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.

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

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 favored by the reaction kinetics is trimethylamine.^[4]

CH₃OH + NH₃ → CH₃NH₂ + H₂O

In this way, an estimated 115,000 tons were produced in 2005.^[5]

Laboratory methods

Methylamine was first prepared in 1849 by Charles-Adolphe Wurtz via the hydrolysis of methyl isocyanate and related compounds.^[5]^[6] An example of this process includes the use of the Hofmann rearrangement, to yield methylamine from acetamide and bromine.^[7]^[8]

In the laboratory, methylamine hydrochloride is readily prepared by various other methods. One method entails treating formaldehyde with ammonium chloride.^[9]

[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.^[10]

Another method of methylamine production is spontaneous decarboxylation of glycine with a strong base in water.^{[citation needed]}

Reactivity and applications

Methylamine is a good nucleophile as it is an unhindered amine.^[11] 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.^[12]

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.^[5]

Biological chemistry

Methylamine arises as a result of putrefaction and is a substrate for methanogenesis.^[13]

Additionally, methylamine is produced during PADI4-dependent arginine demethylation.^[14]

Safety

The LD₅₀ (mouse, s.c.) is 2.5 g/kg.^[15]

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.^[16]

Regulation

In the United States, methylamine is controlled as a List 1 precursor chemical by the Drug Enforcement Administration^[17] due to its use in the illicit production of methamphetamine.^[18]

In popular culture

Fictional characters Walter White and Jesse Pinkman use methylamine as part of a process to synthesize methamphetamine in the AMC series Breaking Bad.

References

^ 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).
^ 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". Organic Syntheses.; Collective Volume, vol. 1, p. 347
^ Gatterman, Ludwig & Wieland, Heinrich (1937). Laboratory Methods of Organic Chemistry. Edinburgh, UK: R & R Clark, Limited. pp. 157–158.
^ 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.

Molecules detected in outer space

Molecules

Diatomic	Aluminium monochloride Aluminium monofluoride Aluminium(II) oxide Argonium Carbon cation Carbon monophosphide Carbon monosulfide Carbon monoxide Cyano radical Diatomic carbon Fluoromethylidynium Helium hydride ion Hydrogen chloride Hydrogen fluoride Hydrogen (molecular) Hydroxyl radical Iron(II) oxide Magnesium monohydride Methylidyne radical Nitric oxide Nitrogen (molecular) Imidogen Sulfur mononitride Oxygen (molecular) Phosphorus monoxide Phosphorus mononitride Potassium chloride Silicon carbide Silicon monoxide Silicon monosulfide Sodium chloride Sodium iodide Sulfur monohydride Sulfur monoxide Titanium(II) oxide
Triatomic	Aluminium(I) hydroxide Aluminium isocyanide Amino radical Carbon dioxide Carbonyl sulfide CCP radical Chloronium Diazenylium Dicarbon monoxide Disilicon carbide Ethynyl radical Formyl radical Hydrogen cyanide (HCN) Hydrogen isocyanide (HNC) Hydrogen sulfide Hydroperoxyl Iron cyanide Isoformyl Magnesium cyanide Magnesium isocyanide Methylene radical N₂H⁺ Nitrous oxide Nitroxyl Ozone Phosphaethyne Potassium cyanide Protonated molecular hydrogen Sodium cyanide Sodium hydroxide Silicon carbonitride c-Silicon dicarbide SiNC Sulfur dioxide Thioformyl Thioxoethenylidene Titanium dioxide Tricarbon Water
Four atoms	Acetylene Ammonia Cyanic acid Cyanoethynyl Formaldehyde Fulminic acid HCCN Hydrogen peroxide Hydromagnesium isocyanide Isocyanic acid Isothiocyanic acid Ketenyl Methylene amidogen Methyl cation Methyl radical Propynylidyne Protonated carbon dioxide Protonated hydrogen cyanide Silicon tricarbide Thioformaldehyde Tricarbon monoxide Tricarbon monosulfide Thiocyanic acid
Five atoms	Ammonium ion Butadiynyl Carbodiimide Cyanamide Cyanoacetylene Cyanoformaldehyde Cyanomethyl Cyclopropenylidene Formic acid Isocyanoacetylene Ketene Methane Methoxy radical Methylenimine Propadienylidene Protonated formaldehyde Silane Silicon-carbide cluster
Six atoms	Acetonitrile Cyanobutadiynyl radical E-Cyanomethanimine Cyclopropenone Diacetylene Ethylene Formamide HC₄N Ketenimine Methanethiol Methanol Methyl isocyanide Pentynylidyne Propynal Protonated cyanoacetylene
Seven atoms	Acetaldehyde Acrylonitrile Vinyl cyanide Cyanodiacetylene Ethylene oxide Glycolonitrile Hexatriynyl radical Methylacetylene Methylamine Methyl isocyanate Vinyl alcohol
Eight atoms	Acetic acid Aminoacetonitrile Cyanoallene Ethanimine Glycolaldehyde Hexapentaenylidene Methylcyanoacetylene Methyl formate Propenal
Nine atoms	Acetamide Cyanohexatriyne Cyanotriacetylene Dimethyl ether Ethanol Methyldiacetylene Octatetraynyl radical Propene Propionitrile
Ten atoms or more	Acetone Benzene Benzonitrile Buckminsterfullerene (C₆₀, C₆₀⁺, fullerene, buckyball) C₇₀ fullerene Cyanodecapentayne Cyanopentaacetylene Cyanotetra-acetylene Ethylene glycol Ethyl formate Methyl acetate Methyl-cyano-diacetylene Methyltriacetylene Propanal n-Propyl cyanide Pyrimidine Heptatrienyl radical