Dimethylamine

Dimethylamine
Names
Preferred IUPAC name
N-Methylmethanamine
Other names
(Dimethyl)amine
Identifiers
3D model (JSmol)
3DMet B00125
605257
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.272
EC Number 204-697-4
849
KEGG
MeSH dimethylamine
RTECS number IP8750000
UNII
UN number 1032
Properties[1][2]
(CH3)2NH
Molar mass 45.09 g·mol−1
Appearance Colorless gas
Odor Fishy, ammoniacal
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
log P −0.362
Vapor pressure 170.3 kPa (at 20 °C)
310 μmol Pa−1 kg−1
Basicity (pKb) 3.29
Thermochemistry
−21–−17 kJ mol−1
Hazards
GHS pictograms
GHS signal word DANGER
H220, H302, H315, H318, H332, H335
P210, P261, P280, P305+351+338
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propaneHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
4
2
0
Flash point −6 °C (21 °F; 267 K) (liquid)
401 °C (754 °F; 674 K)
Explosive limits 2.8–14.4%
Lethal dose or concentration (LD, LC):
698 mg/kg (rat, oral)
316 mg/kg (mouse, oral)
240 mg/kg (rabbit, oral)
240 mg/kg (guinea pig, oral)[3]
4700 ppm (rat, 4 hr)
4540 ppm (rat, 6 hr)
7650 ppm (mouse, 2 hr)[3]
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 10 ppm (18 mg/m3)[4]
REL (Recommended)
 TWA 10 ppm (18 mg/m3)[4]
IDLH (Immediate danger)
 500 ppm[4]
Related compounds
Related amines
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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,[5] 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:[6]

2 CH3OH + NH3 → (CH3)2NH + 2 H2O

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.[7]

Uses

Dimethylamine is a precursor to several industrially significant compounds.[5][8] 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.

Biochemistry

The German cockroach utilizes dimethylamine as a pheromone for communication.[9]

It is an attractant for boll weevils.[10]

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.

Amido derivatives

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.

Toxicology

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.).[11]

See also

References

  1. ↑ "Dimethylamine". NIST Chemistry WebBook. USA: National Institute of Standards and Technology. Retrieved 21 October 2011.
  2. ↑ "Dimethylamine 38931 - ≥99.0%". Aldrich. Sigma-Aldrich Co. Retrieved 21 October 2011.
  3. 1 2 "Dimethylamine". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0219". National Institute for Occupational Safety and Health (NIOSH).
  5. 1 2 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
  6. ↑ 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.
  7. ↑ Neurath, G. B.; et al. (1977). "Primary and secondary amines in the human environment". Fd. Cosmet. Toxicol. 15: 275–282. doi:10.1016/s0015-6264(77)80197-1.
  8. ↑ Ashford's Dictionary of Industrial Chemicals, 3rd edition, 2011, pages 3284-3286
  9. ↑ 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.
  10. ↑ The Merck Index, 10th Ed. (1983), p.470, Rahway: Merck & Co.
  11. ↑ 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
  • International Chemical Safety Card 0260 (gas)
  • International Chemical Safety Card 1485 (aqueous solution)
  • "NIOSH Pocket Guide to Chemical Hazards #0219". National Institute for Occupational Safety and Health (NIOSH).
  • Properties from Air Liquide
  • MSDS at airliquide.com
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