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Glycerol acetalization reaction with acetone was performed at 343 K and using a 1:1 molar ratio of glycerol to acetone in the feed over hierarchical zeolites comprising pores of different diameters (MFI, BEA, and MOR). The best catalytic performance for glycerol acetalization was exhibited by hierarchical (micro-mesoporous) MFI zeolites. Glycerol conversion over MFI zeolites exceeded 80%, with almost 100% selectivity to the desired product (4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane known as solketal). A significant increase in glycerol conversion and also selectivity to solketal in the studied reaction resulted from the easier accessibility of the active sites to reagents due to the formation of mesopores by means of desilication of the microporous zeolites.

The oxidation reactions of alkanes with hydrogen peroxide and peracids (peracetic acid (PAA) and m-chloroperoxybenzoic acid (mCPBA)) catalysed by two Fe(II) complexes of pentadentate {N5}-donor ligands have been investigated. Kinetic isotope effect experiments and the use of other mechanistic probes have also been performed. While the total yields of oxidized products are similar regardless of oxidant (e.g. 30–39% for oxidation of cyclohexane), the observed alcohol/ketone ratios and kinetic isotope effects differ significantly with different oxidants. Catalytic reactions in H2O2 medium are consistent with the involvement of hydroxyl radicals in the Csingle bondH bond cleavage step, and resultant low kinetic isotope effect values. On the other hand, catalytic reactions performed using peracid media indicate the involvement of an oxidant different from the hydroxyl radical. For these reactions, the kinetic isotope effect values are relatively high (within a range of 4.2–5.1) and the C3/C2 selectivity parameters in adamantane oxidation are greater than 11, thereby excluding the presence of hydroxyl radicals in the Csingle bondH bond cleavage step. A low spin Fe(III)-OOH species has been detected in the H2O2-based catalytic system by UV/Vis, mass spectrometry and EPR spectroscopy, while an Fe(IV)-oxo species is postulated to be the active oxidant in the peracid-based catalytic systems. Computational studies on the Csingle bondH oxidation mechanism reveal that while the hydroxyl radical is mainly responsible for the H-atom abstraction in the H2O2-based catalytic system, it is the Fe(IV)-oxo species that abstracts the H-atom from the substrate in the peracid-based catalytic systems, in agreement with the experimental observations. (Less)

Direct activation of CH4 to oxygenates and unsaturated light hydrocarbons was investigated using Fe-modified ZSM-5 and Ferrierite (FER) for a partial oxidation of CH4 with N2O oxidant. The amount of active α-oxygen sites and number of Bronsted acid sites on the Fe-modified zeolites were well correlated with CH4 conversion rate and product distributions. The amount of α-oxygen sites was largely changed according to preparation method such as wet impregnation or ion-exchange of iron precursor and types of zeolites. A large number of Bronsted acid sites and α-oxygen sites on the Fe-modified FER revealed a higher oxygenate formation such as methanol and dimethyl ether (DME) with COx, and a larger number of strong acid sites on Fe-modified ZSM-5 was also responsible for a higher selectivity to light hydrocarbons by a successive dehydration of oxygenates formed. The different catalytic performances were verified through proper measurements of the amount and type of acidic sites as well as the α-oxygen sites measured by N2O pulse chemisorption. The Fe-modified FER prepared by impregnation method possessed a larger amount of α-oxygen sites due to abundant Bronsted acid sites, which was responsible for a higher rate of CH4 conversion to oxygenates with the help of N2O decomposition on the α-oxygen sites originated from iron oxide nanoparticles.

Gadolinium (Gd)-doped silver orthophosphate (Ag3PO4) nanoparticles, with spherical morphology, were synthesized by a co-precipitation method and their photocatalytic activities were evaluated in degradation of Reactive Blue 19 (RB19), as a model organic pollutant. The synthesized Ag3PO4 and Gd-doped Ag3PO4 were characterized using X-ray diffraction pattern analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, diffuse reflectance UV–vis spectroscopy and photoluminescence spectroscopy. In comparison with Ag3PO4, the experimental results revealed a considerable enhancement in photocatalytic activity of Gd-doped Ag3PO4. The optimum mole fraction of Gd loading in Ag3PO4 was 3%. Lower photocatalytic degradation efficiency of RB19 in the presence of oxalate anion and p-benzoquinone indicated the crucial role of photogenerated holes and superoxide anion-radicals in photocatalysis on Gd-doped Ag3PO4. The enhancement of photocatalytic activity was attributed to scavenge the photoexcited electrons, and to suppress their recombination with holes and generation of active oxygen species. A nonlinear empirical kinetic model was introduced to predict the apparent first order rate constant (kapp) as a function of operational parameters, including initial RB19 concentration, Gd-doped Ag3PO4 dosage and light intensity. Degradation byproducts were identified using gas chromatography-mass spectrometry and a probable pathway was proposed. Moreover, Gd-doped Ag3PO4 samples displayed adequate reusability after three successive experiments.

Reaction of dimethylamine adduct of 1-methyl-3-borolene with [(C2H4)2RhCl]2 gives the triple-decker complex (η-C4H4BMe)Rh(μ-η:η-C4H4BMe)Rh(η-C4H4BMe) (1a) in 62% yield and trace amount (

N-benzylethanolamine (Hbea) and triisopropanolamine (H3tipa) were applied as unexplored aminoalcohol N,O-building blocks for the self-assembly generation of two novel dicopper(II) compounds, [Cu2(μ-bea)2(Hbea)2](NO3)2 (1) and [Cu2(H3tipa)2(μ-pma)]·7H2O (2) {H4pma = pyromellitic acid}. These were isolated as stable and aqua-soluble microcrystalline products and were fully characterized by IR spectroscopy, ESI–MS(±), and single-crystal X-ray diffraction, the latter revealing distinct Cu2 cores containing the five-coordinate copper(II) centers with the {CuN2O3} or {CuNO4} environments. Compounds 1 and 2 were used as homogeneous catalysts for the mild oxidation of C5–C8 cycloalkanes to give the corresponding cyclic alcohols and ketones in up to 23% overall yields based on cycloalkane. The reactions proceed in aqueous acetonitrile medium at 50 °C using H2O2 as an oxidant. The effects of different reaction conditions were studied, including the type and loading of catalyst, amount and kind of acid promoter, and water concentration. Despite the fact that different acids (HNO3, H2SO4, HCl, or CF3COOH) promote the oxidation of alkanes, the reaction is exceptionally fast in the presence of a catalytic amount of HCl, resulting in the TOF values of up to 430 h−1. Although water typically strongly inhibits alkane oxidations due to the reduction of H2O2 concentration and lowering of the alkane solubility, in the systems comprising 1 and 2 we observed a significant growth (up to 5-fold) of an initial reaction rate in the cyclohexane oxidation on increasing the amount of H2O in the reaction mixture. The bond-, regio- and stereo-selectivity parameters were investigated in oxidation of different linear, branched, and cyclic alkane substrates. Both compounds 1 and 2 also catalyze the hydrocarboxylation of C5–C8 cycloalkanes, by CO, K2S2O8, and H2O in a water/acetonitrile medium at 60 °C, to give the corresponding cycloalkanecarboxylic acids in up to 38% yields based on cycloalkanes.

