N-Methylmethanimine

N-Methylmethanimine or N‐methyl methylenimine is a reactive molecular substance containing a methyl group attached to an imine. It can be written as CH₃N=CH₂. On a timescale of minutes it self reacts to form the trimer trimethyl 1,3,5-triazinane. N-Methylmethanimine is formed naturally in the Earth's atmosphere, by oxidation of dimethylamine and trimethylamine, both of which are produced by animals, or burning.^[1]

N-Methylmethanimine

Identifiers
CAS Number	1761-67-7
3D model (JSmol)	Interactive image
ChemSpider	120899
PubChem CID	137199
CompTox Dashboard (EPA)	DTXSID50170085
InChI InChI=1S/C2H5N/c1-3-2/h1H2,2H3 Key: NYVSDPNXBIEFPW-UHFFFAOYSA-N
SMILES CN=C
Properties
Chemical formula	C2H5N
Molar mass	43.069 g·mol−1
Related compounds
Related compounds	dimethylamine Methanimine Ethanimine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Production

N-Methylmethanimine can be produced in two steps from dimethylamine, by first chlorinating the nitrogen atom with solid N-chlorosuccinimide, and then treating with potassium tert-butoxide at 90°C.^[2] Also it can be formed directly by thermal decomposition.^[3]

It can also be prepared from the trimer: 1,3,5-trimethyl-1,3,5-triazinane by heating to 450 °C (842 °F).^[2]

At 515 °C (959 °F), trimethylamine decomposes into methane and N-methylmethanimine.^[4]

Natural occurrence

N-Methylmethanimine should be formed in the atmosphere as a result of degradation by oxidation of di- and trimethylamine. These occur at concentrations of a few parts per billion. But N-methylmethanimine cannot be detected. This is likely because it forms the trimer, gets absorbed onto particles, such as cloud droplets, and hydrolyses to form methylamine and formaldehyde.^[1]

Properties

The N-Methylmethanimine molecule has Cs symmetry.^[2] The infrared spectrum and microwave spectrum have been observed.^[5]

The bond length for C=N is 1.279 Å, and for the N-C bond it is 1.458 Å. The ∠ C=N-C is 116.6°.^[4]

The electric dipole moment is 1.53 Debye.^[6]

When heated to 535°, N-methylmethanimine decomposes to hydrogen cyanide (HCN) and methane (CH₄).^[4]

Between 400 and 550°C, the cyclic amine, aziridine decomposes to a mixture of N-methylmethanimine and ethylideneimine.^[7]

References

1. Bunkan, Arne Joakim C.; Reijrink, Nina G.; Mikoviny, Tomáš; Müller, Markus; Nielsen, Claus J.; Zhu, Liang; Wisthaler, Armin (11 May 2022). "Atmospheric Chemistry of N -Methylmethanimine (CH ₃ N═CH ₂ ): A Theoretical and Experimental Study". The Journal of Physical Chemistry A. 126 (20): 3247–3264. Bibcode:2022JPCA..126.3247B. doi:10.1021/acs.jpca.2c01925. PMC 9150125. PMID 35544412.
2. Demaison, J.; Burie, J.; Denis, J.M.; Van Eijck, B.P. (October 1984). "Centrifugal distortion and internal rotation analysis of the rotational spectra of N-methylmethanimine d0 and d5". Journal of Molecular Spectroscopy. 107 (2): 250–260. doi:10.1016/0022-2852(84)90004-3. hdl:1874/23789.
3. Mulcahy, Christopher P.A.; Carman, April J.; Casey, Sean M. (July 2000). "The adsorption and thermal decomposition of dimethylamine on Si(100)". Surface Science. 459 (1–2): 1–13. Bibcode:2000SurSc.459....1M. doi:10.1016/S0039-6028(00)00487-8.
4. Fujiwara, Hideo; Egawa, Toru; Konaka, Shigehiro (January 1995). "Electron diffraction study of thermal decomposition products of trimethylamine: molecular structure of CH3NCH2". Journal of Molecular Structure. 344 (3): 217–226. doi:10.1016/0022-2860(94)08440-S.
5. Yu, Gang; Duxbury, Geoffrey (September 1992). "High-resolution diode laser spectroscopy of the ν16 band of N-methylmethylenimine". Journal of Molecular Spectroscopy. 155 (1): 105–114. doi:10.1016/0022-2852(92)90551-X.
6. Sastry, K. V. L. N.; Curl Jr., R. F. (1964). "Microwave Spectrum of N-Methyl Methylenimine". J. Chem. Phys. 41 (1): 77. Bibcode:1964JChPh..41...77S. doi:10.1063/1.1725653.
7. Stolkin, I.; Ha, T.-K.; Günthard, Hs.H. (May 1977). "N-methylmethyleneimine and ethylideneimine: Gas- and matrix-infrared spectra, AB initio calculations and thermodynamic properties". Chemical Physics. 21 (3): 327–347. Bibcode:1977CP.....21..327S. doi:10.1016/0301-0104(77)85189-6.