Quaternary Ammonium and Phosphonium Salts

Some are combustible.

Quaternary ammonium salts often serve as catalysts in reactions. They are incompatible with many strong oxidizers and reducing agents, such as metal hydrides, alkali/active metals, and organometallics.

Quaternary ammonium compounds can display a range of health effects, from mild skin and respiratory irritation up to severe caustic burns on skin and gastro-intestinal lining (depending on concentration), gastro-intestinal symptoms (e.g., nausea and vomiting), coma, convulsions, hypotension and death. They are thought to be the chemical group responsible for anaphylactic reactions that occur with use of neuromuscular blocking drugs during general anaesthesia in surgery. Quaternium-15 is the single most often found cause of allergic contact dermatitis of the hands.

This group covers compounds with the structure [NR4]+, R being an alkyl group or an aryl group. Unlike the ammonium ion, [NH4]+, and the primary, secondary, or tertiary ammonium cations, the quaternary ammonium cations are permanently charged, independent of the pH of their solution. Quaternary ammonium salts or quaternary ammonium compounds (called quaternary amines in oilfield parlance) are salts of quaternary ammonium cations with an anion. These compounds often are used as phase transfer reagents to accelerate reactions in mixed organic-aqueous systems where separate reactants primarily are soluble in different layers. Quaternary ammonium salts are used as disinfectants, surfactants, fabric softeners, and as antistatic agents (e.g. in shampoos). In liquid fabric softeners, the chloride salts are often used. In dryer anti-cling strips, the sulfate salts are often used. Spermicidal jellies also contain quaternary ammonium salts.

Tetramethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetraphenylammonium bromide, tetraphenylammonium borate, chlormequat chloride, propantheline bromide, tetramethylphosphonium bromide.