Oxidative Desulfurization-Fluorination -- Facile Synthesis of Organofluorine Compounds and Development of Fluorine-containing Novel Liquid-Crystalline Materials--
Kiyoshi KANIE, Manabu KUROBOSHI† and Tamejiro HIYAMA* ††
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo; Hongo, Bunkyo-ku, Tokyo 113-8656 Japan
† Department of Applied Chemistry, Faculty of Engineering, Okayama University; Tsushima-naka, Okayama-shi 700-8530 Japan
†† Department of Material Chemistry, Graduate School of Engineering, Kyoto University; Yoshida, Sakyo-ku, Kyoto-shi 606-8501 Japan
The oxidative desulfurization-fluorination reaction of organosulfur compounds using an N-halo imide and a fluoride source is demonstrated to be an effective and mild fluorination method that allows to synthesize various types of organofluorine compounds containing a difluoromethylene unit, trifluoromethyl-substituted aromatics, trifluoromethyl ethers, and N-trifluoromethylamines in high yields with high chemoselectivity. Herein briefly summarized are the synthetic procedures for such organofluorine compounds and scope and limitations of the reaction. The reaction is applied to the synthesis of novel liquid-crystalline materials having a fluorine functional group such as an N-trifluoromethylamino, trifluoromethoxy, or 1,2-difluoroethylene group. The fluorine-containing liquid-crystalline materials are compared with the corresponding non-fluorinated materials in respect to phase transition behaviors and electro-optical properties. The novel fluorine-containing liquid crystals are shown to be suitable for not only super twisted nematic (STN) but also thin film transistor (TFT)-addressed liquid crystal displays.
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