二氧化钨(VI)核二氧化硅负载多相催化剂选择性氧化苯甲醇,Applied Organometallic Chemistry

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二氧化钨(VI)核二氧化硅负载多相催化剂选择性氧化苯甲醇
Applied Organometallic Chemistry ( IF 3.7 ) Pub Date : 2022-10-22 , DOI: 10.1002/aoc.6939
Neda Heydari ₁ , Rahman Bikas ₂ , Maryam Shaterian ₁ , Tadeusz Lis ₃

Affiliation

二氧化钨 (VI) 络合物 [WO ₂ L(CH ₃ OH)]·0.5(CH ₃ OH) ( 1 ) 通过 WCl ₆和三齿 ONO-供体席夫碱配体 ( H ₂ L )的反应制备由 2-羟基-1-萘醛与 4-氨基苯甲酰肼反应得到。H ₂ L 和1均通过各种分析进行了表征，包括核磁共振 (NMR)、傅里叶变换红外光谱 (FT-IR) 和紫外-可见光谱以及元素分析。单晶X-ray分析确定了配合物的晶体结构，表明含有一个游离的-NH ₂组在其结构中。因此，通过在丙酰氯功能化硅胶上负载1获得多相催化剂。通过漫反射光谱（ DRS）、热重分析（TGA）、红外光谱、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）、能量色散光谱（ EDS）和 X 射线粉末衍射（XRD）分析。多相催化剂（Si-W）被用于H ₂ O _{2氧化苯甲醇衍生物}在空气气氛回流条件下。研究了氧化剂浓度、温度和溶剂性质对所得化合物催化性能的影响，结果表明它们对Si-W的活性和选择性有很大影响。多次回收非均相催化剂并重新用于氧化反应。包括 FT-IR 光谱、SEM、TGA、EDS 和 XRD 在内的各种分析结果表明，回收的催化剂与新鲜催化剂之间没有显着差异。结果表明，合成的二氧化硅负载的二氧化钨（VI）配合物是一种活性稳定的苯甲醇氧化催化剂，其选择性取决于反应条件。

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Selective oxidation of benzyl alcohols by silica-supported heterogeneous catalyst containing dioxidotungsten(VI) core

A dioxidotungsten(VI) complex, [WO₂L(CH₃OH)]·0.5(CH₃OH) (1), was prepared by the reaction of WCl₆ and tridentate ONO-donor Schiff base ligand (H₂L) that was obtained from the reaction of 2-hydroxy-1-naphthaldehyde with 4-aminobenzoic hydrazide. Both H₂L and 1 were characterized by various analyses including nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR) and UV–Vis spectroscopy, and elemental analysis. Single crystal X-ray analysis was used to determine the crystal structure of the complex, which revealed that there is a free -NH₂ group in its structure. Therefore, the heterogeneous catalyst was obtained by supporting of 1 on propionyl chloride-functionalized silica gel. The synthesized supported catalyst (Si-W) was characterized by diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TGA), FT-IR, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive spectroscopy (EDS), and X-ray powder diffraction (XRD) analyses. The heterogeneous catalyst (Si-W) was utilized in the oxidation of benzyl alcohol derivatives with H₂O₂ under reflux condition at air atmosphere. The effects of the concentration of oxidant, temperature, and the nature of solvent on catalytic performance of the resulting compound were investigated and the results indicated that they have considerable effect on the activity and selectivity of Si-W. The heterogeneous catalyst was recovered several times and reused for oxidation reaction. The results of various analyses including FT-IR spectroscopy, SEM, TGA, EDS, and XRD indicated that there are no considerable differences between recovered catalyst and the fresh one. The results show that the synthesized silica supported dioxidotungsten(VI) complex is active and stable catalyst for oxidation of benzylic alcohols and its selectivity depends on the reaction condition.

更新日期：2022-10-22

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