Catalyst For Cycloaddition Of Epoxides Research Articles

A Pyridinium‐Pyridinium Zinc(II) Porphyrin Ion Porous Organic Polymer as Efficient Heterogeneous Catalyst for Cycloaddition of Epoxides with CO2

AbstractA zinc(II)porphyrin‐based ion porous organic polymer (ZnTPyPBr4‐iPOP) is successfully synthesized from newly designed pyridinium‐functionalized cationic Zn‐porphyrin monomer (ZnTPyPBr4) by free radical self‐polymerization, and is employed as an efficient bifunctional heterogeneous catalyst for CO2 cycloaddition reaction with epoxides. The ZnTPyPBr4‐iPOP exhibits excellent catalytic performance and good substrate expansion in CO2 cycloaddition reaction under solvent‐free and cocatalyst‐free conditions with a TOF as high as 15,500 h−1 for the cycloaddition of CO2 and epichlorohydrin. The synergistic effect of zinc(II)porphyrin as the Lewis acidic site and the Br− anion as the nucleophile in ZnTPyPBr4‐iPOP responds to the high catalytic activity. Moreover, ZnTPyPBr4‐iPOP can easily be recovered and reused at least seven times without the loss of activity. This work provides a valuable approach for the synthesis of novel and efficient heterogeneous catalyst for CO2 cycloaddition.

Co(III)-Salen immobilized cellulose nanocrystals for efficient catalytic CO2 fixation into cyclic carbonates under mild conditions

Searching for green, recyclable and highly efficient catalyst for the synthesis of cyclic carbonates from CO2 is of great importance because it is profitable for reducing the greenhouse effects and meets the principles of green chemistry. Herein, a series of cellulose nanocrystals, either the pristine or modified ones (TEMPO oxidized and Co(III)salen immobilized), were explored as catalysts for cycloaddition of epoxides and carbon dioxide. The impact of surface properties on the performance of the as-made catalysts was investigated. Co(III)-salen grafted cellulose nanocrystals was proven to be the most effective catalyst in this study, which could afford excellent yield up to 99 % after 24 h even under low CO2 pressures of 0.1 MPa. They can be easily recovered and reused for at least 4 times, demonstrating their excellent stability. We found that the surface functional groups such as enriched sulfate or carboxylic groups could also account for the enhanced catalytic activity. This work highlights the applications of green and sustainable nanoparticles in a cycloaddition reaction and offers a sustainable solution in industrial catalysis related to CO2 conversions.

Green synthesized cobalt-bipyridine constructed conjugated microporous polymer: An efficient heterogeneous catalyst for cycloaddition of epoxides via CO2 fixation under ambient conditions

Abstract The conversion of carbon dioxide into valuable cyclic carbonates has been of intensive interest owing to the 100% atomic economy. Conjugated microporous polymers (CMPs) are attractive porous materials contain organic functionalities for applications in gas capture, energy storage, and catalysis. Herein, we developed a new synthesis method of CMP, obtained at room temperature which is one of the “dream reaction”, possessing large surface areas (1356 m2/g) and exhibiting excellent CO2 capture (77.26 cm3/g at 273.15 K/1.00 bar). After loading cobalt acetate, we obtained Co-coordinated CMP (named as TBB-BPY-Co), exhibiting extraordinary activities (turnover frequencies of up to 250 h-1) for the coupling epoxides with CO2 forming cyclic carbonates at room temperature and atmospheric with free-solvent. Moreover, the heterogeneous catalyst showed even better catalytic efficiency than relevant homogeneous catalyst and a higher recyclability (up to 10 times). This study provided an effective and efficient strategy for the carbon dioxide conversion of industrial and economic value.

Metalloporphyrin-based porous organic polymer as an efficient catalyst for cycloaddition of epoxides and CO2

The chemical fixation of carbon dioxide to afford value added chemicals under solvent free and ambient conditions has gained considerable attentions. In this work, we successfully synthesized the porphyrin-based porous organic framework (PPOPs) through Schiff base reaction using 5,10,15,20-tetra(4-aminbiphenyl) porphyrin (TAPP) and 4,4′-biphenyldicarbaldehyde (BDA) as starting materials, which was then coordinated with cobalt to yield related metal complex (Co-PPOPs). The chemical structure and morphology of Co-PPOPs were characterized by absorption spectrum, FT-IR, X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and nitrogen physisorption. Co-PPOPs showed excellent catalytic activity towards the conversion of carbon dioxide to cyclic carbonates under ambient conditions. Furthermore, Co-PPOPs was recovered easily and could be used repeatedly (more than five times) without losing any catalytic activity. Thus, the as-prepared Co-PPOPs was a promising heterogeneous catalyst for carbon dioxide conversion, providing high turnover number than the previously reported catalysts.

Phosphonium-Based Porous Ionic Polymer with Hydroxyl Groups: A Bifunctional and Robust Catalyst for Cycloaddition of CO2 into Cyclic Carbonates.

The integration of synergic hydrogen bond donors and nucleophilic anions that facilitates the ring-opening of epoxide is an effective way to develop an active catalyst for the cycloaddition of CO2 with epoxides. In this work, a new heterogeneous catalyst for the cycloaddition of epoxides and CO2 into cyclic carbonates based on dual hydroxyls-functionalized polymeric phosphonium bromide (PQPBr-2OH) was presented. Physicochemical characterizations suggested that PQPBr-2OH possessed large surface area, hierarchical pore structure, functional hydroxyl groups, and high density of active sites. Consequently, it behaved as an efficient, recyclable, and metal-free catalyst for the additive and solvent free cycloaddition of epoxides with CO2. Comparing the activity of PQPBr-2OH with that of the reference catalysts based on mono and non-hydroxyl functionalized polymeric phosphonium bromides suggested that hydroxyl functionalities in PQPBr-2OH showed a critical promotion effect on its catalytic activity for CO2 conversion. Moreover, PQPBr-2OH proved to be quite robust and recyclable. It could be reused at least ten times with only a slight decrease of its initial activity.