Different functional groups (i.e. NH2, COOH, OH and nitrogen-doping) modified CNTs (denoted as AMCN, CMCN, HMCN and NMCN, respectively) supported ruthenium catalysts (Ru/AMCN, Ru/CMCN, Ru/HMCN and Ru/NMCN) were prepared by incipient wetness impregnation method. They were fully characterized by XRD, TG, Raman, XPS, TPD and TEM to elucidate the relationship between the physical property and their catalytic performance. TEM results shown that Ru particles were well dispersed on the surface for all the samples with the size of 1.48–1.99 nm. The effects of functional groups of carbon nanotubes (CNTs), nitrogen doping and base additive types on activity and selectivity of ethylene glycol (EG) and propylene glycol (1,2-PD) were investigated. In addition, the activity and final products distribution were much influenced by the properties of functional groups on CNTs and the type of metal cation of the base promoters, which probably participated in the reaction for accelerating a retro-aldol reaction for C C cleavage. Among the catalysts, Ru supported on AMCN exhibited the best catalytic activities and glycols selectivities than on MCN, CMCN, HMCN and NMCN.

In this work, the catalytic activity of ruthenium II and III complexes containing chloride, pyridine, phosphine and CO ligands was investigated in the hydroformylation – hydrogenation and hydroformylation – acetalization reactions. The complexes mer-[RuCl3(dppb)(H2O)](1), mer-[RuCl3(dppb)(4-Vpy)](2), mer-[RuCl3(dppb)(4-tBupy)](3), mer-[RuCl3(dppb)(py)](4), mer-[RuCl3(dppb)(4-Phpy)](5), mer-[RuCl3(dppb)(4-Mepy)](6), cis-[RuCl2(CO)2(dppb)](7), trans-[RuCl2(CO)2(dppb)](8), RuCl3·xH2O(9), [RuCl2(PPh3)3](10) and [RuCl2(PPh3)2(dppb)](11) were used as supplied or synthesized as previously described in the literature {Where PPh3 = triphenylphosphine, dppb = 1,4-bis(diphenylphosphino)butane, py = pyridine, 4-Mepy = 4-methylpyridine, 4-Vpy = 4-vinylpyridine, 4-tBupy = 4-tert-butylpyridine and 4-Phpy = 4-phenylpyridine}. These complexes were used as a pre-catalysts in a hydroformylation catalytic system to produce C C, C O and C O bonds, where 1-decene resulted in a formation of respective alcohol and dimethyl acetals. Several reactions were performed in order to find the best reaction conditions presenting the best conversion (64% after 24 h). The 1-decene was also used as a substrate in two type tandem reactions labeled as: hydroformylation – hydrogenation (HH) and hydroformylation – acetalization (HA) reactions. The relationship between Ru – catalyst/substrate was 1:100, without free ligands or additives, in a controlled temperature and pressure. All the products of catalytic reactions HH and HA were analyzed by CG-FID with good yields.

Two types of heterogeneous catalytic materials, Mn II -L 3 imid@Cox and Mn II -L 3 imid@PCox , have been synthesized and compared by covalent grafting of a catalytically active [ Mn II -L 3 imid] complex on the surface of an oxidized activated carbon ( Cox) and an oxidized pyrolytic carbon from recycled-tire char ( PCox) . Both hybrids are non-porous bearing graphitic layers intermixed with disordered sp 2 /sp 3 carbon units. Raman spectra show that (I D /I G ) activatedcarbon > (I D /I G ) pyrolyticcarbon revealing that oxidized activated carbon( Cox) is less graphitized than oxidized pyrolytic carbon ( PCox) . The Mn II -L 3 imid@Cox and Mn II -L 3 imid@PCox catalysts were evaluated for alkene oxidation with H 2 O 2 in the presence of CH 3 COONH 4 . Both showed high selectivity towards epoxides and comparing the achieved yields and TONs, they appear equivalent. However, Mn II -L 3 imid@PCox catalyst is kinetically faster than the Mn II -L 3 imid@Cox (accomplishing the catalytic runs in 1.5 h vs . 5 h). Thus, despite the similarity in TONs Mn II -L 3 imid@PCox achieved extremely higher TOFs vs . Mn II -L 3 imid@Cox . Intriguingly, in terms of recyclability, Mn II -L 3 imid@Cox could be reused for a 2th run showing a ∼20% loss of its catalytic activity, while Mn II -L 3 imid@PCox practically no recyclable. This phenomenon is discussed in a mechanistic context; interlinking oxidative destruction of the Mn-complex with high TOFs for Mn II -L 3 imid@PCox , while the low-TOFs of Mn II -L 3 imid@Cox are preventive for the oxidative destruction of the Mn-complex.

A facile and efficient method to introduce alkyne groups to the C-1 position of biologically interesting 1,2,3,4-tetrahydroisoquinolines via direct C H-functionalization is reported. Various alkynylated N-substituted 1,2,3,4-tetrahydroisoquinolines could be obtained by using copper(I)-chloride as catalyst, alkynoic acids as alkyne source and t-BuOOH as oxidant, in a one-pot two-step decarboxylation- alkynylation reaction in moderate to high yields. Furthermore, a one-pot protocol of a three-step decarboxylation-alkynylation-1,3-dipolar cycloaddition reaction leading to 1-triazolyl-tetrahydroisoquinolines was developed, a hitherto unknown reaction cascade.

AgTaO 3 /AgBr heterojunction was constructed for visible light driven photocatalytic purpose in order to investigate the relevance of phase conversion, electronic structure and photocatalytic properties. The result indicated that AgBr grafted on AgTaO 3 to form AgTaO 3 /AgBr heterojunction gave intense visible light absorption, which exhibits highly enhanced photocatalytic performance than their individual counterpart. Theoretical and experimental investigation showed that the matched electronic structure between AgTaO 3 and AgBr induced an efficient transfer of photogenerated electrons from AgBr to AgTaO 3 , leading to efficient charge separation and the subsequent improved photocatalytic activity. Partial AgBr converted to AgBr/Ag during the photocatalytic process, leading to the construction of ternary AgTaO 3 /AgBr/Ag photocatalyst. Because of the surface plasmon resonance effect of Ag, the resulting AgTaO 3 /AgBr/Ag exhibited wide range absorption and improved charge separation efficiency, which showed high durability and superior photocatalytic activity toward methyl orange degradation. On the basis of spin resonance measurement and trapping experiment, it is expected that photogenerated electrons, O 2 − , and OH active species dominate the photodegradation of methyl orange.

