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Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes
Published on: January 30, 2015
Reduction of vinyl groups in naturally occurring chlorophylls-a
Hitoshi Tamiaki1, Daisuke Takekoshi, Tadashi Mizoguchi
1Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan. tamiaki@se.ritsumei.ac.jp
Abstract:
3,8-Divinyl-chlorophyll(Chl)-a possessing a phytyl ester was hydrogenated in acetone by rhodium catalyst on alumina to afford 3-vinyl-8-ethyl-, 3-ethyl-8-vinyl- and 3,8-diethyl-Chls. The ratio of produced 3-ethyl-8-vinyl- over 3-vinyl-8-ethyl-Chls was determined to be 1.2, indicating that the reactivity of the 3-vinyl group was slightly higher than that of the 8-vinyl group. Catalytic hydrogenation of divinyl-protochlorophyll-a possessing a porphyrin π-skeleton (C17C18) instead of the above chlorin moiety (C17H-C18H) gave an equal amount of mono-reduced regioisomers. The slight (or no) selectivity is different from that in the enzymatic reduction of divinyl-(proto)chlorophyllides-a lacking a phytyl ester in the biosynthetic pathway of Chl-a where the sole 8-vinyl group is transformed to the ethyl group.
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