Home About us Contact
|
Home About us Contact | ||
|
|
||
Order Reaction (order + reaction)
Kinds of Order Reaction Selected AbstractsInorganic reactions of iodine(+1) in acidic solutionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2004Guy Schmitz We present a thorough analysis of the former works concerning the hydrolysis of iodine and its mechanism in acidic or neutral solutions and recommend values of equilibrium and kinetic constants. Since the literature value for the reaction H2OI+ , HOI + H+ appeared questionable, we have measured it by titration of acidic iodine solutions with AgNO3. Our new value, K(H2OI+ , HOI + H+) , 2 M at 25°C, is much larger than accepted before. It decreases slowly with the temperature. We have also measured the rate of the reaction 3HOI , IO3, + 2I, + 3H+ in perchloric acid solutions from 5 × 10,2 M to 0.5 M. It is a second order reaction with a rate constant nearly independent on the acidity. Its value is 25 M,1 s,1 at 25°C and decreases slightly when the temperature increases, indicating that the disproportionation mechanism is more complicated than believed before. An analysis of the studies of this disproportionation in acidic and slightly basic solutions strongly supports the importance of a dimeric intermediate 2HOI , I2O·H2O in the mechanism. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:480,493, 2004 [source] A review of the kinetics of degradation of inosine monophosphate in some species of fish during chilled storageINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2006Peter Howgate Summary A literature search was made for data on the concentrations of inosine monophosphate (IMP) and its degradation products, inosine (Ino) and hypoxanthine (Hx), in the flesh of vertebrate fish during storage in ice. Twenty-one publications containing data for forty-five species were selected for review. A mathematical model was developed for analysing the data by assuming that the kinetics of degradation of IMP could be modelled as consecutive first order reactions. The model was fitted to the data and in about half of the cases examined in the review the data suggested that IMP and degradation products were lost by leaching and the kinetic model was extended to allow for this loss. In all of the cases reviewed the mathematical model was a good fit to the experimental data and the reaction rates for the reactions are tabulated in the paper. In all species the concentration of IMP decreased as a first order reaction, but for thirteen of the species examined the enzyme model of IMP to Ino to Hx did not fit the data in that either Ino or Hx did not accumulate in the muscle. There were only a few examples of replications of storage trials within species and comparison of the outcomes of these replications suggested that season or, in the case of farmed fish, genetic stock or cultural practices might influence initial IMP concentrations or reaction rates. [source] Kinetics of Lysine and Other Amino Acids Loss During Extrusion Cooking of Maize GritsJOURNAL OF FOOD SCIENCE, Issue 2 2003S. Ilo ABSTRACT: Maize grits were extrusion-cooked in a conical, counter-rotating twin-screw extruder at different barrel temperatures, feed moistures, and screw speeds. Residence time distribution was measured by a dye tracer technique. Experiments with lysine-fortified maize grits showed a 1st order reaction for lysine loss. A detailed kinetic study has been performed for the losses during extrusion cooking of lysine, cystine, and arginine. The 1st-order rate constants were dependent mainly on product temperature and feed moisture, whereas screw speed had no influence. Activation energy of lysine, arginine, and cystine loss was 127, 68, and 76 kJ/mol, respectively. Shear stress significantly affected the rate constants of amino acids loss in extrusion cooking. [source] Atom transfer radical polymerization and copolymerization of vinyl acetate catalyzed by copper halide/terpyridineAICHE JOURNAL, Issue 3 2009Huadong Tang Abstract Copper-mediated atom transfer radical polymerization (ATRP) is versatile for living polymerizations of a wide range of monomers, but ATRP of vinyl acetate (VAc) remains challenging due to the low homolytic cleavage activity of the carbon-halide bond of the dormant poly(vinyl acetate) (PVAc) chains and the high reactivity of growing PVAc radicals. Therefore, all the reported highly active copper-based catalysts are inactive in ATRP of VAc. Herein, we report the first copper-catalyst mediated ATRP of VAc using CuBr/2,2,:6,,2,-terpyridine (tPy) or CuCl/tPy as catalysts. The polymerization was a first order reaction with respect to the monomer concentration. The molecular weights of the resulting PVAc linearly increased with the VAc conversion. The living character was further proven by self-chain extension of PVAc. Using polystyrene (PS) as a macroinitiator, a well-defined diblock copolymer PS-b-PVAc was prepared. Hydrolysis of the PS-b-PVAc produced a PS-b-poly(vinyl alcohol) amphiphilic diblock copolymer. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Fluorescence Quenching of Pheophytin-a by Copper(II) IonsCHINESE JOURNAL OF CHEMISTRY, Issue 3 2009Mingbo HU Abstract A method was developed for determination of Cu(II) ions quantitatively by measuring fluorescent intensity of pheophytin-a (Pheoa) solution. The Pheoa was obtained by de-intercalation of magnesium from the porphyrin ring of chlorophyll-a (Chla) extracted from fresh spinach leaves. Its two UV-Vis absorption peaks at 505 and 535 nm in acetone solution have been observed but disappeared when the acetone solution of Pheoa was mixed with a Cu(II) ion aqueous solution. A fluorescence quenching phenomenon was thus observed when the acetone solution of Pheoa was mixed with an aqueous solution of Cu(II) ions. However, other physiologically relevant cations rarely caused any quenching fluorescence of Pheoa under the same experimental conditions. Kinetics of the fluorescence fading process was investigated by measuring the effects of Cu(II) ion concentration, reaction time and reaction temperature on the fluorescence intensity of the Pheoa acetone solution. An activation energy of (10±1) kJ·mol,1 was estimated from Arrhenius empirical relation assuming that the interaction between the Pheoa and the Cu(II) ions was the first order reaction. The calibration graph obtained with the fluorescence was linear over the Cu(II) concentration range of 8.0×10,5,8.0×10,7 mol·dm,3 with a detection limit of 8.0×10,7 mol·dm,3 for Cu(II) ion. [source] A review of the kinetics of degradation of inosine monophosphate in some species of fish during chilled storageINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2006Peter Howgate Summary A literature search was made for data on the concentrations of inosine monophosphate (IMP) and its degradation products, inosine (Ino) and hypoxanthine (Hx), in the flesh of vertebrate fish during storage in ice. Twenty-one publications containing data for forty-five species were selected for review. A mathematical model was developed for analysing the data by assuming that the kinetics of degradation of IMP could be modelled as consecutive first order reactions. The model was fitted to the data and in about half of the cases examined in the review the data suggested that IMP and degradation products were lost by leaching and the kinetic model was extended to allow for this loss. In all of the cases reviewed the mathematical model was a good fit to the experimental data and the reaction rates for the reactions are tabulated in the paper. In all species the concentration of IMP decreased as a first order reaction, but for thirteen of the species examined the enzyme model of IMP to Ino to Hx did not fit the data in that either Ino or Hx did not accumulate in the muscle. There were only a few examples of replications of storage trials within species and comparison of the outcomes of these replications suggested that season or, in the case of farmed fish, genetic stock or cultural practices might influence initial IMP concentrations or reaction rates. [source] Kinetics of degradation of adenosine triphosphate in chill-stored rainbow trout (Oncorhynchus mykiss)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2005Peter Howgate Summary Trout that had been held in freshwater or in sea water were stored at 0, 5, or 10 °C, and in the case of sea-water-held trout, also at 15 °C. Samples were taken during storage for analysis of ATP-derived metabolites. The kinetics of degradation of ATP were investigated using two mathematical models, one depending on only endogenous enzymes acting in a sequence of consecutive first order reactions, and one assuming inosine was additionally converted to hypoxanthine by bacterial action. The former model adequately fitted the data from trout held in sea water, but the latter model was a better fit to data from the trout held in freshwater. The activation energy of loss of inosine monophosphate was estimated to be 17.4 kcal mol,1. [source] Pyrolysis Kinetics of Wood and Wood ComponentsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 10 2005T. Willner Abstract The kinetics of pyrolysis decomposition reactions of wood and its components are described employing mathematical modeling tools for first and nth order reactions, autocatalytic reactions, and parallel first order and autocatalytic reactions. Secondary reactions may accelerate the reaction rate and a new autocatalytic reaction model was developed to describe this specific behavior. [source] | ||||||||||