N,N-diethylmethylamine
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| Names | |
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| IUPAC name
N-ethyl-N-methylethanamine
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| Preferred IUPAC name
N,N-Diethylmethylamine | |
| Identifiers | |
3D model (JSmol)
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C5H13N | |
| Molar mass | 87.166 g·mol−1 |
| Appearance | Volatile liquid at room temp. |
| Density | 0.72 g/mL |
| Melting point | −196.0 °C (−320.8 °F; 77.1 K) |
| Boiling point | 66.0 °C (150.8 °F; 339.1 K) |
| 310.5 g/L | |
| Acidity (pKa) | 10.35 (for the conjugate acid) (H2O) |
| Hazards | |
| Main hazards | acute toxicity |
| GHS pictograms |    
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| GHS Signal word | Danger |
| H225, H301, H314, H332 | |
| P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P301+310, P301+330+331, P303+361+353, P304+312, P304+340, P305+351+338, P310, P312, P321, P330, P363, P370+378, P403+235 | |
| Flash point | −24 °C; −11 °F; 249 K |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
N,N-diethylmethylamine (diethylmethylamine) is a tertiary amine with formula C5H13N. It is an industrial chemical that is mainly used in the desalination of brackish water or used as a chemical intermediate and acid neutralizer. N,N-Diethylmethylamine is a clear, colorless to pale yellow liquid at room temperature.
Diethylmethylamine is a dangerous and toxic chemical which will cause bad effect on human body. There are evidences show that skin contact with diethylmethylamine will cause a sensitization reaction is some people. And, a few evidences indicate long time exposure in diethylemthylamine may damage organs. Diethylmethylamine is kind of tertiary amine which can become nitrosamine through nitrosating agents. Nitrosamine is considered as carcinogen. However, it occurs in certain food and daily use product as a byproduct from production. Not only from the production, nitrosamine can also form during the preparation of production, even at room temperature. Fortunately, by using vitamin C and vitamin E can stop the formation of nitrosamine. For consumers' safety, commercial goods with significant amount of nitrosamine is not allowed. Due to those reasons, it need be carefully store in approved plastic containers and avoid contact with acid.[1]
Preparation[edit]
Diethylmethylamine can be produced by the reaction between methyl toluate and diethylamine:
CH3C6H4COOCH3 + HN(C2H5)2 → CH3C6H4COOH + CH3N(C2H5)2
This reaction required a temperature between 200oC to 250oC and a pressure between atmospheric and 1000 p.s.i. The diethylmethylamine produced by the reaction is a typical organic tertiary amine which have the same characteristic as other amine. This was obtained from the experiment results. Since in this reaction, diethylmethylamine is an additional product which only have a little amount, the industrial production may use other reaction.[2]
Properties[edit]
Basic properties like density and melting point are shown in the information box. The properties also contained part that need be discussed in micro level. Since diethylmethylamine is a polymer, it can have several isomers, the structural of the molecular is always focused.
Molecular structure and conformation[edit]
Due to the rotation of a single bond, conformational isomers are formed. Conformational isomers have the same structural formula but different characteristic. This has always been interested by the scientist. In 1978, Crocker and Goggin had experimented on determined the conformation of diethylmethylamine. They used IR and Raman spectra on diethylmethylamine in the solid, liquid, and gas phases. Results showed two conformers exist in the solid phase and can be determined as tt (trans-trans conformer) and g+t (gauche+-trans conformer). Because of the complexity of the vapor spectrum, they can only infer there are two or more conformers that exist in the gas phase.[3]
Present studies used gas-phase IR spectra and FT-Raman spectra of the liquid to get more detailed results. The results of the regular coordinate analysis indicated there were four conformers, and the diffraction data showed the conformation of diethylmethylamine is 35 (14)% tt + 27 (14)% g+t + 20 (17)% g-t (gauche--trans conformer) + 18 (23)% g+g+(gauche+-gauche+ conformer). To confirm the result, a vibrational analysis of hydrocarbon analog in the liquid phase was done, and it identified the conformers were the same as diffraction data showed. Moreover, tt and g+t conformers were found more stable than the other two. The conformational stability of diethylmethylamine can be explained by the numbers of trans CNCC fragment that two fragments of tt and g+t conformers trans conformation and one fragment of g-t and g+g+ conformers trans conformation. Further study showed the reason why diethylmethylamine did't have a g-g+ (gauche--gauche+ conformer) conformer that is the steric repulsion between terminal methyl groups.[4]
