bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclization—Homogeneous
Authors: Kaloko Joseph J. , Chaterpaul Stephen J. , Gary Teng Yu‐Han , Lin Chi‐Feng , Chien Chih‐Wei , Ojima Iwao 
Published: September 2010

AbstractDevelopment of highly efficient catalytic processes for the synthesis of natural and unnatural compounds of medicinal interest or useful as intermediates for functional materials is a central focus in modern organic synthesis. One of the most efficient approaches to such methodology developments is to apply transition‐metal catalyzed cyclization reactions for the transformations of simple starting materials into monocyclic, bicyclic, and polycyclic scaffolds that can be further elaborated into specific targets. This article concisely summarizes recent advances in the cyclizations promoted by homogeneous catalysts, including various carbocyclizations, carbonylative carbocyclizations, cyclohydrocarbonylations, intramolecular hydrosilylations, and silylformations, compiling relevant references up to late 2008. Among these catalytic cyclization processes, the carbocyclization and carbonylative carbocyclization are extremely important and useful reactions for the syntheses of a variety of carbocyclic and heterocyclic compounds. Cascade carbocyclization is a powerful method, providing a rapid access to polycyclic skeletons in one step. Cyclohydrocarbonylation is another powerful catalytic cyclization process, which finds a host of applications in organic syntheses. Intramolecular hydrosilylations and silylformations also provide unique methods for a variety of organic syntheses. Accordingly, catalytic cyclization reactions not only serve as highly useful synthetic methods in laboratories but also have high potential as future industrial processes.
Dehydrocyclization—Heterogeneous
Authors: Paál Zoltán 
Published: September 2010

AbstractThe formation of aromatic rings from alkanes such as hexane, heptane, octane, and so on (aromatization or dehydrocyclization) on oxide catalysts: chromia, lanthana, metals, such as platinum, palladium, and so on, and nonacidic (Na‐ or Ba‐L zeolite) supports is a “monofunctional” route, catalyzed by the active ingredient itself. A bifunctional route prevails in naphtha reforming (platforming) over Pt on acidic supports (eg, alumina). Interactions of Pt with acidic or alkaline support can be important for aromatization. The metallic function can also catalyze the formation of five‐membered ring(s): C5‐cyclization. The effect of added metallic components resulting in bimetallic catalysts (such as PtRe, PtSn, and so on) as well as the effect of nonmetallic components (Cl, S, C, H) is discussed. Aromatization requiring skeletal rearrangement (eg, of alkylpentane feeds) can also take place. Cyclic hydrocarbons may undergo ring enlargement and ring contraction. The same catalyst may promote the formation of a second ring in alkylcyclopentanes. The buildup of aromatic rings is also possible from smaller molecules (ethane, propane, butane) by dehydrocyclodimerization over bifunctional catalysts, such as ZSM 5 zeolites containing Pt, Zn, but first of all Ga (eg, in the CYCLAR process). Aromatics can be produced even from methane (Mo carbide‐ZSM‐5 or Pd‐Co catalysts).
History of Catalysis
Authors: Smith John Kenly 
Published: September 2010

AbstractCatalysis has played a central role in the chemical industry from its beginning in the late eighteenth century. Today, catalytic processes are used to make gasoline, to synthesize most pharmaceuticals, chemicals, polymers, and to reduce pollution from cars and power plants. The discovery of new catalysts creates new products, such as polypropylene, or dramatically improves the manufacture of existing ones, such as gasoline. In the first decades of the nineteenth century, scientists, including Michael Faraday, investigated chemical reactions initiated by platinum. In 1836, Berzelius coined the word catalysis to generalize a growing body of experimental data. A half century later, Wilhelm Ostwald linked catalysis to chemical thermodynamics and kinetics by defining catalysts as substances that alter the velocity of chemical reactions without appearing in the end products. About the same time, many chemists were using heterogeneous catalysts to develop new processes, the most significant of which was the Haber, Bosch, and Mittasch ammonia process. The dramatic success of the chemical industry throughout most of the twentieth century in no small part derived from the discovery of new catalysts. Given the growing importance of catalysis to the chemical industry, many researchers investigated the fundamental mechanisms of catalysis. While many specific advances were made, no general theory emerged. Since the 1960s, academic research in catalysis has used increasingly sophisticated analytical techniques to explore catalytic phenomena at the atomic level. In part due to the maturity of the chemical industry, this new knowledge has not yet been converted into major new catalytic technologies.
Hydrogen Generation—Homogeneous
Authors: Gábor Laurenczy 
Published: September 2010