A new hybrid Fe3O4@mSiO(2)@Cu-4 material was constructed by loading a bio-inspired tetracopper(II) coordination compound [Cu-4(mu(4)-O){N(CH2CH2O)(3)}(4)(BOH)(4)][BF4](2) (Cu-4) onto the Fe3O4@mSiO(2) core-shell nanoparticles (NPs) composed of a magnetite (Fe3O4) core and mesoporous silica (mSiO(2)) shell with perpendicularly aligned channels. The obtained Fe3O4@mSiO(2)@Cu-4 magnetic nanoparticles were characterized by transmission electron microscopy (TEM), FT-IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and field-dependent magnetization. This hybrid material acts as a magnetically recoverable C-H functionalization nanocatalyst, namely for the mild oxidation, by t-butyl hydroperoxide at 50-70 degrees C in acetonitrile medium, of cycloalkanes (cyclopentane, cyclohexane, cycloheptane, and cyclooctane) to the corresponding alcohols and ketones (with up to similar to 15% yields based on cycloalkane; TON 335). A related oxidation process using cyclohexanol as a more reactive substrate leads to the formation of cyclohexanone in up to similar to 25% yield (TON 570). The Fe3O4@mSiO(2)@Cu-4 nanocatalyst can be recycled five times without an appreciable loss of activity. The bond-, regio-, and stereoselectivity parameters were investigated in the oxidation of different alkane substrates (n-hexane, n-heptane, n-octane, methylcyclohexane, adamantane, cis- and trans-1,2-demethylcyclohexane), and the obtained results were compared with the homogeneous systems based on the Cu-4 catalyst. In particular, the high bond selectivity parameters detected in the oxidation of methylcyclohexane (1 degrees:2 degrees:3 degrees of 1:8:142) and adamantane (2 degrees:3 degrees of 1:21) catalyzed by Fe3O4@mSiO(2)@Cu-4 suggest that the reactions possibly occur in hydrophobic pockets of the nanocatalyst. (C) 2016 Elsevier B.V. All rights reserved.

A novel Ru(III) and Fe(III) complexes of ligands 1 and/or 2 {where 1 = 2,2′-((1E,1′E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene))diphenol and 2 = 2,2′-((1E,1′E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene)) bis(4-nitrophenol)} have been synthesized as ‘neat’ and zeolite Y encapsulated complexes. These catalysts are characterized by various analytical tools such as FTIR, UV–vis, elemental analysis, ICP-AES, molar conductivity, 1 H- and 13 C NMR, TGA, SEM, AAS, BET, magnetic susceptibility and powder XRD to endorse the complex formation, absence of peripheral redundant ligands and complexes, conservation of zeolite Y morphology and crystallinity, and the encapsulation of complexes without devastation in the zeolite Y framework. Out of these synthesized catalysts, 5Y is found to be a potent candidate for styrene (Conv. 76.1%, TOF: 2130 h −1 ), cyclohexene (Conv. 84.4%, TOF: 2351 h −1 ), limonene (Conv. 81.6%, TOF: 2273 h −1 ), and α-pinene (Conv. 72.6%, TOF: 2023 h −1 ) oxidation with high selectivity of respective allylic products excluding the styrene oxidation, which undergoes epoxidation only. The addition of H 2 SO 4 in an identical reaction catalyzed by 5Y not only surge the conversion up to 100% in a short time span with high TOF but also increase the selectivity of respective epoxidation products. This switchover in the selectivities could be credited to the presence of H 2 SO 4 that facilitates the heterolytic O O bond cleavage of metal hydroperoxide and stimulates the epoxidation over allylic oxidation. Furthermore, the results establish that the heterogeneous systems are effortlessly recovered and reused without ample drop in the activity and selectivity.

The structure of alumina-supported copper-nickel catalysts prepared by impregnation method was studied by using a combination of various characterization techniques including XRD, N 2 -sorption, TEM, H 2 -TPR, NH 3 -TPD, XANES/EXAFS and CHNS methods. A series of characterizations revealed that dispersion of copper increases with an increase in nickel loading on ɣ-Al 2 O 3 due to strong interaction between nickel and copper oxide particles. This also led to the formation of mixed copper-nickel oxides in calcined catalysts at the highest loading of nickel and copper (i.e. Cu/Ni = 1). In catalytic activity, both the monometallic Cu/ɣ-Al 2 O 3 and Ni/ɣ-Al 2 O 3 showed lower activity and selectivity towards hydrogenation of both Furfural and 5-Hydroxymethylfurfural to 2-methylfuran (2-MF) and 2, 5-dimethylfuran (DMF), respectively. However, with increase in nickel loading, the activity and the selectivity of Cu/ɣ-Al 2 O 3 drastically increased for both the cases and Cu-Ni/ɣ-Al 2 O 3 (Cu/Ni = 1) showed the highest catalytic activity. Furthermore, combination of Cu/Ni ratios and temperature plays a significant role in the product distribution, as in the case of furfural hydrogenation, at a lower temperature, furfuryl alcohol (FOL) appears as the main product while at a higher temperature, 2-methylfuran (2-MF) is found to be the dominant product over Cu-Ni/ɣ-Al 2 O 3 (Cu/Ni = 1) catalysts. Similarly, 2,5-bishydroxymethylfuran (BHF) is found to be the major product at a lower temperature and 2,5-dimethylfuran (DMF) is selectively produced at a higher temperature in the HMF hydrogenation. Furthermore, reaction pathways are discussed for both the reactions.

In our previous study, we applied Pd@SiO2 core-shell catalysts to hydrogen peroxide synthesis and obtained a higher yield of hydrogen peroxide than that obtained with the use of general supported-catalysts (Pd/SiO2). As an extension of the previous study on Pd@SiO2 catalysts, the effects of the core-shell thickness on the hydrogen peroxide synthesis reaction were examined in this study. A shell below a certain thickness in the core-shell structure of the Pd nanocatalyst results in a decrease in the catalytic activity. Overall, a volcano curve is observed for the hydrogen peroxide production rate as a function of the shell thickness. Through N2-adsorption and desorption, TEM, CO-chemisorption, and XRD analyses, we identify the causes for the improved direct hydrogen peroxide synthesis yields and later optimize the shell thickness for the efficient utilization of Pd.

