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This report presents the development of an inexpensive mesoporous nanocatalyst i.e. silica coated N -doped carbon modified with ruthenium nanoparticles (Ru/RuO 2 @NSAC). The carbon and nanosilica components were derived from waste materials namely waste tea extract and rice husk respectively highlighting the sustainable approach to the synthesis process. The nanocatalyst was thoroughly characterized using various advanced techniques such as Fourier transform infrared spectroscopy (FTIR), Powder X-ray diffraction (P-XRD), Field emission gun-scanning electron microscopy (FEG-SEM), Energy dispersive X-ray analysis (EDX), High resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray resonance fluorescence (XRF) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). These characterizations provided comprehensive insights into the structural features of the nanocatalyst. XPS analysis confirmed the presence of both metallic ruthenium and Ru (IV) on the nanocatalytic support. The particle size of Ru/RuO 2 @NSAC was determined using Scherrer's equation and came out to be 21.37 nm. This nanocatalyst demonstrated remarkable performance as a robust heterogeneous catalyst for the oxidation of alkylarenes and alcohols to their corresponding carbonyl compounds. It exhibited excellent recyclability, maintaining its activity for up to five consecutive runs. Post-recycling, the catalyst was again characterized by P-XRD and FEG-SEM to ensure its structural integrity. Additionally, the antibacterial activity of Ru/RuO 2 @NSAC was evaluated against both Gram-positive and Gram-negative bacteria. A density functional theory study was also conducted to support the experimental findings, providing a theoretical basis for the observed catalytic behavior. [Display omitted] • Hydrothermal synthesis of Ru/RuO 2 @NSAC nanocatalyst using waste tea leaves, rice husk as activated carbon and SiO 2 sources. • Ru/RuO 2 @NSAC characterized by various spectroscopy techniques and showed excellent recyclability. • Activated carbon showed antimicrobial activity and a DFT study of Ru/RuO2@NSAC was conducted to analyze bonding parameters. [ABSTRACT FROM AUTHOR]

Todays, the heteroatom-doped mesoporous carbon resulting from Metal-Organic Framework (MOF) has attracted the substantial consideration in various filed especially in the heterogeneous catalytic protocols due to their adaptable features. These materials have a high Specific Surface Area (SSA), which offers copious activated sites for the catalytic activity. The mesoporous nature also simplifies the effectual mass transfer, thereby amplifying the overall catalytic procedure. In this study, a highly effective Zr@NC-T samples were synthesized via pyrolyzing a composite of g-C 3 N 4 and UiO-66. The mesoporous structure of Zr@NC-T, revealed a desired SSA varying from 591.38 to 404.26 m2.g−1 due to its surface defect and disorder. Among the synthesized catalysts, Zr@NC-700 (pyrolyzed at 700 °C) exposed preferred catalytic proficiency in the selective oxidation of BnOHs to BnCHO due to its higher surface defect which is caused the higher SSA and structure defect. Furthermore, the Zr@NC-700 catalyst as well proved the acceptable chemical stability due to its reusability. [Display omitted] [ABSTRACT FROM AUTHOR]

Partial oxidation of some organics is desirable in some scenarios for compensation of the heat required for pyrolysis, which, however, impacts not only composition of bio-oil but also possibly property of biochar. This was investigated herein by oxidative pyrolysis of poplar sawdust from 300 to 600 °C and further analysis of the pyrolytic products, especially biochar. The results showed that O 2 could oxidize some organics on surface of biochar, forming more volatiles below 400 °C. Above this temperature the excessive oxidation of the light and heavy organics with π-conjugated structures in bio-oil dominated, producing more gases. Weight loss of biochar from oxidation of organics on its surface was only remarkable at 300 °C, while some weight gain was observed from introduction of additional oxygen-containing functionalities from the oxidation. The removal of aromatic structures on biochar at 500 or 600 °C via oxidation was rather difficult. However, the oxidation reactions did make the biochar oxygen-rich but hydrogen-deficient, which, in overall, improved thermal stability and comprehensive combustion performance of the biochar. Additionally, oxygen presence enhanced aromatic degree of biochar by increasing regularity of (100) facet of carbon crystals while narrowing interplanar spacing of (002) facets. The oxygen-rich nature also made the biochar from the oxidative pyrolysis more hydrophilic while the removal of some organics via oxidation promoted development of the pore structures. • 400 °C is a boundary temperature for oxidation of organics on biochar to bio-oil or further oxidation to gases. • Oxidation makes biochar O-rich but H-deficient, due to preferential oxidation of H. • Oxidation improves regularity of carbon crystals while narrows interplanar spacing of (002) facets. • Oxidation improves combustion, thermostability, and development of pore of biochar. [ABSTRACT FROM AUTHOR]

Mn or Co supported CeO 2 fiber catalysts were synthesized following a biotemplating route and evaluated in soot combustion and benzene total oxidation. The catalysts were characterized by SEM, EDX, N 2 physisorption, FTIR-ATR, XRD, RAMAN and XPS. SEM results confirmed that the "twisted ribbon" morphology of the biotemplate was mostly maintained. XRD and Raman showed that Mn and Co cations partially insert into ceria lattice and also segregate at the surface of the fibers. XPS allowed to determine that both set of catalysts exhibit Ce3+ and Ce4+ species, in addition to adsorbed and lattice oxygen. Also, the average oxidation state (AOS) of surface Mn could be calculated. Compared to bare Fib Ce, the performances for both reactions were improved for the supported catalysts, except from the catalyst with lowest Mn content for soot combustion. The catalytic activity was discussed in terms of the physicochemical features of the supported catalysts. [Display omitted] • A biomorphic synthesis was used to easily obtain an active fibrous support (CeO 2 biofibers). • Mn and Co oxide phases were supported on the biomorphic support via wet impregnation. • For soot combustion, the higher the concentration of lattice oxygen (O latt) and Ce3+, the better the performance. • All supported catalysts improved the activity of the bare support in benzene oxidation reaction. • The best catalyst for benzene oxidation has the highest Ce3+/Ce4+ surface ratio and O latt concentration, along with the presence of oxygen vacancies. [ABSTRACT FROM AUTHOR]

[Display omitted] • The nanohybrid has been prepared as an ultrafast photocatalyst toward the selective generation of aldehydes under visible LED light. • Uniform dispersion of very small TiO 2 /CeCoO 3 /PMO-IL nanohybrid. • Easy separation of charge carriers and reduce their recombination rate. • The impressive stability of TiO 2 /CeCoO 3 /PMO-IL nanohybrid during the photocatalytic process. The construction of perovskite-based wide bandgap semiconductors with uniform dispersion is one of the main strategies to improve the catalytic activity of semiconductor materials. Here, a heterojunction catalyst was obtained by nucleating TiO 2 on CeCoO 3 nanopowders and producing TiO 2 /CeCoO 3 hetero nanostructures at 450 °C. Then by putting them on the PMO-IL as a porous substrate, TiO 2 /CeCoO 3 /PMO-IL nanohybrid was prepared. The properties of nanohybrid were characterized by FE-SEM, EDS, XRD, BET, XPS, HRTEM, SAED, FT-IR, DRS, and PL spectroscopy. The photocatalytic efficiency of TiO 2 /CeCoO 3 and TiO 2 /CeCoO 3 /PMO-IL toward the selective fabrication of aldehydes was studied under the irradiation of visible light. The synthesized nanohybrid demonstrated excellent catalytic activity compared to TiO 2 /CeCoO 3 and PMO-IL alone. Therefore, this nanohybrid could be used as a capable heterogeneous photocatalyst due to its high activity, selectivity, and recyclability. [ABSTRACT FROM AUTHOR]

