bluuebunny/crossref_metadata_2025 huggingface dataset:
Corresponding states for electrolyte solutions
Authors: Weingärtner Hermann
Published: October 2007

The equilibrium properties of electrolyte solutions over wide ranges of concentration, temperature, and solvent dielectric constant are discussed on a corresponding-states basis. If low-melting salts are used, these properties can be studied up to the pure fused salt. We mainly focus on systems at low reduced temperature, where the depth of the interaction potential is large compared with the thermal energy. Examples are singly charged ions in solvents of low dielectric constant and of highly charged ions in water. The state of the ions is discussed on the basis of thermodynamic, electrical conductance and dielectric constant data. Special attention is given to the transition to the fused salt, where ion clusters have to redissociate to form the dissociated structure of the salt. This transition can lead to liquid­liquid phase separations. The resulting critical points serve as important targets for testing theories. Examples are given for large deviations from corresponding-states behavior caused by specific short-range interactions.
Molality-based primary standards of electrolytic conductivity (IUPAC Technical Report)
Authors: Pratt K. W. , Koch W. F. , Wu Y. C. , Berezansky P. A.
Published: October 2007

New values of electrolytic conductivity were determined for aqueous KCl solutions with molalities of 0.01, 0.1, and 1.0 mol/kg in the temperature range 0 to 50 °C, at 5 K intervals. Expanded uncertainties, 2u
c, were also calculated in accordance with the presently accepted protocol for the treatment of uncertainty. The new conductivity values are recommended as primary standards of electrolytic conductivity based on molality. They replace the previous values, based on the nonstandard demal scale, which were determined only at 0, 18, and 25 °C. The accuracy of the technique used was evaluated by repeating the determination of the previously recommended demal-based IUPAC standards of electrolytic conductivity and through comparison with other absolute measurements.
Electrochemical technology for environmental treatment and clean energy conversion
Authors: Walsh F. C.
Published: October 2007

The applications of electrochemical technology in environmental treatment, materials recycling, and clean synthesis are briefly reviewed. The diversity of these applications is shown by the number of industrial sectors involved. The scale of operation ranges from microelectrodes to large industrial cell rooms. The features of electrochemical processes are summarized.

Available and developing electrode designs are considered and illustrated by examples including the regeneration of chromic acid electroplating baths, metal ion removal by porous, 3-dimensional cathodes, rotating cylinder electrodes (RCEs), and a reticulated vitreous carbon (RVC) RCE. The use of performance indicators based on mass transport, electrode area, and power consumption is emphasized.

Electrochemical reactors for energy conversion are considered, with an emphasis on load-leveling and proton-exchange membrane (PEM) (hydrogen­oxygen) fuel cells. Ion-exchange membranes play an essential role in such reactors, and the variation of electrical resistance vs. membrane thickness is described for a series of extruded, Nafion® 1100 EW materials. The characterization of high-surface-area, platinized Nafion surfaces is also considered. The development of modular, filter-press cells as redox flow cells in electrical load-leveling applications is concisely described.

Trends in electrode, membrane, and reactor design are highlighted, and the challenges for the development of improved reactors for environmental treatment are noted.
Green processes for environmental application. Electrochemical ozone production
Authors: Da Silva L. M. , De Faria L. A. , Boodts J. F. C.
Published: October 2007

Several aspects of electrochemical ozone production (EOP) on b-PbO2 were investigated. The morphology of the electrode material was determined in situ using extensive (total, external, and internal differential capacity) and intensive parameters (the morphology factor, j) permitting comparison with results of other laboratories if appropriate electrode characterization parameters are available. The influence of the nature of the supporting electrolyte on the oxygen evolution reaction (OER)/EOP processes was investigated using polarization curves, recorded under quasi-stationary conditions, point-by-point polarization, and chronopotentiometry. The performance of the several b-PbO2/electrolyte system was evaluated using the apparent specific power criterion. A detailed mechanism for EOP is proposed.
Direct electrochemistry of nanoparticulate Fe2O3 in aqueous solution and adsorbed onto tin-doped indium oxide
Authors: McKenzie Katy J. , Marken Frank
Published: October 2007

Nanoparticulate iron oxides occur naturally, for example, in soil, water, and in the cytoplasm of living cells. The redox properties and detection of these nanoparticles are therefore of considerable importance. Understanding and mimicking nanoparticle-based redox reactions may lead to new types of water-based electrochemical processes. In this study, the electrochemical detection of 4­5 nm diameter Fe2O3 nanoparticles dissolved in aqueous buffer solutions is investigated as a model system.

