Photopolymerization of Derivatives of Umbelliferone

• Main Authors: Rong-Tzung Hong, 洪榮宗
• Other Authors: Professor Yun-Chen
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/23838893776923963504

碩士 === 國立成功大學 === 化學工程研究所 === 82 === Eight diesters (3,4) have been successfully synthesized from 7-hydroxycoumarin(or 7-hydroxy-4-methyl coumarin) and various diacidchlorides.Upon benzophenone-sensitized irradiation with 350 nm light, intramolecular cycloadducts or intermolecular polymers are formed with three kinds of cyclobutanes depending on the length of flexible methylene chain, substituted groups on double bonds, and solvent used. The structures of these cycloadducts and polymers are characterized by H NMR and fluorescence spectra. On irradiation of the unsubstituted diesters(3) in dimethyl sulfoxide, singlet excited state excimers are formed and lead to syn head-to-head products. On the other hand, the dimerizations of all dicoumarins in dichloromethane are progressed via triplet excited state in the present of benzophenone. The photopolymerization kinetics of 4c are also studied. The reaction obeys zero-order and first-order kinetics for coumarin and benzophenone, respectively. This is a pertinent estimate for the proposed mechanism derived from triplet excited state reaction.