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Graphical abstract Highlights • A simple approach for catalytic oxidation of cyclohexylamine to CHO has been afforded. • Supported TiO 2 /MCM-41 is demonstrated to be efficient and eco-friendly catalyst. • Surface titanium hydroxyl groups is responsible for excellent catalytic performance. • TiO 2 /MCM-41 catalyst has highly stable reactivity, easy regeneration and reusability. • The green approach for production of CHO has important industrial application prospects. Abstract A green and efficient approach for solvent-free selective catalytic oxidation of cyclohexylamine to cyclohexanone oxime in liquid phase has been developed. The results showed that the supported 30%TiO 2 /MCM-41 as efficient and eco-friendly catalyst gave 78.4% of cyclohexylamine conversion with 89.1% of selectivity to cyclohexanone oxime. It has been demonstrated that the catalytic active sites are the surface titanium hydroxyl groups of catalyst. Moreover, the present catalyst can be easily separated, recycled, regenerated and reused. The probable catalytic reaction mechanism of cyclohexylamine with molecular oxygen over supported TiO 2 /MCM-41 was suggested. This work affords a new and environmentally friendly route for the synthesis of cyclohexanone oxime, and has important industrial application prospects. [ABSTRACT FROM AUTHOR]

Vanadium-zirconium catalyst was prepared with zirconium tetrachloride and ammonium metavanadate, which were supported on different supports, such as activated carbon, g-C 3 N 4 , MWCNTs (multiwall carbon nano tubes), acidified MWCNTs, bentonite, and γ -Al 2 O 3 . Various techniques were employed to characterize the catalysts such as X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption, and Raman spectrum. It was found that Zr 4+ and V 5+ in the vanadium-zirconium catalyst were dispersed on support in the form of zirconium pyrovanadate. The performance of catalysts on hydroxylation of benzene to phenol with O 2 as the oxidant was investigated. The vanadium-zirconium catalyst with different supports showed different catalytic performance and the reason was studied. It was found that the catalytic performance was related to the nature of the supports including the surface area and the composition of the supports. The yield of phenol reached to 8.6% and selectivity reached to about 80% when the activated carbon acted as support. Kinetic study showed that the first step of the consecutive reaction was first order for benzene and the second step was first order for phenol. [ABSTRACT FROM AUTHOR]

The oxidative dehydrogenation of allyl alcohol to acrolein over bulk alloyed and supported silver catalysts has been studied, with the aim of designing optimal Ag-based catalysts for this specific reaction. All of the tested catalysts were highly active and selective to acrolein at temperatures ranging between 340 and 380 °C. The results show that the alloying of Ag with Au or Cu leads to alloys with upper surface compositions comprising approximately between 35 and 65% silver. Although these elements improve the activity of Ag catalysts, they decrease their selectivity, leading to lower acrolein yields. Various different Ag catalyst supports were prepared (LaPO 4 , Carbon nanotubes CNT, TiO 2 , Al 2 O 3 and SiO 2 ) using the impregnation method, and subsequently tested. This study reveals that the catalyst with the best performance is Ag/SiO 2 with a yield in acrolein of 87.2% at 360 °C. The results obtained with the tested catalysts are discussed, and the reasons of performance improvement or degradation caused by the presence of Au or Cu on the active silver sites, or by the presence of the supports, are raised. [ABSTRACT FROM AUTHOR]

Catalysts with atomically dispersed active sites are highly desirable to maximize atom efficiency. Herein, we reported atomically cobalt dispersed onto nitrogen-doped graphene (denoted as Co-NG) by heat-treating cobalt salts and graphene oxide in ammonia atmosphere. The Co-NG catalyst was characterized by various analysis techniques, such as XPS, XRD, Raman, TEM, SEM, HAADF-STEM and nitrogen adsorption. Characterization results showed that the surface O content decreased as the doping temperature increased, while the surface N content kept increasing up to 7.94 at% at the doping temperature of 750 °C. The coordination of N with Co should improve the catalytic behavior of Co-NG. The Co-NG catalyst has extremely high atom efficiency and shows high activity and excellent stability for the selective oxidation of various alcohols (e.g. benzyl alcohol, 4-chloro-benzyl alcohol, 4-methyl-benzyl alcohol, 4-methoxy-benzyl alcohol, 4-hydroxy-benzyl alcohol, phenethyl alcohol, 2-methyl heptanol, etc) by oxygen molecule. For example, 94.8% benzyl alcohol conversion and 97.5% benzaldehyde selectivity can be achieved over Co-NG after reaction for 5 h, and the catalyst yields an average TOF of over 500 h −1 . [ABSTRACT FROM AUTHOR]

