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Abstract: This work reports a 1 mol scale catalytic process to synthesize adipic acid directly from cyclohexane in solvent‐free conditions using air as oxidant. Catalysts based on vanadium phosphorus oxides were prepared, characterized and tested. They showed good activity and remarkably high selectivity to adipic acid in comparison to other already known heterogeneous catalysts. The use of solvent‐free conditions permits the easy separation of the product from the reactant mixture, which is very important from the industrial point of view. The process can be used at industrial scale for sustainable adipic acid synthesis. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysts were prepared by covalent bonding of transition-metal salicylaldimine complex to α-zirconium phosphate, abbreviated as {α-ZrP.M(salicylaldimine) where M = Co, Mn and Cu}. The resulting compounds were characterized by BET surface area, TGA analysis, X-ray diffraction, Scanning electron micrograph, energy dispersive X-ray analysis, Fourier transform infrared and Atomic absorption spectroscopy. The catalytic activity of α-ZrP.M(salicylaldimine) was studied for the liquid phase oxidation of cyclohexane using tert -butylhydroperoxide as an oxidant under solvent free condition. In the oxidation reaction, cyclohexane was oxidized to cyclohexanol, cyclohexanone and some unidentified products. It was found that the reactivity of α-ZrP.M(salicylaldimine) catalyst for the oxidation reaction decreased in the order α-ZrP.Co(salicylaldimine) > α-ZrP.Mn(salicylaldimine) > α-ZrP.Cu(salicylaldimine). A maximum conversion of cyclohexane (14.18%) and selectivity of cyclohexanol (4.99%), cyclohexanone (87.34%) and some other products (7.67%) was observed for catalyst, α-ZrP.Co(salicylaldimine) after 6 h at 353 K. The catalyst, α-ZrP.Co(salicylaldimine) was reused for four cycles without significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

Molybdenum blue (MB), is a polyoxometalate with a nanoring structure comprising Mo-O-Mo bridges, which is active for the catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone. However, little is known about the mechanistic features responsible of this catalytic activity. In the present work, the Mo-O-Mo moieties embedded in the MB nanoring structure were characterized using diffuse reflectance-UV-Visible spectroscopy and solid state EPR spectroscopy. The amount of Mo centres was then varied by thermal treatment of the polyoxometalate in the absence of oxygen, and the resultant effect on the catalytic activity was investigated. It was observed that, an increased amount of Mo centres preserved the conversion of cyclohexane (ca. 6 %) but led to a loss of selectivity to cyclohexanol giving cyclohexanone as the major product, and the simultaneous formation of adipic acid. To rationalise these results the catalysts were studied using EPR spin trapping to investigate the decomposition of cyclohexyl hydroperoxide (CHHP), a key intermediate in the oxidation process of cyclohexane. This analysis showed that CHHP has to be bound to the MB surface in order to explain its catalytic activity and product distribution. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Two novel oxomolybdenum(V)-trispyrazolylborate complexes [(TpMoO)(μ 2 -O) 2 (MoOTp)](Tp = tris(pyrazolyl)borate) ( 1 ) and [(Tp 4I MoOCl)(μ-O)(MoOClTp 4I )](Tp 4I = tris(4-iodinpyrazolyl)borate) ( 2 ) were synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. Their catalytic performances in cyclohexane (Cy) oxidation were studied. It is found that the catalytic performances of molybdenum(V) complexes 1 and 2 were far more better than the molybdenum(VI) complexes with the similar structure. The influence of the amount of H 2 O 2 , HNO 3 and the solvents on the Cy oxidation were investigated too. [ABSTRACT FROM AUTHOR]

A series of coordination oxidovanadium(IV) complexes: [VOSO 4 (bpz-eaT)]·C 4 H 6 O 4 ( 1 ), [VOSO 4 (bpz-eaT)]·0.5(C 10 H 18 O 4 ) ( 2 ) and [VOSO 4 (bpz-eaT)]·C 5 H 8 O 4 ·CH 3 CN ( 3 ) (bpz-eaT = 2,4-bis (3,5-dimethyl-1H-pyrazol-1-yl)-6-diethylamino-1,3,5-triazine) were synthesized in MeCN. All of the complexes are characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The single-crystal X-ray diffraction analyses reveal that the vanadium atoms are six-coordinated in all complexes. In the study of Cyclohexane (Cy) oxidation, promoted by our complexes, the effects of the amount of H 2 O 2 and HNO 3 were investigated. It was found that complex 3 exhibited the highest catalytic activity in MeCN at 9 h, 60 °C, which is the first oxidovanadium(IV) complex catalyst that we found can catalyze Cy produce more cyclohexanone (CyO) than cyclohexanol (CyOH) oxidated by H 2 O 2 . [ABSTRACT FROM AUTHOR]

Day by day more restrictive regulations concerning environment protection induce progress in the technology of chemical processes. This is why there is a growing interest in the field of catalysis, which is probably one of the greatest contributions of chemistry or chemical technology to both economic growth and environmental protection. The area of molecular sieves has been developed in the last decades into an impressive group of inorganic-hybrid materials with a vast number of industrial applications, particularly in the field of catalysis. They include zeolites, mesoporous materials and metal-organic frameworks (MOFs). In particular, zeolites are crystalline aluminosilicates formed by nanocavities and channels of strictly regular dimensions. They are of different sizes and shapes. Especially the three-dimensional large internal pore (∼13 Å) zeolite-Y, which has been studied here as host lattices. Entrapment of transition metal complexes in the supercages of zeolite-Y seems to be a good method to satisfy environmental demands and to obtain catalysts which preserve the properties of homogeneous systems. The as-prepared inorganic-hybrid material not only has heterogeneous catalysis characteristics, but also retains high catalytic efficiency originating in homogeneous catalysis due to the "site isolated effect." For a better tomorrow, the development of environmentally benign catalysts is a challenge in front of scientists. The catalyst should be easily separable, inexpensive, noncorrosive, recyclable, and also the metal ion leaching from the catalyst should be nil. To achieve the above-mentioned goal, in this chapter we report on zeolite-Y enslaved nanohybrid materials as eco-friendly catalysts over liquid-phase hydroxylation of phenol and oxidation of cyclohexane using 30% H2O2 as an oxidant. The effi ciency of these catalysts has been studied using optimized reaction conditions such as the effect of reaction time, effect of solvent, effect of amount of catalyst and effect of temperature to get utmost yield. No considerable decreases in the effi ciency of the catalysts were observed after two cycles of operation. [ABSTRACT FROM AUTHOR]

