Tetramethylammonium

Tetramethylammonium (TMA) or (Me4N+) is the simplest quaternary ammonium cation, consisting of four methyl groups attached to a central nitrogen atom, and is isoelectronic with neopentane. It is positively charged and can only be isolated in association with a counter-ion. Common salts include tetramethylammonium chloride and tetramethylammonium hydroxide. Tetramethylammonium salts are used in chemical synthesis and are widely employed in pharmacological research. Tetramethylammonium (TMA) or (Me4N+) is the simplest quaternary ammonium cation, consisting of four methyl groups attached to a central nitrogen atom, and is isoelectronic with neopentane. It is positively charged and can only be isolated in association with a counter-ion. Common salts include tetramethylammonium chloride and tetramethylammonium hydroxide. Tetramethylammonium salts are used in chemical synthesis and are widely employed in pharmacological research. In the toxicological literature, naturally occurring tetramethylammonium (anion unspecified) is often referred to by the name 'tetramine'. Unfortunately, this non-systematic or 'trivial' name is also used for other chemical entities, including a toxic rodenticide (Tetramethylenedisulfotetramine). Similarly, the acronym 'TMA', which is frequently used for tetramethylammonium in the pharmacological literature, may also refer to the investigational drug 3,4,5-trimethoxyamphetamine, which, being a close structural analog of mescaline, has been the subject of numerous publications. TMA has been detected in or isolated from a number of marine organisms, mostly amongst the Cnidaria and Mollusca, notably in some species of Neptunea (commonly called whelks) that are eaten by humans. It has also been found in one plant, the African Courbonia virgata (Cappariaceae). One of the most straightforward methods of preparing a simple salt containing the tetramethylammonium ion is by the reaction between trimethylamine and a methyl halide: -labeled TMA has been made by this method. Although this reaction is suitable for the common halides, tetramethylammonium salts with more complex anions may be prepared by salt metathesis reactions, e.g. tetramethylammonium borohydride has been made from tetramethylammonium hydroxide as shown: Me4N+− + Na+− → Me4N+− + Na+ + HO− Although TMA salts do possess some of the phase-transfer catalytic properties that are characteristic of quaternary ammonium compounds, they tend to behave atypically because of the relatively high hydrophilicity of the TMA cation. TMA cation is hydrophilic. The partition coefficient of TMA iodide in octanol-water, Po-w, is 1.2×10−4 (or log P ≈ −3.92).