Voltammetric experiments with nanoparticulate Fe2O3 are reported based on two complementary approaches: (i) Fe2O3 nanoparticles adsorbed onto tin-doped indium oxide (ITO) electrodes are shown to give well-defined voltammetric reduction responses and (ii) hydrodynamic voltammety in the presence of fast (24 kHz ultrasound-enhanced) mass transport is shown to allow the direct detection of Fe2O3 nanoparticles in solution. Both the adhesion and the electrochemical reactivity of Fe2O3 nanoparticles at ITO electrode surfaces are strongly affected by the solution composition and the pH.
Green synthesis via electrolysis in microemulsions
Authors: Rusling James F.
Published: October 2007

Electrolysis in microemulsions is a promising approach for environmentally friendly chemical synthetic methods of the future. Employing microemulsions instead of organic solvents for electrosynthesis has the advantages of lower toxicity and cost, high dissolving power for reactants and mediators of unlike solubility, enhancement of reaction rates by controlling the reduction potentials of mediators, possible reaction pathway control, and recycling of microemulsion components. This paper reviews recent progress in using microemulsions for direct and mediated electrosynthesis, including formation of carbon­carbon bonds. Rates of mediated reactions can be controlled by manipulating microemulsion composition. Examples are presented, in which reaction pathways of direct and mediated electrolyses can be controlled with microemulsions to give desired products in high yields. Such control has been demonstrated with dissolved and surface-bound mediators. For a covalently linked scaffold of poly(l-lysine) and cobalt corrin vitamin B12 hexacarboxylate attached to graphite, catalytic turnover rate for reduction of 1,2-dibromocylcohexane was optimized by optimizing microemulsion composition.
Status of organochlorine (DDT) pollutants and steps toward electrocatalytic reductions
Authors: Kiflom Welderufael G. , Wandiga Shem O. , Kamau Geoffrey N.
Published: October 2007

The accumulation of DDT in the environment over the years is a major concern in the world today. The extent to which DDT may be absorbed and translocated from 14C-p,p¢-DDT contaminated soils into cowpea plant tissues, and the variation of uptake of p,p¢-DDT by the plants in relation to the dissipation of p,p¢-DDT in the soils was studied using a radioisotope technique. Significant absorption and accumulation of residues was observed for the cowpeas grown in two different sites, coastal and highland regions. The degree of uptake varied with soil type and growing conditions. Further results indicated that the higher the water retention by the soil the higher the rate of evaporation of p,p¢-DDT. Coastal region p,p¢-DDT soil samples showed DDE to be the major metabolite. DDT residue in the plants ranged from 0.94 to 7.73 mg/kg, while that in the soils ranged from 88.9 to 32.0 mg/kg. Preliminary electrode reactions indicated lowering of overpotential for reduction of p-chlorophenol by about 1 V, using copper phthalocyanine tetrasodium tetrasulfonate as the catalyst in microemulsion. Microemulsions and appropriate catalysts are a promising system for the decomposition of DDT.
Electrochemical approaches to alleviation of the problem of carbon dioxide accumulation
Authors: Sánchez-Sánchez C. M. , Montiel V. , Tryk D. A. , Aldaz A. , Fujishima A.
Published: October 2007

The electrochemical reduction of CO2, which includes a number of different specific approaches, may show promise as a means to help slow down the accumulation of this greenhouse gas in the atmosphere. Two types of approaches are examined briefly here. First, CO2 can be used as a reagent in the electrocarboxylation reaction to produce organic carboxylic acids, for example, the pharmaceutical ibuprofen. Second, CO2 can be converted to a fuel, either directly or via synthesis gas. The latter can be produced with reasonably good energy efficiency in a gas-diffusion, electrode-based cell even at present with existing electrocatalysts. Oxygen gas is produced as a by-product. Further work is needed to improve the selectivity and efficiency in this and other approaches.
Oxidation of chlorophenols on Pt electrode in alkaline solution studied by cyclic voltammetry, galvanostatic electrolysis, and gas chromatography­mass spectrometry
Authors: Ezerskis Z. , Jusys Z.
Published: October 2007

Potentiodynamic investigations on a platinum electrode show that oxidation of phenol, monochlorophenols, dichlorophenols, 2,3,6-, 2,4,5-, 2,4,6-trichlorophenols, and pentachlorophenol in 1 M NaOH solution, containing 1 mM of phenols, proceeds in the potential region of Pt oxide formation. The oxidation rate of phenols decreases with the increase in the number of chlorine atoms in the benzene ring in the row: phenol > monochlorophenols > dichlorophenols > trichlorophenols > pentachlorophenol. The electrochemical stability of phenols, as studied using a cyclic voltammetry, depends on their chlorination degree and isomerism.

Galvanostatic oxidation of 1 M NaOH solutions containing 1 mM of phenol, monochlorophenols, dichlorophenols, 2,3,6-, 2,4,5-, 2,4,6-trichlorophenols, and pentachlorophenol were carried out on a platinum electrode using 30 mA cm­2 current density. The electrolysis of the solutions was performed in the course of 10 h, and concentration of phenols in the anolytes was monitored during oxidation. The concentration of phenolic compounds diminishes from 1 mM to 10­50 mM during 4­5 h of electrooxidation and does not change during further galvanostatic oxidation.