Operation of an industrial installation for cyclohexane oxidation was analyzed, and causes of the low process selectivity (45-52%) were elucidated. The relationships of cyclohexane oxidation under laboratory conditions maximum similar to those of the industrial process were studied. Measures were suggested for optimizing the process so as to increase the yield of the target products by a factor of 1.2-1.6, decrease the amount of cyclohexane spent for the formation of by-products by a factor of 1.2-1.8, and increase the process selectivity to 68%. [ABSTRACT FROM AUTHOR]

To get a better understanding of low temperature oxidation chemistry of long-side-chain cycloalkanes, the low- and intermediate-temperature oxidation mechanisms and kinetics of ethylcyclohexane (ECH) have been investigated by using a combination of electronic-structure theory, transition state theory (TST) and Rice-Ramsberger-Kassel-Marcus/Master-Equation (RRKM/ME) theory in this work. The high pressure limit rate constants for reactions with tight transition states are obtained by the TST, while the high pressure limit rate constants for barrierless reactions are obtained by the variational transition state theory (VTST). The rate constants in the fall-off range for pressure-dependent reactions are obtained by RRKM/ME theory. Depending on the position of the extracted H atom on the ring or on the side chain, the oxidation of ECH is mainly initiated by H-abstraction with OH radical to form cyclic C 8 H 15 radicals having six isomers (R1–R6) at low (500−900 K) and intermediate (900−1100 K) temperature and in this study we focus on the kinetics of the reactions starting from these isomers. At low temperature, it is shown that, for addition reactions of O 2 to cyclic C 8 H 15 radicals, the calculated rate constants when the unpaired electron of the radicals is in the side-chain are smaller than when in the ring. The intramolecular isomerization reactions of six cycloalkylperoxy radicals (R1OO–R6OO) by H-shift can lead to a large number of hydroperoxycycloalkyl radicals (QOOH) and it is shown that the 1,5 H-shift is more competitive than the 1,6 H-shift in the R1OO–R6OO. Furthermore, unimolecular elimination reactions of QOOH can form OH, HO 2 , cyclic ethers, ketones, aldehydes and conjugated olefins. The calculated results indicate that the formation cyclic ethers of ECH oxidation are inclined to 1-oxaspiro[3.5]octane, 8-methyl-7-oxa-bicyclo[4.2.0]octane, 7-methyl-6-oxa-bicyclo[3.2.1]octane and 2-ethyl-6-oxa-bicyclo[3.1.1]heptane. At intermediate temperature, the most important reaction type of R1–R6 consumption is the C–C bond fission to form smaller products. The reaction pathways and potential energy surfaces to form the main products (ethylene, butadiene, 1-butene, and so on) of R1–R6 decomposition are also performed and the rate constants of the corresponding reactions are calculated by using the TST. Rate constants of these reactions are fitted by a nonlinear least-squares method to the form of a modified Arrhenius rate expression, which can be directly used for the modeling study of low temperature oxidation of cycloalkanes. [ABSTRACT FROM AUTHOR]

A detailed study of the selective oxidation of cyclohexane has been performed using bimetallic gold–palladium catalysts supported on magnesium oxide. Mono-metallic supported gold or palladium catalysts show limited activity for cyclohexane oxidation. However, a significantly enhanced catalytic performance is observed when supported gold–palladium alloy catalysts are used for this particular reaction. This synergy is observed for alloys spanning a wide range of gold-to-palladium molar ratios. Mechanistic studies reveal a promotion effect that occurs from alloying palladium with gold on the supported catalyst, which significantly improves the homo-cleavage of the O–O bond in cyclohexyl hydroperoxide, an important intermediate species in cyclohexane oxidation. [ABSTRACT FROM AUTHOR]

Controllable catalytic oxidation of cyclohexane with high selectivity under mild conditions is a major objective in oxidation chemistry and industrial chemistry. A functional electrocatalytic membrane reactor (ECMR) assembled by nano-MnO x loading porous Ti membrane as an anode was employed for controllable oxidation of cyclohexane to produce cyclohexanone and cyclohexanol. A ternary solution system of cyclohexane, water and acetic acid was used as the feed solution. The effects of operation parameters such as residence time, reaction temperature, current density and feed concentration on cyclohexane conversion and selectivity to cyclohexanone and cyclohexanol were investigated. The results showed that 14.6% conversion of cyclohexane and 99.8% total selectivity to cyclohexanone and cyclohexanol were obtained under certain conditions of ECMR. The high performance is associated with the synergistic effect between electrochemical oxidation and convection-enhanced diffusion in the ECMR. In particular, MnO x as electrocatalysts play a key role on the oxidation of cyclohexane. [ABSTRACT FROM AUTHOR]

A new μ-oxo diiron(III) complex of the lithium salt of the pyridine-based unsymmetrical ligand 3-[(3-{[bis(pyridin-2-ylmethyl)amino]methyl}-2-hydroxy-5-methylbenzyl)(pyridin-2-ylmethyl)amino]propanoate (LiDPCPMPP), [Fe2(μ-O)(LiDPCPMPP)2](ClO4)2, has been synthesized and characterized. The ability of the complex to catalyze oxidation of several alkanes and alkenes has been investigated by using CH3COOH/H2O2 (1:1) as an oxidative system. Moderate activity in cyclohexane oxidation (TOF = 33 h-1) and good activity in cyclohexene oxidation (TOF = 72 h-1) were detected. Partial retention of configuration (RC = 53 %) in cis- and trans-1,2-dimethylcyclohexane oxidation, moderate 3°/2° selectivity (4.1) in adamantane oxidation, and the observation of a relatively high kinetic isotope effect for cyclohexane oxidation (KIE = 3.27) suggest partial metal-based oxidation, probably in tandem with free-radical oxidation. Low-temperature UV/Vis spectroscopy and mass spectrometric studies in the rapid positive detection mode indicate the formation of a transient peroxido species, [Fe2(O)(O2)(LiDPCPMPP)2]2+, which might be an intermediate in the metal-based component of the oxidation process. [ABSTRACT FROM AUTHOR]

