Progressive steps and catalytic cycles in methanol-to-hydrocarbons reaction over acidic zeolites

Aim and Objective: The synthesis of bipyridines, especially 2, 2’-bipyridines, remains challenging because the catalytic cycle can be inhibited due to coordination of bipyridine to transition metal. Thus, the development of efficient methods for the synthesis of bipyridines is highly desirable. In the present work, we presented a promising approach for preparation of bipyridines via a Pd-catalyzed reductive homocoupling reaction with simple piperazine as a ligand. Materials and Methods: Simple and inexpensive piperazine was used as a ligand for Pd-catalyzed homocoupling reaction. The combination of Pd(OAc)2 and piperazine in dimethylformamide (DMF) was observed to form an excellent catalyst and efficiently catalyzed the homocoupling of azaarenyl halides, in which DMF was used as the solvent without excess reductants although stoichiometric reductant was generally required to generate the low-oxidation-state active metal species in the catalytic cycles. </P><P> Results: In this case, good to excellent yields of bipyridines and their (hetero) aromatic analogues were obtained in the presence of 2.5 mol% of Pd(OAc)2 and 5 mol% of piperazine, using K3PO4 as a base in DMF at 140°C. Conclusion: According to the results, piperazine as an inexpensive and efficient ligand was used in the Pd(OAc)2-catalyzed homocoupling reaction of heteroaryl and aryl halides. The coupling reaction was operationally simple and displayed good substrate compatibility.

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Transformation of methanol to hydrocarbons over Y zeolites with varying Si/Al ratio

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19871701 ◽

1987 ◽

Vol 52 (7) ◽

pp. 1701-1707 ◽

Cited By ~ 1

Author(s):

Miloslav Křivánek ◽

Nguyen Thiet Dung ◽

Pavel Jírů

Keyword(s):

Catalytic Activity ◽

Reaction Time ◽

Coke Formation ◽

Aliphatic Hydrocarbons ◽

Y Zeolite ◽

Y Zeolites ◽

Methanol To Hydrocarbons

The catalytic activity of Na, H-Y zeolite samples with a varying Si/Al ratio (2·5 to 20) in the transformation of methanol was determined. The amounts of formed individual aliphatic hydrocarbons as function of reaction time were correlated with the amount of Bronsted and Lewis centres on the catalysts. The effect of coke formation on the over-all course of the reaction has been demonstrated.

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Merging Pd 0 /Pd II Redox and Pd II /Pd II Non‐redox Catalytic Cycles for the Allylarylation of Electron‐Deficient Alkenes

Chemistry - A European Journal ◽

10.1002/chem.202100075 ◽

2021 ◽

Author(s):

Kazuhiko Semba ◽

Naoki Ohta ◽

Fritz Paulus ◽

Masaki Ohata ◽

Yoshiaki Nakao

Keyword(s):

Catalytic Cycles

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Enhanced Wastewater Treatment by Immobilized Enzymes

Current Pollution Reports ◽

10.1007/s40726-021-00183-7 ◽

2021 ◽

Author(s):

Jakub Zdarta ◽

Katarzyna Jankowska ◽

Karolina Bachosz ◽

Oliwia Degórska ◽

Karolina Kaźmierczak ◽

...

Keyword(s):

Wastewater Treatment ◽

Process Optimization ◽

Organic Pollutants ◽

Large Scale ◽

Removal Rate ◽

Immobilized Enzymes ◽

Future Research ◽

Process Conditions ◽

Removal Rates ◽

Catalytic Cycles

Abstract Purpose of Review In the presented review, we have summarized recent achievements on the use of immobilized oxidoreductases for biodegradation of hazardous organic pollutants including mainly dyes, pharmaceuticals, phenols, and bisphenols. In order to facilitate process optimization and achievement of high removal rates, effect of various process conditions on biodegradation has been highlighted and discussed. Recent Findings Current reports clearly show that immobilized oxidoreductases are capable of efficient conversion of organic pollutants, usually reaching over 90% of removal rate. Further, immobilized enzymes showed great recyclability potential, allowing their reuse in numerous of catalytic cycles. Summary Collected data clearly indicates immobilized oxidoreductases as an efficient biocatalytic tools for removal of hazardous phenolic compounds, making them a promising option for future water purification. Data shows, however, that both immobilization and biodegradation conditions affect conversion efficiency; therefore, process optimization is required to achieve high removal rates. Nevertheless, we have demonstrated future trends and highlighted several issues that have to be solved in the near-future research, to facilitate large-scale application of the immobilized oxidoreductases in wastewater treatment.

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