A decrease in concentration of phenols during galvanostatic electrolysis weakly depends on the isomerism and a chlorination degree of the compounds. A rapid decrease in concentration of studied phenols during the first 4­5 h of electrolysis and a nonselective oxidation of different chlorophenols suggest that the oxidation proceeds via electrochemically generated oxidants. Further decrease in concentration of phenols is rather small due to deactivation of the electrode as a result of polymerization of corresponding phenols and diffusion limitations.
Biphasic sonoelectrosynthesis. A review
Authors: Wadhawan Jay D. , Marken Frank , Compton Richard G.
Published: October 2007

Electrosynthesis can be carried out in emulsions formed in situ via sonication of otherwise immiscible liquid/liquid systems. The basic physical principles underlying these experiments are introduced and illustrated via three examples: the electroreduction of liquid olefins, the Kolbe electrooxidation, and the electrogeneration of leuco-methylene green.
Electrochemical sensors for environmental monitoring. Strategy and examples
Authors: Brett Christopher M. A.
Published: October 2007

The strategy and useful applications of electrochemical sensors for environmental monitoring are surveyed. Potential benefits and important design factors are outlined. Trends in important areas are focused on with illustrative examples, and future perspectives are considered.
Development of a new amperometric biosensor based on polyphenoloxidase and polyethersulphone membrane
Authors: Climent P. V. , Serralheiro M. L. M. , Rebelo M. J. F.
Published: October 2007

An amperometric biosensor based on the enzyme polyphenoloxidase (PPO), which makes the bioelectrocatalysis of phenolic compounds, was developed and optimized using cathecol as substrate. Polyethersulphone membranes were used for enzyme immobilization. Polyphenoloxidase oxidizes monophenols (cresolase activity) and diphenols (catecholase activity) into the corresponding o-quinones; the o-quinones formed in the enzymatic catalysis are then reduced back to cathecol at ­200 mV (vs. Ag, AgCl) at a platinum electrode. The polyphenoloxidase immobilized was from commercial origin or extracted from mushrooms. p-Cresol and phenol substrates were also tested. Reproducibility, response time, linearity, sensitivity, and stability of the biosensor were studied.
Chalcogenide-based chemical sensors for atmospheric pollution control
Authors: Marian S. , Tsiulyanu D. , Marian T. , Liess H.-D.
Published: October 2007

The authors report about characterization of chalcogenide-based thin films, as a materials for gas-sensing applications. The sensing behavior of the As­S­Te films was tested with environmental pollutant gases such as NO2, CO, and SO2. A significant sensitivity has been observed for nitrogen dioxide. The detection range for NO2 was between 0.95­1.9 ppm in ambient air. The response and the recovery time is rapid, with good reproducibility and high sensibility. All the measurements were performed at room temperature. Gas-sensing applications are considered.
Hydrolyzing metal salts as coagulants
Authors: Gregory John , Duan Jinming
Published: October 2007

Aluminium and ferric salts are widely used as coagulants in water and wastewater treatment. They are effective in removing a broad range of impurities from water, including colloidal particles and dissolved organic substances. Their mode of action is broadly understood in terms of essentially two mechanisms: charge neutralization of negatively charged colloids by cationic hydrolysis products and incorporation of impurities in an amorphous precipitate of metal hydroxide. The relative importance of these two mechanisms depends on many factors, especially pH and coagulant dosage.

Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation.

Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved
Extraction and separation of metal cations in solution by supported liquid membrane using lasalocid A as carrier
Authors: Canet L. , Seta P.
Published: October 2007

Flat-sheet-supported liquid membranes incorporating lasalocid A (a natural ionophore), were previously shown to be permeable to metal cations (Cd2+ and Zn2+) against a proton gradient (DpH), which is the driving force of the process [1]. This transport process has been extended to other metal species such as Pb2+, Na+, and Ag+ and also to the case where two metal species compete for transport. A higher transport flux for Pb2+ as compared to Cd2+ and Zn2+ is observed and partly explained by a higher rate of interfacial complexation owing to the smaller hydration shell of this species. This effect is confirmed by the data obtained with Ag+. However, the size of the metal cation in relation to its hydration shell does not appear as the major parameter to take into account for an estimate of the trans-membrane transport efficiency, as the Na+ ions escape to this behavior, which has been considered until now as a general trend for metal cation ionophores.

Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation.

Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved
Use of TOF-SIMS for the analysis of surface metals in H2O2-bleached lignocellulosic fibers
Authors: Mancosky Douglas G. , Lucia Lucian A.
Published: October 2007

Oxidation of cellulose, caused by metal-catalyzed hydrogen peroxide decomposition, is one of the main potential reactions that can occur during the alkaline peroxide bleaching of pulp. This oxidation decreases the individual fiber strength and thus the sheet strength. The bleaching reaction should be controlled to limit cellulose degradation. The goal of this project was to characterize the fiber surface metal distribution using time-of-flight secondary ion mass spectrometry (TOF-SIMS) on laboratory-generated hydrogen peroxide-bleached pulps.

For this study, a single black spruce was chosen and kraft pulped. Peroxide bleaching was conducted via benchtop polyethylene bag bleaching in a temperature-controlled waterbath. The overall metals content was determined using inductively coupled plasma (ICP), whereas the surface metals were determined with TOF-SIMS. Many fundamental approaches to study metal identity and content in fibers have been undertaken, including ICP, electron spectroscopy for chemical analysis (ESCA), X-ray fluorescence, and UV­vis. None of these methods can provide the localized density distribution and metal-mapping ability that is available through TOF-SIMS. It has spectacular imaging capabilities that were exploited for evaluating metals on the fiber sheets used in this work.

