|Molar mass||31.06 g·mol−1|
|Density||656.2 kg m−3 (at 25 °C)|
|Melting point||−93.10 °C; −135.58 °F; 180.05 K|
|Boiling point||−6.6 °C; 20.0 °F; 266.5 K|
|1.08 kg L−1 (at 20 °C)|
|Vapor pressure||186.10 kPa (at 20 °C)|
|1.4 mmol Pa−1 kg−1|
|Viscosity||230 μPa s (at 0 °C)|
|Dipole moment||1.31 D|
Std enthalpy of
|−23.5 kJ mol−1|
|GHS signal word||DANGER|
|H220, H315, H318, H332, H335|
|P210, P261, P280, P305+351+338, P410+403|
|EU classification||F+ Xn|
|R-phrases||R12, R20, R37/38, R41|
|S-phrases||(S2), S16, S26, S39|
|Flash point||−10 °C; 14 °F; 263 K (liquid, gas is not flammable)|
|430 °C (806 °F; 703 K)|
LD50 (Median lethal dose)
|100 mg kg−1 (oral, rat)|
LC50 (Median lethal concentration)
|1860 ppm (mouse, 2 hr)|
|US health exposure limits (NIOSH):|
|TWA 10 ppm (12 mg/m3)|
|TWA 10 ppm (12 mg/m3)|
IDLH (Immediate danger)
|ethylamine, dimethylamine, trimethylamine|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Methylamine is an organic compound with a formula of CH3NH2. This colorless gas is a derivative of ammonia, but with one H atom replaced by a methyl group. It is the simplest primary amine. It is sold as a solution in methanol, ethanol, THF, and water, or as the anhydrous gas in pressurized metal containers. Industrially, methylamine is transported in its anhydrous form in pressurized railcars and tank trailers. It has a strong odor similar to fish. Methylamine is used as a building block for the synthesis of many other commercially available compounds.
Methylamine is prepared commercially by the reaction of ammonia with methanol in the presence of a silicoaluminate catalyst. Dimethylamine and trimethylamine are coproduced; the reaction kinetics and reactant ratios determine the ratio of the three products. The product most favoured by the reaction kinetics is trimethylamine.
- CH3OH + NH3 → CH3NH2 + H2O
In this way, an estimated 115,000 tons were produced In 2005.
Methylamine was first prepared in 1849 by Wurtz by the hydrolysis of methyl isocyanate and related compounds. An example of this process includes the use of Hofmann rearrangement to yield methylamine from acetamide and bromine gas.
- NH4Cl + H2CO → [CH2=NH2]Cl + H2O
- [CH2=NH2]Cl + H2CO + H2O → [CH3NH3]Cl + HCOOH
The colorless hydrochloride salt can be converted to the amine by the addition of strong base, like NaOH:
- [CH3NH3]Cl + NaOH → CH3NH2 + NaCl + H2O
Reactivity and applications
Methylamine is a good nucleophile as it is highly basic and unhindered, although, as an amine it is considered a weak base. Its use in organic chemistry is pervasive. Some reactions involving simple reagents include: with phosgene to methyl isocyanate, with carbon disulfide and sodium hydroxide to the sodium methyldithiocarbamate, with chloroform and base to methyl isocyanide and with ethylene oxide to methylethanolamines. Liquid methylamine has solvent properties analogous to those for liquid ammonia.
Representative commercially significant chemicals produced from methylamine include the pharmaceuticals ephedrine and theophylline, the pesticides carbofuran, carbaryl, and metham sodium, and the solvents N-methylformamide and N-methylpyrrolidone. The preparation of some surfactants and photographic developers require methylamine as a building block.
The Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH) have set occupational exposure limits at 10 ppm or 12 mg/m3 over an eight hour time-weighted average.
- "NIOSH Pocket Guide to Chemical Hazards #0398". National Institute for Occupational Safety and Health (NIOSH).
- 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.
- Karsten Eller, Erhard Henkes, Roland Rossbacher, Hartmut Höke "Amines, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a02_001
- Charles-Adolphe Wurtz (1849) "Sur une série d'alcalis organiques homologues avec l'ammoniaque" (On a series of homologous organic alkalis containing ammonia), Comptes rendus … , 28 : 223-226. Note: Wurtz's empirical formula for methylamine is incorrect because chemists in that era used an incorrect atomic mass for carbon (6 instead of 12).
- Mann, F. G.; Saunders, B. C. (1960). Practical Organic Chemistry, 4th Ed. London: Longman. p. 128. ISBN 9780582444072.
- Cohen, Julius (1900). Practical Organic Chemistry 2nd Ed. London: Macmillan and Co., Limited. p. 72.
- Marvel, C. S.; Jenkins, R. L. (1941). "Methylamine Hydrochloride". Org. Synth.; Coll. Vol. 1, p. 347
- Gatterman, Ludwig; and Wieland, Heinrich (1937). Laboratory Methods of Organic Chemistry. Edinburgh, UK: R & R Clark, Limited. p. 157-158.
- M. G. DeBacker, El B. Mkadmi, F. X. Sauvage, J.-P. Lelieur, M. J. Wagner, R. Concepcion. J. Kim, L. E. H. McMills, J. L. Dye "The Lithium−Sodium−Methylamine System: Does a Low-Melting Sodide Become a Liquid Metal?" J. Am. Chem. Soc., 1996, vol. 118, pp 1997–2003. doi:10.1021/ja952634p
- Thauer, R. K., "Biochemistry of Methanogenesis: a Tribute to Marjory Stephenson", Microbiology, 1998, 144, 2377-2406.
- Ng, SS; Yue, WW; Oppermann, U; Klose, RJ (February 2009). "Dynamic protein methylation in chromatin biology.". Cellular and molecular life sciences : CMLS 66 (3): 407–22. PMID 18923809.
- The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.
- CDC - NIOSH Pocket Guide to Chemical Hazards