J. Technology and Education, Vol.14, No.1, pp.1-4, 2007
研究論文
希土類金属トリフラートを用いるtrans-ケイ皮酸エステルの光異性化
長原 滋*，坂口亜紀，中川 茜，水谷友美，冨澤好太郎
鈴鹿工業高等専門学校 生物応用化学科（〒510－0294 三重県鈴鹿市白子町）
*nagahara@chem.suzuka-ct.ac.jp
Photoisomerization of trans-Cinnamate Using Rare-Earth Metal Triflates
Shigeru NAGAHARA,* Aki SAKAGUCHI, Akane NAKAGAWA, Yumi MIZUTANI,
and Kohtaro TOMIZAWA
Department of Chemistry and Biochemistry, Suzuka National College of Technology
(Shiroko-cho, Suzuka, Mie 510-0294, Japan)
(Received November 21, 2006; Accepted December 12, 2006)
Abstract
Irradiation of trans-methyl cinnamate in dry CH3CN solvent under argon in a Pyrex reactor with a high-pressure mercury lamp resulted in the formation of a photostationary state consisting of 49% cis- and 51% trans-isomer. In the presence of Sc(OTf)3 (molar ratio of Sc(OTf)3 / trans-methyl cinnamate = 2.0), a photostationary state mixture of 88% cis- and 12% trans-isomer was obtained under the same irradiation condition. After this photoisomerization, Sc(OTf)3 could be recovered quantitatively and reused with no loss of activity. In the use of other rare-earth metal triflates, Yb(OTf)3 and Y(OTf)3, the conversion of the photoisomerization of trans-methyl cinnamate to cis-isomer increased slightly. The irradiation of trans-ethyl cinnamate and trans-benzyl cinnamate in the presence of Sc(OTf)3 (molar ratio of Sc(OTf)3 / trans-cinnamate = 2.0) afforded cis-ethyl cinnamate (88%) and cis-benzyl cinnamate (83%), respectively. Even in commercial CH3CN solvent without any treatment under the atmosphere, the irradiation of these trans-cinnamates in the presence of Sc(OTf)3 resulted in the optimum conversion to the corresponding cis-isomers.
Key words: isomerization, trans-cinnamate, rare-earth metal triflate, photoreaction