The catalytic peroxidative oxidation (with H 2 O 2 ) of cyclohexane in an ionic liquid (IL) using the tetracopper(II) complex [(CuL) 2 (μ 4 - O,O′,O′′,O′′′ -CDC)] 2 ·2H 2 O [HL = 2-(2-pyridylmethyleneamino)benzenesulfonic acid, CDC = cyclohexane-1,4-dicarboxylate] as a catalyst is reported. Significant improvements on the catalytic performance, in terms of product yield (up to 36%), TON (up to 529), reaction time, selectivity towards cyclohexanone and easy recycling (negligible loss in activity after three consecutive runs), are observed using 1-butyl-3-methylimidazolium hexafluorophosphate as the chosen IL instead of a molecular organic solvent including the commonly used acetonitrile. The catalytic behaviors in the IL and in different molecular solvents are discussed. [ABSTRACT FROM AUTHOR]

Effect of l -cysteine as the cocatalyst on the oxidation of cyclohexane by tert -butylhydroperoxide (TBHP) catalyzed by manganese tetraphenylporphyrin (MnTPP) has been investigated. The results showed that l -cysteine could moderately improve the catalytic activity of MnTPP and significantly increase the selectivity of cyclohexanol. Different from imidazole and pyridine, the l -cysteine may perform dual roles in the catalytic oxidation of cyclohexane. Besides as the axial ligand for MnTPP, the l -cysteine could also react with cyclohexyl peroxide formed as the intermediate to produce alcohol as the main product. [ABSTRACT FROM AUTHOR]

Bimetallic Au75Pd25nanocrystals with shapes of icosahedron and octahedron weresynthesized by adding different amounts of iodide ions, and were employedas catalysts for solvent-free aerobic oxidation of cyclohexane. Althoughboth icosahedrons and octahedrons were bounded by {111} facets, theturnover frequency number of Au75Pd25icosahedronsreached 15 106 h–1, almost three times ashigh as that of Au75Pd25octahedrons. The conversionof cyclohexane reached 28.1% after 48 h using Au75Pd25icosahedrons, with the selectivity of 84.3% to cyclohexanone.Density functional theory calculations along with X-ray photoelectronspectroscopy examinations reveal that the excellent catalytic performanceof AuPd icosahedrons could be ascribed to twin-induced strain andhighly negative charge density of Au atoms on the surface. [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiNPs) with the average size of 8.4 nm have been synthesized and functionalized with the reaction of Cl-sulfonylphenylethyl tri-methoxysilane. These functionalized SiNPs have been anchored in scorpionate compounds i.e., [CuCl 2 {HOCH 2 C(pz) 3 }], [V OCl 2 {HOCH 2 C(pz) 3 }], and [V(acac) {HOCH 2 C(pz) 3 }] as hybrid nano-catalysts. The presence of metal compound over support was confirmed with FTIR, EPR, TGA, TEM, XRD, AAS, and TEM–EDS. These catalysts have produced remarkable high TONs ca. 1216–2607 with yields 13.7–27.3% for the selective oxidation of cyclohexane ( Cy-hx ) with molecular oxygen under relatively mild conditions. Very high about 95% products selectivity of Cy = O and Cy-OH was also attained. The TGA analysis indicates that all the catalysts were thermally stable under operating reaction temperature and reusable up to five more cycles. [ABSTRACT FROM AUTHOR]

Intensification of solvent for cyclohexane oxidation was performed over Au/SiO 2 catalyst in different solvents. Propylene carbonate (PC) was found to significantly enhance the reaction of cyclohexane oxidation with 21.9% cyclohexane conversion while remain a high selectivity of 83.2% towards cyclohexanone and cyclohexanol. The intensified effect of PC can be attributed to its high polarity resulting from its high dipole moment that is induced by its cyclic carbonate structure, which is analyzed by quantum calculation based on Gaussian and COSMO-RS. Moreover, PC can facilitate the reaction by promoting the decomposition of cyclohexyl hydroperoxide. [ABSTRACT FROM AUTHOR]

Direct functionalization of saturated C-H bonds by metalloporphyrin catalysts is among the topical and challenging areas within the chemical industry and synthetic chemistry. In this work, supported CoD(p-Cl)PPCl metalloporphyrin catalysts were prepared and characterized. It has been found that the CoD(p-Cl)PPCl/ZnO catalyst shows better catalytic activity than the supported catalyst (ZrO2, MCM-41, kaolin, Zr(OH)2, and boehmite (BM)) in cyclohexane oxidation with dioxygen. The effects of the reaction pressure, reaction temperature, and reaction time on the catalytic activity were considered by the supported CoD(p-Cl)PPCl/ZnO catalyst. The CoD(p-Cl)PPCl/ZnO catalyst can be facilely recovered and was recycled up to seven times without a significant decrease in catalytic performance. The average cyclohexane conversion and selectivity to KA oil are 10.98% and 84.34%, respectively, and the turnover number is 2.10 × 107. [ABSTRACT FROM AUTHOR]

The mesoporous molecular sieve MCM-41 was amino-functionalized using γ-aminopropyltriethoxysilane. The obtained NH-MCM-41 was then hydrophobic modified by methyltriethoxysilane, dimethyldiethoxysilane and trimethylethoxysilane, respectively. N,N′-Bis (salicylidene) ethylenediiminocobalt (Cosalen) was grafting into the modified MCM-41 through the complex effect of NH group. The prepared Cosalen/(CH)-NH-MCM-41 (n = 0, 1, 2, 3) were characterized by the technique of FT-IR, XRD, N adsorption-desorption, TG and so on. The catalytic performance of the Cosalen/(CH)-NH-MCM-41 (n = 0, 1, 2, 3) for the cyclohexane liquid-phase oxidation by oxygen were compared. The results showed the selectivity of the polar product cyclohexanol and cyclohexanone significantly improved with the introduction of methyl groups into the surface of the MCM-41 carrier. Using Cosalen/CH-NH-MCM-41 as catalyst, the conversion of cyclohexane is 8.3 % under mild conditions with oxygen in absence of solvent, only 0.1 % cyclohexyl hydroperoxide was among the products, the total selectivity of the cyclohexanone and cyclohexanol is up to 93.6 %. Graphical Abstract: Methyltriethoxysilane, dimethyldiethoxysilane and trimethylethoxysilane were used to modify the hydrophobic performance of the mesoporous molecular sieve MCM-41, the active component Cosalen was immobilized on the carrier through NH group after amino-functionalized using γ-aminopropyltriethoxysilane. In the solvent-free cyclohexane oxidation with molecular oxygen, the obtained Cosalen/CH-NH-MCM-41 as catalyst, the conversion of cyclohexane is 8.3 %, only 0.1 % cyclohexyl hydroperoxide was among the products, the total selectivity of the cyclohexanone and cyclohexanol is up to 93.6 %.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this work, spectrophotometric titrations of first- (Mn III TPPCl), second- (Mn III APTPPCl and Mn III T4CMPPCl), and third- (Mn III Br 9 APTPPCl and Mn III Br 8 T4CMPPCl) generation manganese(III) porphyrins ([Mn III P] + ) were carried out in order to investigate the axial coordination equilibrium between imidazole (Im) and these metalloporphyrin complexes. Cyclohexane oxidation by PhIO or PhI(OAc) 2 catalyzed by the aforementioned [Mn III P] + , in the presence of various [Mn III P] + /Im molar ratios, was investigated as a means to study the contribution that the penta-, [Mn III P(Im)] + , or hexacoordinate, [Mn III P(Im) 2 ] + , species at equilibrium may exert into catalyst efficiency and oxidative stability. The computational program SQUAD was used to analyze the spectrophotometric data and calculate the equilibrium constants used by program HySS to generate the species distribution curves for the various [Mn III P] + /Im systems. In general, higher catalytic efficiency in the PhIO systems was achieved with the use of imidazole ranging from 1:0.5 to 1:5 [Mn III P] + /Im ratio, depending on the nature of [Mn III P] + . The catalytic systems with PhI(OAc) 2 as oxidant were more sensitive to Im addition, and optimum yields were achieved with lower [Mn III P] + /Im ratio (up to 1:1). It is noteworthy that the presence of imidazole reduced the usual instability of the third-generation catalyst Mn III Br 8 T4CMPPCl toward oxidative destruction by PhI(OAc) 2 , but did not exert such a protective effect in the PhIO oxidations. [ABSTRACT FROM AUTHOR]

