The Photochemistry of 4-Chlorophenol in Water Revisited: The Effect of Cyclodextrins on Cation and Carbene Reactions
作者:Ilse Manet、Sandra Monti、Pietro Bortolus、Maurizio Fagnoni、Angelo Albini
DOI:10.1002/chem.200401227
日期:2005.7.4
photofragmentation of 1; however, it does influence the course of the reaction because the major portion of the intermediates are reduced to phenol within the cavity (k'(red)> or = 5 x 10(7) s(-1)) either via a radical 8 or via a radical cation 9(+)(.). Under these conditions, neither 2-propenol nor oxygen trap the intermediates to a significant extent.
通过稳态和时间分辨实验研究了4-氯苯酚(1)在水中和在存在环糊精的情况下的光化学性质。这些结果表明1在三重态下经历了C-Cl键的光杂环分解,从而产生了与4-氧代环己-2,5-二烯基(3)3处于平衡状态的4-羟苯基阳离子(3)2。这些三重态中间体几乎不会与亲核试剂(例如水)反应,也不会从该溶剂中提取氢,因此它们的寿命很长(大约1微米)。已经实现了两种中间体的特异性捕集。阳离子加到2-丙烯醇中,k(add)约为1.3 x 10(8)m(-1)s(-1),形成长寿命的离子11(λ(max)= 290 nm),然后将其转化为3-(4-羟苯基)丙烷-1,2-二醇(10)。碳(3)3被氧气俘获,得到苯醌,并被D-葡萄糖(k(q)= 8.5 x 10(6)m(-1)s(-1)还原)得到苯氧基(8)和苯酚(9)。已发现环糊精能更有效地捕获中间体(含β-CD的k(q)= 9.4 x 10(8)m(-1)s(