Dimethylamine
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content
Dimethylamine
IUPAC name Dimethylamine
Identifiers
CAS number [124-40-3]
SMILES
 
Properties
Molecular formula C2H7N
Molar mass 45.08 g/mol
Appearance Colorless gas with pungent odor
Density 1.883 kg/m3 (21 °C, 1 atm)
Melting point

−92.2 °C
Boiling point

7 °C
Solubility in water 354 g/100 mL
Dipole moment  ?
Thermochemistry
Std enthalpy of
formation ΔfHo298		 -18.422 kJ/mol
Standard molar
entropy So298		  ? J/K/mol
Hazards
EU classification Highly flammable (F+)
Harmful (Xn)
EU Index 612-001-00-9
NFPA 704
4
3
0
 
R-phrases R12, R20, R37/38, R41
S-phrases (S2), S16, S26, S39
Flash point Flammable gas
Autoignition
temperature		 400 °C
Explosive limits 2.8–14.4%
RTECS number IP8750000
Related compounds
Related amine Methylamine
Trimethylamine
Diethylamine
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Dimethylamine is an organic compound with the formula (CH3)2NH. This secondary amine is a colorless, flammable liquid with an ammonia- or fish-like odor. Dimethylamine is generally encountered as a solution in water at concentrations up to around 40%. In 2005, an estimated 270,000 tons were produced.[1]

Contents

Structure and properties

The molecule consists of a nitrogen atom with two methyl substituents and one proton. Dimethylamine is a 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]

2 CH3OH + NH3 → (CH3)2NH + 2 H2O

Uses

Dimethylamine is a precursor to several industrially significant compounds.[1] It reacts with carbon disulfide to give dimethyldithiocarbamate, 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.[3]

DMA undergoes nitrosation under weak acid conditions to give dimethlynitrosamine. This animal carcinogen has been detected and quantified in human urine samples and it may also arise from nitrosation of DMA by nitrogen oxides present in acid rain in highly industrilized countries.

See also

References

  1. ^ a b 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
  2. ^ 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. 
  3. ^ Zhang AQ, Mitchell SC, Smith RL (1998) Dimethylamine formation in the rat from various related amine precursors. Food Chem Toxicol 36, pp. 923-7.


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