Abstract

Today industrial hydrogen production is dominated by processes based on heterogeneous catalysts, using fossil fuels as H
2
sources. However, homogeneous catalysts are becoming more popular in the generation of H
2
for hydrogen storage, delivery, and in mobile/on‐site or small volume hydrogen applications. Generally for these applications, the H
2
gas produced should be pure (eg, no CO contamination), the hydrogen generation should take place under mild conditions, and the H
2
supply unit should be small. Most notably, research into homogeneous catalysis has focused on the chemical storage/delivery systems, based on sodium borohydride, ammonia‐borane, hydrocarbons/alcohols, and formic acid. In the HCOOHCO
2
, cycle the greenhouse carbon dioxide gas is used as the hydrogen vector.

The use of solar energy in homogeneous catalytic H
2
gas production from water and from other hydrogen sources is the subject of extensive studies. A direct photochemical process converts solar energy into hydrogen much more efficiently than the two‐step electricity–water electrolysis/H
2
gas route.
Hydrogenases—Biological
Authors: Cammack Richard 
Published: September 2010

AbstractHydrogenases are enzymes that produce or consume hydrogen gas. Each type of hydrogenase contains, as a minimum, an iron atom, with CO and CN ligands which tune its redox potential and Lewis‐acidity to optimize the binding of dihydrogen. The Fe‐hydrogenase from methanogenic bacteria is the simplest hydrogenase and catalyzes a direct hydride transfer from H2to its organic substrate. All other hydrogenases catalyze reduction of electron acceptors, according to the equation H2= H++ 2e−. The hydrogen‐binding sites are of two types: the [NiFe(Se)]‐hydrogenases, which contain a dinuclear center of nickel and iron, and the [FeFe]‐hydrogenases, which contain a dinuclear iron site, the H cluster. In each case, the protein is arranged to leave a vacant position in the active site for binding H2, as well as separate channels for transfer of H2and H+to the surface. A chain of iron‐sulfur clusters provides a pathway for electrons to a binding site on the surface for electron acceptors and donors. O2and CO are inhibitors that bind to the vacant site and block access to H2; O2also causes oxidation of the metal centers and sulfur ligands. Some hydrogenases from aerobic bacteria, which are resistant to this inhibition, are of interest for applications in biofuel cells.
Kinetics of Catalyzed Reactions—Heterogeneous
Authors: Thybaut Joris W. , Marin Guy B. 
Published: September 2010

AbstractThe kinetics of heterogeneously catalyzed reactions are challenging many scientists in various fields. Catalysis is of utmost importance on the route to a sustainable society and, hence, a fundamental understanding of catalytic phenomena is of great importance. This contribution presents the requirements in order to adequately measure the intrinsic rates of catalytic reactions and how these rates can be assessed through proposed reaction mechanisms and corresponding kinetic models.
Metal Carbides
Authors: Lee Jae Sung 
Published: September 2010

AbstractTransition metal carbides of early transition metals attracted considerable attention as catalysts because of their availability with high specific areas and surface cleanness. Their refractory properties render them resistance against attrition and sintering under reaction conditions. They are catalytically active in many reactions, particularly those involving hydrogen transfer such as hydrotreating (hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation), hydrogenation, dehydrogenation, isomerization, hydrogenolysis, reforming, and aromatization. Recently, they are also receiving attention as electrocatalysis. In many of these reactions, metal carbides behave like group 8–10 metals (Pt, Pd, Rh, Ru, etc) of high cost and limited supply and have potential to replace them. Structure, bonding, synthesis, and surface reactivity of transition metal carbides are discussed.
Metal Nitrides
Authors: Lee Jae Sung , Ham Dong Jin 
Published: September 2010

