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Reactions and purifications, including carbon-carbon bond forming reactions, can be carried out on a cellulose support on which the substrates are non-covalently absorbed.

Cellulose chromatography paper provides a novel non-covalent support for synthesis and in-situ purification of multi-dimensional arrays.

Paraformaldehyde was employed as a hydride source in the palladium-catalyzed hydrodehalogenation of aryl iodides and bromides. High throughput screening using a paper-based colorimetric iodide sensor (PBCIS) showed that Pd(OAc)2 and Cs2CO3 were the best catalyst and base, respectively. Aryl iodides and bromides were hydrodehalogenated to produce the reduced arenes using Pd(OAc)2 and Pd(PPh3)4 catalyst. This catalytic system showed good functional group tolerance. In addition, it was found that paraformaldehyde is the hydride source and the reducing agent for the formation of palladium nanoparticles.

Invited for the cover of this issue is the group of Arjan Kleij at the Institute of Chemical Research of Catalonia (ICIQ). The image shows how naturally occurring compounds such as tannic acid can be used to devise highly efficient CO2 conversion catalysis. The Full Paper itself is available at 10.1002/cssc.201500710.

Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine-tuning of multiple "upstream" (i.e., lignin bioengineering, lignin isolation and "early-stage catalytic conversion of lignin") and "downstream" (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a "beginning-to-end" analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.

This review presents an overview of the initial targeted chemical processing stages for conversion of lignocellulosic biomass to platform molecules that serve as intermediates for the production of carbon-based fuels and chemicals. We identify four classes of platform molecules that can be obtained in an initial chemical processing step: (i) sugars, (ii) dehydration products, (iii) polyols and (iv) lignin monomers. Special emphasis is placed on reporting and comparing parameters that affect process economics and/or sustainability, including product yields, amount of catalyst used, processing conditions, and product concentrations. We discuss the economic trade-offs associated with choices related to these parameters, depending on the product that is targeted. We also address the effects of real biomass on the ability to recover, recycle, and potentially regenerate catalysts and solvents used in the biomass conversion processes.

ingredients 11 of 100 g of pulp of tamarind fruit contain water (15-30%), protein (2-9%), fat (0.5-3%), total carbohydrate (56-82%), edible fiber (2.2-18.3%), ash (2.1-3.3%), calcium (81-466 mg), phosphorous (86-190mg), iron (1.3-10.9 mg), sodium (23-28 mg), potassium (62-570 mg). It also contains 41-58% sugars of which 25-45% is in the form of reducing sugars and 16% is in the form of non-reducing sugars and tartaric acid (8-18%) and ascorbic acid (3-9 mg). The composition of the tamarind fruit juice varies with geographical, cultural and seasonal harvesting and processing. An aqueous extract of tamarind fruit juice is acidic having pH 3.0 and acidity percentage is 50.3% and hence it will be work as an acid catalyst for condensation of carbonyl compounds and indoles. Therefore, we have used this fruit extract as natural catalyst for synthesis of bis-, tris-, and tetraindolyl compounds.

Biodiesel is the main alternative to fossil diesel and it may be produced from different feed stocks such as semi refined vegetable oils, waste frying oils or animal fats. The new process technologies developed during the last years made it possible to produce biodiesel from recycled frying oils comparable in quality to that of virgin vegetable oil biodiesel with an added attractive advantage of being lower in price. Increasing number of researches focusing on the use of solid heterogeneous catalysts for the production of biodiesel provides evidence that these catalysts continue to evolve as viable alternatives. While liquid alkaline metal alkoxides remain to be appealing in the industries, it is expected that solid base catalyst will soon become more attractive due to the economics and environmental concern. Limited researches have shown that the conversion by solid base catalysts was comparable to that of the existing alkoxide system. In this review article various types of heterogeneous solid acids and bases in the production of biodiesel from trans-esterification of triglycerides and their yields and conversion from various catalytic systems are compared.

Although many methods for enzyme immobilization have been described in patents and publications, relatively few processes employing immobilized enzymes have been successfully commercialized. The cost of most industrial enzymes is often only a minor component in overall process economics, and in these instances, the additional costs associated with enzyme immobilization are often not justified. More commonly the benefit realized from enzyme immobilization relates to the process advantages that an immobilized catalyst offers, for example, enabling continuous production, improved stability and the absence of the biocatalyst in the product stream. The development and attributes of several established and emerging industrial applications for immobilized enzymes, including high-fructose corn syrup production, pectin hydrolysis, debittering of fruit juices, interesterification of food fats and oils, biodiesel production, and carbon dioxide capture are reviewed herein, highlighting factors that define the advantages of enzyme immobilization.

