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Reaction Behavior (reaction + behavior)
Selected AbstractsRoom-Temperature Solid-State Reaction Behavior, Hydrothermal Crystallization and Physical Characterization of NaRE(MoO4)2, and Na5Lu(MoO4)4 CompoundsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010Jianhua Wu In the context, a novel composite synthesis technology is engaged in the preparation of NaRE(MoO4)2 (RE=Y, La, Nd, Eu, Gd, Tb, Er, and Yb) and Na5Lu(MoO4)4 compounds, which involves a room-temperature solid-state reaction and hydrothermal crystallization process. The synthesis mechanism is predicted, indicating that higher temperature and moisture can speed up the reaction process and especially the existence of crystalline water molecules in the precursor is necessary for the solid-state reaction at room temperature. It is found that different rare-earth nitrate precursors present different reactivity to sodium molybdate at room temperature. The crystallization degree of the products after the room-temperature solid-state reaction depends on the melting point of rare-earth nitrate precursors. The hydrothermal treatment is beneficial for the good crystallization of NaRE(MoO4)2 (RE=Y, La, Nd, Eu, Gd, Tb, Er, and Yb) and Na5Lu(MoO4)4. Finally, the photoluminescent spectra for these NaRE(MoO4)2:Eu3+ (La, Gd, and Y) are studied, which depend on the species of rare-earth ions. [source] Subcritical Water Reaction Behavior of D -Glucose as a Model Compound for Biomass Using Two Different Continuous-Flow Reactor ConfigurationsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2009T. Saito Abstract Recently, cellulosic materials have been considered as a useful resource for the recovery of valuable chemicals and liquid fuels, etc. Cellulose is a homopolymer of D -glucose, which is often used as a model compound for biomass. Reactions of D -glucose in subcritical water as the reaction solvent were conducted using a single-flow-type reactor (S1) and an admixture-type reactor with feed and preheated-water flow (S2) at temperatures from 200 to 240,°C, pressures from 15 to 20 MPa, residence times from 40 to 120 s, and initial feed concentrations of 1.5,10 wt %. D -Glucose was converted into aldehydes, organic acids and furans, with mainly organic acids obtained at 240,°C. D -Glucose decomposition using reactors S1 and S2 revealed that the conversion rate of D -glucose was promoted more using S2 than by S1. The yield of furans with S1 was higher than with S2, while the yield of organic acids from S1 was lower than that from S2. [source] Palladium(II) Complexes of C2 -Bridged Chiral Diphosphines: Application to Enantioselective Carbonyl-Ene ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010He-Kuan Luo Abstract (11bR,11,bR)-4,4,-(1,2-Phenylene)bis[4,5-dihydro-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin] [abbreviated as (R)-BINAPHANE], (3R,3,R,4S,4,S,11bS,11,bS)-4,4,-bis(1,1-dimethylethyl)-4,4,,5,5,-tetrahydro-3,3,-bi-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin [(S)-BINAPINE], (1S,1,S,2R,2,R)-1,1,-bis(1,1-dimethylethyl)-2,2,-biphospholane [(S,S,R,R)-TANGPHOS] and (2R,2,R,5R,5,R)-1,1,-(1,2-phenylene)bis[2,5-bis(1-methylethyl)phospholane] [(R,R) -i- Pr-DUPHOS] are C2 -bridged chiral diphosphines that form stable complexes with palladium(II) and platinum(II) containing a five-membered chelate ring. The Pd(II)-BINAPHANE catalyst displayed good to excellent enantioselectivities with ee values as high as 99.0% albeit in low yields for the carbonyl-ene reaction between phenylglyoxal and alkenes. Its Pt(II) counterpart afforded improved yields while retaining satisfactory enantioselectivity. For the carbonyl-ene reaction between ethyl trifluoropyruvate and alkenes, the Pd(II)-BINAPHANE catalyst afforded both good yields and extremely high enantioselectivities with ees as high as 99.6%. A comparative study on the Pd(II) catalysts of the four C2 -bridged chiral diphosphines revealed that Pd(II)-BINAPHANE afforded the best enantioselectivity. The ee values derived from Pd(II)-BINAPHANE are much higher than those derived from the other three Pd(II) catalysts. A comparison of the catalyst structures shows that the Pd(II)-BINAPHANE catalyst is the only one that has two bulky (R)-binaphthyl groups close to the reaction site. Hence it creates a deep chiral space that can efficiently control the reaction behavior in the carbonyl-ene reactions resulting in excellent enantioselectivity. [source] Copolymerization of 2-Acrylamido-2-methyl-1-propanesulfonic Acid and 1-Vinylimidazole in Inverse MiniemulsionMACROMOLECULAR REACTION ENGINEERING, Issue 2 2008Susann Wiechers Abstract The copolymerization behavior of the acidic monomer 2-acrylamido-2-methyl-1-propanesulfonic acid (APSA) and 1-vinylimidazole in inverse miniemulsion was studied under various