臺灣博碩士論文加值系統

將香豆素衍生物(7-羥基香豆素與7-羥基-4甲基-香豆素)與二溴烷進行醚
化反應，可合成八種不同亞甲基個數且其二末端含有光反應性香豆素基團
的二香豆素3，4(Scheme 2)。此二香豆素於光增感劑(二苯甲酮)存在下，
以350nm的紫外光照射適當時間，香豆素基團上的雙鍵之間會進行[2＋2]
光聚合反應，可合成各種高黏度的聚醚5，6(Scheme 3)。而這些產物的結
構（順式頭-對-頭、順式頭-對-尾、反式頭-對-頭、反式頭-對-尾）會因
兩個香豆素基團間的亞甲基長度、內酯雙鍵上的甲基取代、反應溶劑以及
增感劑的含量而有所不同。所有聚醚5，6結構的鑑定皆藉由NMR之化學位
移來獲得。內酯雙鍵上沒有甲基取代的二香豆素3在二氯甲烷中照光，易
生成頭-對-頭的照光產物，而內酯雙鍵上有甲基取代的二香豆素4於二氯
甲烷中照光，易生成頭-對-尾的照光產物,以二氯甲烷為溶劑照光會因溶
劑所提供的重原子效應及三重態增感劑(Benzophenone)的影響，使光反應
經由三重激發而得到反式結構的照光產物。針對二香豆素3c作一系列的聚
合動力探討，得知起始反應速率與二香豆素濃度成零階反應，而與二苯甲
酮濃度成一階的反應。最後，將聚醚溶於二氧陸圜溶液中，照射254nm紫
外光(Scheme 5)，探討其光裂解，以及裂解後於350nm紫外光下再聚合的
可逆性。

Eight dicoumarins (3,4) were successfully synthesized from
7-hydroxycoumarin (or 7-hydroxy-4-methylcoumarin) and various
dibromoalkanes. Photopolymerization of the dicoumarins
under 350nm light gives various corresponding polyethers
5,6. The structures of the coumarin dimer component
depend on the length of flexible methylene chain,
substituted groups on double bonds, polarity of solvent, and
sensitizer used. The structures were characterized by NMR
spectra. Dicoumarins (3) without 4-methyl substituent
photopolymerize to give head-to-head products in
dichloromethane. However, dicoumarins (4) with methyl
substituent give head-to-tail products. Photopolymerization
kinetics of 3c was also investigated. The reaction obey zeroth-
order and first-order kinetics for dicoumarin and
benzophenone, respectively. Finally, the polymers were
photocleavaged symmetrically by 254nm UV light and then
repolymerized by 350nm UV light in order to study their
reversible properties.