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
Identifiers
Abbreviations MMA
CAS number 74-89-5 YesY
PubChem 6329
ChemSpider 6089 YesY
EC number 200-820-0
UN number 1061
DrugBank DB01828
KEGG C00218 YesY
MeSH methylamine
ChEBI CHEBI:16830 N
ChEMBL CHEMBL43280 YesY
RTECS number PF6300000
Beilstein Reference 741851
Gmelin Reference 145
3DMet B00060
Jmol-3D images Image 1
Properties
Molecular formula CH5N
Molar mass 31.06 g mol−1
Appearance Colorless gas
Odor Fishy, ammoniacal
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
Solubility in water 1.08 kg L−1 (at 20 °C)
log P −0.472
Vapor pressure 186.10 kPa (at 20 °C)
kH 1.4 mmol Pa−1 kg−1
Basicity (pKb) 3.36
Viscosity 230 μPa s (at 0 °C)
Dipole moment 1.31 D
Thermochemistry
Std enthalpy of
formation
ΔfHo298
−23.5 kJ mol−1
Hazards
MSDS 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
GHS hazard statements H220, H315, H318, H332, H335
GHS precautionary statements P210, P261, P280, P305+351+338, P410+403
EU Index 612-001-00-9
EU classification Extremely Flammable F+ Harmful Xn
R-phrases R12, R20, R37/38, R41
S-phrases (S2), S16, S26, S39
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
Flash point <−30 °C
Explosive limits 4.9–20.8%
LD50 100 mg kg−1 (oral, rat)
Related compounds
Related alkanamines ethylamine, dimethylamine, trimethylamine
Related compounds ammonia
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Methylamine is the organic compound with a 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. Over 1 million tonnes are produced annually.[1]

Industrial production[edit]

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, more than 400 tons are produced annually.[citation needed]

Laboratory methods[edit]

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[edit]

Methylamine is a good nucleophile as it is highly basic and unhindered, although, 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 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[edit]

Methylamine arises as a result of putrefaction and is a substrate for methanogenesis.[10]

Safety[edit]

The LD50 (mouse, s.c.) is 2.5 g/kg.[11]

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.[12]

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.

References[edit]

  1. ^ S.N. Bizzari (November 2008). "CEH Marketing Research Report: ALKYLAMINES (C1-C6)". Chemical Economics Handbook. SRI consulting. Retrieved July 2011. 
  2. ^ Corbin D.R.; Schwarz S.; Sonnichsen G.C. (1997). "Methylamines synthesis: A review". Catalysis Today 37 (2): 71–102. doi:10.1016/S0920-5861(97)00003-5. 
  3. ^ a b 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: 347 
  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. ^ The Merck Index, 10th Ed. (1983), p.864, Rahway: Merck & Co.
  12. ^ CDC - NIOSH Pocket Guide to Chemical Hazards