Methylamine, also known as methanamine, 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.
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| Names | |||
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| Pronunciation | /ˌmɛθələˈmiːn/ (METH-ə-lə-MEEN), /ˌmɛθəˈlæmən/ (METH-ə-LA-mən), /məˈθɪləˌmiːn/ (mə-THIL-ə-meen)[2] | ||
| Preferred IUPAC name
Methanamine[1] | |||
Other names
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| Identifiers | |||
3D model (JSmol)
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| 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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| UNII | |||
| UN number | 1061 | ||
CompTox Dashboard (EPA)
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| Properties | |||
| CH3NH2 | |||
| Molar mass | 31.058 g·mol−1 | ||
| Appearance | Colorless gas | ||
| Odor | Fishy, ammoniacal | ||
| Density | 0.6562 g/cm3 (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 | ||
| 1008 g/L (at 20 °C) | |||
| log P | −0.472 | ||
| Vapor pressure | 186.10 kPa (at 20 °C) | ||
Henry's law
constant (kH) |
1.4 mmol/(Pa·kg) | ||
| Acidity (pKa) | 10.66 | ||
| Conjugate acid | [CH3NH3]+ (Methylammonium) | ||
| -27.0·10−6 cm3/mol | |||
| Viscosity | 230 μPa·s (at 0 °C) | ||
| 1.31 D | |||
| Thermochemistry | |||
Std enthalpy of
formation (ΔfH⦵298) |
−23.5 kJ/mol | ||
| 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 | −10 °C; 14 °F; 263 K (liquid, gas is extremely flammable)[3] | ||
| 430 °C (806 °F; 703 K) | |||
| Explosive limits | 4.9–20.7% | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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100 mg/kg (oral, rat) | ||
LC50 (median concentration)
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1860 ppm (mouse, 2 hr)[3] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible)
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TWA 10 ppm (12 mg/m3)[3] | ||
REL (Recommended)
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TWA 10 ppm (12 mg/m3)[3] | ||
IDLH (Immediate danger)
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100 ppm[3] | ||
| Safety data sheet (SDS) | emdchemicals.com | ||
| Related compounds | |||
Related alkanamines
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ethylamine, dimethylamine, trimethylamine | ||
Related compounds
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ammonia | ||
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 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 rotten fish. Methylamine is used as a building block for the synthesis of numerous other commercially available compounds.
Industrial production
editMethylamine has been produced industrially since the 1920s (originally by Commercial Solvents Corporation for dehairing of animal skins).[4] This was made possible by Kazimierz Smoleński and his wife Eugenia who discovered amination of alcohols, including methanol, on alumina or kaolin catalyst after WWI, filed two patent applications in 1919[5] and published an article in 1921.[4][6]
It is now 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 favored by the reaction kinetics is trimethylamine.[4]
- CH3OH + NH3 → CH3NH2 + H2O
In this way, an estimated 115,000 tons were produced in 2005.[7]
Laboratory methods
editMethylamine was first prepared in 1849 by Charles-Adolphe Wurtz via the hydrolysis of methyl isocyanate and related compounds.[7][8] An example of this process includes the use of the Hofmann rearrangement, to yield methylamine from acetamide and bromine.[9][10]
In the laboratory, methylamine hydrochloride is readily prepared by various other methods. One method entails treating formaldehyde with ammonium chloride.[11]
- [NH4]Cl + CH2O → [CH2=NH2]Cl + H2O
- [CH2=NH2]Cl + CH2O + H2O → [CH3NH3]Cl + HCOOH
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.[12]
Another method of methylamine production is spontaneous decarboxylation of glycine with a strong base in water.[13]
Reactivity and applications
editMethylamine is a good nucleophile as it is an unhindered amine.[14] 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.[15]
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.[7]
Biological chemistry
editMethylamine arises as a result of putrefaction and is a substrate for methanogenesis.[16]
Additionally, methylamine is produced during PADI4-dependent arginine demethylation.[17]
Safety
editThe LD50 (mouse, s.c.) is 2.5 g/kg.[18]
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.[19]
Regulation
editIn the United States, methylamine is controlled as a List 1 precursor chemical by the Drug Enforcement Administration[20] due to its use in the illicit production of methamphetamine.[21]
In popular culture
editFictional characters Walter White and Jesse Pinkman use aqueous methylamine as part of a process to synthesize methamphetamine in the AMC series Breaking Bad.[22][23]
See also
editReferences
edit- ^ Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 670. doi:10.1039/9781849733069-00648. ISBN 978-0-85404-182-4.
- ^ "Methylamine Definition & Meaning". Retrieved 22 April 2022.
- ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0398". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b c 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.
- ^ PL application 90B1, PL application 91B1, https://uprp.gov.pl/sites/default/files/2019-12/KWARTALNIK_100_lat_wydanie_specjalne.pdf
- ^ Not Available (1922). Chemical Abstracts (1922) Vol.16, No.18.
- ^ 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". Organic Syntheses; Collected Volumes, vol. 1, p. 347.
- ^ Gatterman, Ludwig & Wieland, Heinrich (1937). Laboratory Methods of Organic Chemistry. Edinburgh, UK: R & R Clark, Limited. pp. 157–158.
- ^ Callahan, Brian P.; Wolfenden, Richard (2003-07-31). "Migration of Methyl Groups between Aliphatic Amines in Water [J. Am. Chem. Soc. 2003, 125, 310-311]". Journal of the American Chemical Society. 125 (34): 10481–10481. doi:10.1021/ja033448j. ISSN 0002-7863.
- ^ Peter Scott, ed. (13 October 2009). Linker Strategies in Solid-Phase Organic Synthesis. John Wiley & Sons. p. 80. ISBN 9780470749050.
...an unhindered amine such as methylamine
- ^ 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): 2377–406. doi:10.1099/00221287-144-9-2377. PMID 9782487.
- ^ Ng, SS; Yue, WW; Oppermann, U; Klose, RJ (February 2009). "Dynamic protein methylation in chromatin biology". Cellular and Molecular Life Sciences. 66 (3): 407–22. doi:10.1007/s00018-008-8303-z. PMC 2794343. PMID 18923809.
- ^ The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.
- ^ CDC - NIOSH Pocket Guide to Chemical Hazards
- ^ Title 21 Code of Federal Regulations
- ^ Frank, R. S. (1983). "The Clandestine Drug Laboratory Situation in the United States". Journal of Forensic Sciences. 28 (1): 18–31. doi:10.1520/JFS12235J. PMID 6680736.
- ^ Matthews, Dylan (15 August 2013). "Here's what 'Breaking Bad' gets right, and wrong, about the meth business". Washington Post. Archived from the original on 3 February 2023.
- ^ Harnisch, Falk; Salthammer, Tunga. "The Chemistry of Breaking Bad". Chemistry Views. Chemistry Europe. Archived from the original on 8 February 2024.