Endorsing Organic Porous Polymers in Regioselective and Unusual Oxidative C═C Bond Cleavage of Styrenes into Aldehydes and Anaerobic Benzyl Alcohol Oxidation via Hydride Elimination

Oxidative cleavage of styrene C═C double bond is accomplished by employing a nitrogen-rich triazine-based microporous organic polymer as an organocatalyst. We report this regioselective reaction as first of its kind with no metal add-ons to afford benzaldehydes up to 92% selectivity via an unusual Wacker-type C═C bond cleavage. Such a reaction pathway is generally observed in the presence of a metal catalyst. This polymer further shows high catalytic efficiency in an anaerobic oxidation reaction of benzyl alcohols into benzaldehydes. The reaction is mediated by a base via the in situ generation of hydride ions. This study is supported by experiments and computational analyses for a free-radical transformation reaction of oxidative C═C bond cleavage of styrenes and a hydride elimination mechanism for the anaerobic oxidation reaction. Essentially, the study unveils protruding applications of metal-free nitrogen-rich porous polymers in organic transformation reactions.

In situ synthesis and encapsulation of copper phthalocyanine into MIL-101(Cr) and MIL-100(Fe) pores and investigation of their catalytic performance in the epoxidation of styrene

In this work, copper phthalocyanine (CuPc) was encapsulated into mesocages of MIL-101(Cr) and MIL-100(Fe) by assembling CuPc’s constitutional fractions using a deep eutectic solvent. The prepared materials, CuPc@MIL-101(Cr) and CuPc@MIL-100(Fe), were characterized by powder X-ray diffraction (PXRD), FT-IR, UV-vis and diffuse reflectance UV (DR-UV) spectroscopies, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ICP-OES spectrometry. The prepared materials were used as heterogeneous catalysts for catalytic epoxidation of styrene with molecular oxygen and also tert-butyl hydroperoxide (TBHP) as oxidants in acetonitrile as a solvent. The impact of MOFs and the role of the CuPc complex as the active species in the MOFs’ cages in the epoxidation of styrene were investigated. Among the prepared catalysts, CuPc@MIL-101(Cr) showed the best performance. The heterogeneity of the catalysts was examined by a hot filtration test and ICP-OES of the filtrates after the reaction. Spent catalysts were analyzed by PXRD, FT-IR, UV-DRS, and TEM for reusability investigation and also to further explore the heterogeneous nature of the hybrid materials. Results showed that the prepared catalysts could be recycled and used for several concoctive times without a considerable drop in activity.

MoO2 Formed on Mesoporous Graphene Oxide: Efficient and Stable Catalyst for Epoxidation of Olefins

A novel mesoporous MoO2 composite supported on graphene oxide (m-MoO2/GO) has been designed and applied as an efficient epoxidation catalyst. The m-MoO2/GO composite was characterised by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmet–Teller surface area analysis, field emission scanning electron microscopy, and transmission electron microscopy. Compared with pure mesoporous MoO2 (m-MoO2) and amorphous MoO2-graphene oxide (a-MoO2/GO), m-MoO2/GO exhibits the best catalytic activity. The conversion and selectivity for cyclooctene are both over 99 % in 6 h. Remarkably, the mesoporous structure in m-MoO2/GO which derives from SiO2 nanospheres endows the catalyst better catalytic performance for long chain olefins: the conversion of methyl oleate can be as high as 82 %. Such a robust catalyst can be easily recycled and reused five times without significant loss of catalytic activity. This novel catalyst is promising in the synthesis of epoxides with a long carbon chain or large ring size.

Synthesis of a BiFeO3 nanowire-reduced graphene oxide based magnetically separable nanocatalyst and its versatile catalytic activity towards multiple organic reactions

Herein, we report for the first time synthesis of a BiFeO₃ nanowire-reduced graphene oxide nanocatalyst (BFO–RGO) using a hydrothermal method.