The one-pot myrtenol amination was studied over Au (3 wt.%)/ZrO2 catalyst under mixed N2/H2 atmosphere (9 bar). The effect of hydrogen addition was explored with the aim to increase selectivity to the target amines. Hydrogen addition timing depending on myrtenol conversion and hydrogenation temperature affected selectivity to the reaction products. Hydrogen addition (1 bar) after almost complete myrtenol conversion at 100 °C increased the yield to amine up to 68% preserving C C bond in the initial myrtenol structure. Hydrogen addition at 180 °C irrespective of the myrtenol conversion level provoked reduction of both C C and C N bonds with formation of two diastereomers (yield up to 93%), with trans-isomer formation being preferred when hydrogen was added at almost complete myrtenol conversion. It was shown, that in the presence of a gold catalyst controlled hydrogenation of competitive C C and C N groups can be performed during one-pot alcohol amination by regulation of the reaction conditions.

Different inorganic acids were used to activate sepiolite, and the acid-activated sepiolites supported nickel and potassium bimetallic catalysts were prepared. Nitrogen adsorption-desorption, hydrogen chemisorption, ammonia temperature programmed desorption (NH 3 -TPD), temperature programmed reduction (TPR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and energy dispersive X-ray (EDX) were used to characterize the catalysts. The catalytic performance of the acid-activated sepiolite supported K-Ni bimetallic catalysts were investigated in 1,6-hexanedinitrile (HDN) hydrogenation in liquid phase. It was revealed that the potassium could increase the alkalinity of the catalyst with the aim of inhibiting the formation of the 1-azacycloheptane (ACH). And the addition of potassium reduces the particle size of nickel and improves its dispersion. Compared with hydrochloric acid and sulfuric acid, nitric acid treatment increases more silanol groups (Si OH) on the sepiolite surface, which is helpful to nickel particles adsorption and dispersion. Nitric acid activated sepiolite supported nickel and potassium bimetallic catalysts (K-Ni/NASEP) present the best catalytic performance, the conversion of HDN comes up to 92.0% under moderate conditions of lower temperature and pressure, the selectivity to 6-aminocapronitrile (ACN) and 1,6-hexanediamine (HDA) is up to 95.2%.

The results on the investigation of alkane activation kinetics and mechanisms in aqueous and acidic media, including theoretical and experimental approaches to the problem, proposed by the author are summarized. The new concepts are introduced: a “direct kinetic study of CH activation”, “visible and hidden reagent preactivation”, the “strongest reactant and earliest transition state” (ETS), the “5/6 effect” (the ratio of C H bonds splitting constant rates in the с-C5H10/с-C6H12 couple), “single-factor compensation effect” (SCE), and a “refined compensation temperature”. The compensation effect (CE) exists in reality, but it is necessary to exclude the influence side factors, for example, to go from rate constants to the 5/6 effect to observe its purest form. The 5/6-CE combination as an example SCE is a new instrument for studying CH-activation mechanisms. Temperature dependences of (5/6) values for the reagents in aqueous solution (PtII, MnO4−, HMnO4, HOCl, HOONO, HVO2 – RuIV, OH , SO4 −) and sulfuric acid (PdII, HgII, CrO3, MnIII, CoIII, NO2+, OH+, 1-adamantyl cation, C14H11+, СН2OH+, SO3H+) are found. The only influencing factor on the (5/6) value is conformational strain difference in the C5 and C6 rings, which in a series of one-type reactions decreases with increasing the reagent activity. Four mechanisms are revealed: H-atom abstraction by anionic (I−), uncharged (I0) and cationic (I+) oxygen-centered “O-reactants”, and a bifunctional incorporation into C H bond of electrophilic cation – base adduct (II+). Various SCE lines (the entropy change versus enthalpy changing) for these groups are found. They converge in a “SCE pole” (the first example of ETS). Features of these mechanisms, differences of PtII, PdII, HgII acidocomplexes as the reagents and a surprising similarity between the Shilov reactant PtIICl3(H2O) and OH radicals in the water are discussed. The probable general cause of CEs in various processes is compensation effects in thermodynamics of interparticle interactions.

The quest of selective catalytic reactions for direct conversion of alkanes into valued products remains to be the most important task objective of modern chemistry and metal complex catalysis. Nowadays it is adopted that the formation of metal–alkyl intermediates (M R) is a necessary condition for activation and functionalization of alkanes on metal complexes but the mechanism of subsequent reactions of metal alkyls remain obscure, so that effective catalytic systems of this kind are still rare and uncommon. Although it is widely adopted that alkane σ-complexes (M·RH) most frequently are primary hydrocarbon intermediates in these processes, low profile in the literature is given to their reactivity and these are often considered simply just as some ‘collision complexes’. Nevertheless, theoretical and experimental studies provide more and more evidence that the С Н bonds in such complexes may be markedly weakened and/or polarized, thus opening wide horizons for occurrence of subsequent direct homolytic or heterolytic reactions of alkanes. This review addresses the discussion of new routes for activation and oxygenation of saturated hydrocarbons, including those via alkane σ-complexes, without formation of metal–alkyl intermediates.

In the present work, four mononuclear iron(III) complexes containing BMPA (BMPA = bis-(2-pyridylmethyl)amine) and derivative ligands, have been studied as catalyst in toluene oxidation, at 25 °C and 50 °C, using hydrogen peroxide as oxidant and acetonitrile as solvent. All catalysts were able to oxidize toluene with satisfactory yields, producing o-, m-, p-cresols, benzaldehyde and benzyl alcohol, as main products, and traces of 2-methylbenzoquinone and benzoic acid. The catalyst [Fe(BMPA)Cl3] presented the most promising results, reaching yields up to 30.2% at 50 °C after 24 h. Furthermore, [Fe(BMPA)Cl3] was applied in the oxidation of other aromatic compounds as benzene, ethylbenzene, cumene, n-propylbenzene, p-xylene and anisole. The reaction with H2O2 was monitored by electronic UV–vis spectroscopy in the presence and absence of toluene and its oxidation products, as well as by ESI-(+)-MS/Q-TOF mass spectrometry, in order to provide some information about the reaction mechanism.

Four cobalt (III) corroles bearing different number of pentafluorophenyl and phenyl groups were synthesized and characterized by elemental analysis, HR-MS, UV–vis, NMR, XPS as well as cyclic voltammetry. The first investigation of cobalt corrole catalyzed oxidation of alkene was conducted by using styrene as substrate. The best yield was obtained in acetonitrile solvent in the air with TBHP oxidant (96% yield based on oxidant, up to 96 TON). Benzaldehyde was detected as the main product by using PhI(OAc)2, TBHP, KHSO5, PhIO as oxidants. In contrast, styrene oxide was found to be the major product when using m-CPBA oxidant. Nearly no products could be found by using H2O2 oxidant. Possible catalytic oxidation pathway was also discussed based on the obsewrvations of UV–vis changes of the ctatalytic system in the absence of substrate and in-situ HR-MS.

