|Preferred IUPAC name
(The name dimethylamine is deprecated.)
|Jmol 3D model||Interactive image|
|Density||649.6 kg m−3 (at 25 °C)|
|Melting point||−93.00 °C; −135.40 °F; 180.15 K|
|Boiling point||7 to 9 °C; 44 to 48 °F; 280 to 282 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 (DSD)
|R-phrases||R12, R20, R37/38, R41|
|S-phrases||(S2), S16, S26, S39|
|Flash point||−6 °C (21 °F; 267 K) (liquid)|
|401 °C (754 °F; 674 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|698 mg/kg (rat, oral)
316 mg/kg (mouse, oral)
240 mg/kg (rabbit, oral)
240 mg/kg (guinea pig, oral)
LC50 (median concentration)
|4700 ppm (rat, 4 hr)
4540 ppm (rat, 6 hr)
7650 ppm (mouse, 2 hr)
|US health exposure limits (NIOSH):|
|TWA 10 ppm (18 mg/m3)|
|TWA 10 ppm (18 mg/m3)|
IDLH (Immediate danger)
Except where otherwise noted, data are 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.
- "Dimethylamine". NIST Chemistry WebBook. USA: National Institute of Standards and Technology. Retrieved 21 October 2011.
- "Dimethylamine 38931 - ≥99.0%". Aldrich. Sigma-Aldrich Co. Retrieved 21 October 2011.
- "NIOSH Pocket Guide to Chemical Hazards #0219". National Institute for Occupational Safety and Health (NIOSH).
- "Dimethylamine". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
- A. B. van Gysel, W. Musin "Methylamines" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH Verlag, Weinheim. doi:10.1002/14356007.a16 535
- Corbin D.R.; Schwarz S.; Sonnichsen G.C. (1997). "Methylamines synthesis: A review". Catalysis Today. 37 (2): 71–102. doi:10.1016/S0920-5861(97)00003-5.
- Neurath, G. B.; et al. (1977). "Primary and secondary amines in the human environment". Fd. Cosmet. Toxicol. 15: 275–282.
- Ashford's Dictionary of Industrial Chemicals, 3rd edition, 2011, pages 3284-3286
- Zhang AQ, Mitchell SC, Smith RL (November 1998). "Dimethylamine formation in the rat from various related amine precursors". Food Chem. Toxicol. 36 (11): 923–7. doi:10.1016/S0278-6915(98)00074-X. PMID 9771553.
- 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