• Advances in oxidations by polymer-supported palladium nanoparticles and complexes, are described. • Synthetic methods are highlighted for attaining the polymer-supported palladium catalysts. • Catalytic oxidation of alcohols, olefins, alkenes, carbon monoxide, etc. are presented. • Future challenges and opportunities on oxidation reactions using Pd catalysts, are discussed. This review describes the recent advances in the fabrication, characterization and applications of palladium nanoparticles (Pd NPs)/complexes supported on polymers. Nanostructured materials and NPs of various natures, shapes and sizes in combination with polymers, provide unique physicochemical properties and significant potential applications. An overview in catalysis encompassing the preparation of polymer-supported Pd nanocatalysts and Pd complexes for the oxidation of alcohols, olefins, alkenes, carbon monoxide, etc. is presented. Heterogeneous oxidation catalysis, a vital tool in chemical synthesis and transformations, includes the development of various synthetic strategies for the fabrication of Pd-based catalysts; eminent role played by polymer supports in the morphological and structural properties of the ensuing catalysts, is highlighted. [ABSTRACT FROM AUTHOR]

Highlights • Ellagitannin disappearance occurs even in the absence of oxygen. • Oxygen increases the ellagitannin disappearance rate. • Vescalagin disappears faster than castalagin under inert and oxidative atmosphere. • The presence of more than one type of ellagitannin increases the disappearance rate. • The conformation of C1 conditions the effect on the other ellagitannins in solution. Abstract The disappearance of the C -glycosidic ellagitannins over time can occur even in absence of oxygen and their disappearance rate seems to be affected by the presence of other ellagitannins in the media. The objective of this work was to study the influence of the presence of other ellagitannins and/or oxygen on the individual evolution of the main oak ellagitannins in simple model systems in order to understand their behaviours in more complex media, such as wine. In all the studied conditions, vescalagin disappeared faster than castalagin, highlighting its greater reactivity. Oxygen increased the individual disappearance rate, as also occurred when more than one type of ellagitannin was present, above all if the additional ellagitannin(s) contained the same conformation in C1 as vescalagin. Experimental data were fitted to a kinetic model considering both the oxygen-dependent and oxygen-independent reactions, making possible the comparison between individual compounds in different scenarios. [ABSTRACT FROM AUTHOR]

Novel and magnetic catalyst, Co@GO/Fe 3 O 4 /L-dopa was successfully synthesized. Fe 3 O 4 coated GO were used as core particles and L-dopa was used as surfactant as well as interparticle linker. Co@GO/Fe 3 O 4 /L-dopa catalyzed Suzuki cross-coupling reaction and oxidation of hydrocarbon and secondary alcohols; afforded products in good to excellent yields. [Display omitted] • Novel and magnetic catalyst, Co@GO/Fe 3 O 4 /L-dopa was successfully synthesized. • Fe 3 O 4 coated GO were used as core particles. • L-dopa was used as surfactant as well as interparticle linker. • Magnetic Co nanoparticles catalyzed Suzuki cross-coupling reaction. • Oxidation of hydrocarbon and secondary alcohols. We report the synthesis of inexpensive and environmentally benign cobalt(0) nanoparticles on L -3,4-dihydroxyphenylalanine (L -dopa) functionalized and magnetite (Fe 3 O 4) grafted graphene oxide (Co@GO/Fe 3 O 4 /L-dopa) which was fully characterized with different techniques such as Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Photoelectron Spectroscopy (XPS), X-ray Powder Diffraction (XRD), Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Vibrating Sample Magnetometer (VSM), Carbon Hydrogen Nitrogen (CHN) analysis, Energy Dispersive X-ray (EDX) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Graphene oxide was used as the core material due to its mechanical, electrical and thermal properties. In order to avoid the cumbersome process of separation, magnetite nanoparticles were coated over the graphene oxide. After the successful preparation of graphene oxide based magnetic nanoparticles, L -dopa was grafted over Fe 3 O 4 nanoparticles so as to provide firm anchoring agent for cobalt nanoparticles. Finally, cobalt(0) nanoparticles were immobilized on the developed magnetic support. The catalytic efficiency of the synthesized catalyst was tested for Suzuki cross-coupling and oxidation reactions, usually carried out by precious and expensive second and third row transition metals; products were obtained in good to excellent yields. The synthesized catalyst represents an attractive alternative to conventional catalysts for Suzuki cross-coupling and oxidation reactions, and is recyclable up to five runs. [ABSTRACT FROM AUTHOR]

Abstract Nitrite (NO 2 −) oxidation reactions (NOR) have been performed using a pristine glassy carbon (GC) electrode and Pd modified GC electrode to investigate catalysis and kinetics of oxidation reaction. The XPS analysis revealed that Pd nanoparticles (NPs) on GC is differed electronically from Pd particles alone. Electrochemical observations entailed that the Pd-GC electrode improved the catalytic efficiency by lowering peak potential and improving peak current compared to those obtained by GC or Pd electrode alone. Additionally, the onset potential (E i) of kinetic process concerning NOR was appeared at 0.63 V for Pd-GC electrode which is smaller than 0.81 V and 0.75 V observed by GC and Pd electrodes, respectively. These observations suggest that the Pd–GC electrode can obtain faster electron transfer and maximum catalytic sites. The validation of Pd-GC as noble catalyst is also supported by observing least free energy of activation at peak (Δ G p ‡ = 0.461 eV). The nitrite ions involve a single electron transfer reaction with NO 2 molecules being the product, which later undergoes through a dispropornation reaction yielding NO 2 − and NO 3 − as final products. The precise observations by RDE experiments revealed that the charge transfer reaction followed by an irreversible first order kinetics with standard rate constant (k 0) of 1.98 × 10−4 cm/s and formal potential (E o ′) of 0.03 V. Graphical abstract Efficient electrocatalytic oxidation of nitrite (NO 2 −) is attained while a Pd modified glassy carbon (GC) electrode. Nitrite undergoes one electron transfer oxidation reaction on a Pd-GC surface to yield nitrogen dioxide gas which undergoes disproportionation reaction to yield NO 2 − and NO 3 −. Unlabelled Image Highlights • Pd-GC electrode is more effective than GC towards the Nitrite oxidation reaction (NOR). • One electron transfer involves in NOR. • First order irreversible process of NOR • Concerted mechanism followed by NOR • Low onset potential Pd-GC electrode [ABSTRACT FROM AUTHOR]