The samples were subjected to other sheet and fiber testing. Tests conducted on select samples included brightness and viscosity. Factors in this experiment included metal addition, chelation, and peroxide charge.
Effect of lignin content and magnesium-to-manganese ratio on the selectivity of oxygen delignification in softwood kraft pulp
Authors: Lucia Lucian A. , Smereck Rachel S.
Published: October 2007

A series of oxygen delignification experiments were performed on two softwood kraft pulps that had differing starting lignin contents. One had an initial kappa of 40 and the other 25, corresponding to lignin contents of 6% and 3.75% by dry mass, respectively. Several chemical process modifications were examined to determine their influence over the delignification selectivity and final pulp viscosity. A 2k factorial format was used to assess the significance of varying the temperature, time, and Mg/Mn ratio during the oxygen delignification of the pulps. It was found that the lower lignin content pulp displayed greater delignification selectivity than the higher lignin content pulp. Kappa numbers, viscosity values, and ICP metals contents were determined and are the basis of discussion for the results obtained.
Functional group diversity by ruthenium-catalyzed olefin cross-metathesis
Authors: Toste F. Dean , Chatterjee Arnab K. , Grubbs Robert H.
Published: October 2007

Ruthenium-catalyzed olefin cross-metathesis tolerates a wide range of functional groups, including phosphine-boranes, sulfides, amines, phenols, and oxazolines. The high functional group tolerance allows for the use of an olefin as a linchpin for the synthesis of a variety of bi-, tri-, and tetradentate chiral ligands with a high degree of functional group diversity.
Functionalized main-group organometallics for organic synthesis
Authors: Knochel Paul , Hupe Eike , Dohle Wolfgang , Lindsay David M. , Bonnet Véronique , Quéguiner Guy , Boudier Andreas , Kopp Felix , Demay Stéphane , Seidel Naka , Calaza M. Isabel , Vu Viet Anh , Sapountzis Ioannis , Bunlaksananusorn Tanasri
Published: October 2007

Highly functionalized Grignard-reagents can be easily obtained by an iodine­magnesim exchange reaction and further reacted with various electrophiles. Via a B­Zn exchange reaction, a formal Michael addition with umpolung of the reactivity can be achieved. Chiral phosphine ligands can be easily synthesized by a 2.3 sigmatropic rearrangement and used successfully in asymmetric synthesis.
New applications of organometallic catalysts in organic chemistry
Authors: Fu Gregory C.
Published: October 2007

An overview is provided of our work on tin hydride-catalyzed processes, palladium-catalyzed coupling reactions, and asymmetric catalysis with "planar-chiral" heterocycles.
Copper-mediated asymmetric transformations
Authors: Alexakis Alexandre
Published: October 2007

Copper-catalyzed reactions include the enantioselective conjugate addition and the SN2¢ substitution. We describe the genesis of these reactions, the choice of the primary organometallic reagent, and our studies on finding new Michael acceptors and new ligands. We also report on the use of the zinc enolate generated upon conjugate addition.
Organoboron compounds as mild nucleophiles in Lewis acid- and transition metal-catalyzed C­C bond-forming reactions
Authors: Batey Robert A. , Quach Tan D. , Shen Ming , Thadani Avinash N. , Smil David V. , Li Sze-Wan , MacKay D. Bruce
Published: October 2007

The use of air- and water-stable organoboron compounds for C­C bond-forming reactions are reported. These studies include the Lewis acid-promoted additions of boronic esters to N-acyliminium ions and allyl and crotyltrifluoroborate salts to aldehydes. Aryl and alkenyltrifluoroborate salts will add to aldehydes under the influence of rhodium catalysis or in the presence of zinc metal. These salts also participate in palladium-catalyzed Suzuki­Miyaura and other cross-coupling reactions. Finally, a new type of N-heterocyclic carbene ligand is reported and used for Pd-catalyzed Suzuki­Miyaura couplings.
Novel cyclization and reductive coupling of bicyclic olefins with alkyl propiolates catalyzed by nickel complexes
Authors: Rayabarapu Dinesh Kumar , Cheng Chien-Hong
Published: October 2007

In this article, new metal-mediated cyclization and reductive coupling reactions of bicyclic olefins with alkynes are described. Oxabicyclic alkenes undergo cyclization with alkyl propiolates at 80 C catalyzed by nickel complexes to give benzocoumarin derivatives in high yields. The reaction of bicyclic alkenes (oxa- and azacyclic alkenes) with alkyl propiolates at room temperature in the presence of the same nickel complex gave 1,2-dihydro-napthelene derivatives in good-to-excellent yields. This reductive coupling reaction proceeds under very mild conditions in complete regio- and stereoselective fashion. A mechanism to account for the coumarin formation and the reductive coupling is proposed.
Pauson­Khand-type reaction mediated by Rh(I) catalysts
Authors: Jeong Nakcheol , Sung Byung Ki , Kim Jin Sung , Park Soon Bong , Seo Sung Deok , Shin Jin Young , In Kyu Yeol , Choi Yoon Kyung
Published: October 2007

Cocyclization of alkynes, alkenes, and carbon monoxide by transition metals (known as Pauson­Khand reaction when dicobalt octacarbonyl complexes are used) has been accepted as one of the most powerful tools in the synthesis of cyclopentenones. Despite significant progress in the various aspects of the reaction, we still needed new catalysts to expand the scope of the reaction further.

