|Melting point||−93.00 °C; −135.40 °F; 180.15 K|
|Boiling point||7 °C; 44 °F; 280 K|
|3.540 kg L−1|
|Vapor pressure||170.3 kPa (at 20 °C)|
|310 μmol Pa−1 kg−1|
Std enthalpy of
|−21–−17 kJ mol−1|
|GHS signal word||DANGER|
|H220, H302, H315, H318, H332, H335|
|P210, P261, P280, P305+351+338|
|EU classification||F+ Xn|
|R-phrases||R12, R20, R37/38, R41|
|S-phrases||(S2), S16, S26, S39|
|Flash point||−6 °C (21 °F; 267 K)|
|401 °C (754 °F; 674 K)|
|US health exposure limits (NIOSH):|
|TWA 10 ppm (18 mg/m3)|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Dimethylamine is an organic compound with the formula (CH3)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%. In 2005, an estimated 270,000 tons were produced industrially, but it is also found as a natural product.
Structure and properties
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 (10.64) and trimethylamine (9.79).
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:
- 2 CH3OH + NH3 → (CH3)2NH + 2 H2O
Dimethylamine is found quite widely distributed in animals and plants, and is present in many foods at the level of a few mg/kg.
Dimethylamine is a precursor to several industrially significant compounds. It reacts with carbon disulfide to give dimethyl dithiocarbamate, a precursor to a family of chemicals widely used in the 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.
Dimethylamine undergoes nitrosation under weak acid conditions to give dimethylnitrosamine. This animal carcinogen has been detected and quantified in human urine samples and it may also arise from nitrosation of dimethylamine by nitrogen oxides present in acid rain in highly industrialized countries.
The toxicology of dimethylamine is discussed as part of a NIH monograph concerning dimethylamine borane. LD50: 736 mg/kg (mouse, i.p.); 316 mg/kg (mouse, p.o.); 698 mg/kg (rat, p.o.); 3900 mg/kg (rat, dermal); 240 mg/kg (guinea pig or rabbit, p.o.). 
The unattributed LD (lethal dose) given in the Merck index for i.v. administration to rabbits, 4000 mg/kg, is unexpectedly high, and appears to be inconsistent with values given above.
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- The Merck Index, 10th Ed. (1983), p.470, Rahway: Merck & Co.
- Chemical Information Profile for Dimethylamine Borane, National Toxicology Program, NIEHS, NIH (2008), p.4: http://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/DimethylamineBorane508.pdf