One-step oxidation of cyclohexane to adipic acid (AA) was carried out at 413 K over manganese-doped titanium silicalite with hollow structure (HTS) using oxygen as oxidant without any initiator or solvent. The catalyst exhibited high conversion (13.4%) and reasonable product (AA) selectivity (57.5%). Hot-separation and catalyst-recycle tests proved that the catalyst acted as a heterogeneous one and it could be reused four times without losing its activity. The synthesized materials were characterized by N 2 adsorption–desorption isotherm, FT-IR, UV–vis and XPS techniques. [ABSTRACT FROM AUTHOR]

The use of zinc oxide-promoted catalysis of tetrakis(pentafluorophenyl)porphyrin iron chloride for cyclohexane oxidation was studied. Tetrakis(pentafluorophenyl)porphyrin iron chloride was immobilized onto zinc oxide, generating zinc oxide-supported tetrakis(pentafluorophenyl)porphyrin iron chloride, which was characterized by a variety of spectroscopic techniques and was employed to provide a stable catalyst for the oxidation of cyclohexane in the absence of any solvents or co-reductants. The small amount of tetrakis(pentafluorophenyl)porphyrin iron (1.0 μmol) in the supported catalyst could be reused 10 times for the oxidation optimized at 150 °C and 0.7 MPa. This stable catalyst provided higher turnover numbers and yields of ketone and alcohol than those obtained using the boehmite-supported tetrakis(pentafluorophenyl)porphyrin iron chloride. These results were attributed to the following factors: (1) stronger coordination of ZnO to the iron porphyrin improved its catalysis of the oxidation. (2) Improved dispersal of the iron porphyrin by ZnO enhanced the effective catalytic center. (3) Faster decomposition of peroxide into the main products. [ABSTRACT FROM AUTHOR]

A series of potentially tetradentate and pentadentate ligands modelled on BPMEN has been prepared and their iron(II) bis(triflate) complexes have been isolated and characterised by spectroscopic and crystallographic techniques (BPMEN = N,N'-bis(pyridylmethyl)ethylenediamine). Changes to the BPMEN ligand have invariably led to complexes with different coordination modes or geometries and with inferior catalytic efficiencies for the oxidation of cyclohexane with H2O2. The reaction of an iron(II) complex containing a pentadentate BPMEN-type ligand with O2 has resulted in ligand degradation via oxidative N-dealkylation and the isolation of a bis(hydroxo)-bridged dinuclear iron(III) complex with a picolinatetype ligand. [ABSTRACT FROM AUTHOR]

Cylohexane oxidation is of great industrial importance in the production of intermediates for the manufacture of nylon- 6 and nylon-6,6. Most cyclohexane is commercially converted into a cyclohexanone-cyclohexanol mixture (known as K-A oil) by catalytic oxidation. K-A (Ketone-Alcohol) oil is then used as a raw material for adipic acid and caprolactam production. Practically, if the cyclohexanol content of KA oil is higher than that of cyclohexanone, it is more profitable to convert it into adipic acid; otherwise caprolactam production is more likely. The steady state cyclohexane oxidation reaction model in a stirred tank reactor for K-A oil production is presented and solved in this paper. The model was derived based on the mass balance and mass transfer equations using the kinetic equation. The set of algebraic equations was solved using non linear programming. The advantage of this method is that the relationship among variables can be better understood and an appropriate solution to the equation set can be obtained more quickly. Simulation results are particularly useful for process design such as in determining reactor dimensions and operating conditions. [ABSTRACT FROM AUTHOR]

A series of coordination complexes, [CuCl2(H2L)] ( 1), [Ni(HL)2] ⋅4 CH3CH2OH ( 2), [Cu(H2L)(dipic)] ⋅0.5 HOCH2CH2OH ⋅ 2 H2O ( 3), and [Ni(H2L)(dipic)] ⋅0.5 HOCH2CH2OH ⋅2 H2O ( 4) (H2L=2,6-di(5-methyl-1 H-pyrazol-3-yl)pyridine, H2dipic=2,6-pyridinedicarboxylic acid) are synthesized from bipyrazolyl derivative ligands. All of the complexes have been characterized by elemental analysis, IR and UV/Vis spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction. Structural analyses reveal that the H2L ligand in complexes 1-4 connects with one metal center in a tridentate manner. In addition, these complexes are potential catalysts in cyclohexane (Cy) oxidation with an acidic mixture of HCl and lactic acid. A putative mechanism for Cy oxidation promoted by complex 2 is also proposed. [ABSTRACT FROM AUTHOR]

