An amine oxide
, also known as amine-N-oxide
, is a chemical compound
that contains the functional group
(sometimes written as R3
N=O or R3
N→O). In the strict sense the term amine oxide
applies only to oxides of tertiary amines
-containing aromatic compounds
, but is sometimes also used for the analogous derivatives of primary and secondary amines.
Amine oxides are used as protecting group for amines and as chemical intermediates. Long-chain alkyl amine oxides are used as nonionic surfactants and foam stabilizers.
Amine oxide are highly polar molecules have a high polarity close to that of quaternary ammonium salts. Small amine oxides are very hydrophilic and have an excellent water solubility and a very poor solubility in most organic solvents.
Amine oxides are weak bases with a pKa of around 4.5 that form R3N+-OH, cationic hydroxylamines, upon protonation at a pH below their pKa.
Pyridine N-oxide is a crystalline solid with melting point 62-67°C and soluble in water N-Methylmorpholine N-oxide is an oxidant.
Amine oxides are prepared by oxidation
of tertiary amines or pyridine analogs with hydrogen peroxide
), Caro's acid
Amine oxides are common metabolites of medication and psychoactive drugs. Examples include nicotine, Zolmitriptan, and morphine.
Amine oxides of anti-cancer drugs have been developed as prodrugs that are metabolized in the oxygen deficient cancer tissue to the active drug.