Alkanesulfonyloxy-	-sulfonate	Methyl sulfonate	CH3-S(=O)2-O-CH3
Thiosulfates	Thiosulfate group	R-S(=O)2-O-S-R'	Alkanethiosulfonyloxy-	-thiosulfate	Ethyl thiosulfate	CH3CH2-S(=O)2-O-CH2CH3

Phosphorus Functional Groups

Chemical Name	Group	Formula	Prefix	Suffix	Example	Structural Formula
Phosphines	Phosphino group	R3P	Phosphino-	-phosphine	Tributylphosphine	(C4H9)3P
Phosphates	Phosphate group	RO4P	Alkyl/aryl-	-phosphate	Dimethyl phosphate	(CH3O)2PO
Phosphonates	Phosphonate group	RO3P	Alkyl/aryl-	-phosphonate	Dimethyl phosphonate	(CH3O)PO2
Phosphoric esters	Phosphate ester group	RO3P	Alkyl/aryl-	-phosphate	Diethyl phosphate	(C2H5O)2PO
Phosphonothioates	Phosphonothioate group	RO2PSR'	Alkyl/aryl-	-phosphonothioate	Dimethyl phosphonothioate	(CH3O)PSCH3
Phosphinic acids	Phosphinic acid group	R2PO2H	Alkyl/aryl-	-phosphinic acid	Dimethyl phosphinic acid	(CH3O)2POH
Phosphonodithioates	Phosphonodithioate group	RO2PS2R'	Alkyl/aryl-	-phosphonodithioate	Dimethyl phosphonodithioate	(CH3O)PS2CH3
Phosphoric amides	Phosphoric amide group	RO2PNR'R''	Alkyl/aryl-	-phosphoric amide	Dimethyl phosphoric amide	(CH3O)2P(NH2)

Halogen Functional Groups

Chemical Name	Group	Formula	Prefix	Suffix	Example	Structural Formula
Alkyl halides	Haloalkanes	R-X	None	-ane	Chloromethane	CH3-Cl
Alkene halides	Haloalkenes	R2C=CHX	None	-ene	1,2-Dichloroethene	ClHC=CHCl
Alkyne halides	Haloalkynes	RC≡CX	None	-yne	2-Bromo-1-pentyne	BrCH2CH2C≡CH
Aryl halides	Haloarenes	Ar-X	None	-aryl	Chlorobenzene	Cl-C6H5
Acyl halides	Haloacyl compounds	R-CO-X	None	-oyl halide	Acetyl chloride	CH3CO-Cl
Alcohol halides	Haloalcohols	RO-X	None	-ol	2-Chloroethanol	Cl-CH2CH2-OH