Atom efficient synthesis of various value added products has been focused as an intense research area after Kyoto protocol. Styrene epoxidation is a challenging reaction as styrene epoxide is an important monomer for large number of polymers. It has been found that surface acidity and redox property of the catalyst has a major contribution to the catalytic activity for oxidation reaction. In this study Co-HMS-X catalyst was prepared and characterized by BET surface area and porosity measurement, SAXS, SANS, FESEM, HRTEM, UV-vis spectra, FTIR, 29Si NMR, H2-TPR and NH3-TPD techniques. It is observed that 5 mol% Co-HMS-X showed highest catalytic activity for styrene epoxidation reaction using molecular O2 as an oxidant. Interestingly it is found that among three different dopant (Al, Ga, Tl), the Ga promoted Co-HMS-X catalyst (Si:Co:Ga = 100:5:1.25) showed highest catalytic activity in terms of styrene conversion (100%) and styrene epoxide selectivity (68%). The unusual trend of Al, Ga and Tl towards the activity of Co-HMS-X (5 mol%) catalyst has been discussed from the results obtained in the H2-TPR and NH3-TPD study. [ABSTRACT FROM AUTHOR]

Abstract: A new convenient method for the synthesis of dimethyl carbonate from dimethoxymethane and O2 in the presence of catalytic amounts of Cu-MCM-48 was described. The XRD results indicate that the structure of Cu-MCM-48 is gradually distorted with the increase in the copper content, whereas the framework structure of Cu-MCM-48 is basically retained until the incorporated copper content reaches to 0.62wt%. The SEM, TEM and N2 adsorption studies show that copper content of 9.51wt% completely changes the morphology and structure of Cu-MCM-48. Effects of the amount of the incorporated copper in catalyst, catalyst amount used and other reaction conditions on the catalytic activity are investigated in details to obtain the optimized reaction conditions. Short reaction time, easy recycling of the catalyst and excellent yields are the main advantages of this process. [Copyright &y& Elsevier]

Abstract: Water-soluble aluminum-coordinated polyoxotungstates, Cs4[α-PW11{Al(OH2)}O39]·8H2O (Cs-1), [(CH3)4N]4[α-PW11{Al(OH2)}O39]·8H2O (TMA-1), K6Na[(A-PW9O34)2{W(OH)(OH2)}{Al(OH)(OH2)}{Al(μ-OH)(OH2)2}2]·19H2O (KNa-2), and K7[α2-P2W17{Al(OH2)}O61]·14H2O (K-3), were used as homogeneous catalysts or catalyst precursors for the oxidation of alcohols with 1atm molecular oxygen in a water–alcohol biphasic medium. The catalytic activities and the stabilities of polyoxoanions were significantly affected by the structures around the aluminum sites constructed in the polyoxotungstates. In particular, polyoxoanion 1 exhibited high turnover numbers and high selectivities of the corresponding carbonyl products, and the molecular structure of 1 was remarkably stable for oxidations with long time intervals. [Copyright &y& Elsevier]

Abstract: Binary layered double hydroxides (LDHs) of Mg–Al and Co–Al having varied cation molar ratio were studied for the catalytic epoxidation of styrene with molecular O2 as an oxidant and DMF as a solvent. The effect of various reaction variables, reconstruction and reuse of LDH samples on the catalytic activity was evaluated. The cation molar ratio of LDH as well as concentration of DMF significantly affected the catalytic activity. The highest styrene conversion was observed with LDH having cation molar ratio (Mg/Co:Al) of 3:1. Mg–Al LDH showed highest styrene conversion of 85% with 80% styrene oxide selectivity and Co–Al LDH sample exhibited highest styrene conversion of 97% with 83% oxide selectivity at 100°C after 4h. [Copyright &y& Elsevier]