Recent approaches to furfural synthesis from hemicellulosic biomass and pentose sugars with both homogeneous and solid acidic catalysts have been summarized by addressing the associated sustainability issues. The features of deconstruction of hemicellulosic biomass by acid hydrolysis to produce pentose sugar feedstock for furfural have been discussed in brief. Several strategies including solvent extraction in a biphasic process, application of surface functionalized materials such as acidic resins, mesoporous solids and mechanistic insight in limited cases are discussed. The present status of the promising furfural platform in producing second generation biofuels (furanics and hydrocarbon) is reviewed. The performances of each catalytic system are assessed in terms of intrinsic reactivity and selectivity toward furfural production. Overall, this minireview attempts to highlight the scope of further developments for a sustainable furfural process and upgrading to fuels.

1.0. Introduction 4044 2.0. Biomass Chemistry and Growth Rates 4047 2.1. Lignocellulose and Starch-Based Plants 4047 2.2. Triglyceride-Producing Plants 4049 2.3. Algae 4050 2.4. Terpenes and Rubber-Producing Plants 4052 3.0. Biomass Gasification 4052 3.1. Gasification Chemistry 4052 3.2. Gasification Reactors 4054 3.3. Supercritical Gasification 4054 3.4. Solar Gasification 4055 3.5. Gas Conditioning 4055 4.0. Syn-Gas Utilization 4056 4.1. Hydrogen Production by Water−Gas Shift Reaction 4056

An iron-catalyzed direct C–C double-bond formation process is described in this paper. Using DTBP as the oxidant and FeCl3·6H2O (20 mol%) as the catalyst, N-2-pyridinecarbonyl glycine esters were coupled with malonates to provide amido acrylates in moderate to good yields. A possible reaction pathway for the formation of the products is also discussed in this paper.

Water pollution aggravates water scarcity by contaminating large volumes of available water. There has been increasing interest in the use of bimetallic particles and bimetallic oxides for the removal of contaminants in water. This paper reviews the recent advances in the development of bimetals and bimetal oxides, and application in the treatment of environmental contaminants. 183 published studies (1999–2015) are reviewed in this paper. The synthesis methods of bimetals including chemical methods, physical methods, and biosynthesis methods and the synthesis of bimetal oxides including hydrothermal, impregnation, sol–gel, spray pyrolysis, and precipitation methods are summarized. Then the application of bimetals and bimetal oxides to remove different environmental contaminants in water including chlorinated organic compounds, heavy metal, arsenic and selenium, nitro compounds and azo dyes, anions and oxyanions are reviewed. The review focuses on experimental conditions, removal efficiency of contaminants, and reaction mechanism in the application of bimetals and bimetal oxides. Compared with monometals, bimetals have high catalytic or removal ability for contaminants. The synthesis and application of bimetals and bimetal oxides is remarked on.

The synthesis of architecturally designed catalytic nanostructures and their in situ characterization under reaction conditions enable the development of catalysts with improved stability, reactivity, and product selectivity. Throughout this review paper, we will explore three recent reports that demonstrate the invaluable synergetic impact of combining synthesis, catalysis, and in situ spectroscopy for catalysts development. In the first example, product selectivity in 1,3 butadiene hydrogenation reaction was tuned by employing size-selected Pt nanoparticles as catalysts. SFG vibrational spectroscopy measurements uncovered the mechanism that induced the size-dependent selectivity. The important role of metal/metal-oxide interface during CO oxidation reaction is demonstrated in the second part of this review paper. In situ synchrotron-sourced X-ray spectroscopy correlated between the oxidation state of the metal-oxide support and its impact on the catalytic reactivity of supported Pt nanoparticles. In the third example, dendrimer-encapsulated Au nanoparticles were used as catalyst for cascade reactions, which were previously catalyzed by homogeneous catalysts. Reactants into product evolution and the oxidation state of catalytically active Au nanoparticles within the flow reactor were mapped with micrometer-sized IR and X-ray beams. These three examples demonstrate the important role of colloidal synthesis and in situ spectroscopy measurements for in-depth analysis of structure–reactivity correlations.

