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Rates and kinetics

Lin C Y and Dunbar R C 1994 Time-resolved photodissociation rates and kinetic modeling for unimolecular dissociations of iodotoluene ions J. Rhys. Chem. 98 1369-75... [Pg.1360]

The influence of added species upon the rates and kinetic forms of nitration in organic solvents were of the greatest importance in elucidating details of the processes involved, particularly of the steps leading to the nitronium ion. These influences will first be described, and then in the following section explained. The species to be considered are sulphuric acid, nitrate ions, urea and water. The effect of nitrous acid is considered later ( 4.3). [Pg.40]

TABLE 18-6 Growth Rates and Kinetic Equations for Some Industrial Crystallized Products... [Pg.1662]

Experimental analysis involves the use of thermal hazard analysis tests to verify the results of screening as well as to identify reaction rates and kinetics. The goal of this level of testing is to provide additional information by which the materials and processes may be characterized. The decision on the type of experimental analysis that should be undertaken is dependent on a number of factors, including perceived hazard, planned pilot plant scale, sample availability, regulations, equipment availability, etc. [Pg.25]

RELATIVE RATES (AND KINETIC ORDERS) FOR BROMINATION IN HOAC-CHCI3 (OR... [Pg.115]

It has often been questioned whether the rates and kinetics of purified enzymes, determined in very dilute solutions with high concentrations of their substrates, but not always of their cofactors, can be extrapolated to the conditions prevailing in the matrix. Much of the mitochondrial water will be bound to protein by hydrogen bonds and electrostatically, but there is also a pool of free water which may only be a fraction of the total water (Gitomer, 1987). The molar concentrations of intermediates of the citrate cycle and of p-oxidation are very low, usually less than those of most enzymes (Srere, 1987 Watmough et al., 1989 Sumegi et al., 1991). The extent to which cofactors and intermediates bind specifically or nonspecifically to enzymes is not known. It is therefore difficult to estimate concentration of these... [Pg.117]

The reaction is strongly acid-inverse below pH 4 but becomes acid-independent above pH 5.5. The rate and kinetics are identical with those of the autoxidation of Mo( V)2 and it seemd probable that dissociation of the dimer is rate-determining, viz. [Pg.468]

The kinetics of ethylene hydrogenation on small Pt crystallites has been studied by a number of researchers. The reaction rate is invariant with the size of the metal nanoparticle, and a structure-sensitive reaction according to the classification proposed by Boudart [39]. Hydrogenation of ethylene is directly proportional to the exposed surface area and is utilized as an additional characterization of Cl and NE catalysts. Ethylene hydrogenation reaction rates and kinetic parameters for the Cl catalyst series are summarized in Table 3. The turnover rate is 0.7 s for all particle sizes these rates are lower in some cases than those measured on other types of supported Pt catalysts [40]. The lower activity per surface... [Pg.156]

Table 3. Ethylene hydrogenation reaction rates and kinetic parameters for both series of Pt/SBA-15 catalysts [13,16]. Table 3. Ethylene hydrogenation reaction rates and kinetic parameters for both series of Pt/SBA-15 catalysts [13,16].
Reaction (15) contributes to the chain propagation. The higher rates of this reaction correspond to lower inhibitory efficiencies and lower stoichiometric coefficients of inhibition. The equations describing the induction period, oxidation rate, and kinetics of oxygen consumption for this mechanism when ki5[02] [In] > v i are given here. [Pg.497]

Table 7 Water-gas shift rates and kinetic data for M(CO)6 catalysts54... Table 7 Water-gas shift rates and kinetic data for M(CO)6 catalysts54...
Table 61 Rates and kinetic data for supported Cu catalysts. Rates at 200 °C, 1 atm pressure, 7%CO, 8.5% COz, 22%H20, 37%H2, and 25%Ar331... Table 61 Rates and kinetic data for supported Cu catalysts. Rates at 200 °C, 1 atm pressure, 7%CO, 8.5% COz, 22%H20, 37%H2, and 25%Ar331...
Table 67 Water-gas shift rate and kinetic parameters for Pt and Rh promoted AI2O3, Ce02/ ai2o3364 ... [Pg.220]

Rates and Kinetic Parameters for the Internal Rotation of Substituted 2-Methylphenyl-di-ferf-butylcarbinol (74) in Dodecane (ap — sp)... [Pg.46]

The extent to which a given reactant, such as oxygen, is able to utilize this additional surface area depends on the difficulty in diffusing through the particle to reach the pore surfaces and on the overall balance between diffusion control of the burning rate and kinetic control. To broadly characterize these competing effects, three zones of combustion of porous particles have been identified, as shown in Fig. 9.21. In Zone I the combustion rate is fully controlled by the surface reaction rate (kinetically controlled), because the diffusion... [Pg.539]

Seymom-, S.L. and Klinman, J.P. (2002). Comparison of rates and kinetic isotope effects using PEG-modified variants and glycoforms of glucose oxidase the relationship of modification of the protein envelope to C-H activation and turmeUng. Biochemistry 41, 8747-8758... [Pg.76]