Abstract: Mn–Ni mixed hydroxide was synthesized by a facile co-precipitation method and the catalytic performance in the aerobic oxidation of benzyl alcohol using molecular oxygen was examined. The Mn/Ni molar ratio played an important role and the sample with Mn/Ni molar ratio of 6:4 showed the best catalytic activity. High specific activity of 8.9mmol/(gh) along with the benzaldehyde selectivity of 99% was achieved at 100°C within 1h. Characterizations of X-ray diffraction, X-ray absorption and hydrogen temperature-programmed reduction suggested that co-precipitation method afforded the formation of Mn-in-Ni(OH)2 solid solution without phase segregation. Excess amounts of Mn resulted in segregated Mn3O4 crystalline phase, which showed low surface area and poor catalytic activity. The synergistic interactions between Mn(III) and Ni(II) cations through oxygen bonding were suggested to enhance the activity of Mn–Ni mixed hydroxide catalysts for benzyl alcohol oxidation. [Copyright &y& Elsevier]

Abstract: Selective catalytic oxidation of geraniol to citral with molecular oxygen in supercritical carbon dioxide (scCO2) has been investigated. The catalyst used was a chromium containing mesoporous molecular sieve catalyst viz. CrMCM-41. Comparison studies were performed with CoMCM-41, PtMCM-41 and PdMCM-41 catalysts. Among the various catalysts studied, CrMCM-41 showed a high conversion of geraniol and an excellent selectivity for citral. In contrast CoMCM-41, PtMCM-41 and PdMCM-41 catalysts exhibited low conversion of geraniol. However all three catalysts compared showed similar citral selectivity to CrMCM-41. The effect of CO2 pressure and reaction temperature geraniol oxidation was studied with CrMCM-41. Supercritical CO2 medium was found to enhance the conversion of geraniol and/or yield of citral. It was noticed that the catalyst can be recycled with negligible loss of conversion. [Copyright &y& Elsevier]

Abstract: We report the facile synthesis of alumina supported copper–manganese mixed oxide catalysts by a homogeneous deposition–precipitation method and the catalytic applications of these catalysts in the oxidation of benzyl alcohol using molecular oxygen. Benzyl alcohol conversion of ca. 90.9% was achieved with benzaldehyde as the main product. The catalyst can be recycled consecutively up to seven runs without appreciable loss of its activity and selectivity. Characterizations with X-ray diffraction, transmission electron microscopy, Raman, X-ray absorption spectroscopy, and hydrogen temperature-programmed reduction suggested the formation of a mixed oxide (Mn1.5Cu1.5O4) microcrystalline phase after adding copper to the manganese supported on alumina. Such formation would account for the high catalytic performance. Calcination under high temperature decomposed this mixed oxide phase, resulting in a poor catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: A series of vanadium pyrophosphate oxide catalysts were prepared by thermally treating catalyst precursor VOHPO4·0.5H2O in the temperature range of 500–900°C in nitrogen and their catalytic activities were evaluated in glycerol dehydration with molecular oxygen. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric–differential thermal analysis and temperature programmed desorption of ammonia. The dehydration activity depends on treatment temperature on the catalyst precursor; the catalyst treated at 800°C exhibits the best result with 100% glycerol conversion and more than 95% selectivity for useful products, including acrolein (64%), acetaldehyde, acetic acid and hydroxyacetone. We observed that the addition of molecular oxygen into reaction could greatly reduce the selectivity for by-products from 20% to 4% and can avoid coke formation. The dehydration activities of the catalysts were correlated with the characteristics of the catalysts. [Copyright &y& Elsevier]

