Methylamine
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| Names | |||
|---|---|---|---|
| IUPAC name
aminomethane, methanamine
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Other names
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| Identifiers | |||
3D model (JSmol)
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| 3DMet | |||
| Abbreviations | MMA | ||
| 741851 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| DrugBank | |||
| ECHA InfoCard | 100.000.746 | ||
| EC Number |
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| 145 | |||
| KEGG | |||
| MeSH | methylamine | ||
PubChem CID
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| RTECS number |
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| UN number | 1061 | ||
CompTox Dashboard (EPA)
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| Properties | |||
| CH5N | |||
| Molar mass | 31.058 g·mol−1 | ||
| Appearance | Colorless gas | ||
| Odor | Fishy, ammoniacal | ||
| Melting point | −93.10 °C; −135.58 °F; 180.05 K | ||
| 1.08 kg L−1 (at 20 °C) | |||
| log P | −0.472 | ||
| Vapor pressure | 186.10 kPa (at 20 °C) | ||
Henry's law
constant (kH) |
1.4 mmol Pa−1 kg−1 | ||
| Basicity (pKb) | 3.36 | ||
| Viscosity | 230 μPa s (at 0 °C) | ||
| 1.31 D | |||
| Thermochemistry | |||
Std enthalpy of
formation (ΔfH⦵298) |
−23.5 kJ mol−1 | ||
| Hazards | |||
| GHS labelling: | |||
  
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| Danger | |||
| H220, H315, H318, H332, H335 | |||
| P210, P261, P280, P305+P351+P338, P410+P403 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | <−30 °C | ||
| Explosive limits | 4.9–20.8% | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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100 mg kg−1 (oral, rat) | ||
| 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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Methylamine is the organic compound with a formula of CH3NH2. This colourless 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 sold 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. Over 1 million tonnes are produced annually.[1]
Production
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.[2]
- CH3OH + NH3 → CH3NH2 + H2O
In this way, more than 400M kg are produced annually.
In the laboratory, methylamine hydrochloride is readily prepared by treating formaldehyde with ammonium chloride.[3]
- NH4Cl + H2CO → [CH2=NH2]Cl + H2O
- [CH2=NH2]Cl + H2CO + H2O → [CH3NH3]Cl + HCOOH
The colourless hydrochloride salt can be converted to the amine by the addition of strong base, like NaOH:
- [CH3NH3]Cl + NaOH → CH3NH2 + NaCl + H2O
Methylamine was first prepared by Wurtz by the hydrolysis of methyl isocyanate and related compounds.[4]
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.
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.[4]
Liquid methylamine can be used as a solvent analogous to liquid ammonia. It shares some of the properties of liquid ammonia, but is better for dissolving organic substances, in the same way that methanol is better than water.[5] Methylamine can also be used for scavenging H2S from hydrocarbon in refining applications.
Biological chemistry
Methylamine arises as a result of putrefaction and is a substrate for methanogenesis.[6]
Safety
The LD50 (mouse, s.c.) is 2.5 g/kg.[7]
Methylamine is also controlled as a List 1 precursor chemical by the United States Drug Enforcement Administration (DEA); the DEA has listed methylamine as a precursor ingredient to methamphetamine.
References
- ^ S.N. Bizzari (November 2008). "CEH Marketing Research Report: ALKYLAMINES (C1-C6)". Chemical Economics Handbook. SRI consulting. Retrieved July 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ 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.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Marvel, C. S.; Jenkins, R. L. (1941). "Methylamine Hydrochloride". Organic Syntheses
{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 1, p. 347. - ^ a b 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
- ^ H. D. Gibbs (1906). "Liquid methylamine as a solvent, and a study of its chemical reactivity". J. Am. Chem. Soc. 28 (10): 1395–1422. doi:10.1021/ja01976a009.
- ^ Thauer, R. K., "Biochemistry of Methanogenesis: a Tribute to Marjory Stephenson", Microbiology, 1998, 144, 2377-2406.
- ^ The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.