Reaction variation

Song K and Chesnavich W J 1989 Multiple transition states in chemical reactions variational transition state theory studies of the HO2 and HeH2 systems J. Chem. Rhys. 91 4664-78... 

T1(III)+U(IV) reaction variation of kinetic orders with concentration... 

The enzymic phase is affected by the same factors that affect all enzyme reactions. Variation in the amount of enzyme has the largest effect (Castle and Wheelock 1972). Temperature and pH each affect the enzyme reaction in two ways. As temperature is increased the rate of K-casein cleavage increases until the temperature becomes high enough... 

When the rate equation is complex, the values predicted by the two models are not necessarily limiting. Complexities can arise from multiple reactions, variation of density or pressure or temperature, incomplete mixing of feed streams, minimax rate behavior as in autocatalytic processes, and possibly other behaviors. Sensitivity of the reaction to the mixing pattern can be established in such cases, but the nature of the conversion limits will not be ascertained. Some other, possibly more realistic models will have to be devised to represent the reaction behavior. The literature has many examples of models but not really any correlations (Naumann and Buffham, 1983 Wen and Fan Westerterp et al., 1984). 

Sada, E., and H. Kumazawa, Gas Absorption Accompanied by a Complex Chemical Reaction -Variation of the Enhancement Factors with the Order of Reaction," personal communication with Professor P. V. Danckwerts, 1972. 

Figure 2. Kinetic model for second-step reactions variation of K (or interfacial surface area) with A/O ratio for isobutane-to-olefin feed ratio of 5 1...

Fig. III.2. Two-step consecutive reaction. Variation of intermediate concentration. B is concentration of intermediate with maximum concentration K. x represents amount of reactant A used up.

Equation (XIV.G.3) represents, of course, one special case among many possible examples of chain-branching reactions. Variations of this equation may be obtained by adding terms that represent homogeneous first-order termination ka C) to Eq. (XIV.6.3) or wall-initiation terms to the auxiliary boundary equation (XIV.6.4). The addition of terms which are second-order in radicals, such as second-order recombination in the gas phase, or second-order branching leads to equations which are nonlinear and which may only be solved cither numerically or by approximation. 

Hydroboration of Rh(acac)(coe)2 (54) + L2 with excess HBcat affords acacBcat and the zwitterionic complex Rh(/)6-catBcat)L2 (55), which is believed to be the catalyst resting state in these reactions. Variation of the ligands has a profound effect on these... 

Reactions. Chemical reactions extend the structure representation by adding information about what role the structure plays in the reaction (reactant, catalyst, solvent, product, etc.). Reaction representation may also include information about what bonds are made or broken during the reaction, and which atoms are involved in reacting centers. It is also common to use a hierarchical organization for reaction information (reaction > variation > reactants, catalysts, solvents, products, etc.). 

Fig. 2. The O+OCIO reaction. Variation of (O], [CIO] and [OCIO] with [OC10]o at 1.45 torr total pressure and 298 °K. Inert gas is Nj plus Ar. From Clyne and Coxon with permission of...

The polarity of the medium has a drastic effect on the mechanism of the reaction. Variations of the polarity obtained by adding methanol to DME, had no effect on the reaction course up to ca. 2.5 M of MeOH. The fraction of the elimination reaction then rises steeply, from 0.1 at 3 M to 0.5 at 6 M of MeOH. Experiments with other solvent systems indicated that the shift in mechanism occurs at Ej(30) values around 47... 

Both problems involve comparing the rates of closely related reactions in the case of orientation, reactions at different sites in the same compound in the case of reactivity, reactions with different compounds. For such closely related reactions, variations in rate are due mostly to differences in act by definition, act is the difference in energy content between reactants and transition state. 

Note that this term accounts for enthalpy of reaction variation with temperature. Folger s approach is employed in the solution to this problem. 

Rate portrait of the second order reaction. Variation with - e" . The value of p t) on curve labeled is IO . ... 

A cursory analysis of the catalytic cycle, as shown in Fig. 4.3, reveals the simplicity of the overall process [2]. An oxidative addition of the organohalide (RrX) with a derivative of the palladium catalyst (L Pd ) affords an intermediate (L XPdRi) that then undergoes a transmetalation with an organometallic reagent (M-Rj). It is the nature of this species that gives rise to the named-reaction variation, as illustrated. Finally, the resultant... 

Because of the lack of randomization in time, the variation in the data observed from time point to time point within a reaction (whole plot) is likely to be less than that observed from reaction to reaction. In effect, two process variance terms have been introduced, one reflecting the within-reaction variation, and a second reflecting the variation from reaction to reaction. This has consequences for how to determine which factor is having effects beyond the inherent process variation. Fundamentally, any factor effect measures need to be compared against the correct comprehensive variance estimate. 

Screening results in animals or humans must be interpreted with great care because of the uncertainties due to the reaction variations, both inter- and intraspecies. Often it happens that the importance of some screening result is overemphasised and only corrected in later years, whereas another result is not appreciated at an early moment. Certainly this report may suffer from such shortcomings. 

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