相转移催化合成2,4-二氯苯氧乙酸新工艺研究

以2,4-二氯苯酚和氯乙酸为原料,在碳酸钾作用下筛选相转移催化剂(四丁基溴化铵、四乙基溴化铵和PEG-600)进行醚化反应,制备2,4-二氯苯氧乙酸。所获得的最佳工艺条件是:催化剂选PEG-600/KI为最佳,二氯苯酚和氯乙酸原料物质的量比1∶2,相转移催化剂PEG-600用量为二氯苯酚的6%,KI用量为二氯苯酚量的10%。在此合成条件下,2,4-二氯苯氧乙酸收率达94.2%。

Identification of origin of insulating polymer maneuvered photoredox catalysis

Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalizedπelectrons along the molecular chain framework.Up to date,origin of insulating polymer regulated charge transfer has not yet been uncovered.In this work,we unleash the root origin of charge transport capability of insulating polymer in photocatalysis.We ascertain that insulating polymer plays crucial roles in fine tuning of electronic structure of transition metal chalcogenides(TMCs),which mainly include altering surface electron density of TMCs for accelerating charge transport kinetics,triggering the generation of defect over TMCs for prolonging carrier lifetime,and acting as hole-trapping mediator for retarding charge recombination.These synergistic roles contribute to the charge transfer of insulating polymer.Our work opens a new vista of utilizing solid insulating polymers for maneuvering charge transfer toward solar energy conversion.

不同第六轴向配体的苯酚锰(Ⅲ)四苯基卟啉配合物的研究

在不同的溶剂体系中合成并分离出标题化合物呋喃，吡啶，咪唑．进行了元素分析和可见吸收光谱、红外光谱研究，用循环伏安法测定了氧化还原电位．

Chemoselective Transfer Hydrogenation of Cinnamaldehyde over Activated Charcoal Supported Pt/Fe3O4 Catalyst

A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt （Ⅳ） and Fe （Ⅱ） precursors as driving force. The formed Fe3O4 nanoparticles （NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe304 nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe3O4 catalyst exhibits 94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of einnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.

Progress of electrochemical CO_(2)reduction reactions over polyoxometalate-based materials

Electrochemical CO_(2)reduction to value-added fuels and chemicals is recognized as a promising strategy to alleviate energy shortages and global warming owing to its high efficiency and economic feasibility.Recently,understanding the activity origin,selectivity regulation,and reaction mechanisms of CO_(2)reduction reactions(CO_(2)RRs)has become the focus of efficient electrocatalyst design.Polyoxometalates(POMs),a unique class of nanosized metal-oxo clusters,are promising candidates for the development of efficient CO_(2)RR electrocatalysts and,owing to their well-defined structure,remarkable electron/proton storage and transfer ability,and capacities for adsorption and activation of CO_(2),are ideal models for investigating the activity origin and reaction mechanisms of CO_(2)RR electrocatalysts.In this review,we focus on the activity origin and mechanism of CO_(2)RRs and survey recent advances that were achieved by employing POMs in electrocatalytic CO_(2)RRs.We highlight the significant roles of POMs in the electrocatalytic CO_(2)RR process and the main factors influencing selectivity regulation and catalytic CO_(2)RR performance,including the electrolyte,electron-transfer process,and surface characteristics.Finally,we offer a perspective of the advantages and future challenges of POM-based materials in electrocatalytic CO_(2)reduction that could inform new advancements in this promising research field.

The FCC Flue Gas SOx Transfer Additive RFS Developed by RIPP

The present paper introduces the development of FCC flue gas SOx transfer additives by RIPP with a brief discussion of SOx transfer mechanism. The second-generation SO transfer additives of the RFS series are RIPP＇s proprietary additives with significantly improved performances. The results of commercial tests indicate that the RFS additive can effectively control SO emission of the FCC regenerator while maintaining product yields and product quality when the additive is used in a proper concentra- tion range.

Synthesis of TiO_2/g-C_3N_4 nanocomposites with phosphate–oxygen functional bridges for improved photocatalytic activity

One of the most general methods to enhance the separation of photogenerated carriers for g‐C3N4is to construct a suitable heterojunctional composite,according to the principle of matching energy levels.The interface contact in the fabricated nanocomposite greatly influences the charge transfer and separation so as to determine the final photocatalytic activities.However,the role of interface contact is often neglected,and is rarely reported to date.Hence,it is possible to further enhance the photocatalytic activity of g‐C3N4‐based nanocomposite by improving the interfacial connection.Herein,phosphate-oxygen(P-O)bridged TiO2/g‐C3N4nanocomposites were successfully synthesized using a simple wet chemical method,and the effects of the P-O functional bridges on the photogenerated charge separation and photocatalytic activity for pollutant degradation and CO2reduction were investigated.The photocatalytic activity of g‐C3N4was greatly improved upon coupling with an appropriate amount of nanocrystalline TiO2,especially with P-O bridged TiO2.Atmosphere‐controlled steady‐state surface photovoltage spectroscopy and photoluminescence spectroscopy analyses revealed clearly the enhancement of photogenerated charge separation of g‐C3N4upon coupling with the P-O bridged TiO2,resulting from the built P-O bridges between TiO2and g‐C3N4so as to promote effective transfer of excited electrons from g‐C3N4to TiO2.This enhancement was responsible for the improved photoactivity of the P-O bridged TiO2/g‐C3N4nanocomposite,which exhibited three‐time photocatalytic activity enhancement for2,4‐dichlorophenol degradation and CO2reduction compared with bare g‐C3N4.Furthermore,radical‐trapping experiments revealed that the·OH species formed as hole‐modulated direct intermediates dominated the photocatalytic degradation of2,4‐dichlorophenol.This work provides a feasible strategy for the design and synthesis of high‐performance g‐C3N4‐based nanocomposite photocatalysts for pollutant degradation and CO2reduction.