Silica-supported magnetic cobaltferrite complex oxides, CoFe2O4/SiO2, with different loading of 5,10, 20, and 50% were simply prepared by a sol–gel autocombustionmethod using colloidal aqueous silica solution as a cheap silica source.The as-prepared samples were well characterized by X-ray diffractometry(XRD), Fourier transform infrared spectrophotometry (FT-IR), transmissionelectron microscopy (TEM), and N2physisorption. Metalscontents of the samples were also determined by atomic absorptionspectrophotometry. Their catalytic performances were evaluated oncyclohexane oxidation using oxygen as oxidant in the absence of solventsand reductants. The supported catalysts have shown high catalyticactivities for cyclohexane oxidation. Especially, when 5% loadingof CoFe2O4/SiO2was employed, 4181turnover number and 95.4% selectivity for cyclohexanone and cyclohexanolwere obtained under 1.6 MPa of initial oxygen pressure at 418 K after6.0 h of reaction. The sample of 50% of CoFe2O4/SiO2has strong magnetism and can be magnetically separatedeasily. This sample was employed as catalyst to optimize the reactionconditions. The catalyst showed prominent reusability, and no obviousloss in activity was observed when reused in six consecutive runs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthesis of methoxysilane Schiff-base pentacoordinate metal complexes. [•] Immobilized complexes into HMS as supported catalysts. [•] Gas–liquid phase O2 oxidation of cyclohexane. [•] High catalytic TONs and product selective. [•] Proposed reaction mechanism. [Copyright &y& Elsevier]

Highlights: [•] Using more accessible 8-quinolinolato iron(III) (Q3FeIII) complexes to catalyze the selective oxidation of organic compounds by hydrogen peroxide. [•] Important substituent's effect of the Q3FeIII catalyst on their oxidative activity. [•] Significant and outstanding accelerating effect of visible light on the Q3FeIII-catalyzed oxidations. [Copyright &y& Elsevier]

Abstract: Cyclohexane oxidation using molecular oxygen as oxidant is one of the most challenge subjects. A novel photocatalytic reduction method to prepare Gold nanoparticles Au@TiO2/MCM-41 was proposed. The prepared samples were characterized by XRD, N2 adsorption isotherm, FT-IR, TEM and EDS. The results showed that gold nanoparticles were well-dispersed on TiO2/MCM-41, and TiO2 was dispersed on the surface of the support and the gold existed as Au0. Newly-developed catalyst was promising for the cyclohexane oxidation, achieving a turnover frequency (TOF) as high as 29,145h−1 with 9.87% conversion of cyclohexane. [Copyright &y& Elsevier]

Highlights: [•] Synthesis of a novel β-brominated catalyst derived from a non-symmetric porphyrin. [•] Water acting as an efficient additive in cyclohexane oxidation by PhIO. [•] Stability of β-brominated catalyst toward oxidative degradation in PhI(OAc)2 systems. [ABSTRACT FROM AUTHOR]

Vanadium oxide-based catalyst obtained by grafting VOCl on Florisil (MgO:SiO) with the molar ratio of 15:85 have been studied for the selective oxidation of cyclohexane in order to obtain cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone. The performances obtained have been compared with those of other catalysts in which vanadium oxide was supported on the same support by impregnation with ammonium oxalate. All the prepared catalysts have been characterized using XRD, FTIR, TEM, SEM, EDX, DRS and TGA in order to rationalize the differences in performance observed. The presence of magnesium oxide species (15 % MgO) on the surface of silica significantly modifies the molecular structure of the surface vanadium oxide species and changes their molecular structure from hydrated VO/VO polymers to less polymerized VO species and/or isolated VO(OH) species. The catalytic activities indicate that the VO/Florisil catalysts show high conversions and TONs for those types containing isolated VO. Compared to previously studied VO/SiO catalysts, the Florisil based systems show significantly improved leaching behavior. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Two multinuclear complexes [Fe6(μ3-O)2(μ4-O2)L10(OAc)2(H2O)2]·2.625Et2O·2.375H2O (1) and [FeIII11Cl(μ4-O)3(μ3-O)5L16(dmf)2.5(H2O)0.5]·Et2O·1.25dmf·3.8H2O (2), where HL = 3,4,5-trimethoxybenzoic acid and dmf = dimethylformamide, have been prepared from trinuclear iron(iii) carboxylates via their structural rearrangement in dimethylformamide or diethyl ether–dimethylformamide 9 : 1, respectively, and slow vapor diffusion of diethyl ether into the reaction mixture. Both compounds have been characterized by X-ray diffraction, optical, Mössbauer spectroscopy, and magnetic measurements. Complex 1 possesses a hexanuclear ferric peroxido–dioxido {Fe6(O2)(O)2}12+ core unit, which adopts a recliner conformation, while complex 2 contains an unprecedented {Fe11O8Cl}16+ core, in which 9 ferric ions are six-coordinate and the remaining two are five-coordinate. Another structural feature of note of the undecanuclear core is the presence of a deformed cubane entity {Fe4(μ3-O)(μ4-O)3}4+. Both complexes act as catalyst precursors for the oxidation of cyclohexane to cyclohexanol and cyclohexanone with aqueous H2O2, in the presence of pyrazinecarboxylic acid. Remarkable TONs and TOFs (the latter mainly for 1) with concomitant quite good yields have been achieved under mild conditions. Moreover, 1 exhibits remarkably high activity in an exceptionally short reaction time (45 min), being unprecedented for any metal catalyzed alkane oxidation by H2O2. The catalytic reactions proceed via Fenton type chemistry. [ABSTRACT FROM AUTHOR]

Highlights: [•] Gold was loaded on carbon materials by sol immobilisation and double impregnation. [•] Au/carbon materials were tested on the oxidation of cyclohexane under mild conditions. [•] Au on carbon nanotubes prepared by the sol method was the most active catalyst. [•] Yield values comparable to the industrial process were obtained at room temperature. [•] High selectivity towards the formation of cyclohexanol and cyclohexanone was achieved. [ABSTRACT FROM AUTHOR]

A new binuclear oxovanadium(v) complex [{VO(OEt)(EtOH)}2L] (1) where H4L is bis(2-hydroxybenzylidene)terephthalohydrazide has been synthesized and fully characterized. The combination of 1 with pyrazine-2-carboxylic acid (PCA; a cocatalyst) affords a catalytic system for the efficient oxidation of saturated hydrocarbons, RH, with hydrogen peroxide and air in acetonitrile solution at 50 °C to produce alkyl hydroperoxides, ROOH, as the main primary products. Very high turnover numbers (TONs) have been attained in this reaction: for example, after 2220 min, TON = 44 000 and initial TOF (turnover frequency) = 3300 h−1 per molecule of complex 1. The estimated activation energy of the cyclohexane oxygenation in the presence of 1/PCA is Ea = 16 ± 2 kcal mol−1. This value is identical to that obtained for the cyclohexane oxidation with H2O2 catalyzed by the (n-Bu4N)[VO3]/PCA combination (17 ± 2 kcal mol−1). The dependences of initial oxidation rates W0 on the initial concentrations of all components of the reaction mixture have been determined. Based on these kinetic data and on the regio- and bond-selectivity parameters measured in the oxidation of linear and branched alkanes a mechanism of the oxidation has been proposed which includes the generation of hydroxyl radicals in the crucial stage. [ABSTRACT FROM AUTHOR]