Abstract Two new biomimetic iron-porphyrin heterogeneous catalysts prepared by grafting of iron(III)-5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (FeTHPP) on 3-chloropropyltrimethoxysilane (ClPTMS) functionalized kaolinite and on a silica prepared through hydrolysis and condensation of tetraethylorthosilicate (TEOS) and ClPTMS, are reported. The catalysts were characterized and tested for the epoxidation of (Z)-cyclooctene and oxidation of cyclohexane using iodosylbenzene as oxygen donor. The position of the Soret band confirmed that the structure of FeTHPP was preserved in the final solids. All catalysts showed a high conversion of the substrates, with total selectivity to the epoxide in the oxidation of cyclooctene, and high selectivity to the ketone in the oxidation of cyclohexane. The catalysts were also used for degradation of dyes in aqueous solutions. The ferroporphyrin-silica catalyst showed the best behavior for (Z)-cyclooctene (48% epoxide) and cyclohexane (48% conversion, sum of alcohol and ketone as products) and also for the degradation of the dyes (97% for methylene blue, although with simultaneous adsorption, close to 85% for Orange II and Brilliant Green), while the ferroporphyrin-kaolinite system showed the best behavior for cyclohexane oxidation (48%, with total selectivity to the ketone). Graphical abstract Unlabelled Image Highlights • The matrix (kaolinite or silica) conditioned the catalytic oxidation performance of the solids. • The kaolinite materials in the design of more selective catalysts. • The catalysts were tested in oxidation of cyclooctene and cyclohexane. • The silica-supported led to more efficient catalysts, and the kaolinite led to high selectivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Key features of Fluorous Biphasic Catalysis (FBC) are summarized. • The evolution of the FBC concept is showcased using selective oxidations, as a model. • The design of fluorophilic transition metal complexes for FBC is discussed. • Current state, challenges, and the future of FBC are presented. Abstract Fluorous Biphasic Catalysis (FBC) has been a more than a two decades old concept, that constituted a paradigm shift in bi and triphasic homogeneous catalysis reactions. FBC has expanded over the years to include a variety of conceptually innovative strategies, enabling the quick separation and recovery of suitable precatalysts, from substrates and products. An overview of the development of selective FBC oxidation reactions, including allylic oxidation, peroxidation, epoxidation of alkenes, and oxidation of primary and secondary alcohols to carbonyl compounds, is presented, with the major focus on the authors' contributions to the field, showcasing the principles of fluorous precatalyst design, and the potential of FBC in its many variants. [ABSTRACT FROM AUTHOR]

Abstract Carotenoids are lipid soluble plant pigments that make part of human daily diet. These compounds are able to react with diverse reactive species and originate a myriad of oxidation products that have similar or even more reactivity than their parent compounds. These products may be short-chain carbonyl compounds and, the commonly designated, apo-carotenoids. The effects fo these products in the human body are not yet fully understood, but it is believed that they are intimately related with their oxidative potential. As so, carotenoids and their oxidation products have undeniable potential as bioactive compounds. However, the multifactorial elements that influence their activity/reactivity make really hard, or probably impossible, the task to classify them as anti- or pro-oxidant compounds. This manuscript provides a thorough review on the reactions of carotenoids with the most physiologically relevant reactive oxygen and nitrogen species, and scrutinizes the resulting oxidation products that have been hitherto identified. Finally, the dual anti- vs. pro-oxidant activities of carotenoids are discussed, mostly based on studies which use physiologic relevant reactive species in oxidative stress. Definitely, there is an open window to the development of deeper studies in this field with a greater number of carotenoids, especially with the ones hitherto not studied. Graphical abstract Image 1 Highlights • Carotenoids' classification, structure, occurrence, and ADME. • Review on carotenoids' reaction with physiologically relevant reactive oxygen and nitrogen species. • Anti- versus pro-oxidant activities of carotenoids and their oxidation products are influenced by multifactorial elements. • Future focus: define the exact conditions that make carotenoids and their oxidative products profitable anti- or pro-oxidants. [ABSTRACT FROM AUTHOR]

The hexadentate ligand, 2,2′-bis(salicylideneamino)azobenzene, 1 has been synthesized from 2,2′-diaminoazobenzene and salicylaldehyde in refluxing diethyl ether. Reaction of ligand 1 with Cu(II) acetate and Cu(II) perchlorate separately in methanol afforded tetradentate (N,N,N,O) Cu(II) complexes, Cu(L) & [Cu(HL)]ClO 4 respectively [where H 2 L represent the one imine moiety cleavage product of ligand 1 (H represents the dissociable amino and phenolic protons)]. These were characterized by microanalytical data and spectroscopic studies. In addition, the crystal structures of the ligand 1 and complexes Cu(L) & [Cu(HL)]ClO 4 were determined by X-ray diffraction analysis. The diffraction analysis revealed that the ligand (H 2 L) binds Cu(II) centers in (N,N,N,O) tetra dentate fashion in distorted square planer geometry. In complex [Cu(HL)]ClO 4 the apical position of copper center is weakly coordinated with one perchlorate ion. The dimeric structure of the molecule [Cu(HL)]ClO 4 is stabilized through NH 2 ···O hydrogen bonds. The fluorescence and redox property of ligand 1 and complexes Cu(L) & [Cu(HL)]ClO 4 were studied. Preliminary DFT calculations were carried out using crystallographic coordinates to understand the electronic spectra and redox properties of the ligand and complexes. The complex Cu(L) shows very good catalytic activities towards oxidation of benzyl alcohol to benzaldeyhde (under solvent-free condition) and organic thioethers to sulfoxide and sulfones using H 2 O 2 as the oxidant. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Successful synthesis of pristine and Fe(III)-amino acid intercalated CaAl-LDHs. • Models of the intercalated complexes based on the results of a range of experimental methods. • Successful applications the oxidations of cyclohexene and in Ullmann coupling. • The organic-inorganic composites proved to be efficient and recyclable catalysts. Abstract Synthesis of intercalated composites were carried out using CaAl-LDH (layered double hydroxide) as host and the anionic form of Fe(III)-amino acid complexes as guest materials. Intercalation was attempted with two methods either introducing the preformed complexes or constructing the complex among the layers of the LDH. After optimization of the synthesis parameters, structural characterization was performed by X-ray diffractometry, scanning electron microscopy as well as mid and far infrared spectroscopies. Quantitative data about the intercalated complexes were collected by chemical analysis and X-ray absorption spectroscopy investigating the near edge region as well as the extended fine structure. Structural models based on characterization measurements are also given. Catalytic activities, selectivities and recycling abilities of the substances were studied in the oxidation reactions of cyclohexene with peracetic acid and in situ formed iodosylbenzene as oxidants in the liquid phase. The catalysts were active in the Ullmann-type etherification coupling reaction as well. The intercalated substances were found to be efficient and highly selective catalysts with very good recycling abilities. [ABSTRACT FROM AUTHOR]

• Application of agricultural wastes (AWs) in the production of nanomaterials. • AW-derived nanomaterials show catalytic activity for chemicals/materials production. • Catalytic reduction for organic synthesis, hydrolysis, etc., are presented. • Future challenges for AW-derived nanomaterials preparation are discussed. Numerous nations around the world have made agriculture their primary industrial sector as it provides employment to millions of people and contributes a significant portion to their national income. However, the increasing demand for agricultural products also leads to producing a substantial amount of agricultural waste. To address this issue, more affordable catalysts are being developed using natural substances like biopolymers, aluminosilicates, zeolites and agricultural wastes including sugarcane bagasse (SCB), coconut husk (CH), corn cobs, wheat straw, rice husks (RH), etc. Since these substances are natural, they don't have an adverse effect on the environment. They are also affordable and cost-effective because they are viewed as a form of waste. Agricultures and their wastes can have an important impact on the design and implementation of more secure and less expensive catalytic systems because of their superior chemical properties for many applications, like coupling, oxidation reactions, organic synthesis, hydrolysis, and others. This review has covered the use of agricultural wastes as effective supports and ecologically friendly reducing agents for the preparation of chemicals and they can be used to produce heterogeneous catalysts by recovering activated carbon (AC) from them because of the beneficial substances they contain. Also, the wide applications of agricultural waste-derived (nano)catalysts are highlighted. In addition, the existing challenges and potential opportunities for research in the near future are proposed. [ABSTRACT FROM AUTHOR]