We found rhodium (I) catalysts, e.g., RhCl(PPh3)3, trans-RhCl(CO)(PPh3)2, RhCl-(CO)(dppe), and trans-[RhCl(CO)(dppp)]2, were also effective for this transformation. The scope and the efficiencies of the reaction could be tuned and expanded by the choice of catalysts. For example, we were able to devise an enantioselective PK-type reaction and a tandem strategy employing two catalysts in one pot. These results will be presented.
Asymmetric dihydroxylation of C,C double bonds using catalytic amounts of osmium tetroxide, selenides, and air
Authors: Krief Alain , Colaux-Castillo Catherine
Published: October 2007

Selenides, selenoxides, osmium tetroxide, and potassium osmate dihydrate are in equilibrium in aqueous tert-butanol containing potassium carbonate. We took advantage of this feature to withdraw the equilibrium in each of the two directions to produce allylalcohols from allylselenides and diols from olefins. The latter reaction performed in the presence of catalytic amounts of Cinchona alkaloids and osmium tetroxide allows the enantioselective dihydroxylation of C,C double bonds.
Bioinspired organometallic chemistry
Authors: Liebeskind Lanny S. , Srogl Jiri , Savarin Cecile , Polanco Concepcion
Published: October 2007

Given the stability of the bond between a mercaptide ligand and various redox-active metals, it is of interest that Nature has evolved significant metalloenzymatic processes that involve key interactions of sulfur-containing functionalities with metals such as Ni, Co, Cu, and Fe. From a chemical perspective, it is striking that these metals can function as robust biocatalysts in vivo, even though they are often "poisoned" as catalysts in vitro through formation of refractory metal thiolates. Insight into the nature of this chemical discrepancy is under study in order to open new procedures in synthetic organic and organometallic chemistry.
Bidentate Lewis acid catalysts in asymmetric synthesis
Authors: Maruoka Keiji
Published: October 2007

The chemistry of bidentate Lewis acids belongs to an unexplored field of science, and so far has been only poorly studied. This paper illustrates the design of several bidentate Al and Ti Lewis acids, and their successful application to selective organic synthesis, particularly to asymmetric synthesis. For example, a new, chiral bidentate Ti(IV) complex is successfully designed by adding commercially available Ti(OPri)4 and (S)-binaphthol sequentially to 2,2'-bis(tritylamino)-4,4'-dichlorobenzophenone in CH2Cl2, and can be utilized for simultaneous coordination to aldehyde carbonyls, thereby allowing the precise enantioface discrimination of such carbonyls for a new catalytic, practical enantioselective allylation of aldehydes with allyltributyltin. This chiral bidentate Ti(IV) catalyst exhibits uniformly high asymmetric induction as well as high chemical yields for various aldehydes. The present enantioselective allylation is highly chemoselective in the presence of other carbonyl moieties.
Nickel-catalyzed cyclizations of alkynyl enones and alkynyl enals
Authors: Montgomery John , Amarasinghe Kande K. D. , Chowdhury Sanjoy K. , Oblinger Eric , Seo Jeongbeob , Savchenko Alexey V.
Published: October 2007

Substrates that possess an a,b-unsaturated carbonyl tethered to an alkyne have been utilized in a variety of nickel-catalyzed processes. Depending on ligand structure, reagent structure, reaction conditions, and workup conditions, several different monocyclic and bicyclic ring systems may be accessed from a common substrate. Evidence for a nickel metallacycle as a common intermediate is provided.
Curiosity and simplicity in the invention and discovery of new metal-mediated reactions for organic synthesis
Authors: Motherwell William B.
Published: October 2007

Two organometallic themes of current interest are presented. The scope and generality of the reductive deoxygenation of carbonyl compounds to organozinc carbenoids using zinc in combination with a silicon electrophile is discussed. Alkoxycyclopropanation can be achieved using orthoformates as substrates. Preliminary observations on the development of a rhodium-catalyzed tandem hydrosilylation­intramolecular aldol sequence are discussed.
Metal-assisted amination with oxime derivatives
Authors: Narasaka Koichi
Published: October 2007

Electrophilic amination of Grignard reagents is accomplished by using O-sulfonyl-oximes of benzophenone derivatives. In the presence of a catalytic amount of CuCN, O-sulfonyloxime of 4,4¢-bis(trifluoromethyl)benzophenone reacts with alkyl Grignard reagents in tetrahydrofuran (THF) and hexamethylphosphoramide (HMPA), yielding primary alkyl-amines by successive hydrolysis of the resulting N-alkylimines. Arylamines are also prepared as well as alkylamines by treating O-sulfonyloxime of 3,3¢,5,5¢-tetrakis(trifluoromethyl)benzophenone in toluene-ether with Grignard reagents.