Stereodynamics (dynamics of stereochemical reaction) of N,N-diethylmethylamine[edit]
diethylmethylamine is the simplest trialkylamine that can be tested with two processes about the nitrogen atom in it. The first one is indeed pyramidal inversion, and the second is the isolated rotation of nitrogen carbon bond. From these two processes, the 1H dynamic nuclear magnetic resonance spectroscopy obtained clear evidence for nitrogen pyramidal inversion. Also, the result indicates there were several " familiars" of rotamers exist in diethylmethylamine.[5]
Rotation inversion[edit]
Rotation is part of the conformational isomer, so study the rotational isomer help the scientists to understand the chemical better. Rotation study of diethylmethylamine was done by Bushweller and Laurenzi. From the research image of 1H DNMR spectrum of diethylmethylamine at 200 K, ethyl group shows a A2 X3 spectrum and N-methyl protons shows a singlet. Two resonances can be tested in temperature range 140 K to 200 K---N-methyl and C-methyl resonances and they are independent. The result of DNMR also indicated, the slow nitrogen inversion in diethylmethylamine was caused by the coalescence phenomenon connected with CH2 resonance. The nitrogen inversion process in diethylmethylamine contained not only the inversion of nitrogen but also rotation about the C-N bond, which can be named as inversion rotation. Inversion rotation means nitrogen inversion always occur with rotation about the C-N bond. Other studies found out that at low temperature (99 K), the 1H DNMR spectrum of diethylmethylamine has more change. At 99 K, N-methyl and C-methyl resonance separate into more peaks. Two important things need to be mentioned. First, peaks of the N-methyl in diethylmethylamine can be assumed as broad singlets. Second, the C-methyl resonance can be assumed as equivalent for all three methyl protons.[6]
Usage[edit]
As a useful chemical, diethylmethylamine can be used in many fields. In research, it can be the lineshape standard of the NMR test. In industry, it always play a role in extraction reaction due to its characteristic.
Lineshape standard of nuclear magnetic resonance experiment[edit]
For an nuclear magnetic resonance (NMR) experiment, the most important thing is to make sure the existence of narrow peak and maximum sensitivity, which can be achieved by adjusting shimming field to enhance the magnetic field homogeneity. A typically used sample is not very useful during low temperature (150 K) experiments, because the peak showed will broaden. Since no available samples can use in low temperature experiments, many tests were done under the condition that the researchers assume the field condition was the same for both low-temperature terms and room temperature conditions. This will influence the NMR result since the change in inhomogeneity is hard to notice. There were research shows in some instrument, re-shimming the field after changing temperature could improve the homogeneity. So, something is a liquid at standard temperature, and pressure has a low melting point is needed.
N, N-diethylmethylamine was used to experiment. As the experimental results show, diethylmethylamine is useful in shimming magnetic field around 140 K. With other research, diethylmethylamine can be used in shimming the magnetic field at room temperature in NMR experiments and low temperature in dynamic nuclear polarization experiments. diethylmethylamine was very useful around 140 K; however, many low-temperature experiments need to proceed below 140 K. Future research need to focus on finding efficiency substitute of diethylmethylamine to work in experiments below 140 K. For now, diethylmethylamine is the best choice among all substances for low-temperature NMR experiments.[7]
Extraction of oil sand with microemulsions[edit]
Tar sand is an important source of petroleum, which contain 60 percent of the petroleum around the world. Extracting oil from tar sand has become an important part for nowadays industry. One way to extract oil is by using microemulsions which are a mixture of oil, water and surfactant. Extracting oil sand with microemulsions, an important step is to decentralize the light hydrocarbons in the aqueous medium. Usually, alcohols are used as cosurfactants in the microemulsions. A good cosurfactants has two conditions which are strong acid-base type interaction with water and good hydrophilic-hydrophobic balance. However, some studies showed that diethylmethylamine is a more effective cosurfactants in water than commonly used alcohol. Experimental results indicated that a system based on diethylmethylamine and system based on simple alcohols have a similar feature in microemulsions. The result also pointed out diethylmethylamine reacts as medium chain length alcohols, which has both good hydrophilic-hydrophobic balance and high solubility in water and many types of oil. However, this property causes diethylmethylamine has high efficiency and low specificity on nature and temperature.[8]
