Photochemistry of Methoxyhydroquinone and Methoxy-p-benzoquinone in Solution Related to the Photoyellowing of the Lignocellulosics¶
作者:Stéphane Béarnais-Barbry、Roland Bonneau、Alain Castellan
DOI:10.1562/0031-8655(2001)074<0542:pomamp>2.0.co;2
日期:——
excitation of MQ, indicate that the triplet state of the quinone is strongly quenched by MHQ to conduce to a semiquinone radical. The interaction between 3MQ* and MQ is mainly driven by an electron transfer process according to the similar value of the quenching rate constant found with another electron donor compound such as 1,4-dimethoxybenzene. By contrast, no strong quenching of 3EtC* by MHQ was observed
摘要 使用连续照射和激光闪光光解 (LFP) 研究了甲氧基对苯醌 (MQ) 和甲氧基氢醌 (MHQ) 在稀溶液 (10-4-10-3 M) 中的光反应性。在脱气的四氢呋喃 (THF) 中辐照醌生成 MHQ 和与溶剂的加合物。在乙醇中仅观察到对苯二酚的形成,在水中证实羟基化,而该化合物在四氯化碳中稳定。双醌,4,4'-二甲氧基联苯-2,5,2',5'-双醌,和二苯并呋喃-醌,8-羟基-3,7-二甲氧基二苯并呋喃-1,4-醌,在MHQ 的存在,而与乙基松柏醇的反应性较低。当 MHQ 在脱气的 THF 中被选择性照射时,观察到 MQ 和双氢醌,4,4'-二甲氧基-2,5,2',5'-四羟基联苯的形成。二聚体被光化学或热氧化成单或双醌,该过程在碱性介质中加速。醌和氢醌的连续存在强烈有利于二聚体的形成。当在反式-乙基松柏醛 (EtC) 存在下选择性照射 MHQ 时,观察到醌形成和 EtC 的异构化。用