A new binuclear oxovanadium(v) complex [{VO(OEt)(EtOH)}2L] (1) where H4L is bis(2-hydroxybenzylidene)terephthalohydrazide has been synthesized and fully characterized. The combination of 1 with pyrazine-2-carboxylic acid (PCA; a cocatalyst) affords a catalytic system for the efficient oxidation of saturated hydrocarbons, RH, with hydrogen peroxide and air in acetonitrile solution at 50 °C to produce alkyl hydroperoxides, ROOH, as the main primary products. Very high turnover numbers (TONs) have been attained in this reaction: for example, after 2220 min, TON = 44 000 and initial TOF (turnover frequency) = 3300 h−1 per molecule of complex 1. The estimated activation energy of the cyclohexane oxygenation in the presence of 1/PCA is Ea = 16 ± 2 kcal mol−1. This value is identical to that obtained for the cyclohexane oxidation with H2O2 catalyzed by the (n-Bu4N)[VO3]/PCA combination (17 ± 2 kcal mol−1). The dependences of initial oxidation rates W0 on the initial concentrations of all components of the reaction mixture have been determined. Based on these kinetic data and on the regio- and bond-selectivity parameters measured in the oxidation of linear and branched alkanes a mechanism of the oxidation has been proposed which includes the generation of hydroxyl radicals in the crucial stage. [ABSTRACT FROM AUTHOR]

Highlights: [•] The C-scorpionate Fe(II) complex is suitably supported on desilicated MOR zeolite. [•] Generation of mesoporosity in commercial MOR improves the anchorage of Fe complex. [•] The heterogeneous Fe system is notably efficient for the oxidation of cyclohexane. [•] The catalytic activity of the Fe complex is highly improved by heterogenization. [Copyright &y& Elsevier]

Abstract: Gas-solid heterogeneous photocatalytic oxidation (PCO) of cyclohexane in humidified air over TiO2 and Pt/TiO2 catalyst was studied. Pt/TiO2 photocatalysts were synthesized by photodeposition method at different Pt loadings (0.5–2wt.%). The addition of 0.5wt.% Pt does not significantly modify the TiO2 properties. The increase in Pt loading induces to an aggregation of metallic particles on TiO2 surface. The cyclohexane PCO was performed in a fluidized bed photoreactor at 60 and 100°C. Pure TiO2 was more active than 1 and 2wt.% Pt/TiO2 samples at 60°C. Nevertheless, the conversion level increases with temperature on Pt/TiO2 photocatalysts. The cyclohexane was mineralized into CO2, water and low amount of CO. A beneficial effect of Pt addition was found, since total CO2 selectivity was obtained. The Pt/TiO2 photocatalysts prepared by photodeposition provide the total cyclohexane PCO without CO production. Photocatalysts deactivation was not observed in any performed test. Evidence of an opportune tuning of temperature is highlighted. [Copyright &y& Elsevier]

Abstract: Nitrogen-, phosphorous- and boron-doped carbon nanotubes (N-CNTs, P-CNTs and B-CNTs) were prepared by a chemical vapor deposition method using xylene as carbon source and aniline-NH3, triphenyl phosphine and triethyl borate as nitrogen, phosphorous and boron precursors, respectively. By tailoring the composition of reactants and reaction atmosphere, N-CNTs with nitrogen contents from 0% to 4.36% and P-CNTs with phosphorous contents from 0.55% to 5.14% were synthesized. N- and P-CNTs are active for the oxidation of cyclohexane in the liquid phase with molecular oxygen as oxidant. The highest mass-normalized activity, 761mmolg−1 h−1, was achieved over N-CNTs synthesized from aniline in an NH3 atmosphere, while the highest surface-area-normalized activity, 28mmolm−2 h−1, was observed over P-CNTs. B-doping does not improve the activity of CNTs. The effect of the number of nitrogen functionalities and defects was investigated to reveal the structure–activity relationship of the doped CNTs. By using the work function as an indicator of the electron donation of carbon, an exponential dependence of specific activity on work function was discovered for N- and P-CNTs, suggesting that the electron transfer on the surfaces of CNTs plays a central role in the CNT-catalyzed oxidation of cyclohexane. [Copyright &y& Elsevier]

An important issue for the application of metalloporphyrins in the chemical industry is the preparation of a reusable and active supported catalyst. In this work, a new nanocatalyst material consisting of boehmite and a second-generation iron tetraphenylporphyrin with electron-donating groups (methoxyl) has been prepared and characterised using UV-Vis and FT-IR spectroscopy, X-ray powder diffraction, scanning electron microscopy and thermal analysis. The reusability of the boehmite-supported iron tetra (p-methoxylphenyl) porphyrin catalyst for the aerobic oxidation of cyclohexane was investigated. The supported catalyst material containing only 1 mg of iron tetra (p-methoxylphenyl) porphyrin per 1 g of boehmite could be recovered easily and reused effectively for at least 10 times for the oxidation of cyclohexane. The oxidative results gave, on average, 5.1% cyclohexane conversion, 91.2% selectivity (ketone + alcohol) and a catalyst turnover number of 7.91 × 104over several cycles using moderate reaction conditions. The special character of the catalyst material is related to the structure of the combined boehmite and iron porphyrin. [ABSTRACT FROM PUBLISHER]

Abstract: Selective oxidation of cyclohexanone to ɛ-caprolactone by H2O2 was investigated on β-zeolites with various Si/Al ratio. The yield of ɛ-caprolactone was increased with decreasing Si/Al ratio. The β-zeolites in which Si/Al ratio was lower than 117 showed the almost constant yield of ɛ-caprolactone with slight decrease of selectivity. The hydrolysis product, 6-hydroxycaproic acid, was observed. The conversion of H2O2 was also increased with decreasing Si/Al ratio, whereas the efficiency of H2O2 was kept constant, ca. 80%. At lower Si/Al ratio, the decrease of efficiency was also observed. These results suggest that Brønsted acid sites play an important role in the selective oxidation of cyclohexanone by H2O2. Infrared spectra of cyclohexanone and H2O2 were measured in order to elucidate the role of Brønsted acid sites in the oxidation. The IR spectra suggested that cyclohexanone mainly interacted with silanol groups of β-zeolite, whereas H2O2 selectively interacted with Brønsted acid sites. The evacuation of β-zeolite preadsorbed with cyclohexanone and H2O2 at 393K brought about the formation of the vibration band of ɛ-caprolactone. On Na+ ion exchanged β-zeolite, no specific peak of ɛ-caprolactone was observed. These results can conclude that the Brønsted acid sites activate H2O2 and the silanol groups interact with ketones over β-zeolite with various Si/Al ratios. [Copyright &y& Elsevier]

