Environmentally-friendly chemistry — Converting biomass-derived substances into useful substances using ionic liquids —

Recently, green chemistry, or environmentally-friendly chemistry, has been growing more and more important, as a field of chemistry which aims to use the minimum amount of substances that cause environmental burdens when used in substance synthesis, and to collect and recycle such substances as much as possible if they are discharged. In green chemistry, reactions that convert biomass-derived chemical substances into useful substances hold an important position. A research group led by Professor Akio Kamimura at the Graduate School of Sciences and Technology for Innovation, Yamaguchi University, in collaboration with Doctor Tom Sheppard and Professor Helen Hailes at the Department of Chemistry, University College London in the UK, has developed a reaction in which furfural, which can be obtained in large amounts from plant-derived materials such as the inedible parts of corn, is quickly converted into phthalic acid derivatives using ionic liquids known to be green solvents. Phthalic acid is also used as a substance for resins, and it is anticipated that this reaction will become a method by which plant-derived materials can be converted into useful substances such as plastics.

In this research, what was found in the reaction was that furfural hydrazones, which are derivatives of furfural, reacted with maleimide in an ionic liquid, [bmin][Cl], to trigger a Diels-Alder reaction, and that a subsequent dehydroaromatization proceeded immediately afterward, synthesizing phthalimide [WU1] at a high yield. This reaction is completed in one hour by heating at 120ºC using microwave irradiation. Isolation of the product is possible by means of extraction as well as recrystallization, which also means isolation and purification can be achieved easily. The ionic liquid can be almost completely collected quantitatively, and it was found that the same reaction can be repeated a few times by reusing the collected ionic liquid. This research provides a new method for usefully applying biomass and for performing a reaction to convert it. It is expected to contribute to the development of future green conversion reactions.

The results of this research are the achievement of a research collaboration with the Department of Chemistry at University College London in the UK, a place with a strong connection to Yamaguchi Prefecture which was established in the period from the end of the Edo Period to the Meiji Restoration. In order to promote this research, support was obtained from the Japan Society for the Promotion of Science in order to invite Doctor Valerija Kalarula from UCL to Yamaguchi University as a postdoctoral researcher, and she drove the research forward. It is deeply moving to think that after 150 years, a researcher from the UK came to Japan for the advancement of chemistry, and in so doing made the opposite journey to the one undertaken by the Choshu Five.

This research was aided by JSPS Grants-in-aid for Scientific Research (JP17K19139) and JSPS Postdoctoral Fellowships for Research in Japan (Short-term).

  The research results were published in RCS Advances on June 20 (Wed.).

  DOI: 10.1039/c8ra03895c

  LINK: http://pubs.rsc.org/en/content/articlelanding/2018/ra/c8ra03895c#!divAbstract