Extractive crystallization[edit]
Extractive crystallization is a way to obtain crystal besides using boiling. In the past, researchers used di-isopropylamine (DIPA) to extract water; however, to get the crystal, it need to wait for the solution cool down. To reduce the energy used in refrigeration, diethylmethylamine is decided to use in extractive crystallization since it has similar properties as DIPA and higher critical solution temperature. Critical solution temperature is the boundary that the mixture will mix. If the temperature is under the critical solution temperature, the mixture will remain the state of not mixed. So, a higher critical solution temperature means no refrigeration was needed. From the experiment, first, at low temperature (10oC to -0.5oC), diethylmethylamine can be used in extractive crystallization of sodium chloride; however, the percentage of sodium chloride in the organic phase increases. The best temperature range is 5oC to 10oC. In this range, the solubility of sodium chloride is relatively insensitive to temperature. For the diethylmethylamine/sodium chloride system, the lowest critical solution temperature is -0.6oC. Second, diethylmethylamine can be used in extractive crystallization of sodium sulfate at room temperature (21oC to 25oC). In this range, sodium sulfate solubility in diethylmethylamine is relatively insensitive to temperature. Further, for the diethylmethylamine/sodium sulfate system, the lowest critical solution temperature is 20oC.[9]
Reaction with other chemical[edit]
Interfacial bonding mechanisms between iron and diethylmethylamine[edit]
Metal are easily be corroded when expose in environment, so polymers are always used on the surface of the metal inhibit it from erosion. Although it's common to use polymers on the surface of metal to prevent it from corrosive things, the interfacial bonding mechanisms between them are not understandable yet. Research was done to understand the intersection mechanisms of dissolved diethylmethylamine (dissolve in tetrahydrofuran) to iron surface. From the Fourier transform infrared spectroscopy (FTIR) result of unrinsed and rinsed sample, researchers discovered that diethylmethylamine bonds to Fe surface were washed away because of the rinsing. The potential-time respond showed, the potential maintained constant for both unrinsed and rinsed sample. Further test by ATR-FTIR about the iron surface indicated through the reaction all molecular compound still remains the same as original.[10]
Substrate of trimethylamine dehydrogenase half reaction[edit]
Trimethylamine dehydrogenase is an enzyme which used as catalyst in chemical reaction. Since it's enzyme, a substrate is needed to study the reductive half-reaction of trimethylamine dehydrogenase. If using trimethylamine as a substrate, it is hard to characterize the substrate concentration and pH dependence in detail. Diethylmethylamine has similar characteristic with trimethylamine but react slower than trimethylamine. For a better understanding and observation of the reductive half-reaction, diethylmethylamine was chosen to be the substrate.[11]
Another research use diethylmethylamine to study the role 6-S-cysteinyl-FMN bond of trimethylamine dehydrogenase played in the half-reaction of the enzyme. Since diethylmethylamine is a slow substrate, three well resolved kinetic phases (fast phase, intermediate phase, slow phase) can be observed in detail. This study is mainly to investigate is there any difference between the removal of the 6-S-cysteinyl-FMN bond. Through the experiment, Kfast is depend on the concentration of diethylmethylamine, and Kint (Kintermediate), Kslow are independent to the concentration of diethylmethylamine. Since the fast phase's K value remains the same, it indicated 6-S-cysteinyl-FMN bond has no effect on substrate binding.[12]
Contrasting effect in reduction of protons and oxidation of formic acid[edit]
Commonly a chemical should only have one effect in a reaction. However, diethylmethylamine has two opposite effect in the same reduction, and can change to each other based on different condition. N,N-diethylmethylamine has contrasting effects during the reduction of protons and oxidation of formic acid. Based on different reaction conditions, diethylmethylamine can either inhibit or enhance the electrocatalysis of the liquid. For reduction, it can co-absorb onto Pt surface, which restrains Hupd absorption onto Pt. For oxidation, it reinforces the oxidation of HCOOH. So, through electrocatalysis in PILs, diethylmethylamine plays contrasting roles.[13]
References[edit]
- ^ "N,N-Diethylmethylamine" (PDF). Santa Cruz Biotechnology. Retrieved 2020-02-21.
