Rate constant tabulation

The rate constants tabulated are the averages of those for the two carboxyl groups in each dibasic acid. The rate constants for the two carboxyls were the same within experimental error. Further, a very important observation is that the reactivity of one of the functional groups is not dependent on whether the other has reacted. As in the case of the monocar-boxylic acids, the reactivity of the carboxyl group quickly reaches a limiting value. Similar results were observed for the polyesterification of sebacoyl chloride (Table 2-2). 

The initial rates of oxidation of N2H by Fe " in aqueous HCIO4 are reproducible only for a given stock solution of iron(III) perchlorate (otherwise scatter of 60-100% is noted). In light of this problem, and also because the rate constants tabulated and the data depicted disagree numerically, it will not be considered further. The oxidation of NH2OH by the peroxoacid H3PO5 is catalyzed by... 

The results of this survey are presented in four sections. The first three provide critical reviews of rate constant data for 18 reactions in the N/O, N/H, and N/H/O systems. Arrhenius plots and tabulations of data from selected studies are included together, in most cases, with a recommended rate constant expression. In the fourth section, a more complete listing of N/H/O reactions and rate constants is given, primarily for the convenience of modelers and others interested in a more complete mechanism governing NO kinetics in N/H/O systems. These rate constants have been drawn from a variety of sources and include present evaluations, previous evaluations by the Leeds group, and a large number of estimates. The reader is warned to use such rate constant tabulations with caution in some cases the uncertainties may be quite large. 

The second-order rate constants for the reaction of a number of amines with benzyl chloride are tabulated below. Calculate A// and A5 from the data. Offer an explanation for the relative reactivity order for the amines. What trends do you observe in A// with reactivity ... 

The rates of hydrolysis of the ester group in compounds A and B have been compared. The effect of an added metal ion (Np+) on the rate of hydrolysis has been studied, and the observed rate constants for attack by OH are tabulated. Suggest the most favorable transition-state stmcture for the addition step of the hydrolysis reaction for each substrate under each set of conditions. Discuss the relationship between the stmctures of these transition states and the relative rates of attack by hydroxide ion. 

Rate constants (fifth column) usually correspond to one of the temperatures reported in the original papers and may be either experimentally determined values or those calculated from the activation parameters. In the preparation of the present review, the author has normalized a number of rate constants at arbitrary temperatures to permit direct comparisons with other data these normalized values and temperatures are tabulated (in italics) with the hope that they will offer additional useful information. The rate constants are usually expressed in liter x mole x sec when the values are followed by the symbol (A i) the units are sec. and dH are in kcal/mole JS is in eu. 

Pseudo-unimolecular rate constants measured at various temperatures, one of which is tabulated. 

The rate constants (in absolute solvents unless otherwise specified) are measured at a temperature giving a convenient reaction rate and calculated for a reference temperature used for comparison. These constants have all been converted to the same units and tabulated as 10 A . Where comparisons could otherwise not be made, pseudo-unimolecular constants (Tables IX and XIII, and as footnoted in Tables X to XIV) are used. The reader is referred to the original articles for the specific limits of error and the rate equations used in the calculations. The usual limits of error were for k, 1-2% or or 2-5% and logio A, 5%, with errors up to double these figures for some of the high-temperature reactions. 

Witli defined values of inhibition concentration, rate constant and given dilution rate, the substrate concentration is calculated based on (E.9.4). The tabulated data are given in Table E.9.1. 

The last comprehensive review of reactions between carbon-centered radicals appeared in 1973.142 Rate constants for radical-radical reactions in the liquid phase have been tabulated by Griller.14 The area has also been reviewed by Alfassi114 and Moad and Solomon.145 Radical-radical reactions arc, in general, very exothermic and activation barriers are extremely small even for highly resonance-stabilized radicals. As a consequence, reaction rate constants often approach the diffusion-controlled limit (typically -109 M 1 s"1). 

Alkylperoxy radicals are generated by the reactions of carbon-centered radicals with oxygen and in the induced decomposition of hydroperoxides (Scheme 3.82). Their reactions have been reviewed by Howard452 and rate constants for their self reaction and for their reaction with a variety of substrates including various inhibitors have been tabulated.453... 

Data are given in Table 10-7 to illustrate certain facets of the Marcus cross relation. They refer to six reactions in which the cage complex Mn(sar)3+ is reduced or Mn(sar)2+ oxidized.34 These data were used to calculate the EE rate constant for this pair. The results of the calculation, also tabulated, show that there is a reasonably self-consistent value of fcEE for Mn(sar)3+/Mn(sar)2+ lying in the range 3-51 L mol-1 s-1. When values34 for an additional 13 reactions were included the authors found an average value of kEE = 17 L mol 1 s l. 

Using either of the above approaches we have measured the thermal rate constants for some 40 hydrogen atom and proton transfer reactions. The results are tabulated in Table II where the thermal rate constants are compared with the rate constants obtained at 10.5 volt cm.-1 (3.7 e.v. exit energy) either by the usual method of pressure variation or for concurrent reactions by the ratio-plot technique outlined in previous publications (14, 17, 36). The ion source temperature during these measurements was about 310°K. Table II also includes the thermal rate constants measured by others (12, 13, 33, 39) using similar pulsing techniques. 