Abstract: The combination of ruthenium, manganese as well as cerium oxides formed an active catalytic system for the oxidation of 2-octanol and other alcohols. The addition of manganese species as promotors resulted in more active catalysts than comparable cobalt-doped oxidic materials. The application of RuMnCe oxides on redox-active supports, such as TiO2 or CeO2, by deposition–precipitation caused a further improvement of catalytic activity. A tolerance to nitrogen-containing substrates was observed. [Copyright &y& Elsevier]

Abstract: A series of framework substituted Co-TUD-1 catalysts, prepared by direct hydrothermal synthesis, were characterized using X-ray diffraction, nitrogen physisorption, transmission electron microscopy and UV–vis and Raman spectroscopies. These catalysts showed high conversion and selectivity towards trans-stilbene oxide in liquid phase trans-stilbene epoxidation with molecular oxygen as oxidant in the absence of a sacrificial reductant. The conversion and selectivity did not remarkably differentiate for fresh and recycled catalyst after four reaction runs. The unique pore structure of Co-TUD-1 catalyst is suggested to be beneficial for the epoxidation of bulky alkene molecules comparing with other well-established catalysts, e.g., Co-MCM-41 and Co2+-NaX. Microwave irradiation can significantly shorten the reaction time, whereas high conversion and epoxide selectivity remained. [Copyright &y& Elsevier]

Decatungstate (DT) is very potential photo-catalyst for the dioxygens (O 2)-based selective oxidation but still needs to be improved in photo-catalytic efficiency and regeneration. This paper discloses that Au nanoparticles (NPs)-loaded DT (Au/DT) is conveniently synthesized via the reduction of chloroauric acids introduced in the synthesis of DT. A series of characterizations and quenching tests support that the doped Au NPs can remarkably improve the visible-light- harvesting and photo-excited quantum efficiencies of DT, and as the excellent electronic transport carriers, they also plays an additional role in converting O 2 into the active superoxide (•O 2 -) anion radical. As a result, the suggested Au/DT exhibits a significantly enhanced photo-catalytic efficiency for the visible-light-triggered selective oxidation of inert hydrocarbons under 25–28 °C and 1 atm pure O 2 atmosphere. Under optimized conditions, the best 1%Au/DT achieves 64.2% conversion and 93% acetophenone selectivity in the photo-oxidation of ethylbenzene and it has an outstanding regeneration ability. The hybridizing engineering (HE) strategy of Au NPs doping can improve DT's visible light harvesting efficiency and redox capacity via lowering frontier orbital energy levels, and in which Au NPs as the excellent electronic transport carriers also hoist DT's photo-excited quantum efficiency and the reactivity of O 2 in the visible light-driven selective oxidation of inert hydrocarbons. [Display omitted] • Firstly realizing the doping of Au NPs in the cage of non-lacunary decatungstate (DT). • Doped Au NPs remarkably improve DT's photo-physiochemical and redox properties. • Doped Au NPs play a crucial role in converting O 2 into active •O 2 - anion radical. • Au/DT possesses significantly enhanced visible-light-catalytic performance. • Au/DT has a good application potential in photo-catalytic oxidation of hydrocarbons. [ABSTRACT FROM AUTHOR]