- ^ Class, J.B. (1960). Production of diethylemthylamine. United States Patent Office.
- ^ Crocker, Christopher; Goggin, Peter L. (1978). "Infrared and Raman spectroscopic studies of conformations in liquid and solid triethyl-, diethyl(methyl)- and ethyldimethyl-amines, -phosphines, and -arsines". Journal of the Chemical Society, Dalton Transactions (5): 388. doi:10.1039/dt9780000388. ISSN 0300-9246.
- ^ Takeuchi, Hiroshi; Ito, Masaki; Egawa, Toru (2007-09-17). "Molecular structure and conformation of diethylmethylamine determined by gas electron diffraction and vibrational spectroscopy combined with theoretical calculations". Journal of Molecular Structure. 840 (1–3): 107–113. Bibcode:2007JMoSt.840..107T. doi:10.1016/j.molstruc.2006.11.027. hdl:2115/28245. ISSN 0022-2860.
- ^ Bushweller, C.H.; Fleischman, S.P.; Grady, G.L.; McGoff, P.; Rithner, C.D.; Whalon, M.R.; Brennan, J.G.; Marcantonio, R.P.; Dominigue, R.P. (1982-11-01). "Stereodynamics of diethylmethylamine and triethylamine". Journal of the American Chemical Society. 104 (23): 6224–6236. doi:10.1021/ja00387a012.
- ^ Bushweller, C. Hackett; Laurenzi, Bernard J.; Brennan, John G.; Goldberg, Martin J.; Marcantonio, Richard P. (1979), "The Rotation-Inversion Dichotomy in Trialkylamines Diethylmethylamine and Triethylamine", Stereodynamics of Molecular Systems, Elsevier, pp. 113–129, doi:10.1016/b978-0-08-024629-1.50012-5, ISBN 978-0-08-024629-1
- ^ Fritzsching, Keith J.; Itin, Boris; McDermott, Ann E. (2018-02-21). "N,N-Diethylmethylamine as lineshape standard for NMR above 130 K". Journal of Magnetic Resonance. 287: 110–112. Bibcode:2018JMagR.287..110F. doi:10.1016/j.jmr.2017.12.021. ISSN 1090-7807. PMC 5821130. PMID 29335163.
- ^ Desnoyers, Jacques E.; Quirion, François; HÉTu, Daniel; Perron, GÉRald (1983). "Tar sand extractions with microemulsions: I-the dissolution of light hydrocarbons by microemulsions using 2-butoxyethanol and diethylmethylamine as cosurfactants". The Canadian Journal of Chemical Engineering. 61 (5): 672–679. doi:10.1002/cjce.5450610509. ISSN 0008-4034.
- ^ Ting, Andrew M.; Lynn, Scott; Prausnitz, John M. (1992-04-01). "Liquid-liquid equilibria for aqueous systems containing N,N-diethylmethylamine and sodium chloride or sodium sulfate". Journal of Chemical & Engineering Data. 37 (2): 252–259. doi:10.1021/je00006a032. ISSN 0021-9568.
- ^ Taheri, P.; Terryn, H.; Mol, J.M.C. (2015-11-01). "An in situ study of amine and amide molecular interaction on Fe surfaces". Applied Surface Science. 354: 242–249. Bibcode:2015ApSS..354..242T. doi:10.1016/j.apsusc.2015.08.042. ISSN 0169-4332.
- ^ Jang, M.H.; Basran, J.; Scrutton, N.S.; Hille, R. (1994-12-09). "The reaction of trimethylamine dehydrogenase with diethylmethylamine". Journal of Biological Chemistry. 269 (49): 30869–30879. PMID 7983019.
- ^ Huang, Liuxin; Scrutton, Nigel S.; Hille, Russ (1996-06-07). "Reaction of the C30A Mutant of Trimethylamine Dehydrogenase with Diethylmethylamine". Journal of Biological Chemistry. 271 (23): 13401–13406. doi:10.1074/jbc.271.23.13401. ISSN 0021-9258. PMID 8662829.
- ^ Goodwin, Sean E.; Muhammad, Sayyar; Tuan, Li-Ping; Walsh, Darren A. (2018-06-15). "The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids". Journal of Electroanalytical Chemistry. 819: 187–192. doi:10.1016/j.jelechem.2017.10.021. ISSN 1572-6657.