This review is devoted to oxidative water treatments, with emphasis on catalytic ozonation. The approach tackled herein resides in exposing a wide variety of oxidative treatments attempts as a basis for summarizing the main findings that allow envisaging improvements aiming towards total mineralization of organic pollutants. Comparison between specific operating conditions for specific pollutant-catalyst-oxidizing systems is quite difficult, and is not targeted in the present work. However, when deeply and judiciously analyzed, such a comparison allows demonstrating that, except for some works, most of these attempts seldom took into accounts basic requirements such as the parameter interactions, the role of cation mobility around a solid surface, if any, the multiple pollutant-catalyst-oxidizing species interactions and the significant contribution of adsorption, etc. Otherwise, how to explain that many experiments are still conducted with unsuitable catalysts under totally inadequate operating conditions? A better understanding of the essential requirements for a catalyst to achieve total mineralization of any organic molecules is the main objective of this work. The data summarized herein allow devoting a special interest to ozone, which is a powerful oxidizing agent and probably the most easily handleable, in spite of its low solubility in water. The use of catalysts is an ultimate strategy to improve the ozonation performance, by reducing the chemical oxygen demand (COD), even until total disappearance. However, solid catalysts, more particularly those developing high specific surface areas, such as silicates, aluminosilicates, zeolites, pseudozeolites, and clay minerals and derivatives are expected to display appreciable performances in ozonation. The latest findings show strong dependency of their catalytic activity on the chemical and physical characteristics of their surface, their concentration in the liquid media, the pH level of the reaction mixture and other parameters. The effects of these factors will be systematically examined in this review paper. The state-of-the-art in the catalytic ozonation of organic pollutants may be useful to understand the contribution of both surface and bulk ozonation reaction in the vicinity of the surface of a solid catalyst, and more particularly the role of the catalytic agent and its mobility near the solid surface. A rigorous data synthesis, made available in the present paper, allows understanding the ozone scavenging by the very species present in water, and correlating the highest effectiveness of ozone in the presence of optimum catalyst concentration at optimum pH. This supposes strong interactions between the main factors, which remain to be elucidated for each type of catalyst. The structure of this review makes emphasis on montmorillonite, which exhibits most of the required properties for effective ozonation catalysts. These are common features of natural clay minerals and zeolites, which appear as interesting candidates for large-scale water treatments, targeting complete mineralization of organic pollutants without generating persistent toxins.

The first paper on the hydrophosphonylation of terminal alkenes was published in 1958 by Stiles and coworkers. Afterwards various papers described organometal-catalyzed and free-radical reactions leading to linear anti-Markovnikov adducts and/or branched Markovnikov products. In 1996 Han and Tanaka reported the first example of alkyne hydrophosphonylation catalyzed by a palladium complex. Further studies using other metal catalysts registered poor selectivity as mixtures of adducts were obtained in most of the cases examined. The first example of alkyne hydrophosphonylation by H-phosphonates under free-radical conditions leading to Z- and E-vinylphosphonates in a 1 : 1 ratio was reported by our group. Nevertheless, Z- to E-isomerization took place upon irradiation in the presence of a thiol.

Heterogeneous catalysis by gold is now a very well established research topic and several thousands of papers have appeared since the pioneering studies based on CO oxidation and acetylene hydrochlorination reactions in which, for the first time, supported gold catalysts were shown to be the best catalysts for these reactions. It is now widely recognised that gold either by itself or in combination with other metals is an excellent redox catalyst. In particular gold-containing catalysts are very effective for the selective oxidation of alcohols. Initially it was considered that base was needed to be present for alcohols to be effectively oxidised but efficient catalyst design has enabled alcohols to be oxidised to aldehydes without the need for added base. Gold-containing catalysts are also exceptionally effective for the hydrogenation of oxygen to form hydrogen peroxide. This direct synthesis route shows great potential for a number of applications at this time. More recently gold-containing catalysts have been shown to be effective in C–H activation reactions. Due to the ever increasing opportunities for applying heterogeneous gold catalysts, interest in how effective catalysts are designed and synthesised remains strong. In this paper both the early work and the more recent discoveries concerning heterogeneous catalysis by gold will be considered and some suggestions on the way forward will be presented.

In this paper, an efficient synthesis of cyclopentenyl ketones and cyclohexenyl ketones through tertiary phosphine catalyzed [3 + 2] and [4 + 2] annulations of 1,2-allenic ketones with activated alkenes has been developed. Compared with published synthetic methods on cyclopentenyl ketones and cyclohexenyl ketones, the protocols developed in this paper have the advantages such as readily available starting materials, mild reaction conditions and high efficiency.

This perspective review paper describes the V-containing metal–organic frameworks that have been developed since the first systematic reports on MOFs almost 15 years ago. These hybrid crystalline materials, containing V(III) or V(IV) as metal nodes, show interesting behavior in oxidation catalysis and gas sorption. A significant amount of papers has appeared on the use of these structures in gas (hydrocarbon, CO2) separation. Promising future research and development of V-MOFs is suggested.

