Dimethylamine


Dimethylamine is an organic compound with the formula 2NH. This secondary amine is a colorless, flammable gas with an ammonia-like odor. Dimethylamine is commonly encountered commercially as a solution in water at concentrations up to around 40%. An estimated 270,000 tons were produced in 2005.

Structure and synthesis

The molecule consists of a nitrogen atom with two methyl substituents and one proton. Dimethylamine is a weak base and the pKa of the ammonium salt CH3-NH2+-CH3 is 10.73, a value above methylamine and trimethylamine.
Dimethylamine reacts with acids to form salts, such as dimethylamine hydrochloride, an odorless white solid with a melting point of 171.5 °C. Dimethylamine is produced by catalytic reaction of methanol and ammonia at elevated temperatures and high pressure:

Natural occurrence

Dimethylamine is found quite widely distributed in animals and plants, and is present in many foods at the level of a few mg/kg.

Uses

Dimethylamine is a precursor to several industrially significant compounds. It reacts with carbon disulfide to give dimethyl dithiocarbamate, a precursor to zinc bis and other chemicals used in the sulfur vulcanization of rubber. The solvents dimethylformamide and dimethylacetamide are derived from dimethylamine. It is raw material for the production of many agrichemicals and pharmaceuticals, such as dimefox and diphenhydramine, respectively. The chemical weapon tabun is derived from dimethylamine. The surfactant lauryl dimethylamine oxide is found in soaps and cleaning compounds. Unsymmetrical dimethylhydrazine, a rocket fuel, is prepared from dimethylamine.

Occurrence and reactions

It is an attractant for boll weevils.
Dimethylamine undergoes nitrosation to give dimethylnitrosamine, a carcinogen.
Deprotonation of dimethylamine can be effected with organolithium compounds. The resulting LiNMe2, which adopts a cluster-like structure, serves as a source of "Me2N−". This lithium amide has been used to prepare volatile metal complexes such as tetrakistitanium and pentakistantalum.

Safety

Dimethylamine is not very toxic with the following LD50 values: 736 mg/kg ; 316 mg/kg ; 698 mg/kg ; 3900 mg/kg ; 240 mg/kg.