Rate constants for a large number of atmospheric reactions have been tabulated by Baulch et al. (1982, 1984) and Atkinson and Lloyd (1984). Reactions for the atmosphere as a whole and for cases involving aquatic systems, soils, and surface systems are often parameterized by the methods of Chapter 4. That is, the rate is taken to be a linear function or a power of some limiting reactant - often the compound of interest. As an example, the global uptake of CO2 by photosynthesis is often represented in the empirical form d[C02]/df = —fc[C02] ". Rates of reactions on solid surfaces tend to be much more complicated than gas phase reactions, but have been examined in selected cases for solids suspended in air, water, or in sediments. 

Moelwyn-Hughes (Physical Chemistry, page 1109, Pergamon Press, New York, 1957) has tabulated the following values of the rate constant for the reaction... 

If we let and t2 represent the times corresponding to reaction progress variables and <5J, respectively, the time ratio t2/tl for fixed values of <5 and <5 will depend only on the ratio of rate constants k. One may readily prepare a table or graph of <5 versus k t for fixed k and then cross-plot or cross-tabulate the data to obtain the relation between k and ktt at a fixed value of <5. Table 5.1 is of this type. At specified values of <5 and S one may compute the difference log(fe1t)2 — log f) which is identical with log t2 — log tj. One then enters the table using experimental values of t2 and tx and reads off the value of k = k2/kv One application of this time-ratio method is given in Illustration 5.5. 

The tabulation shows that the reaction favors the mixed oxo-imido complex in each case. The rate constants span a large range. The values of k for Eqs. (55)- (57) are greater than those of kr, often by a large margin. Where determined, AS has large negative values, —134 and —175 JK 1 mol-1 (62). 

The values of the derivatives and of the ratios of the specific rates are tabulated. The first two entries are ignored in taking the averages of the ratios. The ratios are only roughly constant, with k2/k1 = 0.110, k3/ka = 0.028... 

Rate of water loss from metal cations as a function of the ratio of the charge to the radius of the metal ion. Rate constants from Margerum et al. (1978). 2Jx ratios calculated from ionic radii tabulated in the CRC Handbook of Chemistry and Physics. 

Now, appropriate plots of the data are made, which, if linear, would indicate that the assumed model of Eq. (3) is adequate. For example, if ln(CjCA0) were linear with t, a first-order model would be adequate. Alternatively, one could assume a model (including the value of the parameter a), calculate the rate constant k at each data point, and tabulate the constants. If these constants remain constant, or if there is a reasonable trend of the constants with any independent variable, then the data do not reject the assumed model. For example, the value of In k would be expected to be independent of the value of the reaction time and to change linearly with the reciprocal of the absolute temperature. 

Rate constants for many [Fe(CN)6] oxidations and [Fe(CN)g] reductions have been collected and tabulated. ... 

Literature tabulations for E and for homogeneous reactions are normally based on concentrations. The clue to this is that the units for the rate constant are often s liter/mol s, etc., without pressure appearing in the units. 

Figure 2 is a good representation of almost all the 112 runs made with 1-octanol. There was curvature on only a few runs, undoubtedly caused by experimental error since they could not be reproduced. This feature was checked carefully after mathematical analysis indicated reasons to expect curvature. The conditions of reactions and values of k0 have been tabulated (Tables I and II). Since k0 depends upon 1-octanol and TMAE, it is called the pseudo-first-order rate constant. 

If we assume that the chemical properties of the Co(CN)5-2 generated in Reaction 19 are identical u ith those of Reaction 1, then the measured value of ka and the previously tabulated value of k /kz = 2.95 may be used to calculate km, the rate constant for formation of Co(CN)5OH2-2 at various SCN- concentrations. The calculation was carried out using Equation 22, an equation which was derived in the appendix of our original publication (7). 

We can now make sensible guesses as to the order of rate constant for water replacement from coordination complexes of the metals tabulated. (With the formation of fused rings these relationships may no longer apply. Consider, for example, the slow reactions of metal ions with porphyrine derivatives (20) or with tetrasulfonated phthalocyanine, where the rate determining step in the incorporation of metal ion is the dissociation of the pyrrole N-H bond (164).) The reason for many earlier (mostly qualitative) observations on the behavior of complex ions can now be understood. The relative reaction rates of cations with the anion of thenoyltrifluoroacetone (113) and metal-aqua water exchange data from NMR studies (69) are much as expected. The rapid exchange of CN " with Hg(CN)4 2 or Zn(CN)4-2 or the very slow Hg(CN)+, Hg+2 isotopic exchange can be understood, when the dissociative rate constants are estimated. Reactions of the type M+a + L b = ML+(a "b) can be justifiably assumed rapid in the proposed mechanisms for the redox reactions of iron(III) with iodide (47) or thiosulfate (93) ions or when copper(II) reacts with cyanide ions (9). Finally relations between kinetic and thermodynamic parameters are shown by a variety of complex ions since the dissociation rate constant dominates the thermodynamic stability constant of the complex (127). A recently observed linear relation between the rate constant for dissociation of nickel complexes with a variety of pyridine bases and the acidity constant of the base arises from the constancy of the formation rate constant for these complexes (87). 

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