Catalytic efficiency of tetrabutylammonium salts of sandwich tungstophosphates B‐α‐[M 4 (H 2 O) 2 (PW 9 O 34 ) 2 ] n− , M = Co II , Mn II , Fe III , was studied in the oxidation of ( R )-(+)-limonene, geraniol, linalool, linalyl acetate, carveol, and cis -cyclooctene with hydrogen peroxide, in acetonitrile. Oxidation of ( R )-(+)-limonene gave limonene-1,2-diol as main product. Epoxidation of linalool takes place preferentially at the more substituted 6,7-double bond, the corresponding 6,7-epoxide reacting further, yielding furano- and pyrano-oxides, via intramolecular cyclization. Oxidation of linalyl acetate occurred preferentially at the more substituted 6,7-double bond for Mn 4 (PW 9 ) 2 , affording 6,7-epoxide at 82% selectivity. Linalyl acetate 1,2-epoxide was the major product with 51% and 77% selectivity for Co 4 (PW 9 ) 2 and Fe 4 (PW 9 ) 2 , respectively. Oxidation of carveol occurred with very good conversions in the presence of Mn 4 (PW 9 ) 2 , Co 4 (PW 9 ) 2 and Fe 4 (PW 9 ) 2 , yielding carvone and carveol 1,2-epoxide in similar amounts. Oxidation of cis -cyclooctene gave only the epoxide, while oxidation of geraniol at room temperature afforded 2,3-epoxygeraniol as the major product.

A dinuclear complex [(Me3P)3Ru(μ-OH)3Ru(PMe3)3]+[OPh]− (1) (0.5 mol%) catalyzes E-selective dimerization of phenylacetylene, which involves the C–H bond cleavage of phenylacetylene and resulting stereospecific C–C bond forming reaction, at 100 °C for 2 h to give (E)-1,4-diphenylbut-3-en-1-yne in quantitative yield (E/Z = 91/9). Similar reactions using 4-nitro-, 4-cyano-, 4-trifluoromethyl-, 4-acetyl-, and 4-methylphenylacetylene give the corresponding enynes. The kinetic study for dimerization of phenylacetylene shows the second-order and first-order reactions with regard to the phenylacetylene and 1 concentrations, respectively, suggesting this reaction to be catalyzed by a dinuclear ruthenium complex. Addition of PMe3 to the catalytic system strongly discourages the dimerization. These features are consistent with the scenario, where dissociation of a PMe3 ligand from 1 gives a coordinatively unsaturated diruthenium species and one of the ruthenium centers performs as a reaction site for the enyne formation and the other ruthenium center behaves as a spectator in the catalysis.

The coupling of organosilanes and different olefins was performed efficiently in the presence of anionic complexes, [CA]2[PdX4] and [CA]2[Pd2X6], where CA = imidazolium or pyridinium cation. The reaction proceeds according to a Pd(II)-mediated pathway, and Cu(OAc)2 acts as the re-oxidant of Pd(0) formed during the catalytic process. High product yields were obtained for differently substituted olefins at 80 °C in 4 h. Styrylsilanes reacted in the same conditions giving unsymmetrical 1,3-dienes.

A simple and efficient C H activation catalyst was identified through a model structure-activity screening applied to a noncooperative, nonsymmetric bimetallic palladium(II)-N-heterocyclic carbene complex. Mechanistic studies based on kinetics and DOSY NMR spectroscopy provided the origin of the higher efficiency of the identified catalyst.

We report the iridium-catalysed desilylative acylation of styryl and dienyl silanes by acid anhydrides to afford (E)-α,β-unsaturated ketones. The [{Ir(μ-Cl)(cod)} 2 ] catalyst is the first non-rhodium complex successfully applied for this type of transformation. Stoichiometric reaction of [{Ir(μ-Cl)(cod)} 2 ] with (E)-trimethyl(4-chlorostyryl)silane was carried out to gain insight into the reaction mechanism.

A series of new rhodium (I) complexes supported by bidentate nitrogen-donor ligands with varying electronic and steric properties were synthesized in situ and evaluated for catalytic arene C−H/D activation. In trifluoroacetic acid (HTFA), these complexes are proposed to mediate H/D exchange of arene C−H/D bonds by an electrophilic aromatic substitution mechanism that involves Rh-mediated activation of HTFA (or DTFA). DFT calculations support the proposed pathway for the H/D exchange reactions.

Zeolite catalyzed Friedel-Crafts acetylation of 2-methoxynaphthalene to produce 2-methoxy-6-acetylnaphthalene with high selectivity and conversion has been a challenging task, because the obtained compound is a key intermediate for an anti-inflammatory agent, Naproxen. However, no satisfactory results have been obtained with zeolite catalysts, and harmful solvents have been used to gain a high selectivity together with a high conversion. Here, we report the synthesis of 2-methoxy-6-acetylnaphthalene from 2-methoxynaphthalene with a high selectivity and a high conversion under an unprecedented simple reaction system; acetic anhydride as an acetylating agent, acetic acid as a solvent, and proton-type zeolite catalysts with low acidity. Among the examined zeolites, a proton-type H-MOR (SiO2/Al2O3 = 200) with a low acid content shows a conversion of 82% and an 86% selectivity for 2-methoxy-6-acetylnaphthalene. Further, detailed control experiments using H-MOR catalyst in acetic acid solvent were carried out to propose a plausible reaction mechanism.

A novel polyethylene-supported Fe/ionic liquid complex (PEt@Fe/IL) is prepared, characterized and its catalytic performance is investigated in the synthesis of 3,4-dihydropyrimidinones. The chemical properties and thermal stability of the PEt@Fe/IL material were studied by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) analysis. The morphology of the material was obtained using scanning electron microscopy (SEM). The PEt@Fe/IL material was then successfully applied in the Biginelli condensation of aldehydes, urea and alkylacetoacetates to prepare a set of different 3,4-dihydropyrimidinone derivatives in high to excellent yields. The PEt@Fe/IL was recovered and reused several times without significant decrease in efficiency. The other advantages of this novel catalytic system include excellent yield, short reaction time and solvent-free conditions.