Lignosulfonate (LS) is an organic waste generatedas a byproduct of the cooking process in sulfite pulping inthe manufacture of paper. In this paper, LS was used as ananionic supporting material for immobilizing cationic spe-cies, which can then be used as heterogeneous catalysts insome organic transformations. With this strategy, threelignin-supported catalysts were prepared including 1) lignin-SO 3 Sc(OTf) 2 , 2) lignin-SO 3 Cu(OTf), and 3) lignin-IL@NH 2 (IL=ionic liquid). These solid materials were then examined inmany organic transformations. It was finally found that, com-pared with its homogeneous counterpart as well as someother solid catalysts that are prepared by using differentsupports with the same metal or catalytically active species,the lignin-supported catalysts showed better performance inthese reactions not only in terms of activity but also withregard to recyclability. Introduction The synthesis of novel catalysts with well-designed composi-tion and structure tailored to the requirements of a particularapplication is one of the most active fields in catalysis research.The relationship between structure, organized environment,and catalytic properties of active species tells us how to estab-lish a new strategy for the rational design of heterogeneouscatalysts. However, to realize this goal, diversity of solid sup-port has to be extended as much as possible because thechemical properties of the support have been shown to playan important role in determining catalyst activity and selectivi-ty.

Cobalt has been widely used as the main component of catalysts for the hydrolysis of sodium borohydride NaBH4 and, to a lesser extent, for the hydrolysis of ammonia borane NH3BH3. Though active in these reactions, the cobalt-based catalyst generally suffers from rapid deactivation. As emphasized in a perspective paper finalized in 2009 [Phys. Chem. Chem. Phys., 2010, 12, 14651], the nature of the catalytically active phase and the reasons for its deactivation are rather unknown. However, since 2010, significant advances have been reported. Therefore, after 4 years of fruitful research, the present perspective paper aims to (i) answer the questions asked in our previous contribution, (ii) give an overview of the new insights, and (iii) identify the nature of the catalytically active phase of cobalt. The literature of the period 2010–2013 has been exhaustively surveyed while paying attention to the characterization results and problems, the experimental conditions, and the authors' interpretations. Our main observation is that the research groups involved in the field have shown scientific curiosity and dynamism, and demonstrated ingenuity to circumvent the characterization difficulties. Thus, each group has contributed to highlight the nature of the catalytically active phase of cobalt as well as the reasons for its deactivation.

A new process has recently been proposed and investigated for low temperature hydrogen production from hydrocarbons with simultaneous CO2 abatement. It is based on a concept involving simultaneous hydrogen production and CO2 removal, which uses a stationary catalyst phase and a continuously moving adsorbent phase for in situ removal of CO2 and ex situ regeneration of adsorbent. This paper summaries the recent developments in the technology using methane (main composition of natual gas) and glycerol (main by-product of biofuels) as the model feedstocks and microsized hydrotalcite as the CO2 adsorbent. The paper consists of an overview of the new technology, associated fundamental studies including dynamics of adsorption, hydrodynamics, solid hold-up and heat transfer, and chemical reactions. Challenges for further development of the technology and process optimisation are also briefly discussed.

The emissions of nitric oxide and carbon monoxide from internal combustion engines generate a large impact on the environment and on people's health. Catalytic reduction of these species using platinum group metals has already shown significant potential for emissions control. Since catalysts often use carbon monoxide to reduce nitric oxide in these devices, accurate models of their interaction are required to advance catalyst simulations in order to meet increasingly stringent emissions regulations. As a result, this paper reviews the literature of the NO–CO reaction over platinum in order to develop more precise detailed and global reaction mechanisms for use in exhaust after-treatment modeling activities. Moreover, it is found that the reaction between NO and CO over platinum yields carbon dioxide and nitrogen as main products and nitrous oxide as an important side product. Hence, this paper additionally describes the mechanism for nitrous oxide production in advance of greenhouse gas regulations.

In the 1980's appeared the first several scientific papers dealing with chemical vapor deposition (CVD) of nanostructured catalytic materials. Since then, the tremendous increase in the number of related publications indicates the significant importance of CVD for the preparation of catalysts. CVD has the capability to generate various types of catalytically attractive nano-scale structures by modifying the surface properties of massive or even nano-divided substrates. Relatively new CVD processes such as catalytic CVD, fluidized-bed CVD, rotary CVD, two-step CVD and large spot laser CVD allow the formation of nanoparticles, nanotubes, nanofibers, nanocomposites and porous or oriented films. Intensive research is being performed on the production of CNTs and the preparation of supported catalysts by CVD. This paper provides an overview of the relatively new CVD processes involved in the preparation of catalytic materials and some representative examples reported in the open literature.

