A research team including Associate Professor Misaki Katayama (Research Organization of Science and Technology) and Professor Yasuhiro Inada (Department of Applied Chemistry, College of Life Sciences) succeeded in controlling alkane bromination reactivity by inserting a polarization-activated*1 bromine molecule into a hemispherical vanadium oxide cluster*2 with a single-atom cavity entrance. This marked the first time that researchers have successfully observed the polarization of a bromine molecule with spectroscopy.
If alkanes, which are abundant in natural gas and crude oil, can be converted easily into useful raw materials for chemical products, it would allow for the more efficient use of resources in the chemical industry. The key is to increase selectivity by bromination, but since alkanes are poorly reactive, an appropriate reaction field needs to be developed to partially functionalize*3 the poorly reactive alkanes.
Focusing on the hemispherical vanadium oxide clusters, which have a unique nano-sized electric charge distribution and a characteristic hemispherical bowl-like structure that collapses and swells, the researchers found that a bromine molecule will polarize when it is inserted into the cavity entrance. The study revealed that the polarized bromine molecule brominates alkanes such as pentane, butane, and propane and demonstrates a product selectivity different from those observed in the reactions caused by regular bromine molecules.
The researchers hope these findings will be utilized in the design of small-molecule polarized materials and highly functional catalysts in the future.
The paper was published on June 8, 2020 as an accepted article on the online version of the German journal Angewandte Chemie International Edition.
A state in which the densities of electrons in two bonded atoms are not equivalent but biased toward one of the atoms. *2: Vanadium oxide cluster
Negatively charged molecular molybdenum oxide.
The addition of groups of atoms or binding modes to afford new properties or reactions to organic compounds.
Name of journal: Angewandte Chemie, International Edition
Article title: Induced-Fitting and Polarization of Bromine Molecule in an Electrophilic Inorganic Molecular Cavity and Its Bromination Reactivity
Publication date: Published online on June 8, 2020 (Japan time)
Authors: Yuji Kikukawa 1, Kensuke Seto 2, Daiki Watanabe 2, Hiromasa Kitajima 3, Misaki Katayama 4, Shohei Yamashita 5, Yasuhiro Inada 6, Yoshihito Hayashi 1
1. School of Chemistry, College of Science and Engineering, Kanazawa University
2. Division of Material Chemistry (Master's Program), Graduate School of Natural Science and Technology, Kanazawa University (at time of research)
3. Division of Material Chemistry (Master's Program), Graduate School of Natural Science and Technology, Kanazawa University
4. Research Organization of Science and Technology, Ritsumeikan University
5. Institute of Material Structure Science, High Energy Accelerator Research Organization
6. Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University