AbstractTransition metal nitrides are characterized by high melting points, hardness, and resistance to corrosion. These physical properties are desired for catalytic materials that require resistance against attrition and sintering under reaction conditions. Since high specific area materials became available with clean surfaces, they have attracted considerable attention as catalysts or electrocatalysts for many reactions including hydrotreating (hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation) hydrogenation, dehydrogenation, ammonia synthesis, and fuel cell reactions. Metal nitrides demonstrate catalytic advantages over their parent metals in activity, selectivity, and resistance to poisoning. They have been found to be good catalysts for a number of reactions typically catalyzed by noble metals of high cost and limited supply. Structure, bonding, synthesis, surface reactivity, and catalysis of transition metal nitrides are discussed.
Metal Sulfides
Authors: Torres B. , Berhault G. , Chianelli R. R. 
Published: September 2010

Abstract

Transition metal sulfide catalysts are widely used in hydrotreatment applications particularly for removing heteroelements (S, N, O) from petroleum feedstock. The present chapter will provide description of the different catalytically active sulfides, particularly for the MoS
2
‐based catalysts promoted by Co or Ni. The different hypotheses at the origin of promotion will be first presented followed by the general procedures available for the synthesis of metal sulfides. Emphasis will also be applied to the real nature of the active phase under hydrotreating steady‐state conditions. Finally, the most recent studies based on surface science or theoretical studies will be presented.
Methane Conversion—Homogeneous
Authors: Sakakura Toshiyasu 
Published: September 2010

AbstractThis review article summarizes recent progress in utilization of methane as a sustainable carbon resource by homogeneous catalysis. Such conversion is a very difficult subject because the CH bond of methane is too strong to break under moderate conditions where catalyst molecules and common organic solvents can survive, and the concentration of methane in solution is usually too low. Three major synthetic targets are methanol, acetic acid, and acetaldehyde. As for the conversion of methane to methanol, the products are in many cases esters [CH3OC(O)CF3or CH3OSO3H] since it is a smart way to prevent secondary reactions of the products. Acetic acid can be formed via oxidative carbonylation or a seemingly direct addition of CO2. Methane conversions proceed through (1) electrophilic CH bond activation in a strongly acidic medium, (2) radical reactions promoted in many cases by K2S2O8, and (3) CH oxidative additions to low valent transition metal complexes. Related reactions of other hydrocarbons are also described to some extent for reference.
Nickel Enzymes/Models
Authors: Zambelli Barbara , Ciurli Stefano 
Published: September 2010

Abstract
The biochemical properties of the metal ions in a series of nickel enzymes are briefly reviewed. In particular, the properties of urease, hydrogenase, acetyl‐CoA synthase/carbon monoxide dehydrogenase, methyl coenzyme‐M reductase, superoxide dismutase, and acireductone dioxygenase are discussed in terms of relationships between the structure of the Ni ions in the active site and the molecular mechanism of catalysis.
Nitrogen Oxides Removal – Industrial
Authors: Forzatti Pio , Lietti Luca , Tronconi Enrico 
Published: September 2010

Abstract

The heterogeneous selective catalytic reduction (SCR) of NO

x

by NH
3
from stationary sources is addressed in this review. The typical commercial De‐NO

x

SCR catalysts are presented, along with their performances in both the NO

x

reduction and the SO
2
oxidation reactions. Mechanistic and kinetic aspects of the reactions involved in the SCR process, the reactor and process configurations, and the design and modeling of the SCR systems are also illustrated.
Nitrogen Oxides Removal—Industrial
Authors: Forzatti Pio , Lietti Luca , Tronconi Enrico 
Published: September 2010

AbstractThe trend towards more severe emission regulations has motivated in the last decades scientific and technical efforts in the removal of NOx from flue gases of stationary sources. This review surveys the present status and recent advances in the Selective Catalytic Reduction (SCR) of NOx by NH3 in stationary applications, but also includes the most recent developments on the key‐issues of the dynamics of the reaction, which are relevant for nonstationary (mobile) applications as well. Catalytic, mechanistic, kinetic, reactor and process aspects of the SCR reaction are illustrated. An account is also given of the SCONOx process, that has been recently proposed as the lowest achievable emission rate (LAER) technology for NOx removal in stationary applications.
Phase Transfer Catalysis
Authors: Mąkosza Mieczysław , Fedoryński Michał 
Published: September 2010