Three aspects of studies on catalytic oxidation are addressed in this paper. The need to present scientific studies rather than list isolated findings in scientific papers is underlined. The difficulties which accompany such studies when examining mechanistic aspects of catalytic reactions is illustrated by work on cyclo-octene oxygenation at (RhCI(C 8 H 14 ) 2 ) 2 in which techniques with wider applications are described that overcome problems associated with isomerisation of the substrate at the rhodium centre. The potential of low key projects to provide findings of much greater significance is exemplified in a study of iron catalysed oxygenative fragmentation in saturated and αβ-unsaturated aldehyde derivatives. Observations which bear on the mutagenic and protein ageing properties of such aldehydes are reported.

The catalytic dimerization of ethylene stands as the most selective and economical route to polymerization grade butene-1. This approach is currently exemplified by the IFP-SABIC process for the production of butene-1 wherein ethylene is dimerized over the modified Ziegler-Natta homogeneous catalysts Ti(OR')4-A1R3 (R' = C1-C8 alkyl or aryl, R = C1-C6 alkyl). The mass of the published patents and the technical literature dealing with the ethylene dimerization over various transition metal based complexes is overwhelming. Therefore, the literature taken into account in this review was selected in order to give more weight to fundamental studies and less to patent claims. This paper is dedicated to discussing the chemical perspectives of the dimerization reaction over the titanium-based catalytic system with its main objective being to get a more decisive picture on the performance of these catalysts. This review paper identifies the components of this homogeneous system and discusses, in fair detail, the factors controlling its selectivity to butene-1. Other different themes covered include: structure of the active species, kinetics, mechanistic considerations and the principal reaction parameters. Additionally, this survey is supplemented by a summarized account for the corresponding supported titanate catalysts and their usage as a dimerization component in the dual functional catalytic systems.

The selective catalytic hydrogenation of phenylacetylene to styrene presents an attractive and interesting process both from scientific and industrial viewpoints. The process mechanism consists of two consecutive reaction steps in which a high selectivity towards the intermediate product is desired. There have been many papers published so far, that report an increase in the selectivity of adsorption-desorption-based gas-phase processes performed on solid catalysts, due to a periodic (pulsing) operation of the reactor system. Pulsing the gas feed is believed to create more preferential adsorption conditions for the required reactant (transient conditions). This paper presents the results of a theoretical and experimental study concerning the influence of forced periodic oscillations of the gas-phase component on the performance of a three-phase reactor. The theoretical results are based on a heterogeneous mathematical reactor model considering both the transient mass balance over the reactor length as well as accumulation inside the catalyst pellets. Numerical dynamic reactor simulations with a simplified model neglecting accumulation of components within the catalyst pellet showed little improvement in conversion and selectivity when compared to results of the steady-state model. These results were supported by dynamic experiments in a bench scale reactor. It is shown that due to mass transfer limitations, the original square wave shape of the oscillation in the gas-phase concentration was almost completely faded into a smooth and rather flat oscillation at the catalyst surface. Simulations with a model in which accumulation of the relevant components inside the particles was considered showed no further improvement in performance at transient conditions, but demonstrated the impact of accumulation capacity of the pellets on the shape of oscillation present at the catalyst surface. The study is a result of direct cooperation between Politecnico di Torino, where the modelling and calculations were performed, and DSM Research. Its aim was to offer an attractive alternative to the conventional approach.

Heterogeneous acid catalysis attracted much attention primarily because heterogeneous acidic catalysts act as catalysts in petroleum refinery and are known as a main catalyst in the cracking process which is the largest process among the industrial chemical processes. In contrast to these extensive studies of heterogeneous acidic catalysts, fewer efforts have been given to the study of heterogeneous basic catalysts. The types of heterogeneous basic catalysts are listed in Table 1. Except for non-oxide catalysts, the basic sites are believed to be surface O atoms. The studies of heterogeneous catalysis have been continuous and progressed steadily. They have never been reviewed in the chemical Reviews before. It is more useful and informative to describe the studies of heterogeneous basic catalysis performed for a long period. In the present article, therefore, the cited papers are not restricted to those published recently, but include those published for the last 25 years. The paper first describes the generation of basic sites before describing methods used in the characterization of basic surfaces. These are indicator methods, temperature programmed desorption (TPD) of CO{sub 2}, UV absorption and luminescence spectroscopies, TPD of H{sub 2}, XPS, IR of CO{sub 2}, IR of pyrrole, and oxygen exchange betweenmore » CO{sub 2} and the surface. The paper then discusses studies on the catalysis by heterogeneous basic catalysts. Some of these reactions are dehydration, dehydrogenation, hydrogenation, amination, alkylation, ring transformation, and reactions of organosilanes. Catalysts discussed are single component metal oxides, zeolites, non-oxide types, and superbasic catalysts. 141 refs.« less