Abstract: Ti- and Al-containing hexagonal mesoporous silicas (Ti-Al-HMS) were synthesized through a sol–gel reaction using dodecylamine as a surfactant. All Ti4+ ions could enter into the HMS framework until Ti/Si=4mol% and all Al3+ ions could enter into the HMS framework until Al/Si=1mol% in Ti-Al-HMS after calcination at 923K for 4h. The Al3+ ions at the extra-framework of HMS are much stronger acidic sites than the Al3+ ions in the intra-framework of HMS. In a fixed-bed catalytic system, Ti-Al-HMS (Ti/Al/Si=4/1/100 (molar ratio)) showed 47.8% of propylene conversion and 30.6% of selectivity for propylene oxide (PO) for the propylene epoxidation by molecular oxygen at 523K. The simultaneous existence of Ti and Al in the framework of HMS is very important for improving the PO yield. An epoxide-like intermediate formed from Ti site, Al site and adsorbed O2 was proposed for explaining the synergy effect of Ti and Al in Ti-Al-HMS for the propylene epoxidation by molecular oxygen. The Ti4+ ions at the extra-framework had little effect on improving the PO yield, and the Al3+ ions at the extra-framework greatly decreased the selectivity for PO, because their strong acidity promoted the oligomerization-cracking of propylene. The sol–gel method is more effective than the impregnation method for preparing a catalyst containing Ti and Al for the propylene epoxidation by molecular oxygen. Ti-Al-HMS deactivated rapidly for the propylene epoxidation at 523K due to the carbonaceous deposits on the catalyst surface. The deactivated catalyst could be regenerated by calcinating in air at 923K for removing the carbonaceous deposits. Adding a little amount of hydrogen in the feed gas obviously decreased the speed of catalyst deactivation but could not completely suppress the catalyst deactivation. The amounts of the carbonaceous deposits were 2.6wt% without H2 and 0.9wt% with H2 in the feed gases over Ti-Al-HMS after 3h on stream at 523K. The KNO3 additive could improve the selectivity for PO and the Ca(NO3)2 additive could improve the propylene conversion over Ti-Al-HMS for the propylene epoxidation by molecular oxygen. [Copyright &y& Elsevier]

Abstract: The bis(maltolato)oxovanadium complexes cis-[VO(OCH3)(ma)2] 1, cis-[VO(OC2H5)(ma)2] 2, [VO(ma)2] 3 and [VO(py)(ma)2] 4 have been anchored to chemically modified silica gel and are shown to act as supported catalysts for the oxidation of n-pentane and n-hexane, with molecular oxygen under relatively mild reaction conditions, to the corresponding ketones (with good selectivities) and alcohols (in smaller amounts). cis-[VO(OCH3)(ma)2] 1 provides the best results in both cases and the effects of various factors (temperature, time, O2 pressure, catalyst amount) were also investigated towards the optimization of the reaction conditions. 2-pentanone (84% selectivity) and a small amount of 2-pentanol are formed from n-pentane at 150°C, p(O2)=15atm, while 2-hexanone (58% selectivity), 1-hexanol and acetic acid are obtained from n-hexane at 160°C, p(O2)=10atm. The involvement of a carbon- and oxygen-centred radical mechanism is suggested by experiments with free radical traps. Heteroaromatic acids were tested as possible co-catalysts and 2-pyrazinecarboxylic acid was the most effective one. Thermogravimetric analysis (TGA) indicates the catalyst is stable up to ca. 220°C and inductive couple plasma (ICP) shows a notable extensive vanadium loss from the supported catalyst after the reaction, allowing further use of the catalyst even without reactivation. [Copyright &y& Elsevier]

Abstract: Heterogeneous oxidation of liquid cyclohexane by molecular oxygen was carried out over metal-containing ZSM-5 catalysts in a solvent-free system. Among those M-ZSM-5 and M/ZSM-5 catalysts tested, Co-containing ZSM-5 catalysts including Co/ZSM-5 (prepared by ion-exchange and calcination) and Co-ZSM-5 (prepared by ion-exchange and drying) showed the best activity for the oxidation of cyclohexane to cyclohexanone and cyclohexanol. Co/ZSM-5 had almost the same activity as Co-ZSM-5 for the cyclohexane oxidation; however, the leaching of cobalt from Co-ZSM-5 readily occurred. Co/ZSM-5 (calcined) catalyst could achieve about 10mol% conversion of cyclohexane and 97% selectivity of KA-oil (the mixture of cyclohexanone and cyclohexanol) at 393K under the pressure of 1.0MPa O2. In addition, other factors like the temperature, the pressure, the time, various metals, the tert-butylhydroperoxide (TBHP) addition, and the catalyst reuse were investigated carefully. For the titled oxidation, Co/ZSM-5 was recyclable, and could behave as a truly heterogeneous catalyst. [Copyright &y& Elsevier]

