methylamine

Methylamine
Preferred IUPAC name Aminomethane[citation needed]
Systematic name Methanamine[1]
Other names Glycamine[citation needed] Monomethylamine[citation needed]
Identifiers
Abbreviations	MMA[citation needed]
CAS number	74-89-5 Y
PubChem	6329
ChemSpider	6089 Y
EC number	200-820-0
UN number	1061
DrugBank	DB01828
KEGG	C00218 Y
MeSH	methylamine
ChEBI	CHEBI:16830 N
ChEMBL	CHEMBL43280 Y
RTECS number	PF6300000
Beilstein Reference	741851
Gmelin Reference	145
3DMet	B00060
Jmol-3D images	Image 1
SMILES CN
InChI InChI=1S/CH5N/c1-2/h2H2,1H3 Y Key: BAVYZALUXZFZLV-UHFFFAOYSA-N Y
Properties
Molecular formula	CH5N
Molar mass	31.06 g mol−1
Appearance	Colorless gas
Odor	Icthyal, ammoniacal
Melting point	-93 °C, 180.05 K, -136 °F
Boiling point	-7--6 °C, 266.5-267.1 K, 20-21 °F
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
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
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	F+ Xn
R-phrases	R12, R20, R37/38, R41
S-phrases	(S2), S16, S26, S39
NFPA 704	4 3 0
Flash point	<−30 °C
Autoignition temperature	430 °C
Explosive limits	4.9–20.8%
LD50	100 mg kg−1 (oral, rat)
Related compounds
Related alkanamines	Ethylamine Ethylenediamine
Related compounds	Monomethylhydrazine
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Methylamine is the organic compound with a formula of CH₃NH₂. This colourless 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 sold 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.^[2]

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.^[3]

CH₃OH + NH₃ → CH₃NH₂ + H₂O

In this way, more than 400M kg are produced annually.

In the laboratory, methylamine hydrochloride is readily prepared by treating formaldehyde with ammonium chloride.^[4]

NH₄Cl + H₂CO → [CH₂=NH₂]Cl + H₂O

[CH₂=NH₂]Cl + H₂CO + H₂O → [CH₃NH₃]Cl + HCOOH

The colourless hydrochloride salt can be converted to the amine by the addition of strong base, like NaOH:

[CH₃NH₃]Cl + NaOH → CH₃NH₂ + NaCl + H₂O

Methylamine was first prepared by Wurtz by the hydrolysis of methyl isocyanate and related compounds.^[5]

Reactivity and applications

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.

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]

Liquid methylamine can be used as a solvent analogous to liquid ammonia. It shares some of the properties of liquid ammonia, but is better for dissolving organic substances, in the same way that methanol is better than water.^[6] Methylamine can also be used for scavenging H₂S from hydrocarbon in refining applications.

Biological chemistry

Methylamine arises naturally as the result of putrefaction and is a substrate for methanogenesis.^[7] It serves as a buffering agent in the lumen of the chloroplast in plants, effectively siphoning off protons that are heading for ATP synthase.^{[citation needed]}

Safety

The LD₅₀ (mouse) is 2400 mg/m³. Methylamine is also controlled as a List 1 substance by the United States Drug Enforcement Administration (DEA); the DEA lists methylamine as a precursor (to methamphetamine).

References