Two new Cu(II) complexes supported by nitrogen-rich ligands have been synthesized and characterized by absorption spectroscopy, magnetic moment, and cyclic voltammetry. Complex 1 is supported by the ligand TPMEN (N,N,N′-tris(2-pyridylmethyl)-N′-methylethylenediamine) with two amine and three pyridyl nitrogen donors; while 2 is supported by the ligand TQMEN (N,N,N′-tris(2-quinolylmethyl)-N′-methylethylenediamine) where quinoline groups replace the pyridyl groups. Replacing the pyridyl moiety with quinoline has a marked effect on the Cu(II/I) reduction couple. The complexes are capable of reducing superoxide (O 2 − ) to hydrogen peroxide (H 2 O 2 ) in the presence of a proton donor. The reaction between potassium superoxide (KO 2 ) and the Cu-complexes was monitored via absorption spectroscopy, and further probed with electrospray ionization mass spectrometry (ESI-MS). Both 1 and 2 depicted evidence of ligand oxidation in mass-spectrometry. [ABSTRACT FROM AUTHOR]

Superoxide plays a key role in cell signaling, but can be cytotoxic within cells unless well regulated by enzymes known as superoxide dismutases (SOD). Nickel superoxide dismutase (NiSOD) catalyzes the disproportion of the harmful superoxide radical into hydrogen peroxide and dioxygen. NiSOD has a unique active site structure that plays an important role in tuning the potential of the nickel center to function as an effective catalyst for superoxide dismutation with diffusion controlled rates. The synthesis of structural and functional analogues of NiSOD provides a route to better understand the role of the nickel active site in superoxide dismutation. In this work, the synthesis of a series of nickel complexes supported by nitrogen rich pentadentate ligands is reported. The complexes have been characterized through absorption spectroscopy, mass spectrometry, and elemental analysis. X-ray absorption spectroscopy was employed to establish the oxidation state and the coordination geometry around the metal center. The reactivity of these complexes toward KO 2 was evaluated to elucidate the role of the coordination sphere in controlling superoxide dismutation reactivity. [ABSTRACT FROM AUTHOR]

Oxidation is fundamental for many chemical processes and the search for chemoselective oxidants is relevant because most substrates have different functional groups. For unsaturated organo-heteroatom (E) substrates R 1 E(CH 2 ) n CH CR 2 H, the olefin and/or the heteroatom can be oxidized. It is known that molybdenum oxodiperoxo [MoO(O 2 ) 2 L] complexes can selectively oxidize sulfide groups in the presence of alkenes. Thus, the effects of the substituents (R 1 and R 2 ) and of the separation n between the functional groups on the chemoselectivity were investigated by methods based on the density functional theory (DFT) for sulfides (E = S). The chemoselectivity was quantified by the difference between the Gibbs energy of activation at the double bond (TS@C C) and at the heteroatom (TS@E) oxidation pathways, ΔΔ ‡ G = Δ ‡ G (TS@C C) − Δ ‡ G (TS@E). Consistent with experimental observations, this oxidation is chemoselective towards the heteroatom (E = S, Se, and PCH 3 ) for any unsaturated substrate or ancillary ligand L in the complex. For unsaturated organosulfur compounds, it is shown that an increase in the electronegativity of R 1 leads to a decrease of the chemoselectivity, which can be correlated with the atomic charge at the sulfur center. The separation n affects the chemoselectivity similarly to the electronegativity of R 1 , namely, differences between sp 2 and sp 3 carbon centers. The ancillary ligand L = OPH 3 , pyrazole, pyridine N -oxide, and Si(OH) 4 , affects the reactivity of the complex and its chemoselectivity, where L = Si(OH) 4 shows the highest reactivity and the least selectivity; however, ΔΔ ‡ G is still large enough (4.3 kcal/mol) to provide high chemoselectivity. This agrees with the experimental observations related to the oxidations by [MoO(O 2 ) 2 L] complexes supported on silica. These quantitative results and the qualitative trends and correlations can be helpful in the design of more efficient and greener Mo-based oxidants. [ABSTRACT FROM AUTHOR]

An oxidovanadium(IV) complex having a perrhenato ligand [VO(ReO 4 )(4,4′- t Bubpy) 2 ][0.25SO 4 ·0.5ReO 4 ] (4,4′- t Bubpy = 4,4′-di- tert -butyl-2,2′-bipyridine) efficiently catalyzes not only dehydrogenative oxidation of benzylic and propargylic mono-alcohols but also oxidative C C bond cleavage of meso -1,2-diaryl-1,2-ethanediols under atmospheric molecular oxygen, affording the corresponding carbonyl compounds in good yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeMnSi composite synthesized from SiO 2 nanopowder and FeMn hydrotalcite. • Tested in styrene, ethylbenzene and benzyl alcohol oxidations with H 2 O 2. • Characterizations by HRTEM, EPR,SEM, nitrogen physisorption, XRD and Raman spectrocopy. • Si providing a relatively stability on the Fe3+ and Mn4+/ Mn3+ sites for styrene oxidation. • Best reaction conditions at 50 °C, H 2 O 2 /styrene molar ratio = 1 in the presence of acetone for 6 h. FeMnSi composite was synthesized from a mecanosynthesis method using SiO 2 nanopowder and FeMn hydrotalcite. The composite was tested in styrene, ethylbenzene and benzyl alcohol oxidations in the presence of H 2 O 2. The solid was characterized before and after the oxidation reactions through XRD, chemical analyses, textural properties, HRTEM, SEM-EDS, Raman and EPR measurements. Effects of catalyst mass, substrate/H 2 O 2 molar ratios and catalyst' recyclability were investigated to explore the relationship between the physicochemical properties of the solid and the catalytic performance. Results revealed that FeMnSi catalyst exhibited much higher activity for styrene oxidation compared with ethylbenzene and benzyl alcohol counterparts due to Si providing a relatively stability on the Fe3+ and Mn4+/Mn3+ sites. The Si was responsible for improving the texture, structure and morphology of the catalyst in styrene oxidation. Best reaction conditions were achieved at temperature of 50 °C, H 2 O 2 to styrene molar ratio of 1, using 100 mg of catalyst. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (∼13 nm, 4 wt% Au) dispersed on reduced graphene oxide (Au/rGO) surface were prepared via the reduction of gold (III) chloride using sodium citrate on reduced graphene oxide support. The chemical, morphological, and size analyses of Au/rGO by XRD, XPS, TEM, HR-TEM/EDS, AAS, and Raman spectroscopy revealed that the hybrid material comprised of a well-defined rGO support decorated with gold nanoparticles. The ensuing catalyst was evaluated for the oxidation of ethyl benzenes (yields up to 95%) and oxidative esterification of aldehydes (73–97%) using oxygen as an environmentally friendly oxidant in good to excellent yields; reusable and recyclable catalyst displayed high activity without the use of toxic organic solvents. [ABSTRACT FROM AUTHOR]