Abstract: A new potential Ag catalytic system for direct gas-phase epoxidation of hexafluoropropylene with molecular oxygen is reported. The practicability of epoxidation of hexafluoropropylene with molecular oxygen using Ag/γ-Al2O3 catalyst at low temperature and under ambient pressure is investigated. Modified the Ag catalyst by Cs, both the conversion of hexafluoropropylene and the selectivity to hexafluoropropylene oxide could be improved significantly. The catalysts were characterized by XRD, TEM and EDS. [Copyright &y& Elsevier]

In this paper we compare the properties and catalytic activities of immobilised forms of in situ formed cobalt complexes of pyridin-4-ylmethyl-propyl-amine (PYPA), immobilised via grafting of pyridin-4-ylmethyl-(3-triethoxysilanyl-propyl)-amine on pre-formed HMS, and various cobalt salts, formed in aqueous solution. To investigate the role of peroxo species on the catalytic activity, materials with cobalt-alkyl- or hydroperoxo groups were also prepared by addition of TBHP or H2O2 in the loading step of the preparation. The support material and the catalysts were characterised by STA, DRUV, and N2 adsorption. All catalysts are active in the aerial oxidation of styrene and, with few exceptions, 1-decene, and exhibit different reactivities and selectivities towards epoxidation. [Copyright &y& Elsevier]

The epoxidation of propylene catalyzed by a reaction-controlled phase transfer catalyst [π-C5H5NC16H33]3[PW4O16] is investigated. The H2O2 is generated by the oxidation of 2-ethylanthrahydroquinone (EAHQ) with molecular oxygen in the organic solvent. Under mild conditions, the selectivity for propylene oxide, based on propylene, is 95%, and the yield, based on 2-ethylanthrahydroquinone, is 85%. During the epoxidation, the catalytic system is homogeneous. However, after the H2O2 is used up, the catalyst can be recovered as a precipitate and can be reused. After the epoxidation reaction, 2-ethylanthraquinone can be regenerated to 2-ethylanthrahydroquinone by catalytic hydrogenation, and no coproduct is produced. [Copyright &y& Elsevier]

The palladium catalyzed oxidation of alkenes with molecular oxygen is a synthetically important reaction which employs palladium catalysts in solution; therefore, a solvent plays a critical role for the process. In this study, we have tested several green solvents as a reaction medium for the allylic oxidation of a series of alkenes. Dimethylcarbonate, methyl isobutyl ketone, and propylene carbonate, solvents with impressive sustainability ranks and very scarcely exploited in palladium catalyzed oxidations, were proved to be excellent alternatives for the solvents conventionally employed in these processes, such as acetic acid. Palladium acetate alone or in the combination with p -benzoquinone efficiently operates as the catalyst for the oxidation of alkenes by dioxygen under 5–10 atm. For most substrates, the systems in green solvents showed better selectivity for allylic oxidation products as compared to pure acetic acid; moreover, the reactions in propylene carbonate solutions occurred even faster than in acetic acid. [Display omitted] • The palladium catalyzed oxidation of alkenes is an industrially important reaction. • Several green solvents are proposed for the aerobic allylic oxidation of alkenes. • Palladium acetate alone or together with p -benzoquinone operates as the catalyst. • Proposed solvents: dimethylcarbonate, methyl isobutyl ketone and propylene carbonate. • Highly recommended solvents regarding both sustainability and catalyst performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iron and vanadium antimonate catalysts are efficient for the oxidative dehydrogenation of ethyl lactate to ethyl pyruvate. • Characterization in situ that showed that Sb3+/Sb5+ and Fe2+/Fe3+ redox couple are not involved in the reaction mechanism. • Active sites were shown to be V5+ sites which surface concentration passes through a maximum for a given bulk composition. • The study shows the complexity of surface bulk relations for catalysts working with Mars and van Krevelen mechanism. The oxidative dehydrogenation of ethyl lactate to ethyl pyruvate, corresponding to the first step of a new process in the industrial production of methionine, has been investigated. Iron and vanadium antimonates were developed as catalysts, and were optimized to reach 87 % conversion of ethyl lactate, with 88 % selectivity to ethyl pyruvate, at only 275 °C. The catalysts were characterized before and after catalytic testing, and in situ using various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and XANES spectroscopy. The results show that neither the Sb3+/Sb5+ nor the Fe2+/Fe3+ redox couple were involved in the dehydrogenation of ethyl lactate, or in the catalysts re-oxidation. The active and selective catalytic sites correspond to surface V5+ species. These species should not be considered as part of the bulk oxide, but as supra-surface species whose surface content is monitored with the bulk composition. [ABSTRACT FROM AUTHOR]