Abstract: This work reports the catalytic activity, in homogeneous phase, of transition-metal complexes of the first-row (V(IV), Mn(III), Fe(III) Co(III) and Cu(II)) with biomimetic Schiff base ligands with N2O2 coordination sphere, as well as an N4 (Fe(II)), in the room-temperature oxidation of cyclohexane using environmentally benign reagents: hydrogen peroxide (30wt%) as the oxygen source and acetonitrile as the solvent. Nitric acid is also used as promoter of the oxidation reaction. The structure of the ligands is confirmed by FTIR, 1H NMR and high-resolution ESI mass spectrometry. The corresponding transition metal complexes are characterized by elemental analysis, high resolution ESI mass spectrometry, FTIR and UV–vis. Cyclohexanone and cyclohexanol are the main products of the oxidation of cyclohexane, obtained when the following complexes are used as homogeneous catalysts in only 1mol% based on the substrate: VO(IV), Fe(III) and Cu(II) complexes with the N2O2 Schiff base, new Fe(II) complex with the Schiff base with N4 coordination sphere and commercial [VO(acac)2] with O4 coordination sphere. The Fe(III) complex with N2O2 Schiff base ligand ([Fe(salhd)Cl]) is the homogeneous catalyst with highest activity, which could be further enhanced by the addition of methyl electron donating groups to the N2O2 Schiff base aldehyde fragment (reaching 46% oxygenate yields and 45 turnover numbers). Cyclooctane and n-hexane could also be oxidized to the corresponding ketones and alcohols with higher turnover numbers than cyclohexane by the Fe(III) complex with N2O2 Schiff base ligand. [Copyright &y& Elsevier]

Abstract: The preparations of the compounds, [Co3O(C6H5N2O)3(CH3COO)3][PF6].CH3CN (I), [Co4(μ 2-OH)2(η 1:η 1:μ 2-CH3COO)2(CH3COO)2 (η 1:η 1:μ 2-C11H8NO)2(η 1:η 1:η 1:η 1:μ 2-C11H8N3O)2][PF6]2.CH3OH.3H2O (II) and [Co3O(OAc)5(C7H6NO2)(py)3][PF6] (III) and the crystal structures of (I) and (II) are reported. The cation of (I) is an oxo-centred trimer, of a structural type similar to cobalt oxo trimers such as [Co3O(OAc)6(py)3]+, whilst the dication of (II) has a “metallo-crown” structure. Complex (III) is assigned an oxo-centred trimeric structure. The cations, [Co3O(OAc)6(py)3]+, [Co3O(OAc)5(OH)(py)3]+, and sym-[Co2(OH)2(OAc)3(py)4]+, as their PF6 − salts, catalyse the oxidation of cyclohexane in the presence of N-hydroxyphthalimide (NHPI). However, the multinuclear species, (I), (II) and (III) do not catalyse cyclohexane oxidation in the presence or absence of NHPI. [Copyright &y& Elsevier]

Abstract: The promoting effect of boehmite (AlOOH) on the catalyst cobalt tetra(4-carboxyl)phenylporphyrin (CoIITCPP) is reported. CoIITCPP was immobilized on AlOOH and subsequently characterized, and then the supported catalyst was used for the oxidation of cyclohexane to ketones and alcohols (i.e. KA oil). The cyclohexane conversion and the yield of KA oil were increased by 73% and 54%, respectively, compared to those achieved with unsupported CoIITCPP. Moreover, a supported catalyst with 1.5mg of cobalt tetra(4-carboxyl)phenylporphyrin per gram of support could be reused 11 times by virtue of the promotional effect of AlOOH. [Copyright &y& Elsevier]

Abstract: The oxovanadium(IV) complexes [VO(acac)2(Hpz)]·HC(pz)3 1·HC(pz)3 (acac=acetylacetonate, Hpz=pyrazole, pz=pyrazolyl) and [VOCl2{HOCH2C(pz)3}] 2 were obtained from reaction of [VO(acac)2] with hydrotris(1-pyrazolyl)methane or of VCl3with 2,2,2-tris(1-pyrazolyl)ethanol. The compounds were characterized by elemental analysis, IR, Far-IR and EPR spectroscopies, FAB or ESI mass-spectrometry and, for 1, by single crystal X-ray diffraction analysis. 1 and 2 exhibit catalytic activity for the oxidation of cyclohexane to the cyclohexanol and cyclohexanone mixture in homogeneous system (TONs up to 1100) under mild conditions (NCMe, 24h, room temperature) using benzoyl peroxide (BPO), tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid (mCPBA), hydrogen peroxide or the urea-hydrogen peroxide adduct (UHP) as oxidants. 1 and 2 were also immobilized on a polydimethylsiloxane membrane (1-PDMS or 2-PDMS) and the systems acted as supported catalysts for the cyclohexane oxidation using the above oxidants (TONs up to 620). The best results were obtained with mCPBA or BPO as oxidant. The effects of various parameters, such as the amount of catalyst, nitric acid, reaction time, type of oxidant and oxidant-to-catalyst molar ratio, were investigated, for both homogeneous and supported systems. [Copyright &y& Elsevier]

Abstract: An extraordinarily high catalytic performance of up to 28% cyclohexane conversion and above 93% selectivity for cyclohexanone and cyclohexanol in the cyclohexane oxidation has been achieved under mild conditions by using copper-doped hierarchically micro/mesoporous zeolite ZSM-5, which has been fabricated by a facile one-pot hydrothermal synthetic process at a relatively low hydrolysis temperature. The excellent catalytic activity was ascribed to the highly dispersed framework copper ions (Cu+/Cu2+) as catalytic active sites and the hierarchically porous structure to provide the fast diffusion pathway for reactant/product molecules. The presence of the framework Cu(I) was proposed to promote the decomposition of H2O2 and the formation of radicals HO, and thus accelerate the selective oxidation of cyclohexane. More importantly, the synthesized catalyst showed excellent recyclable properties, demonstrating the high catalytic stability and future application prospect of such hierarchical heterogeneous catalysts in chemical industry. [Copyright &y& Elsevier]