conditions. Initially, different surfactants and surfactant concentrations were investigated. After determining a suitable composition of the miniemulsion, changes in the reaction behavior under different pH values and monomer feed compositions were studied. The highest polymerization rates could be produced under neutral conditions over all monomer feed ratios. The addition of acid or base to change the pH value of the monomer mixture also has influence on the polymers obtained. The thermal stability, rheological stiffness and intrinsic viscosity increase when Na-APSA is incorporated. [source] Using the Weapons You Have: The Role of Resources and Competitor Orientation as Enablers and Inhibitors of Competitive Reaction to New Products,THE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 2 2010Marion Debruyne It is a well-accepted notion that to respond to competitive attacks firms need the necessary resources to do so. However, the presence of resources may not be a sufficient condition to enhance competitive responsiveness. Following a managerial decision-making approach, the present paper investigates how the availability of resources affects decision makers' assessment of a competitor's new product and their subsequent reaction to it. This study posits that competitive reaction follows from a decision maker's assessment of a competitive action. This assessment contains a motivation dimension and an ability dimension. The effect of three types of resources,financial, marketing, and technological,are examined. A quasi-experiment with the Markstrat business game as an empirical setting provided 339 questionnaires containing information on 29 different new product introductions. The motivation and ability dimensions are confirmed as important antecedents explaining reaction behavior. The results show that resources possess a dual, and opposing, role in influencing competitive reaction to new products. On the one hand, resources enhance decision makers' belief that they are able to react effectively to competitive attacks, but the presence of resources also makes them less motivated to react. The paper introduces two explanations for this: the liability-of-wealth hypothesis and the strong-competitor hypothesis. The addition of competitor orientation as a moderator allows us to discern between the two competing rationales for the existence of a negative effect of resources on the expected likelihood of success of a competitive new product introduction, supporting the liability-of-wealth hypothesis. The paper demonstrates the key role of competitor orientation and formulates implications from that. [source] Influence of water-miscible organic solvents on kinetics and enantioselectivity of the (R,-specific alcohol dehydrogenase from Lactobacillus brevisBIOTECHNOLOGY JOURNAL, Issue 5 2006Jan Schumacher Abstract Using the organic solvents acetonitrile and 1,4-dioxane as water-miscible additives for the alcohol dehydrogenase (ADH)-catalyzed reduction of butan-2-one, we investigated the influence of the solvents on enzyme reaction behavior and enantioselectivity. The NADP+ -dependent (R,-selective ADH from Lactobacillus brevis (ADH-LB) was chosen as biocatalyst. For cofactor regeneration, the substrate-coupled approach using propan-2-ol as co-substrate was applied. Acetonitrile and 1,4-dioxane were tested from mole fraction 0.015 up to 0.1. Initial rate experiments revealed a complex kinetic behavior with enzyme activation caused by the substrate butan-2-one, and increasing KM values with increasing solvent concentration. Furthermore, these experiments showed an enhancement of the enantioselectivity for (R,-butan-2-ol from 37% enantiomeric excess (ee) in pure phosphate buffer up to 43% ee in the presence of 0.1 mol fraction acetonitrile. Finally, the influence of the co-solvents on water activity of the reaction mixture and on enzyme stability was investigated. [source] Orientational Control of Guest Molecules in an Organic Intercalation System by Host Polymer TacticityCHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2006Shinya Oshita Abstract Four kinds of stereoregular poly(muconic acid)s, which are synthesized by topochemical polymerization and subsequent solid-state hydrolysis, are used as the organic host materials for intercalation. We describe the reaction behavior and layered structure of intercalation compounds using stereoregular poly(muconic acid)s and n -alkylamines as host and guest, respectively. The packing structure of the guest alkylamines was determined by X-ray diffractions as well as IR and Raman spectroscopies. We have found that the orientation of the guest molecules is controlled by the host polymer tacticity, depending on the structure of the two-dimensional hydrogen-bonding network formed in the polymer sheets of the crystals. [source] | |||||||||||||