Protonation of copper-triazolide is a distinctive and final part in CuAAC reaction which has kinetic importance such that it can even affect the product distribution. In the context of this study, the protonation mechanism of copper-triazolide was investigated with quantum mechanical calculations to have a deeper understanding of the mechanism. In aprotic conditions where the alkyne is considered as proton donor, the key finding of DFT calculations performed in this study is that the activation energy barrier for the protonation step is greater than the cycloaddition step. In the absence of a strong proton donor the final protonation step is coupled with the alkyne deprotonation step in the catalytic cycle, which slows down the reaction. A conceivable pathway for acetic acid promoted CuAAC reaction on the basis of experimental and computational studies was also sought. With acetate as ligand, cycloaddition is a facile reaction and the energetics shows that it speeds up the cycloaddition step. Acetic acid in CuAAC reaction provides proton for the final protonation step in the catalytic cycle, decouples the protonation/deprotonation step by acting as a strong proton donor in the last step and facilitates protonation. The energetics presented herein are in accordance with the experimental proposals on rate-determining step in aprotic conditions and decreased reaction times obtained in the experiments in the presence of acetic acid.

Lewis base, N -methylmorpholine (NMM) accelerated Pd-catalyzed Sonogashira coupling of steric hindered super active esters, 1a–1e, and terminal alkynes. This approach provided an efficient synthetic protocol for a broad array of acylated o -alkynoylphenols compounds, 3a–3e, under moderate conditions. The mechanistic study clearly demonstrated that NNM stabilized the catalytic palladium species, and accelerated the leaving of triazine moiety during the catalytic cycle of the cross-coupling reactions. In addition, piperazine was found to efficiently catalyze the 6-endo cyclization of acylated o -alkynoylphenols, which achieved the diversity oriented synthesis of γ -benzopyranones, 4aa–4eg, with 93–99% yields.

The DFT B3LYP/6-31G* calculations were carried out for the reactions of C6H6 and Ad3C6H3 (Ad = 1,3,5-adamantyl) with superelectrophile CBr3+ as a model of superelectrophilic catalyst CBr3+ Al2Br7−. The reaction of C6H6 with CBr3+ proceeds via the classical scheme of electrophilic reactions of aromatic C − H bond to form initially the barrier-free σ-complex C6H6CBr3+. This mechanism was confirmed by the aug-cc-pVDZ basis set calculations. The reaction of Ad3C6H3 with CBr3+ occurs via a quite novel mechanism involving aryl cation formation followed by hydride abstraction of the Ar+ from the 2-Ad group and the rearrangement of the 2-Ad+ cation into the 4-phenyl-4-protoadamantyl cation. The hydride transfer from both arenes was shown to be more favorable than H radical transfer by more than 40 and 55 kcal mol−1 in the case of C6H6 and Ad3C6H3, respectively.

The present work highlights the application of solid acid catalyst to produce alkyl levulinate from levulinic acid in continuous mode under vapor phase conditions. In this context, tungsten oxide incorporated SBA-16 catalysts were prepared by one pot direct synthesis method and evaluated for the titled reaction. Under optimized reaction conditions, 3 wt% WO 3 -SBA-16 catalyst delivered complete conversion of levulinic acid with 95% selectivity towards ethyl levulinate. The synthesized catalysts were characterized to know the physico-chemical features by various techniques, namely, X-ray diffraction, N 2 physisorption, temperature programmed reduction of hydrogen (H 2 -TPR), temperature programmed desorption of ammonia (NH 3 -TPD), DR-UV–vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The characterization results suggest that, the superior catalytic activity can be ascribed due to the enhanced acidity of SBA-16 obtained through incorporation of tungsten oxide and easy of accessibility for the dispersed active sites through uniform pore channels. The constant catalytic activity in 10 h time on study shows the sturdiness of the catalyst and the spent catalyst can be regenerated several times. Moreover, various alkyl levulinates (methyl, n -propyl, and n -butyl) were synthesized with more than 90% selectivity over this catalyst.

DFT modeling of the active centers formation in the catalytic system LTiCl2-Bu2Mg-Et2AlCl for alkene polymerization, where L is a bidentate ligand of saligenin type, suggests the three-step mechanism of this process. This mechanism includes the addition of the most probable alkylating agent, RMg(μ-Cl)2AlR2 or RMg(μ-Cl)2MgR (R = alkyl), to LTiCl2 with the formation of the trinuclear heterocomplex with the alkyl bridge bond Mg–C–Ti, followed by its two-step isomerization into the active center via the β-agostic intermediate. The free energy changes at the stages of the addition and isomerization are negative; the maximal energy barrier on the reaction pathway is small. In the Mg-free system LTiCl2-AlR3, the isomerization proceeds through the single energy barrier with a significantly higher amplitude. This could be the reason for a relatively high activity of the Mg-containing system and inactivity of the Mg-free system.

Ordered mesoporous MCo2O4 (M = Cu, Zn and Ni) spinel catalysts were synthesized via nano-replication method using mesoporous silica KIT-6 as the hard template. They were applied to methane combustion, in comparison with bulk MCo2O4 spinel catalysts prepared by co-precipitation method. A combined N2 adsorption-desorption, XRD and TEM results clearly confirm that mesoporous MCo2O4 (m-MCo2O4) spinel catalysts contain ordered mesostructure, resulting in the higher BET surface area and pore volume than bulk ones (b-MCo2O4). Moreover, the former catalysts demonstrate the better thermal stability as indicated by larger amount of MCo2O4 phase and smaller size of crystallite domain after calcination at 550 °C. Therefore, such excellent properties rationalize that the m-MCo2O4 spinel catalysts reveal higher catalytic activity for methane combustion than bulk counterparts. When it comes to the catalytic performance of the meso catalysts for methane combustion, the m-CuCo2O4 spinel catalyst has superior performance, which is related to the high normalized amount of Co3+ cations on the surface, as evidenced by XPS.

The complexes of copper [Cu(κONN’-HL)(NO3)(DMF)](NO3)∙H2O (1) and [Cu(κONN’-HL)Cl2]∙½DMSO (2), and of manganese [Mn(κON-HL)2Cl2]Cl (3) and [Mn(κON-HL)2(NO3)2](NO3)∙H2O (4) were synthesized by reactions of the respective chloride or nitrate salt with a non-aqueous solutions of the Schiff base aminoalcohol HL (product of condensation of salicylic aldehyde and aminoethylpiperazine) and characterized by X-ray diffraction analysis. The catalytic investigations disclosed a prominent activity of the copper compounds 1 and 2 towards oxidation of cyclohexane with hydrogen peroxide in the presence of various promoters (nitric, hydrochloric, oxalic acids and pyridine), under mild conditions. The unusual promoting effect of pyridine on the catalytic activity of the copper catalysts allowed to achieve yields up to 21% based on cyclohexane. Chromatographic studies revealed that cyclohexyl hydroperoxide is a main reaction product and chlorocyclohexane (in the presence of HCl as promoter) was also detected, suggesting a free radical reaction pathway with hydroxyl radicals as attacking species. Complexes 1 and 2 act also as catalysts in the oxidation of 1-phenylethanol with tert-butylhydroperoxide, showing acetophenone yields up to 62% and TON (turnover numbers) up to 620 in the presence of the K2CO3 promoter.

