Methylamine
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| Names | |||
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| Preferred IUPAC name
Methanamine[citation needed]
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| Other names
Methylamine, aminomethane
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| Identifiers | |||
74-89-5  |
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| 3D model (Jmol) | Interactive image | ||
| 3DMet | B00060 | ||
| Abbreviations | MMA | ||
| 741851 | |||
| ChEBI | CHEBI:16830  |
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| ChEMBL | ChEMBL43280 |
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| ChemSpider | 6089 |
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| DrugBank | DB01828 |
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| ECHA InfoCard | 100.000.746 | ||
| EC Number | 200-820-0 | ||
| 145 | |||
| KEGG | C00218 |
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| MeSH | methylamine | ||
| PubChem | 6329 | ||
| RTECS number | PF6300000 | ||
| UN number | 1061 | ||
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| Properties | |||
| CH5N | |||
| Molar mass | 31.06 g·mol−1 | ||
| Appearance | Colorless gas | ||
| Odor | Fishy, ammoniacal | ||
| Density | 656.2 kg m−3 (at 25 °C) | ||
| Melting point | −93.10 °C; −135.58 °F; 180.05 K | ||
| Boiling point | −6.6 to −6.0 °C; 20.0 to 21.1 °F; 266.5 to 267.1 K | ||
| 1.08 kg L−1 (at 20 °C) | |||
| log P | −0.472 | ||
| Vapor pressure | 186.10 kPa (at 20 °C) | ||
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Henry's law
constant (kH) |
1.4 mmol Pa−1 kg−1 | ||
| Basicity (pKb) | 3.36 | ||
| -27.0·10−6 cm3/mol | |||
| Viscosity | 230 μPa s (at 0 °C) | ||
| 1.31 D | |||
| Thermochemistry | |||
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Std enthalpy of
formation (ΔfH |
−23.5 kJ mol−1 | ||
| Hazards | |||
| Safety data sheet | emdchemicals.com | ||
| GHS pictograms |    |
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| GHS signal word | DANGER | ||
| H220, H315, H318, H332, H335 | |||
| P210, P261, P280, P305+351+338, P410+403 | |||
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EU classification (DSD)
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 F+  Xn |
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| R-phrases | R12, R20, R37/38, R41 | ||
| S-phrases | (S2), S16, S26, S39 | ||
| NFPA 704 | |||
| Flash point | −10 °C; 14 °F; 263 K (liquid, gas is extremely flammable)[1] | ||
| 430 °C (806 °F; 703 K) | |||
| Explosive limits | 4.9–20.7% | ||
| Lethal dose or concentration (LD, LC): | |||
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LD50 (median dose)
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100 mg kg−1 (oral, rat) | ||
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LC50 (median concentration)
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1860 ppm (mouse, 2 hr)[1] | ||
| US health exposure limits (NIOSH): | |||
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PEL (Permissible)
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TWA 10 ppm (12 mg/m3)[1] | ||
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REL (Recommended)
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TWA 10 ppm (12 mg/m3)[1] | ||
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IDLH (Immediate danger)
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100 ppm[1] | ||
| Related compounds | |||
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Related alkanamines
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ethylamine, dimethylamine, trimethylamine | ||
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Related compounds
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ammonia | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 verify (what is ?) |
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| Infobox references | |||
Methylamine is an organic compound with a formula of CH3NH2. This colorless gas is a derivative of ammonia, but with one hydrogen atom being replaced by a methyl group. It is the simplest primary amine. It is sold as a solution in methanol, ethanol, tetrahydrofuran, or 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.
Contents
Industrial production[edit]
Methylamine is prepared commercially by the reaction of ammonia with methanol in the presence of an aluminosilicate catalyst. Dimethylamine and trimethylamine are co-produced; the reaction kinetics and reactant ratios determine the ratio of the three products. The product most favoured by the reaction kinetics is trimethylamine.[2]
- CH3OH + NH3 → CH3NH2 + H2O
In this way, an estimated 115,000 tons were produced in 2005.[3]
Laboratory methods[edit]
Methylamine was first prepared in 1849 by Charles-Adolphe Wurtz via the hydrolysis of methyl isocyanate and related compounds.[3][4] An example of this process includes the use of the Hofmann rearrangement, to yield methylamine from acetamide and bromine gas.[5][6]
In the laboratory methylamine hydrochloride is readily prepared by various other methods. One method entails treating formaldehyde with ammonium chloride.[7]
- NH4Cl + H2CO → [CH2=NH2]Cl + H2O
- [CH2=NH2]Cl + H2CO + H2O → [CH3NH3]Cl + HCO2H
The colorless hydrochloride salt can be converted to an amine by the addition of a strong base, such as sodium hydroxide (NaOH):
- [CH3NH3]Cl + NaOH → CH3NH2 + NaCl + H2O
Another method entails reducing nitromethane with zinc and hydrochloric acid.[8]
Reactivity and applications[edit]
Methylamine is a good nucleophile as it is highly basic and unhindered, but 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 of liquid ammonia.[9]
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.[3]
Biological chemistry[edit]
Methylamine arises as a result of putrefaction and is a substrate for methanogenesis.[10]
Additionally, methylamine is produced during PADI4-dependent arginine demethylation.[11]
Safety[edit]
The LD50 (mouse, s.c.) is 2.5 g/kg.[12]
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.[13]
Methylamine is also controlled as a List 1 precursor chemical by the United States Drug Enforcement Administration due to its use in the production of methamphetamine.
See also[edit]
References[edit]
- ^ a b c d e "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 (24): 71–102. doi:10.1016/S0920-5861(97)00003-5.
- ^ a b c 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 & Wieland, Heinrich (1937). Laboratory Methods of Organic Chemistry. Edinburgh, UK: R & R Clark, Limited. pp. 157–158.
- ^ Debacker, Marc G.; Mkadmi, El Bachir; Sauvage, François X.; Lelieur, Jean-Pierre; Wagner, Michael J.; Concepcion, Rosario; Kim, Jineun; McMills, Lauren E. H.; Dye, James L. (1996). "The Lithium−Sodium−Methylamine System: Does a Low-Melting Sodide Become a Liquid Metal?". Journal of the American Chemical Society. 118 (8): 1997. doi:10.1021/ja952634p.
- ^ Thauer, R. K. (1998). "Biochemistry of methanogenesis: A tribute to Marjory Stephenson:1998 Marjory Stephenson Prize Lecture". Microbiology. 144 (9): 2377. doi:10.1099/00221287-144-9-2377.
- ^ 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. doi:10.1007/s00018-008-8303-z. PMID 18923809.
- ^ The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.
- ^ CDC - NIOSH Pocket Guide to Chemical Hazards
