Methylamine

Methylamine

Methylamine
Skeletal formula of methylamine with all explicit hydrogens added
Ball and stick model of methylamine
Spacefill model of methylamine
Names
IUPAC name
aminomethane, methanamine
Other names
  • monomethylamine
  • MMA
  • glycamine
Identifiers
 Y
3DMet
Abbreviations MMA
741851
ChEBI  N
ChEMBL  Y
ChemSpider  Y
DrugBank  N
EC number 200-820-0
145
Jmol-3D images Image
KEGG  Y
MeSH
PubChem
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
Viscosity 230 μPa s (at 0 °C)
1.31 D
Thermochemistry
−23.5 kJ mol−1
Hazards
Safety data sheet emdchemicals.com
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
H220, H315, H318, H332, H335
P210, P261, P280, P305+351+338, P410+403
Extremely Flammable F+ Harmful Xn
R-phrases R12, R20, R37/38, R41
S-phrases (S2), S16, S26, S39
NFPA 704
4
3
0
Flash point −10 °C; 14 °F; 263 K (liquid, gas is not flammable)[1]
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)
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]
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).
 N  (: Y/N?)

Methylamine is an formula of CH3NH2. This colorless gas is a derivative of ammonia, but with one H atom replaced by a methyl group. It is the simplest primary amine. It is sold as a solution in methanol, ethanol, THF, and 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 1
  • Laboratory methods 2
  • Reactivity and applications 3
  • Biological chemistry 4
  • Safety 5
  • See also 6
  • References 7

Industrial production

Methylamine is prepared commercially by the reaction of ammonia with methanol in the presence of a silicoaluminate catalyst. Dimethylamine and trimethylamine are coproduced; 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 Wurtz by the hydrolysis of methyl isocyanate and related compounds.[3][4] An example of this process includes the use of 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 + HCOOH

The colorless hydrochloride salt can be converted to the amine by the addition of strong base, like 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 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 for 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. ^ a b c d e "NIOSH Pocket Guide to Chemical Hazards #0398".  
  2. ^ Corbin D.R.; Schwarz S.; Sonnichsen G.C. (1997). "Methylamines synthesis: A review". Catalysis Today 37 (24): 71–102.  
  3. ^ 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
  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.  
  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".  
  8. ^ Gatterman, Ludwig; and Wieland, Heinrich (1937). Laboratory Methods of Organic Chemistry. Edinburgh, UK: R & R Clark, Limited. p. 157-158. 
  9. ^ M. G. DeBacker, El B. Mkadmi, F. X. Sauvage, J.-P. Lelieur, M. J. Wagner, R. Concepcion. J. Kim, L. E. H. McMills, J. L. Dye "The Lithium−Sodium−Methylamine System: Does a Low-Melting Sodide Become a Liquid Metal?" J. Am. Chem. Soc., 1996, vol. 118, pp 1997–2003. doi:10.1021/ja952634p
  10. ^ Thauer, R. K., "Biochemistry of Methanogenesis: a Tribute to Marjory Stephenson", Microbiology, 1998, 144, 2377-2406.
  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.  
  12. ^ The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.
  13. ^ CDC - NIOSH Pocket Guide to Chemical Hazards