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结合氢转移方法,研究了木质素模型物2-(2’-甲氧基苯氧基)-1-苯乙醇(1a)分子在无外加氢源的条件下利用金属钯催化剂催化发生C—O键断裂反应.合成并表征了一系列Pd负载型催化剂,通过优化发现反应体系在环己烷溶剂和弱碱添加剂Na2HPO4条件下显示出较好的催化效率.结合反应特点将催化剂进行改进,使用MgO作为载体的催化剂Pd/MgO高效完成了木质素模型物的分子自供氢降解.反应过程可能分为两步进行:首先,模型物在钯表面先进行脱氢过程,含羟基的木质素模型物二聚体1a脱去氢后生成酮式中间体2-(2’-甲氧基苯氧基)-1-苯乙酮(1b),被脱去的氢原子吸附于钯表面.随后,脱氢中间体1b在Pd催化下与其表面吸附的H作用,发生催化C—O键断键过程.
Combined with hydrogen transfer method, the catalytic effect of 2- (2’-methoxyphenoxy) -1-phenylethanol (1a), a lignin model molecule catalyzed by a palladium catalyst, O bond rupture reaction.A series of Pd supported catalysts were synthesized and characterized.It was found by optimization that the reaction system showed good catalytic efficiency in the presence of cyclohexane solvent and weak alkali additive Na2HPO4.The catalyst was improved by using the reaction characteristics MgO catalyst Pd / MgO as a carrier efficiently completes the molecular self-hydrogen degradation of the lignin model. The reaction process may be divided into two steps: first, the model product undergoes dehydrogenation process on the palladium surface, the hydroxyl-containing lignin model The dimer 1a is dehydrogenated to produce the keto intermediate 2- (2’-methoxyphenoxy) -1-acetophenone (1b), and the removed hydrogen atom is adsorbed onto the palladium surface. Subsequently, Hydrogen intermediate 1b is catalyzed by Pd on the surface of its adsorbed H, which catalyzes the C-O bond breaking process.