Black phosphorus incorporated cobalt oxide:Biomimetic channels for electrocatalytic water oxidation

Learning from nature photosynthesis,the development of efficient artificial catalysts for water oxidation is an ongoing challenge.Herein,a lamellar cobalt oxide(CoO),black phosphorus(BP)and reduced graphene oxide(RGO)hybrid electrocatalyst is reported.BP domains are anchored on RGO and coated with CoO via P–O bonds.The widespread P–O bond network constitutes the proton acceptor and forms a proton exit channel,akin to the use of Asp61 in Photosystem II(PSII).The innermost kernel layer RGO serves as the current collector and forms an electron exit channel,mimicking the function of Tyr161 for charge transfer.The outermost encapsulation CoO layer acts as water oxidation catalyst(WOC).These biology‐inspired features endow an outstanding OER performance of the hybrid material with a low overpotential of 206 mV at a current density of 10 mA cm^(-2).This work provides a new design guide for OER electrocatalysts through constructing two specialized channels for proton and electron transfer.

Phase Transfer Catalysis: Oxidation of 2-Methyl-1-butanol

In liquid-liquid systems, the substrates in the liquids are inaccessible to each other for the reaction. By adding a small quantity of phase transfer catalyst, the reaction can be made accessible and accelerated. The present study involves the phase transfer catalyzed oxidation of 2-methyl-l-butanol by quaternary ammonium permanganate （tricaprylyl methyl ammonium permanganate）. The attempt was to compare the kinetics under homogeneous and heterogeneous conditions. Experiments were conducted in a batch reactor to determine the kinetics under homogeneous conditions. A baffled horosilicate agitated reactor was used to find the enhancement factor and the kinetics under heterogeneous conditions. The rate constants determined under both homogeneous and heterogeneous conditions agreed very weU. The oxidation was found to be first order with respect to each of the reactants, quaternary ammonium permanganate and the alcohol, resulting in an overall second order rate expression. Aliquat336 （tricaprylylmethylammonium chloride） was found to be the best compared with the other catalysts tested （triethylbenzylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide and tetrabutylammonium hydrogen sulfate） and it gave an enhancement factor of 9.8.

Oxidative coupling of α-bromoarylacetonitriles and oxidative decyanation of diarylacetonitriles catalyzed by solid-liquid phase transfer

Oxidative coupling of α-bromoarylacetonitriles and oxidative decyanation of diarylacetonitriles are efficiently realized by solid-liquid phase transfer catalysis using anhydrous K 3 PO 4 as base and TBAB as catalyst in acetone at room temperature. In this mild and convenient method, α,β-dicyanostilbenes and diarylketones were prepared in good to excellent yields.

Cloning of a caffeoyl-coenzyme A O-methyltransferase from Camellia sinensis and analysis of its catalytic activity

Epigallocatechin-3-O-（3-O-methyl） gallate（EGCG3＂Me） present in leaves of Camellia sinensis has many beneficial biological activities for human health. However, EGCG3＂Me occurs naturally in tea leaves in extremely limited quantities. Finding an enzyme from C. sinensis to catalyze the synthesis of EGCG3＂Me is an alternative method to make up for the scarcity of EGCG3＂Me in natural situations. In the present study, a complementary DNA（c DNA） encoding region and genomic DNA of the caffeoyl-coenzyme A O-methyltransferase（CCo AOMT） gene were isolated from C. sinensis（designated Cs CCo AOMT）. Nucleotide sequence analysis of Cs CCo AOMT revealed an open reading frame of 738 bp that encodes a polypeptide with a predicted molecular weight of 28 k Da, which correlated well with the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE）. The full-length DNA sequence（2678 bp） contained five exons and four introns. The deduced amino acid sequence of Cs CCo AOMT shared 92% identity with CCo AOMTs from Codonopsis lanceolata and Betula luminifera. The catalytic activity of Cs CCo AOMT was analyzed. Three monomethylated epigallocatechin-3-O-gallate（EGCG） compounds（EGCG4＂Me, EGCG3＂Me, and EGCG3＇Me） were produced by Cs CCo AOMT with K m in the micromolar range. Real-time polymerase chain reaction（RT-PCR） experiments indicated that the Cs CCo AOMT transcript was present at low levels during the early stages of leaf maturity（the first leaf and bud on a shoot） but the relative expression was augmented at advanced stages of leaf maturity（the third or fourth leaf on a shoot）, which accorded well with changes in EGCG3＂Me content in fresh leaves. Hence, we concluded that Cs CCo AOMT catalyzes the syntheses of methylated EGCGs.