The review describes catalytic properties of a unique class of metal complexes—polycyclic cage-like metallasilsesquioxanes. Article is composed in retrospective manner and reflects the progress of the investigations in the field: from classic applications to recently discovered perspectives of cage-like metallasilsesquioxanes in catalysis of oxidation of С–H compounds.

A phosphorous-modified γ-Al2O3 (P-Al2O3), where γ-Al2O3 support was prepared by sol-gel method with a high surface area of ∼350 m2/g, has been applied for a preparation of cobalt-supported Co/P-Al2O3 catalysts. The Co/P-Al2O3 catalysts having a different P/Al molar ratio were investigated to elucidate the roles of phosphorous species on the γ-Al2O3 to the catalytic stability and product distribution for CO hydrogenation to hydrocarbons. The γ-Al2O3 surface was partially transformed to aluminum phosphates after phosphorous modification, and the newly formed aluminum phosphate phases simultaneously altered the surface hydrophilicity and cobalt dispersion as well. The partial formation of tridymite aluminum phosphate (AlPO4) phases on the P-Al2O3 support eventually enhanced the dispersion of the supported cobalt crystallites and suppressed the aggregation of cobalt nanoparticles by forming the strongly interacted cobalt crystallites on the P-Al2O3 surfaces. The phosphorous-modified Fischer-Tropsch synthesis (FTS) catalyst also significantly suppressed heavy hydrocarbon depositions due to an increased surface hydrophilicity originated from partially formed SiO2-like tridymite AlPO4 surfaces. A higher stability of the Co/P-Al2O3 catalyst at an optimal phosphorous content in the range of 0.5–1.0 mol% was attributed to homogeneously distributed cobalt crystallites and less deposition of heavy hydrocarbons by forming macro-emulsion droplets with the help of trace amount of alcohols formed during FTS reaction. This was confirmed by in-situ analysis of adsorbed intermediates with surface hydrophilicity and some surface characterizations such as crystallite size, reducibility, and electronic state of the supported cobalt nanoparticles.

Catalytic systems RhCl 3 –KI–NaCl and RhCl 3 –Cu(OAc f ) 2 –NaCl in aqueous perfluorinated carboxylic acids (CF 3 COOH, C 3 F 7 COOH) are effective in coupled oxidation of alkanes and carbon monoxide with dioxygen. In their presence, predominant is the outer-sphere oxidation of alkanes into respective esters (alcohols) with involvement of peroxo rhodium species as an oxidant (mechanism A ). The process occurs partially by the inner-sphere mechanism B involving Rh–alkyl intermediates. Mechanism B is supported by (a) formation of alkyl chlorides, (b) synthesis of acetic acid in conversion of methane, and (c) positional selectivity in oxidation of propane.

3d metal (Cu, Fe, Co, V) containing composite catalysts for the solvent-free microwave-assisted transformation of 1-phenylethanol to acetophenone with tert-butyl hydroperoxide (TBHP) as oxidant were prepared by ball milling. The influence of multiwalled carbon nanotubes (CNTs) and graphene oxide (GO) additives on the catalytic activity of the catalysts was studied. CNTs or GO were mixed by ball milling with the metal salts (CoCl2), oxides (CuO, Fe2O3, V2O5) or binary systems (Fe2O3-CoCl2, CoCl2-V2O5, CuO-Fe2O3). For CoCl2-based catalytic systems, addition of small amounts (0.1–5%) of CNTs or GO leads to significant improvement in catalytic activity, e.g. 1% of the CNTs additive allows to rise yields from 28 to 77%, under the same catalytic conditions. The CoCl2-5%CNTs composite is the most active among the studied ones with 85% yield and TON of 43 after 1 h.

Palladium substituted CeO 2 , SnO 2 and their mixed oxides have been synthesized in quantitative yields out of non-toxic and inexpensive precursors using a simple and rapid single step solution combustion method. The resulting oxides, especially the mixed oxides Ce 0.79 Sn 0.20 Pd 0.01 O 2-δ , Sn 0.79 Ce 0.20 Pd 0.01 O 2-δ and Sn 0.99 Pd 0.01 O 2-δ proved to be highly active (TOF > 12,000 h −1 ) for Suzuki-Miyaura cross-couplings of phenylboronic acid with various bromoarenes. The reactions were carried out in ambient air at moderate temperatures using environmentally friendly aqueous ethanol solutions as reaction solvents. Minimal amounts of palladium in the product solution ( C coupling catalysts.

Herein, nickel-based metal-organic framework, Ni-MOF-74, was synthesized by a solvothermal method and its properties was characterized by a host of techniques. Ni-MOF-74 exhibited exceptional catalytic activity toward the direct arylation of azoles via C H activation while other Ni-MOFs, nickel-based heterogeneous systems, and homogeneous counter parts displayed lower activity. Optimal conditions involved the use of Li 2 CO 3 or KCl salts in diglyme solvent in 18 h and no additional ligand is required. This is the first and unprecedented report using KCl salt as promoter for arylation of heterocycles. By avoiding the use of strong bases and oxidants, optimized conditions are compatible with wide range of functional groups and heterocycles. Furthermore, by taking advantage of large aperture size of Ni-MOF-74, we are able to utilize optimized conditions to successfully synthesize several bioactive arylated azole derivatives. Previous studies using heterogeneous catalysts to approach these bioactive compounds are not performed in the literature. Leaching tests indicated that homogeneous catalysis via leached active nickel species is unlikely. Thus, the catalyst was facilely separated from the reaction mixture and reused several times without significant degradation of the catalytic reactivity.

Three new water-soluble copper(II) complexes [Cu(HL)(H2O){(CH3)2NCHO}] (1), [Cu(H2L)2(im)4]·CH3OH (2) and [Cu(HL)(CH3OH)]2(μ2-py) (3) were synthesized from copper(II) nitrate and sodium (Z)-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)benzene-sulfonate (NaH2L), in the absence (for 1) and presence of imidazole (im) (for 2) or pyrazine (py) (for 3), and fully characterized. The complexes 1–3 have been tested as stereoselective C H activating catalysts for the model nitroaldol (Henry) condensation of nitroethane with various aldehydes in water. 1 was the most active catalyst affording 64−87% yields with syn/anti diasteroselectivities up to 77:23.