AbstractBasic concept of phase transfer catalysis (PTC), specific features of this general methodology for executing organic reactions, and mechanism of catalytic action of PT catalysts are presented. Scope and limitations of application of PTC as a general tool of organic synthesis and advantages offered by this methodology are discussed. These discussions are illustrated by numerous examples of successful use of PTC in a variety of reactions of inorganic anions (substitution and addition reactions, β‐eliminations, oxidations, and reductions), heteroanions, and particularly carbanions (reactions with alkylating agents, carbonyl groups, activated carbon‐carbon multiple bonds, electrophilic arenes, heteroatom electrophiles) and carbenes. Possibility of use of PTC for reactions of metalloorganic compounds and complexes and for enantioselective reactions is discussed.
Synthesis Gas Generation: Industrial
Authors: van den Oosterkamp P. F. 
Published: September 2010

Abstract

Synthesis gas
or in short
syngas
is the term used for
mixtures of hydrogen and carbon monoxide
. Synthesis gas is an important building block for a number of petrochemicals as well as an important feedstock for liquid fuels.

The catalytic production of synthesis gas involves a number of chemical equilibrium reactions that can take place simultaneously, including undesired carbon‐forming reactions which may occur under unfavorable reaction kinetics, process conditions, or reactor design. The composition of the synthesis gas produced is determined by the thermodynamics of these quilibrium reactions.
The catalytic industrial processes for synthesis gas generation include hydrocarbon steam reforming (HSR), auto thermal reforming (ATR) and various combinations of HSR and ATR, indicated as combined reforming. The noncatalytic routes for synthesis gas generation include partial oxidation (Pox) and gasification. The drive for more fuel efficient process routes for synthesis gas production has resulted in a number of concepts for heat exchange reforming (HER) which aim to utilize the available waste heat to the maximum extent.
The main engineering issues for synthesis gas generation are related to the reactor design. For HSR, the reactor tubes are placed in a furnace, which supplies the required heat flux for the endothermic steam‐reforming reactions.
For ATR, the heat of reaction is produced in the reactor feed gas through the reaction with oxygen. For ATR, burner design is the key engineering issue.
For these high temperature reactors, selection of materials of the reactor with the correct creep rupture strength and oxidation/ carburization resistance is of paramount importance from both economical and safety point of view.
New developments in synthesis gas generation include the use of new catalytic materials, such as in the process of catalytic partial oxidation (CPO) and the use of selective membranes, which may be used to remove one of the products, for example hydrogen which may allow to shift the equilibrium reaction and performing the same conversion at a lower temperature. For all syngas production processes there is a strong integration of the catalytic materials and its associated kinetics, reactor design, and heat management at high temperatures.
Synthesis Gas Generation—Industrial
Authors: van den Oosterkamp P. F. , van den Brink R. W. 
Published: September 2010

Abstract
Synthesis gas or shortly syngas is a term used for a mixture of hydrogen and carbon monoxide. Synthesis gas is an important building block for a number of petrochemicals as well as an important feedstock for liquid fuels via the Fischer Tropsch route or as reducing gas for iron ore reduction.
Vanadium Enzymes/Models
Authors: Rehder Dieter 
Published: September 2010

