From chemical data (1), ethylene imine appears to be a three membered heterocyclic ring similar to cyclopropane and ethylene oxide. It has a very high boiling point, 55°C, as compared with --34°C for cyclopropane and 13°C for ethylene oxide. This has been taken as evidence of strong hydrogen bonding in the liquid, and is supported by the strongly basic character of the imine nitrogen atom. Ethylene imine readily polymerizes to viscous, oily, chain type polymers in the presence of carbon dioxide or mild oxidizing agents. However, Jones and co-workers (2) have reported that ethylene imine polymerizes to a negligible amount at room temperature in the absence of such catalysts.
Proceedings of the Iowa Academy of Science
©1950 Iowa Academy of Science, Inc.
Evans, George E. and Hoffman, Tice
"Infrared Spectrum and Structure of Ethylene Imine,"
Proceedings of the Iowa Academy of Science, 57(1), 235-239.
Available at: https://scholarworks.uni.edu/pias/vol57/iss1/26