Difference between revisions of "Dimethylamine"

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Latest revision as of 13:47, 26 August 2023

Dimethylamine
Names
IUPAC name
N-Methylmethanamine
Other names
N,N-Dimethylamine
Properties
C2H7N
(CH3)2NH
Molar mass 45.085 g/mol
Appearance Colorless gas
Odor Fishy, ammoniacal
Density 0.6804 g/cm3 (0 °C)
Melting point −93.0 °C (−135.4 °F; 180.2 K)
Boiling point 7 °C (45 °F; 280 K)
163 g/100 ml (40 °C)
Solubility Reacts with acids
Soluble in alcohols, dichloromethane, chloroform, diethyl ether
Solubility in butanol 134.4 g/100 g (20 °C)[1]
Solubility in ethanol 198.8 g/100 g (20 °C)[1]
Solubility in methanol 271.3 g/100 g (20 °C)[1]
Solubility in nitrobenzene 40.7 g/100 g (20 °C)[1]
Vapor pressure 1277.355 mmHg (at 20 °C)
Thermochemistry
273.1 J·mol-1·K-1
-18.8 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich (gas, pure)
Sigma-Aldrich (40% aq. solution)
Flash point −6 °C (21 °F; 267 K)
Lethal dose or concentration (LD, LC):
698 mg/kg (rat, oral)
316 mg/kg (mouse, oral)
240 mg/kg (rabbit, oral)
240 mg/kg (guinea pig, oral)[2]
Related compounds
Related compounds
Methylamine
Trimethylamine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Dimethylamine is an organic compound with the formula (CH3)2NH, an amine.

Properties

Chemical

Dimethylamine is a weak Lewis base and the pKa of the dimethylammonium cation is 10.73, a value above methylamine (10.64) and trimethylamine (9.79).

Dimethylamine reacts with acids to yield its corresponding dimethylammonium salts.

(CH3)2NH + HX → (CH3)2NH·HX

Reaction of dimethylamine and formaldehyde gives bis(dimethylamino)methane:[3]

2 (CH3)2NH + CH2O → [(CH3)2N]2CH2 + H2O

Reaction of dimethylamine with carbon monoxide or methyl formate yields the useful solvent dimethylformamide.[4] If methyl acetate is used instead, dimethylacetamide is obtained.

It reacts with carbon disulfide to give dimethyl dithiocarbamate, a precursor to zinc bis(dimethyldithiocarbamate) and other chemicals used in the sulfur vulcanization of rubber.

Physical

Dimethylamine is a colorless gas, with a strong fishy-like. It is very soluble in water and organic solvents, like alcohols.

Availability

Dimethylamine is sold by chemical suppliers. While the compressed gas form is a bit harder to get, it is much more available as aq. solution, usually at around 40%.

Can also be acquired is salt form, more commonly in the form of dimethylamine hydrochloride.

Dimethylamine is also naturally produced in many organisms, like fish, but the amount is small.

Preparation

There are several way to synthesize dimethylamine.

Dimethylamine is produced by catalytic reaction of methanol and ammonia at elevated temperatures and high pressure:[5]

2 CH3OH + NH3 → (CH3)2NH + 2 H2O

Methylamine and trimethylamine are also produced as side products. Dimethylamine needs to be purified from the crude product.

The more common laboratory version relies on the saponification of dimethylformamide using sodium hydroxide. This yields sodium formate and dimethylamine.[6]

(CH3)2NC(O)H + NaOH → (CH3)2NH + HCOONa

Acids can also be used instead of bases. Reaction with hydrochloric acid will yield dimethylamine hydrochloride. This is then reacted with NaOH, and the gaseous dimethylamine vapors are dried and either collected pure or dissolved in another solvent, like alcohol.

Projects

  • Make dimethylamine salts
  • Make metformin
  • Make unsymmetrical dimethylhydrazine
  • Attractant for insects (boll weevils)

Handling

Safety

Dimethylamine is moderate toxic, but in large amounts in can be an asphyxiant in closed chambers. It is irritant to lungs, nose and eyes.

Contact with nitrous acid will yield the extremely toxic, carcinogenic and persistent N-nitrosodimethylamine (NDMA). In the event you've produced this compound, either by accident or as side product from a reaction, open the window to allow sunlight to enter the chamber or use a strong UV lamp to illuminate the chamber. NDMA is very sensitive to UV light, and will break down completely within minutes or hours of exposure. However, in dark places it can remain for months or longer, so make sure you illuminate every corner.

Storage

Gaseous dimethylamine should be kept as compressed form in gas cylinders or lecture bottles, away from corrosive vapors. Solutions of dimethylamine should be kept in cold, well ventilated places. Salts of dimethylamine should be kept in clean bottles, away from stronger alkali.

Disposal

Dimethylamine doesn't require special disposal. Can be strongly diluted and poured into the ground.

References

  1. 1.0 1.1 1.2 1.3 Flick E.W. Industrial solvent handbook. - 5ed. - 1998 pp. 689
  2. https://www.cdc.gov/niosh/idlh/124403.html
  3. Gaudry, Michel; Jasor, Yves; Khac, Trung Bui (1979). "Regioselective Mannich Condensation with Dimethyl(Methylene)ammonium Trifluoroacetate: 1-(Dimethylamino)-4-methyl-3-pentanone". Org. Synth. 59: 153
  4. Weissermel, K.; Arpe, H.-J. (2003). Industrial Organic Chemistry: Important Raw Materials and Intermediates. Wiley-VCH. pp. 45–46.
  5. Corbin D.R.; Schwarz S.; Sonnichsen G.C. (1997). "Methylamines synthesis: A review". Catalysis Today. 37 (2): 71–102
  6. Thy Labs, Making Dimethylamine: A Chemical Used In Big Pharma, https://www.youtube.com/watch?v=D1pvqXeh3TE

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