• Twenty catalysts were screened for the oxidative dehydrogenation of ethyl lactate into ethyl pyruvate. • Iron-substituted phospho-molybdic heteropolyacids were the catalysts with highest efficiency. • Catalyst activity depends on Mo surface sites density and is decreased when Fe substitutes protons in supported acids. • Fe has a positive effect only in FePMo 12 O 40 because it induced a charge transfer improving redox mechanism. • Ethyl pyruvate selectivity depends on the catalyst acidity, strong acid sites promoting side reactions like hydrolysis. This study reports on a new industrial gas-phase process to produce ethyl pyruvate, using the oxidative dehydrogenation of ethyl lactate. In an initial approach, twenty catalysts were screened under reaction conditions required for industrial applications. When evaluated in terms of their maximum selectivity to ethyl pyruvate and their productivity, the best catalyst was found to be a phosphomolybdic polyoxometalate, with iron counter-cations: FePMo12O40. To improve this catalyst, a study was carried out by including cesium counter-cations. The new catalysts exhibited higher yields because of higher Mo active surface site density related to higher specific surface area and although their intrinsic activity was lower. Their ethyl pyruvate selectivity increased with iron content but never overpass that of FePMo12O40. These results are explained in terms of changes in structure and iron counteraction coordination leading or not to electron exchange between iron and molybdenum and influencing the acidity of the catalyst's surface. [ABSTRACT FROM AUTHOR]

Tertiary benzylic C H bonds were converted to corresponding alcohols directly and efficiently employing O 2 as oxidant and T(2,3,6-triCl)PPMn possessing bulkier substituents as catalyst under solvent-free and additive-free conditions, with higher conversion (57.6%) and selectivity (70.5%) than current documents under similar conditions. • Direct conversion of tertiary benzylic C H bonds to alcohols was obtained mildly. • High performances of metalloporphyrins with bulky substituents were demonstrated. • Selectivity toward benzylic alcohols (70.5%) was higher than current documents. • A strategy for direct functionalization of tertiary benzylic C H bonds presented. The direct and efficient oxidation of tertiary benzylic C H bonds to alcohols with O 2 was accomplished in the presence of metalloporphyrins as catalysts under solvent-free and additive-free conditions. Based on effective inhibition on the unselective autoxidation and deep oxidation, systematical investigation on the effects of porphyrin ligands and metal centers, and apparent kinetics study, the oxidation system employing porphyrin manganese(II) (T(2,3,6-triCl)PPMn) with bulkier substituents as catalyst, was regarded as the most promising and efficient one. For the typical substrate, the conversion of cumene could reach up to 57.6% with the selectivity of 70.5% toward alcohol, both of them being higher than the current documents under similar conditions. The superiority of T(2,3,6-triCl)PPMn was mainly attributed to its bulkier substituent groups preventing metalloporphyrins from oxidative degradation, its planar structure favoring the interaction between central metal with reactants, and the high efficiency of Mn(II) in the catalytic transformation of hydroperoxides to alcohols. [ABSTRACT FROM AUTHOR]

