Methylamine

Methylamine
Names
Preferred IUPAC name
Methanamine
Other names
  • Aminomethane
  • Monomethylamine
Identifiers
3D model (JSmol)
3DMet B00060
Abbreviations MMA
741851
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.000.746
EC Number 200-820-0
145
KEGG
MeSH methylamine
RTECS number PF6300000
UN number 1061
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)
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
−23.5 kJ mol−1
Hazards
Safety data sheet emdchemicals.com
GHS pictograms
GHS signal word DANGER
H220, H315, H318, H332, H335
P210, P261, P280, P305+351+338, P410+403
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
4
3
0
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):
100 mg kg−1 (oral, rat)
1860 ppm (mouse, 2 hr)[1]
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 10 ppm (12 mg/m3)[1]
REL (Recommended)
 TWA 10 ppm (12 mg/m3)[1]
IDLH (Immediate danger)
 100 ppm[1]
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. 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.

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 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

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

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

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

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

References

  1. 1 2 3 4 5 "NIOSH Pocket Guide to Chemical Hazards #0398". National Institute for Occupational Safety and Health (NIOSH).
  2. ↑ 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.
  3. 1 2 3 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
  4. ↑ 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).
  5. ↑ Mann, F. G.; Saunders, B. C. (1960). Practical Organic Chemistry, 4th Ed. London: Longman. p. 128. ISBN 9780582444072.
  6. ↑ Cohen, Julius (1900). Practical Organic Chemistry 2nd Ed. London: Macmillan and Co., Limited. p. 72.
  7. ↑ Marvel, C. S.; Jenkins, R. L. (1941). "Methylamine Hydrochloride". Org. Synth.; Coll. Vol., 1, p. 347
  8. ↑ Gatterman, Ludwig & Wieland, Heinrich (1937). Laboratory Methods of Organic Chemistry. Edinburgh, UK: R & R Clark, Limited. pp. 157–158.
  9. ↑ 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.
  10. ↑ Thauer, R. K. (1998). "Biochemistry of methanogenesis: A tribute to Marjory Stephenson:1998 Marjory Stephenson Prize Lecture". Microbiology. 144 (9): 2377. PMID 9782487. doi:10.1099/00221287-144-9-2377.
  11. ↑ 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. PMC 2794343 Freely accessible. PMID 18923809. doi:10.1007/s00018-008-8303-z.
  12. ↑ The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.
  13. ↑ CDC - NIOSH Pocket Guide to Chemical Hazards
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