Various cyclic imines are synthesized by palladium-catalyzed cyclization of olefinic oxime derivatives. That is, the reaction of O-pentafluorobenzoyloximes of olefinic ketones with a catalytic amount of Pd(PPh3)4 and triethylamine in dimethylformamide (DMF) affords nitrogen-containing heterocycles, such as pyrroles, pyridines, isoquinolines, spiro-imines, and aza-azulenes. This reaction proceeds via the initial formation of alkylideneaminopalladium species generated by oxidative addition of oximes to Pd(0), and the successive intramolecular Heck-type amination occurs on the olefinic moiety.
Zirconium-catalyzed enantioselective carboalumination of "unactivated" alkenes as a new synthetic tool for asymmetric carbon­carbon bond formation
Authors: Negishi Ei-ichi , Huo Shouquan
Published: October 2007

The discovery, methodological developments, including those for separation­purification of chiral flexible primary alcohols, and their applications to the syntheses of some natural products of the titled reaction are discussed.
New cyclization reactions in organic syntheses
Authors: Ojima Iwao
Published: October 2007

Recent development in the transition metal-catalyzed cyclization reactions for organic syntheses in the author's laboratories is summarized, which includes (i) novel silylcarbocyclizations (SiCaCs) and carbonylative carbotricyclizations, (ii) intramolecular silylformylations and desymmerization of siloxydiynes by sequential double silylformylation, (iii) efficient total synthesis of (+)-prosopinine, (iv) enantioselective desymmetrization of aminodienes, and (iv) new and efficient routes to 1-azabicyclo[x.y.0]alkane amino acids. All these processes are catalyzed by Rh or Rh­Co complexes, and useful for rapid and efficient construction of a variety of heterocyclic and carbocyclic compounds. Mechanisms of these new carbocyclization and cyclohydrocarbonylation reactions are also discussed.
Stereoselective syntheses of heterocycles via metallated alkoxyallenes
Authors: Reissig Hans-Ulrich , Schade Wolfgang , Okala Amombo G. Marlyse , Pulz Robert , Hausherr Arndt
Published: October 2007

n-Butyllithium smoothly deprotonates alkoxyallenes at C-1. The generated lithiated species reacts with a variety of electrophiles furnishing after cyclization functionalized furan, pyrrole, or 1,2-oxazine derivatives. The formation of new C­C bonds often occurs with high stereoselectivities, which are exploited for efficient and selective syntheses of natural products or other compounds of interest.
Critical evaluation of proven chemical weapon destruction technologies (IUPAC Technical Report)
Authors: Pearson Graham S. , Magee Richard S.
Published: October 2007

A critical evaluation is made of the chemical weapon destruction technologies demonstrated for 1 kg or more of agent in order to provide information about the technologies proven to destroy chemical weapons to policy-makers and others concerned with reaching decisions about the destruction of chemical weapons and agents. As all chemical agents are simply highly toxic chemicals, it is logical to consider the destruction of chemical agents as being no different from the consideration of the destruction of other chemicals that can be as highly toxictheir destruction, as that of any chemicals, requires the taking of appropriate precautions to safeguard worker safety, public health, and the environment. The Chemical Weapons Convention that entered into force in 1997 obliges all States Parties to destroy any stockpiles of chemical weapons within 10 years from the entry into force of the Conventionby 2007with the possibility of an extension for up to 5 years to 2012. There is consequently a tight timeline under the treaty for the destruction of stockpiled chemical weapons and agentsprimarily held in Russia and the United States. Abandoned or old chemical weaponsnotably in Europe primarily from World War I, in China from World War II as well as in the United Statesalso have to be destroyed. During the past 40 years, more than 20 000 tonnes of agent have been destroyed in a number of countries and over 80 % of this has been destroyed by incineration. Although incineration is well proven and will be used in the United States to destroy over 80 % of the U.S. stockpile of 25 800 tonnes of agent, considerable attention has been paid particularly in the United States to alternative technologies to incineration because of several constraints that are specific to the United States. Much of the information in this report is based on U.S. experienceas the United States had, along with the Russian Federation, by far the largest stockpiles of chemical weapons and agents anywhere in the world. The United States has made much progress in destroying its stockpile of chemical weapons and agents and has also done more work than any other country to examine alternative technologies for the destruction of chemical weapons and agents. However, the national decisions to be taken by countries faced with the destruction of chemical weapons and agents need to be made in the light of their particular national conditions and standardsand thus may well result in a decision to use different approaches from those adopted by the United States. This report provides information to enable countries to make their own informed and appropriate decisions.
Plasma processing and chemistry
Authors: Schram Daniel C.
Published: October 2007

Plasma deposition and plasma conversion can be characterized by five steps: production by ionization, transfer of chemistry to precursors, transport of radicals to the surface, surface interactions with deposition, recirculation and generation of new monomers. For very fast deposition, large flows of radicals are needed and a regime is reached, in which monolayer coverage is reached in a very short time. Such large flows of radicals can be obtained by ion-induced interactions, as the C2H radical from acetylene for a-C:H deposition, or by H atom abstraction as the SiH3 radical from SiH4 for a-Si:H deposition. These radicals with intermediate sticking coefficient are advantageous as they are mobile and have a finite dwelling time at the surface. By such a pure radical mechanism, good layers can be formed with very high growth rates, if large radical fluxes can be reached. This regime of high fluence is also interesting for conversion, of which ammonia formation from hydrogen and nitrogen atoms is given as an example. These new approaches offer new possibilities for further development of the field in close connection with surface science, catalysis, and materials science.
Study for plasma etching of dielectric film in semiconductor device manufacturing. Review of ASET research project
Authors: Sekine Makoto
Published: October 2007

