Development of Chloride-free Multicatalytic System in Wacker-Type Oxidation

The oxidation of terminal alkenes by The Wacker system consisting ofPdCl - D22 - D2/CuCl - D22 - D2/O - D22 - D2 to form the corresponding ketones is a well-established方法和一个非常重要的过程在both synthetic和工业chemistry. However，this catalytic system has disadvantages caused by the cholorine anion which leads to the formationof chlorinated by-products and corrodes the reactor，and it is not suitable for higher olefins and cycloalkenes.In this work，Wacker-type oxidation of cyclopentene to cyclopentanone under dioxygen atmosphere was developed bythe use of Pd(OAc) D22 D2 and molybdovanadophosphate supported on activated carbon，[Pd(OAc) - D22 - npmov /C], catalyst under chlorid -free conditions. Thus，the reaction of cyclopentene under O - D22 - D2(1atm) in aqueous acetonitrile acidified byD23 D2SO D23 D2H in the presence of [Pd(OAc) D22 D22 D2-NPMoV/C] produced cyclopentanone in 85%yield along with a small amount of cyclopentenone (1%). In addition，the acetalizaiton of terminal alkenes such as ethyl acrylate and acrylonitrile with alcohols underD22 - D2 was efficiently achieved by Pd(OAc) D22 - D2 supported on activated carbon combined withmolybdovanadophosphate (NPMoV). For example，ethyl acrylate was subjected to acetalization with EtOH acidified by CH D23 D2SO D23 D2H underO - 22 e - D2 (1atm) in the presence of [Pd(OAc) e - D22 e - D2/C] and NPMoV to form ethyl3,3-diethoxypropionate in quantitative yield。

The oxidation of terminal alkenes by the Wacker system consisting of PdClィイD22ィエD2/CuClィイD22ィエD2/OィイD22ィエD2 to form the corresponding ketones is a well-established method and a very important process in both synthetic and industrial chemistry. However, this catalytic system has disadvantages caused by the cholorine anion which leads to the formation of chlorinated by-products and corrodes the reactor, and it is not suitable for oxidation of higher olefins and cycloalkenes.In this work, Wacker-type oxidation of cyclopentene to cyclopentanone under dioxygen atmosphere was developed by the use of Pd(OAc)ィイD22ィエD2 and molybdovanadophosphate supported on activated carbon, [Pd(OAc)ィイD22ィエD2-NPMoV/C], catalyst under chloride-free conditions. Thus, the reaction of cyclopentene under OィイD22ィエD2(1 atm) in aqueous acetonitrile acidified by CHィイD23ィエD2SOィイD23ィエD2H in the presence of [Pd(OAc)ィイD22ィエD2-NPMoV/C] produced cyclopentanone in 85% yield along with a small amount of cyclopentenone (1%). In addition, the acetalizaiton of terminal alkenes such as ethyl acrylate and acrylonitrile with alcohols under OィイD22ィエD2 was efficiently achieved by Pd(OAc)ィイD22ィエD2 supported on activated carbon combined with molybdovanadophosphate (NPMoV). For example, ethyl acrylate was subjected to acetalization with EtOH acidified by CHィイD23ィエD2SOィイD23ィエD2H under OィイD22ィエD2 (1 atm) in the presence of [Pd(OAc)ィイD22ィエD2/C] and NPMoV to form ethyl 3,3-diethoxypropionate in quantitative yield.