Chitosan-supported Mn(III)deuteroporphyrin chlorine [Mn(III)DPCl-CTS] catalyst was prepared by convalent binding of Mn(III)deuteroporphyrin-bearing carboxyl groups on the side chain of the macrocycle ring to chitosan. The supported catalyst was found to efficiently catalyze the hydroxylation of cyclohexane with air as oxygen source. The effect of various reaction parameters, such as reaction time, temperature, and pressure on the catalytic performances, was in detail investigated and the designed installed oxidation equipment was convenient for on-line sampling during the reaction every time. Under an optimum temperature of 140°C and a pressure of 0.7 MPa, the obtained cyclohexane conversion (16.9%) and chemoselectivity (88.7%) for cyclohexanol and cyclohexanone were much better than those observed with unsupported Mn(III)deuteroporphyrin and synthetic Mn(III) tetraphenylporphyrin. An intermolecular interaction between amino moieties in chitosan and dipropionic groups in Mn(III)deuteroporphyrin was suggested to play a role in the high conversion of this system. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The Deepwater Horizon oil spill in the Gulf of Mexico resulted in a deep-sea hydrocarbon plume that caused a shift in the indigenous microbial community composition with unknown ecological consequences. Early in the spill history, a bloom of uncultured, thus uncharacterized, members of the Oceanospirillales was previously detected, but their role in oil disposition was unknown. Here our aim was to determine the functional role of the Oceanospirillales and other active members of the indigenous microbial community using deep sequencing of community DNA and RNA, as well as single-cell genomics. Shotgun metagenomic and metatranscriptomic sequencing revealed that genes for motility, chemotaxis and aliphatic hydrocarbon degradation were significantly enriched and expressed in the hydrocarbon plume samples compared with uncontaminated seawater collected from plume depth. In contrast, although genes coding for degradation of more recalcitrant compounds, such as benzene, toluene, ethylbenzene, total xylenes and polycyclic aromatic hydrocarbons, were identified in the metagenomes, they were expressed at low levels, or not at all based on analysis of the metatranscriptomes. Isolation and sequencing of two Oceanospirillales single cells revealed that both cells possessed genes coding for n-alkane and cycloalkane degradation. Specifically, the near-complete pathway for cyclohexane oxidation in the Oceanospirillales single cells was elucidated and supported by both metagenome and metatranscriptome data. The draft genome also included genes for chemotaxis, motility and nutrient acquisition strategies that were also identified in the metagenomes and metatranscriptomes. These data point towards a rapid response of members of the Oceanospirillales to aliphatic hydrocarbons in the deep sea. [ABSTRACT FROM AUTHOR]

RuOsupported on VO-AlO mixed oxide material was prepared by impregnation method and characterized by XRD, nitrogen adsorption-desorption, SEM, UV-visible and FT-IR spectroscopic techniques. The catalytic activity of the prepared catalyst was evaluated for the liquid-phase oxidation of cyclohexane under mild conditions. In this reaction, conversion of cyclohexane to cyclohexanol and cyclohexanone and the selectivity ratio of cyclohexanol to cyclohexanone were greatly affected by the solvent and the oxidant agent used. The results show that the catalyst exhibit good conversion in polar solvents. The use of acetic acid gives more than 26% conversion in presence of TBHP as oxidant and an ~40% conversion with hydrogen peroxide as oxidant in presence of an initiator, with 92% selectivity for cyclohexanol product. [ABSTRACT FROM AUTHOR]

Adipic acid (AA) is one of the highest volume chemicals in world use with a wide range of commercial applications. This paper demonstrates the possibility of producing significant proportions of AA by the selective oxidation of cyclohexane (CH) in one step using various supported gold-nanoparticle (AuNP) catalysts. The catalysts were characterized by ICP, BET, XRD, X-ray photoelectron microscopy, and TEM. The catalytic activity tests were carried out in the liquid phase using autoclaves in the temperature range of 100-170 °C at 10 bar. A CH conversion of over 25 %, with 26% selectivity of AA and 70% selectivity of KA oil (cyclohexanone+cyclohexanol), was achieved over a nano-gold/TiO2 (anatase) catalyst. The superior performance of this catalyst is attributed to the smaller size of AuNPs, which has an average particle size of 2 nm. Good correlation between activity and Au particle size could be achieved. Overall, the particle size of the AuNPs showed a strong influence on catalytic performance. [ABSTRACT FROM AUTHOR]

Oxidation of cyclohexane (CH) with hydrogen peroxide under mild reaction conditions in the presence of systems containing in situ generated iron complexes with nitrogen-containing ligands (2,2′-bipyridyl and o-phenanthroline) and chlorinated (Cl15) copper phthalocyanine (CuPcCl) have been studied. It has been shown that in water-acetonitrile blends under optimum conditions, CH is oxidized with the formation of cyclohexanol, cyclohexanone, and acids involving cyclohexane hydroperoxide. High total selectivity for ketone and alcohol is reached in the excess of ligands and the substrate. [ABSTRACT FROM AUTHOR]

Large volumes of oil sands process-affected water (OSPW) are produced during the extraction of bitumen from oil sands in Alberta, Canada. The degradation of a model naphthenic acid, cyclohexanoic acid (CHA), and real naphthenic acids (NAs) from OSPW were investigated in the presence of peroxydisulfate (S2O82-) and zerovalent iron (ZVI). For the model compound CHA (50 mg/L), in the presence of ZVI and 500 mg/L S2O82-, the concentration decreased by 45% after 6 days of treatment at 20 °C, whereas at 40, 60, and 80 °C the concentration decreased by 20, 45 and 90%, respectively, after 2 h of treatment. The formation of chloro-CHA was observed during ZVI/S2O82- treatment of CHA in the presence of chloride. For OSPW NAs, in the presence of ZVI alone, a 50% removal of NAs was observed after 6 days of exposure at 20 °C. The addition of 100 mg/L S2O82- to the solution increased the removal of OSPW NAs from 50 to 90%. In absence of ZVI, a complete NAs removal from OSPW was observed in presence of 2000 mg/L S2O82- at 80 °C. The addition of ZVI increased the efficiency of NAs oxidation by S2O82- near room temperature. Thus, ZVI/S2O82- process was found to be a viable option for accelerating the degradation of NAs present in OSPW. [ABSTRACT FROM AUTHOR]