Methylamine

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Methylamine
Skeletal formula of methylamine with all explicit hydrogens added
Ball and stick model of methylamine
Spacefill model of methylamine
Names
Preferred IUPAC name
Methanamine[1]
Other names
  • Aminomethane
  • Monomethylamine
Identifiers
3D model (JSmol)
3DMet
Abbreviations MMA
741851
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.746 Edit this at Wikidata
EC Number
  • 200-820-0
145
KEGG
MeSH methylamine
RTECS number
  • PF6300000
UNII
UN number 1061
Properties
CH5N
Molar mass 31.058 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
1008 g L−1 (at 20 °C)
log P −0.472
Vapor pressure 186.10 kPa (at 20 °C)
1.4 mmol Pa−1 kg−1
Acidity (pKa) 10.66
Conjugate acid CH3NH3+ (Methylammonium ion)
-27.0·10−6 cm3mol−1
Viscosity 230 μPa s (at 0 °C)
Dipole moment
 1.31 D
Thermochemistry
Std enthalpy of
formation (ΔfH⦵298)
 −23.5 kJ mol−1
Hazards
Safety data sheet emdchemicals.com
GHS pictograms GHS02: Flammable GHS05: Corrosive GHS07: Harmful
GHS Signal word Danger
GHS hazard statements
 H220, H315, H318, H332, H335
P210, P261, P280, P305+351+338, P410+403
NFPA 704 (fire diamond)
3
4
0
Flash point −10 °C; 14 °F; 263 K (liquid, gas is extremely flammable)[2]
430 °C (806 °F; 703 K)
Explosive limits 4.9–20.7%
Lethal dose or concentration (LD, LC):
LD50 (median dose)
 100 mg kg−1 (oral, rat)
LC50 (median concentration)
 1860 ppm (mouse, 2 hr)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 10 ppm (12 mg/m3)[2]
REL (Recommended)
 TWA 10 ppm (12 mg/m3)[2]
IDLH (Immediate danger)
 100 ppm[2]
Related compounds
Related alkanamines
 ethylamine, dimethylamine, trimethylamine
Related compounds
 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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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.

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 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.[3]

CH3OH + NH3 → CH3NH2 + H2O

In this way, an estimated 115,000 tons were produced in 2005.[4]

Laboratory methods[]

Methylamine was first prepared in 1849 by Charles-Adolphe Wurtz via the hydrolysis of methyl isocyanate and related compounds.[4][5] An example of this process includes the use of the Hofmann rearrangement, to yield methylamine from acetamide and bromine gas.[6][7]

In the laboratory, methylamine hydrochloride is readily prepared by various other methods. One method entails treating formaldehyde with ammonium chloride.[8]

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.[9]

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.[10] 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.[11]

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]

Biological chemistry[]

Methylamine arises as a result of putrefaction and is a substrate for methanogenesis.[12]

Additionally, methylamine is produced during PADI4-dependent arginine demethylation.[13]

Safety[]

The LD50 (mouse, s.c.) is 2.5 g/kg.[14]

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.[15]

Regulation[]

In the United States, methylamine is controlled as a List 1 precursor chemical by the Drug Enforcement Administration[16] due to its use in the illicit production of methamphetamine.[17]

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. Its use becomes central to the plot line as an alternative to traditional methamphetamine production techniques that involve pseudoephedrine, a cold medication, with the protagonists committing several robberies to get it.

See also[]

References[]

  1. ^ 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.
  2. ^ Jump up to: a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0398". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ 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.
  4. ^ Jump up to: 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
  5. ^ 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).
  6. ^ Mann, F. G.; Saunders, B. C. (1960). Practical Organic Chemistry (4th ed.). London: Longman. p. 128. ISBN 9780582444072.
  7. ^ Cohen, Julius (1900). Practical Organic Chemistry (2nd ed.). London: Macmillan and Co., Limited. p. 72.
  8. ^ Marvel, C. S.; Jenkins, R. L. (1941). "Methylamine Hydrochloride". Organic Syntheses.; Collective Volume, 1, p. 347
  9. ^ Gatterman, Ludwig & Wieland, Heinrich (1937). Laboratory Methods of Organic Chemistry. Edinburgh, UK: R & R Clark, Limited. pp. 157–158.
  10. ^ Peter Scott, ed. (13 October 2009). Linker Strategies in Solid-Phase Organic Synthesis. p. 80. ISBN 9780470749050. ...an unhindered amine such as methylamine
  11. ^ 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.
  12. ^ 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.
  13. ^ 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.
  14. ^ The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.
  15. ^ CDC - NIOSH Pocket Guide to Chemical Hazards
  16. ^ Title 21 Code of Federal Regulations
  17. ^ 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.
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