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%. An estimated 270,000 tons were produced in 2005.
Structure and synthesis
The molecule consists of a
nitrogen atom with two
methyl and one
hydrogen. Dimethylamine is a weak base and the
pKa of the
ammonium CH
3--CH
3 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:[
]
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.
[ Ashford's Dictionary of Industrial Chemicals, 3rd edition, 2011, pages 3284-3286] It reacts with carbon disulfide to give dimethyl dithiocarbamate, a precursor to zinc bis(dimethyldithiocarbamate) and other chemicals used in the sulfur vulcanization of rubber. Dimethylaminoethoxyethanol is manufactured by reacting dimethylamine and ethylene oxide.[Frank, H., 2007. Preparation of N, N-Dimethylaminoethoxyethanol by Reacting Reacting Di-methylamine with Ethylene Oxide US Patent] Other methods are also available producing streams rich in the substance which then need to be further purified.[US8907084B2 - Process for the preparation of 2-(2-aminoethoxy) ethanol (2AEE) and morpholine with 2AEE: morpholine >3 - Google Patents] The solvents dimethylformamide and dimethylacetamide are derived from dimethylamine. It is raw material for the production of many and , such as dimefox and diphenhydramine, respectively. The chemical weapon tabun is derived from dimethylamine. The surfactant lauryl dimethylamine oxide is found in and cleaning compounds. Unsymmetrical dimethylhydrazine, a rocket fuel, is prepared from dimethylamine.
- (CH3)2NH + NH2Cl → (CH3)2NNH2 ⋅ HCl
It is an attractant for .[ The Merck Index, 10th Ed. (1983), p.470, Rahway: Merck & Co.]
Reactions
It is basic, in both the Lewis[ The plots shown in this paper used older parameters. Improved E&C parameters are listed in ECW model. ] and Brønsted senses. It easily forms dimethylammonium salts upon treatment with acids. 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 tetrakis(dimethylamido)titanium and pentakis(dimethylamido)tantalum.
It reacts with many carbonyl compounds. Aldehydes give aminals. For example reaction of dimethylamine and formaldehyde gives bis(dimethylamino)methane:
- 2 (CH3)2NH + CH2O → (CH3)2N2CH2 + H2O
It converts esters to dimethylamides.
Safety
Dimethylamine is not very toxic with the following LD50 values: 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.).[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]
Although not acutely toxic, dimethylamine undergoes nitrosation to give dimethylnitrosamine, a carcinogen.
See also
External links
