Author(s)

Shoko Suzuki¹, Shujiro Sakaki², Shinji Ishizuka², Tomomichi Nishino², Hiroyuki Ito², Risehiro Nonaka², Motoyoshi Noike², Takeshi Kodama², Hajime Nozaka², Tsuneyuki Sato², Hitoshi Agematsu², Koichi Maruyama², Shun Oyamada³, Takashi Kuroishi⁴, Kazuma Sasaki⁴, Kei Yagawa⁴, Mami Yoshioka⁴, Yasuo Yokoyama²

¹Faculty of Education, Kyoto University of Education, Kyoto, Japan.
²Department of Chemical and Biological Engineering, National Institute of Technology, Akita College, Akita, Japan.
³Environment Systems Engineering Course, National Institute of Technology, Akita College, Akita, Japan.
⁴Department of Applied Chemistry, National Institute of Technology, Akita College, Akita, Japan.

Because imines could be used as convenient starting materials in various fields, the development of an easy synthetic method of imine was strongly desired. In response to this demand, we thought that it would be an effective synthesis method if an aldehyde and an amine could be reacted to give an imine in good yield under solvent- and catalyst-free conditions. In fact, we tried the reaction of benzaldehyde with various amines under solvent- and catalyst-free conditions followed by removal of water that was produced in the reaction system by a vacuum pump, and desired imines could be obtained in good yields. Observation of this reaction using a nuclear magnetic resonance spectrometer revealed that the reaction rate was extremely fast at the initial stage but slowed over time. However, the reaction of benzaldehyde with aniline differed greatly, and the reaction rate dramatically improved in 47 - 48 minutes after the start of the reaction. At this time, we found that the reaction system underwent a phase transition from the liquid phase to the solid phase.

Solvent-Free, Catalyst-Free, Pressure Reduction Technique, Imine, Reaction Rate, Phase Transition

Suzuki, S. , Sakaki, S. , Ishizuka, S. , Nishino, T. , Ito, H. , Nonaka, R. , Noike, M. , Kodama, T. , Nozaka, H. , Sato, T. , Agematsu, H. , Maruyama, K. , Oyamada, S. , Kuroishi, T. , Sasaki, K. , Yagawa, K. , Yoshioka, M. and Yokoyama, Y. (2018) Efficient Solvent- and Catalyst-Free Syntheses of Imine Derivatives Applying the Pressure Reduction Technique: Remarkable Change of the Reaction Rate with the Phase Transition. Green and Sustainable Chemistry, 8, 167-179. doi: 10.4236/gsc.2018.82012.