Trimethylamine (N,N-dimethylmethanamine) is a tertiary amine in which each hydrogen atom of ammonia is replaced by a methyl group. Anhydrous trimethylamine is a colourless gas with a fish-like odour that becomes ammonia-like at higher concentrations; it is also handled as an aqueous solution. It is used in organic synthesis, especially of choline salts and quaternary ammonium compounds, and as a flotation agent.