This paper reviews some important recent work on the design and characterization of zeolite-encapsulated and clay-intercalated metal-Schiff base, -porphyrin and-phthalocyanine complexes. After an introduction to the chemistry of clays and zeolites, the incorporation methods of these complexes within the mineral materials are discussed and an overview of their physicochemical characterization is reported. A large part of this paper is devoted to the reactivity of the zeolite- and clay-encapsulated complexes in biomimetic oxidation reactions.

In the paper, we review the preparation and the characterization of CrOx/ZrO2, MoOx/ZrO2 and VOx/ZrO2. Catalysts were prepared by various methods (equilibrium adsorption, impregnation or mechanical mixing) and characterized by XRD, XPS, ESR and FTIR techniques. In the paper, we also review the catalytic activity of the ZrO2 supported systems for propene hydrogenation (CrOx/ZrO2 and MoOx/ZrO2), propane or isobutane dehydrogenation (CrOx/ZrO2), abatement of NO with H2, propane, or propene (CrOx/ZrO2), abatement of NO with NH3 (VOx/ZrO2). In selected cases, in order to assess the influence of the support on the catalytic activity, we compare the activity of the MeOx/ZrO2 samples with that of the same MeOx on other supports.

This paper deals with some of the results concerning a series of oxidation processes, all of which have been interpreted either as concerted oxygen insertions or as radical reactions. This dualism in the mechanistic interpretation concerns Gif systems, metalloporphyrin-catalysed oxidations, oxidations by peracids and by dioxiranes. During these investigations, we have also developed several new syntheses of mixed peroxides, based on the Ingold-Fischer Persistent Radical Effect. Moreover, this paper describes new synthetic developments concerning bromine catalysis in oxidations by hydrogen peroxide and reductive alkylations of alkenes obtained, paradoxically, by oxidising reagents.

This paper briefly summarizes our recent work on the characterization of atom-resolved surface images of TiO2(110) composed of Ti atoms, O atoms, defects and hydroxyls by scanning tunneling microscopy (STM) and non-contact atomic force microscopy (NC-AFM). The paper also presents new kinetic aspects in the catalytic dehydration and dehydrogenation of formic acid on the characterized surface. Switchover of the reaction path from the dehydration to the dehydrogenation occurred by the presence of formic acid undetectable at the surface, where acidic formic acid molecules opened the basic catalysis. In situ STM observation revealed that the dehydrogenation reaction at 400–450 K was strongly suppressed in the vicinity of single-atom height steps. The suppressive effect of step ranged over 2.4 nm into terrace. It is likely that the catalyst with flat surfaces larger than 5 nm is active for the dehydrogenation of formic acid.

Infrared (IR) spectroscopy undoubtedly represents one of the most important tools in catalysis research. In this review, recent catalytic applications of the most popular IR techniques will be presented. Each section starts from the very general basis of the spectroscopic method applied. The last section is devoted to the adsorption of chelating compounds on surfaces of mineral oxides. The aim of adding a large number of illustrations and an appendix is to make the presented material more familiar for young researchers and postgraduate students. Most of the papers discussed have appeared in the last 5–6 years, because the older literature has been reviewed in earlier papers.

In this paper, we report our findings regarding the development of a Lewis acid-catalyzed cyclopropanation of allylic alcohols with bis(iodomethyl)zinc. Iodomethylzinc alkoxides can be formed by treatment of an alcohol with bis(iodomethyl)zinc. These species are not prone to undergo cyclopropanation at low temperature but the addition of a Lewis acid in catalytic amounts induces the cyclopropanation reaction. Using this procedure, we demonstrated that the Lewis acid-catalyzed pathway significantly overwhelms the uncatalyzed one. This paper describes fundamental issues regarding the preparation and stability of halomethyl zinc alkoxides in solution as well as their aggregation state in solution and solid-state structures. Furthermore, the competition reaction between the inter- vs intramolecular cyclopropanation will be studied. Finally, we will discuss the possible activation pathways to explain the Lewis acid activation of halomethylzinc alkoxides. These findings provided new insights on the reactivity o...