Extensive research has been devoted to the assignment of IR bands of CO adsorbed on Pt nanoparticles, which are widely used in heterogeneous and electrocatalysis (e.g. fuel cells). In contrast to single crystal studies, the assignment of CO adsorption to the nanoparticle structure is still controversial. Here we present a case study where we assign CO adsorption bands to the structure of Platinum nanoparticles with a given size distribution. Using a special diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) cell allows to achieve high quality data under in-situ conditions. Temperature dependent CO adsorption spectra are resolved into three bands which depend on the applied flow and pretreatment conditions. Our calculations using Density Functional Theory (DFT) can mimic the experimental findings and link these bands to the particle structure. By explicitly calculating the IR spectra of CO/Pt nanoparticles of different sizes we show that the IR bands are due to a combined size and site effect. For fully covered small nanoparticles the IR bands are attributed to all binding sites. For larger nanoparticles the dominant contribution is related to {111} facets but the other bands are still site independent. Here we provide a tool to assign CO adsorption bands on Platinum nanoparticles with a given size distribution. This can be related to the structure–acitvity relationship which is required for a tailored catalyst design.

Scorpionate ligands provide the benefit of hemilability while minimizing complete dissociation of the ligand. Previous investigations into Tp′PtLnXm complexes [Tp′ = hydridotris(3,5-dimethylpyrazolyl)borate] revealed the importance of hemilability as the Tp′ ligand facilitates Pt(II/IV) interconversions. Here we discuss the synthesis and metalation of a series of asymmetric scorpionate ligands bearing two pyrazolyl rings and one triazolyl ring. In addition to utilizing triazole donor arms with differing substituents, we also compare octahedral structures of Pt(IV) complexes with P = O and CH and BH caps at the pole of the facial tridentate umbrella. Oxidation from Pt(II) to Pt(IV) with electrophilic reagents, simple acids and acid chlorides, leads to isomers in some cases, and the binding properties of the various donor arms dictate the stereochemistry of the products. Investigations into the reactivity of heteroscorpionate tridentate ligands bound to platinum(II) led to CCl activation reactions with methylene chloride and 1,2-dichloroethane. Isolation of a dinuclear platinum complex bridged by an ethylene unit produced an unusual proton NMR AA′XX′ pattern in the 1H NMR spectrum due to chirality at each platinum center.

A novel catalytic reaction of alcohol etherification in the system ROH − PtCl42− ‐ PtCl62− was found. Methanol easily transforms into dimethyl ether in the presence of catalytic amounts of PtII chloro complexes at 70 °C. Under the same conditions reaction of ethanol affords diethyl ether (catalytic) and π-ethylene PtII complex (stoichiometric). The reactions are accompanied by multiple H/D exchange, which is indicative of intermediacy of corresponding alkyl platinum derivatives. The plausible reaction mechanism involves oxidative addition of alcohol forming intermediate alkyl platinum(IV) derivative followed by decomposition of it via reductive elimination step under the action of alcohol giving the ether and regenerating catalyst. In the case of ethyl alcohol reaction, β-hydrogen abstraction from the intermediate Pt-ethyl species yields π-ethylene platinum(II) complex. Although it seems that the reaction does not involve the initial breaking of C H bonds of an alcohol, this system can be regarded as a model for studying of some peculiarities of Shilov chemistry, in particular, of isotope scrambling mechanisms in Shilov alkane activation. In contrast to reactions of dimethyl and diethyl ethers formation, tert-butyl ethers formation in CD3OH/t-BuOH medium is catalyzed by PtIV chloro complexes also and is not accompanied by isotope scrambling. These observations argue against intermediacy of alkyl platinum derivatives suggesting that acid-catalyzed mechanism operates in tert-butyl alcohol etherification.

Counteranion-catalysis represents an appealing but challenging approach for the development of enantioselective oxidative C H bond functionalization reactions. In this work, a new family of 3,3′-triazolyl BINOL-derived phosphoric acids was synthesized and employed in the intramolecular asymmetric C H bond functionalization of N -aryl substituted tetrahydroisoquinolines. As previously reported with related structures, the presence of the triazole groups on the catalysts was key to attain enantioselectivity. Our study also shows the importance of choosing the appropriate regioisomeric triazole groups at the BINOL backbone to achieve a more efficient chirality transfer. Moderate enantiomeric ratios were obtained with the N -benzamide substrates, whereas the change of the nature of the nucleophile fragment was translated to a dramatic loss of the enantioselectivity. Therefore, it can be foreseen that there is a need for designing further superior catalyst structures to develop future counter-anion organocatalyzed asymmetric C H bond functionalization reactions.

Amberlyst A-21 supported CuI was found to be highly efficient novel heterogeneous catalyst for the three-component reaction between ketones, amines and alkynes, commonly called KA2-coupling. This inexpensive, easy-to-prepare, simple and recyclable catalyst has been employed in solventless conditions in the KA2 coupling reaction involving both primary and secondary amines, ketones and various alkynes. The secondary and tertiary propargylamine products were obtained in good to excellent results in moderate reaction times.

In order to obtain monomers from vegetable source, the castor oil epoxidation process was investigated. The catalytic system used in this work, H2O2/alumina/ethyl acetate, can be considered as a green system, free of heavy metals and toxic solvents. These characteristics make the system appropriate for the purpose of this study since they increase the probabilities of obtaining a biomaterial with the desired specifications regarding toxicity. Reaction conditions of castor oil epoxidation were optimized using methyl ricinoleate as a model compound. In order to identify the operating region, it was developed an experimental design 23 with 17 assays (6 axial points and central point in triplicate) in which, methyl ricinoleate, hydrogen peroxide and catalyst initial quantities in the reaction mixture were the studied variables. The system showed great efficiency with 100% of selectivity in the methyl ricinoleate epoxide production. In optimized conditions, it showed conversion of 99% in 6 h. It was obtained a conversion of 94%, an epoxidation percentage of 84 and a selectivity of 89% toward the epoxides for the castor oil epoxidation. These results show the efficacy of the catalytic system used in this work. Epoxidized castor oil structure was confirmed by FTIR, Raman and 1H NMR techniques.

The homogeneously rhodium catalyzed hydroformylation of 1-decene was studied using operando FTIR spectroscopy. The bulky chelating diphosphite ligand BiPhePhos was used for catalyst modification. Special emphasis was given to the transformation of the Rh-precursor Rh(acac)(CO) 2 to the activated HRh(BiPhePhos)(CO) 2 catalyst. Under hydroformylation conditions, this complex was found to be the most abundant catalyst species over a wide range of olefin conversion. Other inactive or non-selective rhodium species were not detectable. Analysis of the turnover frequency revealed a first order dependence of the hydroformylation rate with respect to the concentration of 1-decene. These findings indicate that the coordination of the olefin to the Rh-BiPhePhos catalyst is determining the hydroformylation rate of 1-decene.