The effect of steric hindrance on the rates and kinetic isotope effects for reactions of l-nitro-l-(4-nitrophenyl)alkanes and their deuterated analogues with two bicyclic guanidines of comparable basicity (l,5,7-triazabicyclo[4.4.0]dec-5-ene, TBD, and its 7-methyl derivative, MTBD) in THF has been studied. The results disagree with the notion that deuterium kinetic isotope effects are enhanced by steric hindrance, since for the reactions of MTBD with various carbon acids the KIEs decrease with steric hindrance in the carbon acid but the converse is true for reactions of TBD. [Pg.374]

At the same time, as a chemist I was disappointed at the lack of serious chemistry and kinetics in reaction engineering texts. AU beat A B o death without much mention that irreversible isomerization reactions are very uncommon and never very interesting. Levenspiel and its progeny do not handle the series reactions A B C or parallel reactions A B, A —y C sufficiently to show students that these are really the prototypes of aU multiple reaction systems. It is typical to introduce rates and kinetics in a reaction engineering course with a section on analysis of data in which log-log and Anlienius plots are emphasized with the only purpose being the determination of rate expressions for single reactions from batch reactor data. It is typically assumed that ary chemistry and most kinetics come from previous physical chemistry courses. [Pg.550]

It was detected by Urey, Brickwedde and Murphy in 1932. It occurs in all natural compounds of hydrogen including water, as well as in free hydrogen molecules at the ratio of about one part per 6,000 parts hydrogen. The principal application of deuterium is in tracer studies for measuring rates and kinetics of chemical reactions. It also is used in thermonuclear reactions and as a projectile in cyclotrons for bombardment of atomic nuclei to synthesize isotopes of several transuranium elements. Deuterium oxide, D2O, or heavy water is used as a neutron moderator in nuclear reactors. [Pg.288]

In research and development, facilities for investigating chemical reactions are required. Besides screening tests, reaction-rate and kinetic parameters must be determined. For accurate and safe scale-up of the apparatus of an industrial chemical plant, furthermore, thermodynamic- and transport-data must be measured. For this purpose, a variety of apparatus is described in the open literature. In this chapter, some typical devices for use at high pressure are presented. [Pg.228]

Abstract—A review of the literature is presented for the hydrolysis of alkoxysilane esters and for the condensation of silanols in solution or with surfaces. Studies using mono-, di-, and trifunctional silane esters and silanols with different alkyl substituents are used to discuss the steric and electronic effects of alkyl substitution on the reaction rates and kinetics. The influences of acids, bases, pH, solvent, and temperature on the reaction kinetics are examined. Using these rate data. Taft equations and Brensied plots are constructed and then used to discuss the mechanisms for acid and base-catalyzed hydrolysis of silane esters and condensation of silanols. Practical implications for using organofunctional silane esters and silanols in industrial applications are presented. [Pg.119]

The hydrolysis of alkoxysilane esters has been extensively studied. The influences of the silane ester structure and acids, bases, solvent, and temperature on the reaction rates and kinetics have been investigated. Linear free energy relationships, such as Taft equations and Brensted plots, were used to gain... [Pg.138]

Dilution with toluene slowed the copolymerization rate, and kinetic measurements were carried out in toluene at 0°-30°C. As reported previously (II), the over-all activation energy of the spontaneous copolymerization of CPT and S02 was calculated to be 16.5 kcal/mole from the Arrhenius plot of the initial rate vs. polymerization temperature. Dependence of the intial rate of copolymerization upon monomer concentration was checked at various monomer concentrations and found to be quite high (II) this could not be explained without participation of the monomer in the initiation step. [Pg.223]

The other main source of evidence on the mechanisms of nitrosation comes from the C-nitrosation of aromatic compounds but, for this reaction, the final proton loss from the rate-determining (Challis and Higgins, 1972). Under these conditions, the overall rate and kinetic form of the reaction provide no evidence on the rate and mechanism of the nitrosation stage. Fortunately the work of Challis and his co-workers (Challis and Higgins, 1973 Challis and Higgins, 1975 Challis and Lawson, 1973) has shown that the C-nitrosation stage is rate-determining for the nitrosation of some reactive aromatic substrates (2-naphthol, azulene, 1,2-dimethylindole) in feebly acidic media and these are the reactions referred to below. [Pg.14]

Mark Thachuk joined the UBC Department of Chemistry in 1996. His research program focuses on the study of the dynamics and rates of chemical reactions and processes by mathematical and computational techniques. Typically, such investigations utilize classical, semiclassical, or quantum mechanics, and combine scattering theory with reaction rate and kinetic theories. [Pg.241]

The rate and kinetics of the thermal degradation of cellulosic materials have been investigated under a variety of conditions. However, these studies often relate to one of the physical effects produced by the overall process of heating or pyrolysis, instead of the kinetics of the individual chemical reactions involved. Consequently, the results are controversial and confusing. The variation of the results obtained under different conditions provides a vivid indication of the complexity of the reactions involved and the limited value of the overall kinetic data. [Pg.442]


See other pages where Rates and kinetics is mentioned: [Pg.270]    [Pg.101]    [Pg.115]    [Pg.1136]    [Pg.170]    [Pg.170]    [Pg.262]    [Pg.369]    [Pg.86]    [Pg.270]    [Pg.537]    [Pg.259]    [Pg.304]    [Pg.193]    [Pg.510]    [Pg.152]    [Pg.1463]    [Pg.139]    [Pg.733]    [Pg.747]   
See also in sourсe #XX -- [ Pg.313 , Pg.314 ]




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