This paper describes the direct formation of various O-glycosidic linkages from 1-hydroxy sugars by bismuth(III) triflate-catalyzed dehydrative glycosidation. The condensation reactions of 1 -hydroxy sugars with some primary alcohols in the presence of only 5 mol% bismuth(III) triflate at reflux temperature for 15 min in dichloromethane afforded O-glycosides in good yields. An 1,6-anhydro-β-D-glucopyranosidic linkage was formed by the intramolecular condensation of the corresponding 1-hydroxy sugar performed with similar reaction conditions using 5 mol% bismuth(III) triflate. A reaction using 10 mol% bismuth(III) triflate at room temperature in dichloromethane promoted the self- or cross-condensations of 1-hydroxy sugars to produce several kinds of 1,1'-disaccharides. This paper reports some important properties of bismuth(III) triflate catalyzed dehydrative glycosidation using 1-hydroxy sugars to form various O-glycosidic linkages.

This paper presents a novel Na 2 WO 4 –H 2 O 2 oxidation system. The oxidation of alcohol to ketone or aldehyde was carried out by using N , N -dimethylacetamide, hydrogen peroxide, and a catalytic amount of disodium tungstate dihydrate under neutral conditions. This method is very simple, practical for large-scale manufacturing, and applicable to a variety of substrates including an acid-sensitive substrate. Disodium tetraperoxotungstate dihydrate (Na 2 [W(O 2 ) 4 ]·2H 2 O) was isolated from a mixture of N , N -dimethylacetamide, hydrogen peroxide, and disodium tungstate dihydrate, and a proposal reaction mechanism is discussed in this paper.

The “modern ionic liquids” described in the first article in this issue by Keith Johnson have certainly captured the imagination of chemists across the globe, and without at doubt, nowhere more than in synthesis and catalysis.1 The reasons for such phenomenal interest in this area are due to several factors, notably: 1. synthetic chemists are limited by the available molecular solvents in which they can conduct chemistry; 2. increasingly the solvents chemists like to use are banned by international protocols determined to reduce pollution, of which volatile organic compounds represent a significant part; and 3. the prospect of discovering new chemistry or the ability to design a solvent that facilitates/ allows a specific reaction to occur. The reasons stated above are all important and many papers in the literature respond directly to such challenges. However, there are a large number of papers that justify their existence merely to the fact that ionic liquids are perceived as “green”— since they do not evaporate under ambient conditions—and apart from this aspect, little novelty or insights are reported. In the remainder of this article we have selected examples from the literature that demonstrate the potential of ionic liquids in synthetic applications. These not only offer new opportunities on how to perform known reactions, but can even be tailored to meet specific synthetic needs.

Methane gas is known to be the most destructive greenhouse gas. The current world reserves of natural gas, which contains mainly methane, are also still underutilized due to high transportation costs. Thus, considerable interest is presently shown in conversion of methane to transportable liquid fuels and chemicals of importance to the petrochemical industry. The catalytic methylation of aromatics is one possible new route for converting methane to more valuable higher hydrocarbons. This paper provides a general overview of the recent work that we and other researchers have done on the utilisation of methane for catalytic methylation of aromatic compounds and for direct coal liquefaction for the production of liquid hydrocarbons. In particular, the paper presents a detailed description of more recent substantial experimental evidence that we have provided for the requirement of oxygen as a stoichiometry reactant for benzene methylation with methane over moderately acidic zeolite catalysts. The reaction, which has been termed “oxidative methylation”, was thus postulated to involve a two-step mechanism involving intermediate methanol formation by methane partial oxidation, followed by benzene methylation with methanol in the second step. However, strongly acidic zeolites can cause cracking of benzene to yield methylated products in the absence of oxygen. The participation of methane and oxygen, and the effective use of zeolite catalysts in this methylation reaction definitely have some positive green chemistry implications. Thus, the results of these previous studies are also discussed in this review in light of the principles and tools of green chemistry. Various metrics were used to evaluate the greenness, cost-effectiveness, and material and energy efficiency of the oxidative methylation reaction.

