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 | |
| Std molar
entropy (S |
273.1 J·mol-1·K-1 |
| Std enthalpy of
formation (ΔfH |
-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): | |
| LD50 (Median dose)
|
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.
Contents
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
- ↑ 1.0 1.1 1.2 1.3 Flick E.W. Industrial solvent handbook. - 5ed. - 1998 pp. 689
- ↑ https://www.cdc.gov/niosh/idlh/124403.html
- ↑ 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
- ↑ Weissermel, K.; Arpe, H.-J. (2003). Industrial Organic Chemistry: Important Raw Materials and Intermediates. Wiley-VCH. pp. 45–46.
- ↑ Corbin D.R.; Schwarz S.; Sonnichsen G.C. (1997). "Methylamines synthesis: A review". Catalysis Today. 37 (2): 71–102
- ↑ Thy Labs, Making Dimethylamine: A Chemical Used In Big Pharma, https://www.youtube.com/watch?v=D1pvqXeh3TE