Conventional developments were conducted in a very empirical way, such as a trial and error with many speculations using qualitative data. This approach requires more and more resources and time for the development of future devices with a design rule below 100 nm in the system on a chip (SOC) era. It is necessary to establish a systematic methodology for process development and qualification. ASET Plasma Laboratory had been found to research a basis for the systematic development of the plasma etching technology. Fluorocarbon (CF) plasma for the etching of high-aspect-ratio contact holes in SiO2 was investigated intensively in the 5-year program that finished in March 2001. They introduced 5 plasma sources that can etch 0.1-mm contact holes on a 200-mm wafer in production, and state-of-the-art diagnostics tools for the plasma and etched surface. The SiO2 etch mechanism was revealed from the etch species generation to the reaction in a deep hole. The number of electron collisions to fluorocarbon gas molecule is proposed as an important parameter to control the gas dissociation and etch species flux to the surface. An etch reaction model was also proposed using the estimated-surface-reaction probability that is a function of ion energy and CF polymer thickness that reduces the net ion energy to the reaction layer. The CF polymer thickness was determined by a balance equation of generation term (radical fluxes) and loss terms (etching by ions, radicals, and out-flux oxygen from SiO2). A program was developed and successfully predicts the etch rates of Si-containing materials, including organic dielectrics. Requirements for the next-generation plasma etch tools are also discussed.
Diagnostics of etching plasmas
Authors: Booth Jean-Paul
Published: October 2007

Radio-frequency excited, low-pressure plasmas in halogen-containing gases are widely used to etch submicronic features in a range of materials during integrated circuit manufacture. Costly process-drift problems are often caused by the ubiquitous deposition of polymer layers on the reactor walls. Simple and robust sensors of the reactor performance are needed to monitor and manage these effects. This paper presents results obtained in industrial plasma-etching machines using a deposition-tolerant ion flux probe and broadband UV­vis absorption spectroscopy.
Role of ions in SiO2 deposition with pulsed and continuous helicon plasmas
Authors: Charles Christine
Published: October 2007

Good-quality silicon dioxide films have been deposited at low temperature (200 °C) using continuous and pulsed oxygen/silane plasmas coupled in a high-density, low-pressure helicon reactor. Although the total ion flux determines many of the structural properties of the deposited oxide, we have found that silicon-containing ions contribute to the film growth (up to 50 %) and appear to be responsible for the measured compressive stress.
Plasma-assisted production of hydrogen from hydrocarbons
Authors: Deminsky Maxim , Jivotov Victor , Potapkin Boris , Rusanov Vladimir
Published: October 2007

This paper is dedicated to the discussion of possible plasma applications for hydrogen-rich gas production from hydrocarbons. Different types of plasma, both thermal and nonequilibrium ones, are under consideration. A special attention is devoted to experimental and theoretical results on hydrocarbon conversion in nonequilibrium plasma of pulse microwave discharge. A comparison of plasma methods and conventional catalytic technology is presented as well.
Generation of thermal plasmas in liquid-stabilized and hybrid dc-arc torches
Authors: Hrabovský Milan
Published: October 2007

The paper presents survey of principles and basic physical parameters of liquid and hybrid gas/liquid dc-arc plasma torches and discusses physical mechanisms that control plasma properties. Special attention is devoted to properties of generated plasma that are decisive for performance characteristics in plasma spraying. Characteristics of water and water-argon torches are compared with typical characteristics of commonly used gas torches.
Nonthermal and nonequilibrium effects in high-power pulsed ICP and application to surface modification of materials
Authors: Ishigaki T. , Okada N. , Ohashi N. , Haneda H. , Sakuta T.
Published: October 2007

Newly developed pulse-modulated high-power inductively coupled plasma (ICP) is expected to offer the unique physicochemical condition, such as the increased concentration of chemically reactive species, as well as the appropriate heat flux for materials processing. Two kinds of oxide materials, titanium and zinc oxide, were placed at the downstream of Ar­H2 ICP and irradiated in the plasma of continuous (CN) and pulse-modulated (PM) modes. The CN-ICP irradiation at the position close to the plasma tail gave rise to the thermal reduction of oxides. In the PM-ICP irradiation, the degree of thermal reduction depended on the lower power level during pulse-off time, as well as the total electric power. Irradiation in PM-ICP led to the increased formation of oxygen vacancies in titanium dioxide. In the case of zinc oxide, the UV emission efficiency was improved by PM-ICP irradiation, while the green emission became predominant by CN-ICP irradiation at the appropriate position. Induced effects in the two oxides by PM-ICP would be related to the high concentration of hydrogen radicals in the plasma.
Ultrashort pulsed barrier discharges and applications
Authors: Okazaki Ken , Nozaki Tomohiro
Published: October 2007

Atmospheric pressure nonequilibrium plasmas have made a recent remarkable progress in formation techniques including atmospheric pressure glow discharge (APG), dielectric barrier discharge (DBD), corona discharge, surface discharge, ultrashort pulsed discharge, etc., and are expanding their applications into the field of energy and environment as well as material conversion processes. This paper will especially focus on a large improvement of DBD by combining it with squared ultrashort high voltage pulses and various applications.
"Simple" diagnostics for characterization of low-pressure chemically active plasmas
Authors: Otorbaev D. K.
Published: October 2007