• A low-temperature and highly efficient nitration approach has been developed. • The introduction of molecular oxygen remarkably enhanced the substrate conversion. • Cooperation catalysis of Hβ zeolite and Ac 2 O envidently improved the para - selectivity. • The selectivity distribution of nitration products was explained by DFT calculation. • The possible catalytic nitration mechanism was suggested in O 2 -Ac 2 O-Hβ system. In this work, we developed a low-temperature and efficient approach for the highly selective preparation of valuable p -nitrochlorobenzene from the liquid-phase catalytic nitration of chlorobenzene with NO 2 in O 2 -Ac 2 O-Hβ composite system. The results demonstrated that the introduction of molecular oxygen remarkably enhanced the chlorobenzene conversion and the cooperation catalysis of Hβ zeolite and Ac 2 O envidently improved the selectivity to para -nitro product. Under the optimized reaction conditions, 93.6 % of the selectivity to p -nitrochlorobenzene with 84.0 % of chlorobenzene conversion was obtained, and the ratio of p -nitrochlorobenzene to o -nitrochlorobenzene could reach up to 20.3. Furthermore, the selectivity distribution of nitration products was reasonably explained by the density functional theory (DFT) calculation. Finally, the possible nitration reaction pathway of chlorobenzene with NO 2 was suggested in O 2 -Ac 2 O-Hβ composite catalytic system. The present work affords a new and mild nitration approach for highly selective preparation of valuable para -nitro products, and has potential industrial application prospects. [ABSTRACT FROM AUTHOR]

• An effective strategy is developed to successfully fabricate CQD-hybridized TBADT. • CQD hybridization slightly improves the quality and redox capacity of TBADT. • CQD hybridization enhances visible light use and photoexcited state lifetime of TBADT. • CQD hybridization significantly enhances photocatalyic oxidation performance of TBADT. • The favorable hybridizing effects of CQD on TBADT are magnified by 2 M HCl solution. This paper discloses an efficient strategy for the preparation of carbon quantum dot (CQD)- hybridized (nBu 4 N) 4 W 10 O 32 (TBADT). A key step in this strategy is to hydrothermally treat CQD with TBABr solution to form the TBA+ micelle-encapsulated CQD, which acts as a cationized hybridizer to combine with the W 10 O 32 4− anion to yield the target catalyst. XPS, UV–vis, PL and CV characterizations indicated that CQD hybridizer plays unique roles in improving the structural stability, redox capacity and visible light response of TBADT, especially in enhancing the stability of its photo-excited state. In the visible light-triggered selective oxidation of cyclohexane, toluene, ethylbenzene and benzyl alcohol with dioxygens in acetonitrile, the optimized hybrid containing 3% CQD shows much higher photo-catalytic activity than pure TBADT, affording ca. 21.7% conversion and 84.8% cyclohexanone selectivity in cyclohexane photo-oxidation, Additionally, the additive 2 M HCl further enhances the above hybridization effects, thereby significantly promoting the current photo-catalytic oxidations. [ABSTRACT FROM AUTHOR]

• The aerobic palladium catalyzed oxidation of cis -jasmone, a main aroma constituent of jasmine essential oil, was performed. • In acetic acid solutions and the Pd(OAc) 2 / p -benzoquinone catalytic system, oxidation gave an allylic acetate. • In aqueous dimethylacetamide solutions and PdCl 2 as a sole catalyst, cis -jasmone was oxidized to ketone products. • Poly-functionalized oxygenated jasmonoids obtained are potentially useful as components of perfumes and cosmetic products. The palladium catalyzed oxidation is a versatile method for upgrading of cis -jasmone, a main aroma constituent of jasmine essential oil. Although both olefinic bonds in cis -jasmone are sterically hindered, the substrate has demonstrated a remarkable reactivity in Wacker type oxidations. Depending on the catalyst and the solvent, reactions can be directed to either allylic oxidation or ketone products. The oxidation in acetic acid solutions with a chloride-free Pd(OAc) 2 / p -benzoquinone catalyst gave with high selectivity an allylic acetate. An efficient oxygen-couple catalytic turnover can be achieved either under atmospheric pressure with catalytic amounts of Cu(OAc) 2 to promote the regeneration of p -benzoquinone or at 5–10 at m of oxygen in the absence of any auxiliary co-catalyst. Alternatively, cis -jasmone can be oxidized to ketone products in aqueous dimethylacetamide solutions using molecular oxygen as a final oxidant and PdCl 2 as a sole catalyst. Poly-functionalized jasmonoids obtained are potentially useful as components of perfumes and cosmetics. [ABSTRACT FROM AUTHOR]