Ultrasound-assisted synthesis of a benzimidazole-containing Zn(II) coordination polymer as highly effective Lewis acid catalyst for cycloaddition of epoxides with CO2

A micron sized Zn (II) coordination polymer (CP), namely {[Zn(L)(5-mip)]·EtOH}(1) (L = 1,3-bis(benzimidazol-1-yl)-2-propanol and 5-H2mip = 5-methyisophthalic acid), was synthesized by ultrasonic irradiation at room temperature. The effects of ultrasonic power and time on the morphology and size of 1 were investigated in detail. Interestingly, micron sized 1 with considerable stability is can be used as an excellent and reused heterogeneous catalyst for carbon dioxide cycloaddition to epoxides under mild conditions.

Pyridinium‐functionalized metalloporphyrins as bifunctional catalysts for cycloaddition of epoxides and carbon dioxide

New pyridinium‐functionalized metalloporphyrins MEtPpBr4 (M = Zn2+, Co2+, Ni2+, Cu2+; EtPp = 5, 10, 15, 20‐tetra(4‐(3‐(N‐ethyl‐4‐pyridyl)pyrazolyl)phenyl)porphyrin) were synthesized as bifunctional catalysts for the cycloaddition reactions of epoxides and CO2. The effects of catalyst loading, CO2 pressure, reaction temperature and time on catalytic activity were investigated. ZnEtPpBr4 (1) and CoEtPpBr4 (2) exhibited efficient activities in the cycloaddition reactions of various epoxides with CO2 as at 120 °C under 2 MPa of CO2 pressure without solvent. Most of corresponding cyclic carbonates could be obtained in almost quantitative yields and > 99.9% selectivity with molar ratio of epoxide/catalyst 2222 after 8 hr of reaction.

Robust Cationic Calix[4]arene Polymer as an Efficient Catalyst for Cycloaddition of Epoxides with CO2

The development of green solid polymer materials bearing multiple active sites as highly efficient heterogeneous catalysts with cooperative effects toward the conversion of carbon dioxide (CO2) to high-value-added cyclic carbonate is highly in need. Here a novel cationic polymer based on the moieties of 1-bromomethyl-4-hydroxy calix[4]arene and tri(4-imidazolylphenyl)amine has been synthesized, characterized, and used as a metal-free bifunctional heterogeneous catalyst for CO2 utilization. The presence of abundant phenolic OH groups as hydrogen bond donors and bromide anions as nucleophilic agents provides this polymer with brilliant activities in catalyzing the epoxides into cyclic carbonates under atmospheric pressure and solvent-free conditions. More importantly, this bifunctional catalyst can be conveniently recycled and keeps catalytic ability well. This work not only offers a new method to synthesize a competitive green heterogeneous catalyst but also provides the first example of an ionic polymer that contains calixarene for synthesizing cyclic carbonate through the CO2 cycloaddition reaction.

Polyvinyl alcohol-potassium iodide: An efficient binary catalyst for cycloaddition of epoxides with CO2

In this study, we have for the first time demonstrated that polyvinyl alcohol (PVA) and potassium iodide (KI) can form an efficient catalytic system for synthesis of cyclic carbonates from epoxide and CO2. The catalytic reaction happens in solvent-free conditions. A synergetic effect occur between PVA and KI which considerably increases the reaction yield. This binary catalytic system is mainly suitable for mono-substituted terminal epoxides. In the optimized reaction condition, over 90% reaction yield can be achieved. The binary catalyst is reusable and can be recycled at least five times without significant loss of the catalytic activity. The PVA hydrolysis degree affect the catalytic activity as well. A possible mechanism of synergetic effect of the binary system was proposed. PVA and KI may form a non-toxic, low cost, recyclable, highly-efficiency catalyst for fixing CO2 through cycloaddition with epoxides.

Metalated porous porphyrin polymers as efficient heterogeneous catalysts for cycloaddition of epoxides with CO2 under ambient conditions

We have successfully synthesized a porphyrin based porous organic polymer (POP-TPP) from free-radical polymerization of tetrastyrylporphyrin monomer under solvothermal conditions. Besides high surface area (1200m2/g) and high thermal stability, the obtained polymer features open metal chelating sites, and thus the catalytic activities of metalloporphyrins can be reasonably adjusted by introducing various metal ions. After metalation with Co3+, Zn2+, and Mg2+, the Co/POP-TPP, Zn/POP-TPP, and Mg/POP-TPP as heterogeneous catalysts are very active for cycloaddition of epoxides with CO2 to cyclic carbonates at ambient conditions with n-Bu4NBr as a nucleophilic additive. Particularly, under the relatively low CO2 concentration (15% in volume), the activity of heterogeneous Co/POP-TPP catalyst is even higher than that of the corresponding homogeneous Co/TPP catalyst. More importantly, there is no activity loss even if the Co/POP-TPP is recycled for 18 times. The excellent catalytic activity and superior recyclability of the obtained catalysts indicate that the porphyrin based porous organic polymer is a promising candidate for construction of efficient heterogeneous catalysts in the future.

Hollow-structured Si/SiC@C nanospheres as highly active catalysts for cycloaddition of epoxides with CO2 under mild conditions.

Hollow-structured Si/SiC@C nanospheres were prepared through a magnesiothermic reduction of resin-coated SiO2 spheres. These nanostructured materials with high surface area not only show high adsorption capacities of industrial dyes from wastewater, but also exhibit excellent catalytic activities for chemical fixation of CO2 under mild, solvent-free conditions.