AbstractVanadium is present in the active center of two enzyme families, viz vanadate‐dependent haloperoxidases (VHPOs) and vanadium nitrogenases (VNases). Reports on a third enzyme family, vanadium‐dependent nitrate‐reductases, await confirmation. The VHPOs, which are found in marine macro‐algae (bromoperoxidases) and in terrestrial fungi and lichen (chloroperoxidases), also exhibit sulfoxigenation and epoxidation activity. These enzymes contain vanadate H2VO4−covalently bound to a histidine in the active center. Oxidovanadium complexes with vanadium in a pentacoordinate VO(O3N) array model the VHPOs and have been employed as homogeneous or heterogeneous catalysts in (enantioselective) oxidation and oxygenation reactions, such as oxidative bromination, bromocyclization, epoxidation, sulfoxigenation, and oxygenation of unsaturated compounds. Certain vanadate‐inhibited phosphatases also exhibit haloperoxidase activity. VNases are encoded, along with the molybdenum analogs, in free‐living bacteria (Azotobacter) and cyanobacteria (Anabaena). Here, vanadium is constituent of a dicuboidal cluster (theMcluster) of core composition {VFe7S9}. Along with N2, which is reduced to N2H4and further to NH4+, protons, alkynes, and isonitriles can be substrates. The activation of N2and the reduction of substrates are modeled by low‐valent vanadium complexes.
Recent Advances in Development, Validation, and Exploitation ofQSARModels
Authors: Tropsha Alexander 
Published: September 2010

AbstractCounting more than 45 years of intensive development and applications, QSAR modeling remains one of the major computational approaches for drug discovery and environmental chemical risk assessment. Recent developments in the field reflect the burgeoning growth of bioactivity and chemical databases. This growth provides a never‐ending impetus for the development of a growing body of QSAR models and their application for virtual screening to prioritize chemicals for experimental investigations. This chapter reviews recent and emerging trends in the QSAR modeling field with the emphasis on new approaches to chemical and biological data curation, model validation, virtual screening, and potential application of QSAR models by federal agencies for regulatory decision making.
Mass Spectrometry and Drug Discovery
Authors: van Breemen Richard B. , Newsome Andrew G. , Dahl Jeffrey H. 
Published: September 2010

AbstractIn the twenty‐first century, medicinal chemists are producing large numbers of organic compounds through a process called combinatorial chemistry and then testing them against pharmacological targets such as enzymes or receptors using high‐throughput screening. As a result, lead compounds can emerge from drug discovery programs in a few weeks instead of several years. Although a variety of spectroscopic and chromatographic techniques are used to support drug discovery, only HPLC or UHPLC combined with mass spectrometry (LC‐MS) are compatible with virtually all drug‐like molecules. In addition to providing a universal means to characterize drug molecules based on molecular mass and structural features, mass spectrometry provides high throughput. With the development of routine LC‐MS interfaces and ionization techniques such as electrospray and atmospheric pressure chemical ionization, mass spectrometry has also become an ideal HPLC detector for the analysis of combinatorial libraries. Furthermore, a variety of mass spectrometry‐based screening assays have been developed to screen complex mixtures of compounds including natural product extracts as a means of expanding the molecular diversity of drug leads. The use of mass spectrometry in support of combinatorial library synthesis and purification is addressed as well as screening applications such as frontal affinity chromatography‐mass spectrometry, gel permeation chromatography‐LC‐MS, affinity chromatography‐mass spectrometry, and pulsed ultrafiltration mass spectrometry. Since drug development issues such as metabolic stability and the formation of reactive metabolites are now being considered during the drug discovery process, some applications of mass spectrometry to early drug development are addressed.
Membrane Transport Proteins and Drug Transport
Authors: Swaan Peter W. 
Published: September 2010

AbstractTo exert their intended therapeutic goal, drugs need to cross epithelial barriers to reach their site of action. Transport proteins have critical physiological roles in nutrient absorption and transport of endogenous compounds. These systems can serve as useful pharmacological targets and may be used as a mechanism to increase drug absorption. However, we have little understanding of these proteins at the molecular level because of the absence of high resolution crystal structures. Numerous efforts have been made to characterize the P‐glycoprotein efflux pump, the peptide transporter PepT1, and the apical sodium‐dependent transporter, which are important not only for their native transporter function but also as drug targets to increase absorption and bioactivity.In vitroand computational approaches have been applied to gain some insight into these transporters with some success. This represents an opportunity for optimizing molecules as substrates for the solute transporters and providing a further screening system for drug discovery. Clearly the future growth in knowledge of transporter function will be led by integratedin vitroandin silicoapproaches.