Generation of Strong Basic Site on Hypercrosslinked Porous Polymers as Catalyst for the Catalytic Oxidation of Methylene Compounds

Abstract

Solid base is a kind of important heterogeneous catalyst for the transformation of various chemicals. Although many different novel solid bases have reported, it is a still challenging process to generate strong basic site on many functional supports due to the high temperature treatment of strong base preparation. In this paper, the strong basic site was successfully generated on hypercrosslinked porous polymers (HCPs) via a reducing group strategy. With the reducing groups on HCPs, the decomposition temperature of base precursor KNO3 could be as low as 320 °C. Further investigation illustrated the reducing groups participated in the KNO3 decomposition through a redox strategy. The obtained solid base catalysts showed good oxidation capacity of methylene compounds.

Base-Assisted Aerobic C–H Oxidation of Alkylarenes with a Murdochite-Type Oxide Mg6MnO8 Nanoparticle Catalyst

“… , Therefore, the reactivity difference cannot be simply explained by the oxidizing ability and surface structures of manganese oxides. Next, the basicity of each catalyst was investigated by CO 2 -TPD analysis (Figure b) because the basic property of a catalyst plays an important role in the homogeneously and heterogeneously catalyzed oxidative C–H functionalization. − Since the O 2 formation started from ca. 300 °C under an inert atmosphere due to the structure change from β-MnO 2 to Mn 2 O 3 (MnO 2 → 0.5Mn 2 O 3 + 0.25O 2 ), all the catalysts were pretreated in He at 250 °C and the basic properties were estimated by the CO 2 -TPD profiles from 100 to 250 °C in this study.…”

“…is one of the most crucial factors to determine the reactivity. Isolated Mn species of microporous materials and metal complexes anchored on supports efficiently catalyze the selective oxidation. ,, On the other hand, the acid–base property also plays an important role in improving the catalytic oxidation performance in both homogeneous and heterogeneous systems. − In particular, the basicity of transition-metal oxo complexes and supported metal catalysts has been reported to affect the reaction mechanism and the reaction rate, resulting in the promotion of oxidative C–H activation under mild reaction conditions. − Against this background, we anticipated that isolated high-valent Mn species located in a crystalline basic matrix would be a good candidate as a heterogeneous catalyst for aerobic oxidative C–H functionalization. This approach to catalyst design is distinct from the incorporation of isolated Mn species into acidic matrices (aluminophosphates, zeolites) , and/or crystal structure control of manganese oxides with Mn–O–Mn structures. − ,− , Herein, we focus on the crystal structure of murdochite-type Mg 6 MnO 8 , which can be considered as the rock-salt structure of MgO with the replacement of one-eighth of the Mg 2+ ions with Mn 4+ ions and one-eighth with vacancies, with the Mn 4+ ions and vacancies occupying (111) alternate lattice layers and ordered within the layers (Figure a). , In this paper, we report that Mg 6 MnO 8 nanoparticles (Mg 6 MnO 8 -MA) synthesized by the malic acid-aided method can act as an efficient and reusable heterogeneous catalyst for aerobic C–H oxidation of various alkylarenes under mild reaction conditions.…”

Synthesis and design of hypercrosslinked porous organic frameworks containing tetraphenylpyrazine unit for high‐performance supercapacitor

“…[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The Friedel-Crafts reaction is a common method for producing HPPs, as it allows for the quick establishment of linkages and the creation of a strongly crosslinked framework with enhanced porosity geometry. [34][35][36][37][38][39][40][41][42][43][44] A wide range of aromatic monomers can produce polymer frameworks with different porosities or introduce specific functionalities that increase the surface area and other desirable characteristics of the materials. 44 Hypercrosslinked porous organic frameworks (HPPs) offer a multitude of benefits that make them superior to other materials, such as metal oxides, carbon, and composites for supercapacitor applications.…”

Hypercrosslinked Polymers as a Photocatalytic Platform for Visible‐Light‐Driven CO2Photoreduction Using H2O

“…The employment of external crosslinkers means a large array of aromatic compounds can be considered as monomeric material, providing substantial scope for the design of HCPs. Owing to their low cost and chemical versatility, HCPs are being developed for many different applications such as gas separation and storage, [19,20] solid‐state extraction, [21,22] and catalysis [23] . Recently, Wang et al.…”