In the current paper, the "simple" diagnostics for characterization of nonequilibrium chemically active plasmas are discussed. As to experimental methods, "simple" noninvasive spectroscopic methods of ionizing and recombining plasma characterization have been emphasized. The word "simple" in the title is presented in quotes, which means that the methods are assumed to be simple only conditionally. In order to be sure that the measurements indeed provide correct information on the plasma parameters, a detailed understanding of kinetics of each particular plasma source is required. Moreover, the validity of spectroscopic methods should be checked by independent diagnostic techniques.
Excilamps as efficient UV­VUV light sources
Authors: Tarasenko Victor F.
Published: October 2007

Operating parameters of powerful UV and vacuum ultraviolet (VUV) excilamps with different discharge geometry excited by capacitive discharge, barrier discharge, glow discharge, and UV-preionized discharge were investigated. Intense radiation of Ar2*, Kr2*, Xe2*, ArF*, KrBr*, KrCl*, KrF*, XeI*, Cl2, XeBr*, XeCl*, XeF* molecules and I* atoms was obtained in rare gas or in rare gas­F2 (Br2, CH3Br, Cl2, Br2, HCl, I2, NF3) mixtures.
Superhard nanocomposite coatings. From basic science toward industrialization
Authors: Veprek S. , Jilek M.
Published: October 2007

A variety of superhard coatings with Vickers plastic hardness exceeding 40 GPa have been reported by several research groups during the last five years (for recent reviews see refs [1,2]). However, one has to distinguish between superhard nanocomposites, such as nc-TiN/a-Si3N4, nc-TiN/a-Si3N4/a- and nc-TiSi2, nc-(Ti1-xAlx)N/a-Si3N4, nc-TiN/TiB2, nc-TiN/BN, etc. where the high hardness originates from the nanostrucutre and, therefore, remains stable upon annealing to high temperatures [1], and coatings, such as CrN/Ni, ZrN/Ni, and others [2] in which the measured high hardness is due to a high compressive stress that is induced in the coatings due to energetic ion bombardment during their deposition (e.g., by magnetron sputtering). We also summarize the recent progress in the industrial applications of the superhard nanocomposite coatings on machining tools.
Clustering phenomena in low-pressure reactive plasmas. Basis and applications
Authors: Watanabe Y. , Shiratani M. , Koga K.
Published: October 2007

Clustering phenomena of particles below a few nm in size in low-pressure reactive plasmas have been studied in capacitively coupled high-frequency SiH4 discharges. Clusters nucleate around a size of 0.5 nm, Si4Hx and subsequently grow due to influxes of SinHx (1 < n < 4) and other molecular species. Because of long gas-residence time and small surface loss-probability of clusters, even neutral ones accumulate to nucleate in the reactor. Appearance of negatively charged clusters is considered to become noticeable at around Si4Hx. The growth of clusters is suppressed by using thermophoretic force, gas flow, periodical discharge modulation, and hydrogen dilution. The reactor has been newly developed to suppress the growth of clusters both by thermophoretic force and by gas flow and evacuation without stagnation. Using the reactor, a-Si:H films of extremely high quality have been successfully deposited.
How to exploit ion-induced stress relaxation to grow thick c-BN films
Authors: Ziemann P. , Boyen H.-G. , Deyneka N. , Widmayer P. , Banhart F.
Published: October 2007

A recently developed procedure is reviewed allowing thick (>1 mm), high-quality c-BN films (>80 % c-BN) to be grown. It is based on the observation that compressive stress inevitably present in such films can be released by medium-energy (some hundred keV) ion irradiation without destroying the cubic phase.
Definitions of basic terms relating to polymer liquid crystals (IUPAC Recommendations 2001)
Authors: Barón Máximo , Stepto R. F. T.
Published: October 2007

The document first gives definitions of basic terms related to liquid-crystalline and mesomorphic states of matter and then terms specific to the classification of liquid-crystal polymers. The terms have been restricted to those most commonly encountered in the structural description of the latter class of materials.

The terms have been selected from the recently published comprehensive document "Definitions of basic terms relating to low-molar-mass and polymer liquid crystals" [Pure and Applied Chemistry
73(5), 845-895 (2001)] and are intended to form a readily usable guide for the reader interested in the structural description of polymer liquid crystals. The more comprehensive document should be used for terminology associated with types of mesophases and the optical and physical characteristics of liquid-crystalline materials.

The advice given by representatives of the International Liquid Crystal Society for the preparation of this document is gratefully acknowledged.
Biodiversity: A wonderful source of exciting new pharmacophores. Further to a new theory of memory
Authors: Atta-ur-Rahman  , Choudhary M. Iqbal
Published: October 2007

The diverse biological resources in nature are vast factories of chemical diversity. With the recent advances in the biological and chemical sciences it is now easier than ever to explore the potential uses of immense biological resources in a sustainable manner. Our investigations focused on the bioprospecting of both terrestrial and marine organisms have led to the discovery of a number of interesting chemical compounds. The discovery of a new class of cholinesterase, α-glucosidase and phosphodiesterase I inhibitors, several new antioxidants, and other classes of bioactive natural products is presented. The theory of the chemical basis of memory through hydrogen bonding in the brain is further elaborated.