The Cu(opbmzl) 2 [ohpbmzl = 2-(2′-hydroxyphenyl)benzimidazole] was encapsulated within the super-cage of zeolite-Na-Y through a facile ligand approach and characterized by various analytical techniques such as elemental analysis, X-ray diffraction, inductively coupled plasma-atomic emission, FT-IR, UV–vis-DRS and EPR spectroscopy, thermogravimetric analysis (TGA), BET surface area measurements, pore volume by Horvath-Kawazoe (HK) method and cyclic voltammetry (CV). The shifting of the absorption bands and changes in redox properties of intra-zeolite complex compared to non-encapsulated complex implicated that the zeolite matrix remarkably influenced the structure-electronic properties. The peak potentials of Cu(opbmzl) 2 -Y in cyclic voltammogram were independent of scan rates, further corroborating the intrazeolite mechanism for electron-transfer-pathway in the zeolite-Y. The catalytic activity of Cu-Y, non-encapsulated and encapsulated complex was evaluated for phenol and styrene oxidation. As very low selectivity and formation of tarry products (for phenol oxidation) prevailed with t-butyl hydroperoxide (TBHP), H 2 O 2 was reported to be the reasonable oxidant for the probe reactions. The influence of reaction parameters such as catalyst dosage, substrate concentration, substrate: H 2 O 2 mole-ratio, temperature, time and solvent effects were investigated in detail. All the reaction parameters investigated were very crucial in tuning the product selectivity and conversion efficiency. The encapsulated complex exhibited better catalytic activity and selectivity than the non-encapsulated complex for the probe reactions, associated with exceptional structural stability during the recycling process. From the results, it was derived that the reactions proceeded without the involvement of free radicals and the probable mechanistic pathways based on the intermediate complexes associated with Cu-O species were proposed tentatively. [ABSTRACT FROM AUTHOR]

In trivalent chromium plating processes, the breakdown of useful electrolyte components or the formation of hazardous products, in particular Cr(VI), at the anode is obviously undesired. In this study, the oxidation reactions in trivalent chromium electrolytes with formate as complexing agent are investigated at platinum and at a catalytic mixed metal oxide (MMO) coating comprising iridium oxide (IrO 2 ) and tantalum oxide (Ta 2 O 5 ) using cyclic voltammetry combined with On-Line Electrochemical Mass Spectrometry (OLEMS) measurements.At platinum the following sequence of reaction steps is proposed (all potentials vs. SCE): 1. Oxidative adsorption of [Cr(HCOO)(H 2 O) 5 ] 2+ , reversible at −0.4 V; 2. CO 2 evolution from the Cr(III)-formate complex above +0.4 V; 3. Further oxidation to HCr O 4 − with simultaneous CO 2 and O 2 evolution above +1.2 V. Cr(VI) formation also occurs in the absence of formic acid, i.e. when only C r ( H 2 O ) 6 3 + is present in the electrolyte. At a catalytic MMO coating the adsorption step is absent, as well as any subsequent oxidation of the Cr(III)-formate complex. This suggests that adsorption of the Cr(III) complex is required for Cr(VI) formation. MMO electrodes allow a safe usage of the electrolyte for industrial applications, whereas platinum electrodes do not. [ABSTRACT FROM AUTHOR]

The photocatalytic performance of a series of fluorinated TiO 2 samples (F for O molar substitution ranging from 0 to 1.5 at.%) synthesized by flame spray pyrolysis (FSP) in single step is examined in relation to the results of several complementary characterization techniques, including BET, XRD, XPS and UV–vis analyses. While the rate of photocatalytic hydroxyl radicals production increased when the photocatalyst contained small amounts of fluorine, the rate of formic acid mineralization was maximum with flame-made pure TiO 2 , showing an activity even better than that of P25 TiO 2 in experiments performed in the presence of the same photocatalyst amount. However, the reaction rate decreased with increasing the nominal fluorine content of the materials, as expected for reactions occurring by direct interaction of the substrate with photoproduced holes. On the other hand, incident photon to current efficiency measurements evidenced that the presence of fluorine in the photocatalyst is beneficial, 0.29 at.% effective F for O substitution in TiO 2 leading to the best performing photocatalyst powder, in line with previous results obtained in photocatalytic hydrogen production from methanol steam reforming with similarly FSP-prepared TiO 2 -based materials also containing platinum nanoparticles. [ABSTRACT FROM AUTHOR]

• Mesoporous vanadium sulfides have been synthesized under solvothermal. • The influence of several reaction parameters was studied. • Mesoporous vanadium sulfides as environmental catalysts showed high activity for the cycloaddition of CO2 with 2-(phenoxymethyl)oxirane) and oxidation reactions. • The structure of the prepared materials were studied via a variety of characterization techniques: FTIR, XRD, TGA, BET, FE-SEM, EDX, and X-ray mapping. • Mesoporous vanadium sulfides demonstrates excellent recyclability. Metal sulfide is a vital species of compound semiconductor materials, whose metallic ions are in mono-, bi-, or maybe in multi-form. Considering such materials, layered transition metal sulfide (LTMS) including layered transition metal dichalcogenides (LTMDs) like VS 2 and VS 4 (also called patronite mineral) has attracted growing interest. Moreover, it can be regarded as graphene analogs due to its large interlayer spacing and high theoretical specific capacity, enabling such materials to be applied in different fields i.e. photoelectric staffs, electro-catalysis phenomena, Li-containing batteries, and energy storage usages. Herein, a practical synthetic protocol is designated to construct mesoporous vanadium sulfides (VS 2 and VS 4) with controlled morphologies from VS 2 (Flower-like), VS 4 (Urchin-like), VS 4 (Microsphere), and VS 2 (Nanosheet assemblies) via adjusting the molar ratio of vanadium acetylacetonate and L-cysteine using a one-step solvothermal method. The catalytic activity of vanadium sulfides as an environmental catalyst has been considered for cycloaddition reaction of CO 2 and 2-(phenoxymethyl)oxirane), oxidation of dibenzyl sulfide, and 1-phenylethan-1-ol. The prepared mesoporous vanadium sulfides have a higher surface area than the previously reported ones. The results and analysis revealed that the catalytic behavior of vanadium sulfides significantly depends on physical features such as morphology and specific surface area. The structure of the prepared materials was studied using a variety of characterization techniques: FTIR, XRD, TGA, BET, FE-SEM, EDX, and X-ray mapping [Display omitted] [ABSTRACT FROM AUTHOR]

Tamao–Fleming oxidation of the N -dimethylphenylsilylmethyl group linked to the nitrogen of a peptide bond enables access to dipeptide N,O -acetal functionality. The N -silylmethyl functionality serves as a latent form of the N,O -acetal which is revealed after peptide bond construction. [ABSTRACT FROM AUTHOR]

