Dimethylamine

Dimethylamine
Names
Other names
N-Methylmethanamine[1]
Identifiers
124-40-3 YesY
3DMet B00125
605257
ChEBI CHEBI:17170 YesY
ChEMBL ChEMBL120433 YesY
ChemSpider 654 YesY
EC Number 204-697-4
849
Jmol interactive 3D Image
KEGG C00543 YesY
MeSH dimethylamine
PubChem 674
RTECS number IP8750000
UNII ARQ8157E0Q YesY
UN number 1032
Properties[2][3]
(CH3)2NH
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
Acidity (pKa) 10.64[4]
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
F+ Xn
R-phrases R12, R20, R37/38, R41
S-phrases (S2), S16, S26, S39
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., propane Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
4
3
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)[5]
4700 ppm (rat, 4 hr)
4540 ppm (rat, 6 hr)
7650 ppm (mouse, 2 hr)[5]
US health exposure limits (NIOSH):
TWA 10 ppm (18 mg/m3)[6]
TWA 10 ppm (18 mg/m3)[6]
500 ppm[6]
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,[7] 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:[8]

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.[9]

Uses

Dimethylamine is a precursor to several industrially significant compounds.[7][10] 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.[11]

It is an attractant for boll weevils.[12]

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.

Toxicology

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.). [13]

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.[12]

See also

References

  1. ↑ "dimethylamine - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification. Retrieved 21 October 2011.
  2. ↑ "Dimethylamine". NIST Chemistry WebBook. USA: National Institute of Standards and Technology. Retrieved 21 October 2011.
  3. ↑ "Dimethylamine 38931 - ≥99.0%". Aldrich. Sigma-Aldrich Co. Retrieved 21 October 2011.
  4. ↑ Hall, H.K. (1957). J. Am. Chem. Soc. 79: 5441. doi:10.1021/ja01577a030. Missing or empty |title= (help)
  5. 1 2 "Dimethylamine". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
  6. 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0219". National Institute for Occupational Safety and Health (NIOSH).
  7. 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
  8. ↑ 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.
  9. ↑ Neurath, G. B.; et al. (1977). "Primary and secondary amines in the human environment". Fd. Cosmet. Toxicol 15: 275–282.
  10. ↑ Ashford's Dictionary of Industrial Chemicals, 3rd edition, 2011, pages 3284-3286
  11. ↑ 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.
  12. 1 2 The Merck Index, 10th Ed. (1983), p.470, Rahway: Merck & Co.
  13. ↑ 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

External links

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