This thesis deals with synthetically modified chiral molecules and their application in asymmetric catalysis. The first part of the thesis describes the use of commercially available chiral diamine ligands in the iridium catalyzed transfer hydrogenation of aromatic ketones. The chiral diamine ligands were mixed with an appropriate transition-metal complex, which after addition of suitable base provided a chiral transition metal complex capable of reducing a range of different aromatic ketones in high yields and enantioselectivities. The developed methodology constitutes a cost effective and readily available procedure for transfer hydrogenation reactions. The following chapters in the thesis are completely devoted to rational design of small organic molecules acting as catalyst in various organocatalytic transformations. Organocatalytic methodology, represent a new and complementary approach to asymmetric organic synthesis, as compared to e.g. transition metal based methodology. Advantages of this methodology typically include mild and less stringent reaction conditions. This, in combination with the lack of toxic transition metal by-products, makes the process more environmentally benign; the organocatalytic methodology, therefore represent a promising approach towards implementation of green chemistry in organic synthesis. Despite this promise, typical drawbacks of the current methodology are long reaction times and the need for high catalyst loadings. Thus, a large demand exists for enhancing reactivity and increasing selectivity in organocatalytic reactions. The present thesis describes several efforts where we have tried to rationally design improved catalysts for various enantioselective organocata-lytic reactions. First, a structurally modified L-proline, incorporating a 1H-tetrazolic acid, was synthesized and evaluated in the direct asymmetric organocatalytic aldol reaction. As shown in Paper II, the catalyst displayed very high reactivity and subsequent studies were initiated in order to rationalize the reactivity enhancement (Paper III). Delightfully, the design principle of a 1H-tetrazolic acid as replacement for a carboxylic acid has since been widely used in the community, including our own efforts in organocatalytic asymmetric cyclopropanations (Paper V)and Diels-Alder reactions (Paper VII). Novel catalysts, including other functionalizations, were also designed for organocatalytic asymmetric addition of nitroalkanes to α,β-unsaturated aldehydes (Paper IV) and for cyclopropanations (Paper VI).

Selective oxidation is of key importance in the synthesis of chemical intermediates. For many years a number of oxides and supported metal catalysts have been used. The key questions involved in the design of selective oxidation catalysts are discussed in the initial part of this paper. One of the most exciting recent developments in the field of selective oxidation has been the discovery that supported gold catalysts are active. The second part of the paper discusses Au/C catalysts, which are shown to be particularly versatile for oxidation reactions. Four examples of selective oxidation are described using molecular oxygen as oxidant: (a) selective oxidation of glycerol to glycerate in the presence of base; (b) the oxidation of cyclohexane to cyclohexanol and cyclohexanane in the presence of a radical initiator; (c) the oxidation of hydrogen to hydrogen peroxide, and (d) the oxidation of benzyl alcohol to benzaldehyde under solvent free conditions. In contrast, the Au/C catalysts are not active for oxidation of carbon monoxide at ambient temperature. These examples demonstrate that there exists a rich potential for Au/C as a selective oxidation catalyst and that research efforts should now be focussed on selective oxidation using supported gold catalysts.

This article has been retracted at the request of the authors and the editor. Please see http://www.elsevier.com/locate/withdrawalpolicy . Reason: this article is found to be very similar to a paper published in European Journal of Organic Chemistry (2006) 2060, entitled “Rapid Microwave-promoted catalyst- and base-free Suzuki-type coupling reaction in water” at almost the same time by the same group. The two papers did not reference each other.

This paper reviews the recent progress made in the asymmetric synthesis on chiral catalysts in porous materials and discusses the effects of surface and pores on enantioselectivity (confinement effect). This paper also summarizes various approaches of immobilization of the chiral catalysts onto surfaces and into pores of solid inorganic supports such as microporous and mesoporous materials. The most important reactions surveyed for the chiral synthesis in porous materials include epoxidation, hydrogenation, hydroformylation, Aldol and Diels‐Alder reactions, etc. The confinement effect originated from the surfaces and the pores turns out to be a general phenomenon, which may make the enantioselectivity increase (positive effect) or decrease (negative effect). The confinement effect becomes more pronounced particularly when the bonding between the catalyst and the surface is more rigid and the pore size is tuned to a suitable range. It is proposed that the confinement in chiral synthesis is essenti...

This paper emphasizes novel issues in in situ characterization techniques for catalysts and model surfaces, namely, energy dispersive X-ray absorption fine structure (DXAFS) for time-resolved structure analysis and polarization-dependent total-reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) for 3D structure analysis, which have been developed in the past 5–10 years. DXAFS is a powerful technique for elucidating dynamic structural changes at active metal sites on catalyst surfaces that involve a sequence of formation and breaking of metal–metal, metal–adsorbate, and metal–support bonds; it opens a new area of structure kinetics, revealing kinetic parameters during catalytic reactions, catalyst preparations, and catalyst deactivation and regeneration. PTRF-XAFS is another powerful technique for elucidating 3D structures of active metal sites at single crystal model surfaces, determining structural parameters in three different directions independently with high surface sensitivity, which opens up a new area of catalytic structural chemistry, presenting information on asymmetric and anisotropic bond arrangements and transformations. The issues addressed in this paper are relevant to important key issues in understanding new catalytic structures and reaction mechanisms and to developing new concepts and strategies for novel catalytic materials, which can hardly be addressed by other techniques.