Catalytic properties of niobosilicates were tested in the oxidation reactions with aqueous H 2 O 2 using cyclohexene, methyl phenyl sulphide and geraniol as model substrates. The catalytic performance of niobosilicates was found sensitive to the type of matrix, niobium source and location of niobium. Structural and textural parameters of the materials synthesized and the location of niobium were monitored during the catalytic reactions. Different catalytic activities of the catalysts prepared with different niobium precursors were related to different location of niobium in the matrix. Highly ordered, 3D caged cubic mesoporous silicates containing niobium, NbFDU-1, and 2D hexagonal mesoporous niobosilicates, NbSBA-15, showed good activities and selectivities. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthesis and characterization of a new multidentate ligand and its Cu(II), Ni(II) and Co(III) complexes. [•] Centrosymmetric binuclear entities containing square-pyramidal copper(II) ions bridged through the phenoxo oxygen atoms. [•] Octahedral Ni(II) and Co(III) bis complexes. [•] The luminescence behaviour and redox properties of both the ligand and complex. [•] Catalytic activity of complex toward H2O2 induced oxidation of benzyl alcohol derivatives to carbonyl compounds. [Copyright &y& Elsevier]

Highlights: [•] Fau supported Cr catalysts were prepared by biosorption of waste metal. [•] Diphenyltriazene derivatives proved to be suitable coordination agents for CrFAU. [•] CrFAU catalysts were successfully used in mild condition oxidation reactions. [•] Cr leaching was effectively reduced by the immobilization procedure. [Copyright &y& Elsevier]

Highlights: [•] Ni-, Co- and Mn- dipicolinate-kaolinite heterogeneous catalysts were prepared. [•] The catalysts effectively catalyzed cis-cyclooctene oxidation, 55% yield and total selectivity to the epoxide. [•] The catalysts effectively catalyzed cyclohexane oxidation, 22% yield and total selectivity towards cyclohexanone. [•] The catalysts effectively catalyzed the decolorization of metanil yellow, methylene blue and green light solutions (70–100%). [•] Catalysis was always truly heterogeneous, involving high-valent metal-oxo as active catalytic species. The catalysts were easily reused. [Copyright &y& Elsevier]

Highlights: [•] Iron salts are homogeneous catalysts in the oxidation of cyclohexane and n-hexane. [•] Were anchored onto activated carbon and mesoporous silica by simple procedure. [•] New heterogeneous catalysts for the oxidation of cyclohexane and n-hexane. [•] Room temperature and sustainable conditions were used. [•] Higher yields in oxygenates obtained than in the harsher industrial process. [ABSTRACT FROM AUTHOR]

Abstract: Dialkylphosphate ionic liquids are useful solvents for cellulose dissolution and catalytic reactions. In this paper, a new methodology for the synthesis of hydrophobic phosphate-based ionic liquids is described. This method involves the oxidation reaction of an easily prepared H-phosphonate precursor by using the environmentally friendly and inexpensive oxidizing agent hydrogen peroxide. [Copyright &y& Elsevier]

Abstract: The newly designed multidentate ligand HL, derived from 2-(benzylthio)aniline and 2-hydroxy-5-methylbenzene-1,3-dialdehyde, upon reaction with Cu(II) perchlorate in methanol yielded the binuclear Cu(II) complex [Cu2(L)(μ-OH)](ClO4)2 (1), which was authenticated by single crystal X-ray diffraction. The diffraction analysis revealed that the ligand binds each of the two Cu(II) centers in an (O, N, S) fashion in a distorted square pyramidal geometry where the two copper centers are bridged by μ-phenoxo and μ-hydroxo oxygen atoms. The apical position of one copper center is coordinated by one perchlorate ion and the other center by a water molecule. The packing of the molecule is stabilized through OH2⋯O hydrogen bonds, mediated through solvent water and perchlorate anions. The emission and redox properties of both the ligand and the complex were examined. The electronic spectra and redox properties of the complex have been explained with DFT computations. The complex [Cu2(L)(μ-OH)](ClO4)2 shows very good catalytic activities towards the oxidation of benzyl alcohol to benzaldehyde and organic thioethers to the corresponding sulfoxide and sulfones using H2O2 as the oxidant. [Copyright &y& Elsevier]

Highlights: [•] New polydentate N,O-coordinating ligands were synthesized. [•] The ligands were converted to their respective iron complexes. [•] The new iron complexes were thoroughly characterized. [•] The complexes were employed as catalysts in oxidation reactions. [•] Secondary alcohols and benzylic methylene groups were oxidized to ketones. [Copyright &y& Elsevier]

Abstract: An advanced numerical model for the in-situ combustion process is developed and studied in detail. The model is based on further extension and modification of the virtual kinetic cell (VKC) and virtual combustion tube (VCT) developed by Kristensen et al. (2007) and Kristensen (2008). Moreover, the model is based on SARA representation of a petroleum mixture (saturates–aromatics–resins–asphaltenes), which may react differently with oxygen and produce other components (for example, light oils and coke). In total, the model contains 14 components, which may undergo 15 chemical reactions. The set of reactions in the original model of M.R. Kristensen has been modified in order to account for secondary combustion of the light oil fraction. The results of the model implementation are applied to the four heavy oil systems and qualitatively compared to the results of previous experimental studies. A new parameter, the critical ignition saturation, is introduced, in order to describe the easiness of oil ignition. Its dependence on the different parameters of the oil mixture and injection gas is studied. The conclusions on the processes governing the ignition of oil in the presence of water are made. A parameter which affects most the possibility of ignition is the activation energy of the light fraction of the oil. [Copyright &y& Elsevier]

Abstract: The paper gives a short survey on the coordination properties of H-spirophosphoranes towards transition metals. The emphasis is on the application of H-spirophosphorane complexes in catalysis. Spirophosphoranes supported by transition metals, palladium or rhodium, have been identified as ligands in metal-catalysed enantioselective catalysis; connected to palladium centres, they exhibit catalytic properties in cross-coupling reactions. Rhenium complexes incorporating spirophosphoranes appear to act as excellent co-catalysts in oxidation reactions. It is demonstrated how fine tuning within the structure of phosphorus ligands can determine the catalytic properties of transition metal complexes. [Copyright &y& Elsevier]

Abstract: Two different methods were described for the preparation of manganese complexes with triazenido derivative ligands encapsulated in NaY zeolite. The catalytic behaviour of the heterogeneous catalysts was evaluated for styrene and cyclohexanol oxidation reactions. Encapsulation was achieved by two methods: (i) ion-exchange from an ethanol solution containing both bis(p-tolyl)triazenido ligand and manganese ions, with the ligand: Mn 3:1molar ratio (Method A) and (ii) the flexible ligand method (Method B). The heterogeneous catalysts were characterized by FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD) and chemical analyses. The results show that both preparation methods lead to effective encapsulation of the Mn{bis(p-tolyl)triazenido} (1:1) complex in the NaY zeolite framework. The heterogeneous catalysts show activity in oxidation of styrene and cyclohexanol with tert-butyl hydroperoxide (tBuOOH) as an oxygen source. The catalysts are chemo-selective in cyclohexanol oxidation, whereas in styrene oxidation reaction leads to styrene oxide and benzaldehyde. [Copyright &y& Elsevier]

Abstract: The immobilization of Fe(III) picolinate and Fe(III) dipicolinate complexes on kaolinite furnished heterogeneous catalysts, whose catalytic activity was evaluated. The precursor materials were kaolinite grafted with picolinic (Ka-pa) and dipicolinic (Ka-dpa) acids obtained by melting of the pyridine carboxylic acids. To obtain the catalysts Fe(Ka-pa)-n and Fe(Ka-dpa)-n (n =1, 2, or 3 is the ligand/Fe ratio), the precursors were suspended in Fe3+ solutions with cation/ligand ratios of 1:1, 1:2, or 1:3. The resulting materials were characterized by thermal analyses (simultaneous TG/DTA), X-ray diffraction, UV/vis and infrared spectroscopies, and transmission electron microscopy. The grafted complexes were employed as heterogeneous catalysts in the epoxidation of cis-cyclooctene to cis-cyclooctenoxide and in the oxidation of cyclohexane to cyclohexanol and cyclohexanone at ambient temperature and pressure. Hydrogen peroxide was used as oxygen donor at a catalyst/oxidant/substrate molar ratio of 1:300:100. Fe(Ka-pa)-n catalysts were very efficient for cis-cyclooctene epoxidation (38% conversion). For cyclohexane oxidation, Fe(Ka-dpa)-n was 100% selective for cyclohexanone formation, with substrate conversion of 14%. This last series of catalysts was also very effective in the Baeyer–Villiger reaction, with 60% substrate conversion and 100% selectivity for ξ-caprolactone. After reuse (5 times), the catalysts still led to high substrate conversion. [Copyright &y& Elsevier]

Abstract: Search for the formation of oxidatively base damage in cellular DNA has been a matter of debate for more than 40years due to the lack of accurate methods for the measurement of the lesions. HPLC associated with either tandem mass spectrometry (MS/MS) or electrochemical detector (ECD) together with optimized DNA extraction conditions constitutes a relevant analytical approach. This has allowed the accurate measurement of oxidatively generated single and clustered base damage in cellular DNA following exposure to acute oxidative stress conditions mediated by ionizing radiation, UVA light and one-electron oxidants. In this review the formation of 11 single base lesions that is accounted for by reactions of singlet oxygen, hydroxyl radical or high intensity UVC laser pulses with nucleobases is discussed on the basis of the mechanisms available from model studies. In addition several clustered lesions were found to be generated in cellular DNA as the result of one initial radical hit on either a vicinal base or the 2-deoxyribose. Information on nucleobase modifications that are formed upon addition of reactive aldehydes arising from the breakdown of lipid hydroperoxides is also provided. [Copyright &y& Elsevier]

Abstract: The release of Acid Mine Drainage, AMD, from mine waste rocks in Arctic areas is commonly assumed to be limited by low air temperatures and permafrost. Here we show that heat generation within a sulphidic coal mining waste rock pile in Svalbard (78°N) is sufficiently high to keep the pile warm at roughly 5 °C throughout the year despite average winter air temperatures below −10 °C. A one-dimensional heat and water flow model, CoupModel, is calibrated and validated successfully on the basis of waste rock characteristics and site-specific climate data. Results show that the subsurface temperature regime within the warm waste rock pile can be explained by heat production from microbial-driven pyrite oxidation. Sensitivity analyses indicate that predicted climate changes are likely to increase subsurface temperatures and the associated environmental impact but also that the waste rock pile will freeze if the depth of the pile is reduced or the water content is increased. [Copyright &y& Elsevier]

Abstract: Mononuclear and heterodinuclear complexes of the salen-type ligand H2 LH2 [H2 LH2 =2,2′-[1,2-dihydroxybenzene-4,5-diylbis(nitrilomethylidine)]bis(3,5-di-tert-butylphenol)] were prepared, whereof [{Mn(CH3OH)2}LH2]Cl, [ML()] (M=Ni, Cu, CrCl(py); py=pyridine, Cp∗ =pentamethylcyclopentadienyl) were characterized by X-ray analysis. Additionally, cyclic voltammetric investigations were performed to ascertain the influence of the second transition metal complex fragment []2+ on the metallo salen ligand. Moreover, the complexes were tested in the catalytic epoxidation of styrene. Although the complexes are quite sensitive towards oxidants, monometallic complex [{Mn(CH3OH)2}LH2]Cl exhibited a conversion of 70.6% with styrene oxide selectivity of 88% over 1h at room temperature. [Copyright &y& Elsevier]

Quantum chemical calculations using density functional theory (B3LYP) were carried out to elucidate the reaction pathways for ethylene addition to the ruthenium compound RuO3CH2. These investigations show that the parent compound is relatively unstable and its rearrangement gives access to very diverse isomers and addition products with comparable relative energies and reaction barriers. The results are compared to our previous study on the analogous osmium system OsO3CH2 and we show that reactivity of both compounds towards ethylene is quite similar. In both cases, the [3 + 2]C,O cycloaddition pathway is preferred kinetically and thermodynamically. The exothermicity (–68.8 kcal/mol) of this reaction is higher for the ruthenium system than for the osmium homologue. While this pathway is unrivaled for the osmium system, the [3 + 2]O,O cycloaddition pathway is able to compete kinetically for the ruthenium system. [Copyright &y& Elsevier]

Abstract: The reaction of 2-thiomethylbenzimidazole (Htmbmz) with chloromethylated polystyrene yielded a product designated by (PS-ligand), which corresponds mostly to the tmbmz bound to the polystyrene matrix by the sulfur atom. [VO(acac)2], [MoO2(acac)2] and Cu(CH3COO)2 react with the PS-ligand to give PS-[VO(ligand) n ] (1), PS-[MoO2(ligand) n ] (2) and PS-[Cu(ligand) n ] (3), respectively, with n ≈2. Non-polymer-bound complexes [VO(tmbmz)2] (4), [MoO2(tmbmz)2] (5) and [Cu(tmbmz)2] (6) have also been prepared similarly. The anchored complexes were characterized by elemental analysis, IR, electronic and EPR spectroscopy, field-emission scanning electron micrograph (FE-SEM), energy dispersive X-ray analysis (EDAX) and thermo gravimetric studies and. EPR was particularly useful to characterize the binding modes in PS-[VO(ligand) n ] (1) and PS-[Cu(ligand) n ] (3), confirming that the vanadium and copper centers are well dispersed in the polymer matrix and supporting the presence of N2O2 binding modes in both cases and the preservation of the binding mode at the end of the catalytic reactions carried out. The catalytic potential of these complexes was tested for the oxidation of styrene, cyclohexene and ethylbenzene using 30% H2O2 as an oxidant. Various parameters, such as concentration of oxidant, amount of catalyst and temperature of the reaction mixture, have been optimized to obtain the maximum oxidation of substrates. Under the optimized reaction conditions, styrene gave three products with the selectivity order: benzaldehyde>1-phenylethane-1,2-diol>styrene oxide. Oxidation of cyclohexene gave three products, the order of selectivity being: cyclohexane-1,2-diol>2-cyclohexene-1-one>cyclohexeneoxide. At least four reaction products with the selectivity order: benzaldehyde>phenylacetic acid>acetophenone>1-phenylethane-1,2-diol have been obtained on oxidation of ethylbenzene. The recycle ability of polymer-anchored metal complexes was checked; the results confirm that the polymer-bound complexes are not leached during the reaction/recovery procedures. Catalytic activities of the PS-supported complexes are higher than those of the corresponding non-polymer-bound complexes. Possible mechanisms are outlined and discussed. In all cases, peroxo or peroxy–metal complexes form; the formation of other intermediates is also discussed. [Copyright &y& Elsevier]

Abstract: Dioxovanadium(V) complexes, K[VO2(sal-inh)(H2O)] and K[VO2(sal-bhz)(H2O)] (where H2sal-inh=Schiff base derived from salicylaldehyde and isonicotinoylhydrazide, and H2sal-bhz=Schiff base derived from salicylaldehyde and benzoylhydrazide) have been reacted with polymer bound imidazole (PS-im) to give polymer-supported complexes, abbreviated as PS-K[VO2(sal-inh)(im)] and PS-K[VO2(sal-bhz)(im)]. Characterization and catalytic potential of these complexes for the oxidative bromination of salicylaldehyde, oxidation of methyl phenyl sulfide and benzene using 30% H2O2 as an oxidant have been reported. [Copyright &y& Elsevier]

Abstract: Tridentate Schiff base (H2fsal-β-ala) obtained from 3-formylsalicylic acid and β-alanine has been covalently bonded to divinylbenzene cross-linked chloromethylated polystyrene. This chelating resin, abbreviated as PS-H2fsal-β-ala (PS=polymeric support), reacts with vanadyl sulfate in DMF to give polymer bound complex, PS-[VO(fsal-β-ala)·DMF], formation of which has been confirmed by various physiochemical methods such as elemental analysis, FT-IR and diffused reflectance spectra, thermo gravimetric analysis, and scanning electron micrograph. Catalytic potential of PS-[VO(fsal-β-ala)·DMF] has been tested for the oxidation of various organic substrates such as benzene, cumene, naphthalene, cyclohexane, styrene, cyclohexene and trans-stilbene in the presence of 30% H2O2 as an oxidant. Oxidation products obtained from each substrate have been characterised by gas chromatography and their identities confirmed by gas chromatography–mass spectrometry. [Copyright &y& Elsevier]

Abstract: Monobasic bidentate ligand 2-(2′-hydroxyphenyl)benzimidazole (Hhpbmz) has been covalently bonded to the chloromethylated polystyrene cross-linked with 5% divinylbenzene. Treatment of the resulted chelating resin, abbreviated as PS-Hhpbmz, with [VO(acac)2], [MoO2(acac)2] (Hacac=acetylacetone) and Cu(CH3COO)2·H2O, gave polymer-anchored complexes PS-[VO(hpbmz)2], PS-[MoO2(hpbmz)2] and PS-[Cu(hpbmz)2], respectively. The corresponding neat complexes with Hhpbmz have also been prepared similarly. Structures of these complexes have been established on the basis of elemental analyses, scanning electron micrographs and spectroscopic (infrared and electronic) as well as thermogravimetric studies. These complexes have been tested as catalyst for the oxidation of styrene, ethylbenzene and methyl phenyl sulfide. Reaction conditions for the maximum oxidation of these substrates have been optimised by considering the concentration of oxidant, amount of catalyst, volume of solvent and temperature of the reaction mixture. Under the optimised conditions styrene gave a maximum of 58.9% conversion with five reaction products namely styrene oxide, benzaldehyde, 1-phenylethane-1,2-diol, benzoic acid, and phenylacetaldehyde. Oxidation of ethylbenzene gave 47.7% conversion where benzaldehyde, phenyl acetic acid, styrene, 1-phenylethane-1,2-diol and benzoic acid have been obtained as major oxidation products. A maximum of 76.5% conversion of methyl phenyl sulfide, catalysed by PS-[VO(hpbmz)2], has been achieved. Catalyst, PS-[MoO2(hpbmz)2] has shown comparable (75.1%) catalytic activity while only 44.8% conversion has been achieved with PS-[Cu(hpbmz)2]. Irrespective of their catalytic performances, the selectivity for the formation of sulfoxide is almost similar (ca. 75%) for all these catalysts. These catalysts do not leach metal ions during catalytic activity and are recyclable. [Copyright &y& Elsevier]

Abstract: Cytochrome P450 (P450) enzymes are some of the most versatile redox proteins known. The basic P450 reactions include C-hydroxylation, heteroatom oxygenation, heteroatom release (dealkylation), and epoxide formation. Mechanistic explanations for these reactions have been advanced. A number of more complex P450 reactions also occur, and these can be understood largely in the context of the basic chemical mechanisms and subsequent rearrangements. The list discussed here updates a 2001 review and includes chlorine oxygenation, aromatic dehalogenation, formation of diindole products, dimer formation via Diels–Alder reactions of products, ring coupling and also ring formation, reductive activation (e.g., aristolochic acid), ring contraction (piperidine nitroxide radical), oxidation of troglitazone, cleavage of amino oxazoles and a 1,2,4-oxadiazole ring, bioactivation of a dihydrobenzoxathiin, and oxidative aryl migration. [Copyright &y& Elsevier]

Abstract: Quantum chemical calculations at the B3LYP/TZVP level of theory have been carried out for the initial steps of the addition reaction of ethylene to OsO3(CH2). The calculations predict that there are two reaction channels with low activation barriers. The kinetically and thermodynamically most favored reaction is the [3+2]O,C addition which has a barrier of only 2.3kcalmol−1. The [3+2]O,O addition has a slightly higher barrier of 6.5kcalmol−1. Four other reactions of OsO3(CH2) with C2H4 have significantly larger activation barriers. The addition of ethylene to one oxo group with concomitant migration of one hydrogen atom from ethylene to the methylene ligand yields thermodynamically stable products but the activation energies for the reactions are 16.7 and 20.9kcalmol−1. Even higher barriers are calculated for the [2+2] addition to the Os2.6kcalmol−1) and for the addition to the oxygen atom yielding an oxiran complex (41.2kcalmol−1). The activation barriers for the rearrangement to the bisoxoosmaoxirane isomer (36.3kcalmol−1) and for the addition reactions of the latter with C2H4 are also quite high. The most favorable reactions of the cyclic isomer are the slightly exothermic [2+2] addition across the Osich has an activation barrier of 46.6kcalmol−1 and the [3+2]O,O addition which is an endothermic process with an activation barrier of 44.3kcalmol−1. [Copyright &y& Elsevier]

Abstract: A new mixed-valence copper coordination polymer with copper–copper metal bonds in a two-dimensional network was generated from an in situ oxidation reaction route under hydrothermal conditions. The synthesis of this coordination polymer demonstrated that the novel compounds that may not be accessible using the known methods could be synthesized via an oxidation reaction route. The reaction conditions are mild enough to keep the building blocks intact during the oxidation and self-assembly process under hydrothermal conditions. [Copyright &y& Elsevier]

Abstract: This overview focuses on both dense and porous ceramic membranes for high temperature oxidation reactions, i.e. partial and total oxidations. Non-permselective porous membranes are efficient contactors for total oxidation of VOC or soot. They are also still attractive as oxygen distributors for the partial oxidation of long chain alkanes, although dense mixed conducting membranes are now on the way to be commercialized for methane involving reactions. By a proper selection of the ion conducting materials composition, structure and thickness, and by combining in a suitable way both dense and porous layers, the oxygen flux, performance and stability of dense ceramic membranes can be considerably improved. In view of the large number of material challenges and scientific approaches found in the literature, it is clearly difficult to be exhaustive. New developments in the field of advanced membranes constantly contribute to improve the potential of membrane reactors, through the development of new preparation methods, of optimized layer stacking and of new membrane materials with original or improved properties. After a rapid overview on both dense and porous membranes used for oxidation reactions, examples of the developments in the field of membrane materials, structures, architectures, synthesis methods and reactor designs are reported, coming from either our Institute or from the recent literature on both membrane reactors and SOFCs. [Copyright &y& Elsevier]