Reactivity constant

Selectivity (s) depends on the ratio of the reactivity constant, as well on the ratio of the binding constants, which determines the concentration of the major intermediate. 

Pearson, R.G., Sobel, H., and Songstad, J. (1968) Nucleophilic reactivity constants toward methyl iodide and trans-[Pt(py)2C12]./. Am. Chem. Soc. 90, 319-326. 

There are numerous other transmission mechanisms for substituent effects. Those connected with unsaturated frameworks, such as mesomeric effects and correlations with it charge densities and Hammett-type reactivity constants, and intramolecular hydrogen-bonding effects are beyond the scope of this article and are discussed elsewhere (1,8,25,57). 

The term s is the nucleophile discrimination factor. The values of pt, the nucleophilic reactivity constant, is useful for correlating kinetic data for other Pt(II) complexes. 

AC2O/S11CI4), and nitration [Cu(N03)2] of thienothiophenes 1 and 2. He recently also studied the effect of the a-substitution (with halogen, CH3, SCHj, CN, NO2, COCH3, and COOH groups) on the chemical shifts of protons. He observed a good correlation between the shifts, reactivity constants, F (the field effect), and R (the resonance effect). ... 

You will notice in this case that the nucleophilic reactivity constants—these rate constants—vary roughly with the basicity. Hydroxide ion is almost the most powerful nucleophilic reagent because it is the strongest base that can exist in aqueous solution. Water is the weakest nucleophilic reagent, simply because anything weaker than water is not detectable in an aqueous solution. So this number is the lower limit for nucleophilic reactivity. 

Sacconi found a useful correlation between the spin state of five-coordinate complexes and the sum of the electronegativities and the nucleophilic reactivity constant of the donor groups.582... 

Table 16 Nucleophilicity Reactivity Constants ( pt) to trans-PtCl2(py)2...

There are principally two different approaches of correlating experimental rate data of electrophilic substitution with reactivity indices (1) Correlating the index with the rate data of a given reaction, e.g. bromination. For example, a satisfying correlation of Dewar reactivity numbers with the log of rate constants of the bromination of benzene, naphthalene (1- and 2-position), biphenyl (4-position), phenanthrene (9-position), and anthracene (9-position) has been observed [55]. In correlations of this type the reactivity index corresponds to the reactivity constant in the Hammett equation while the slope of the linear correlation corresponds to the reaction constant (see also Sect. 3) (2) correlating the index with experimental a values. 

Table 2. Reactivation constants of organophosphate-inhibited human erythrocyte AChE...

Figure 4.26 Variation of the reactivity constant r1 versus temperature in ethoxylation of the propoxylated intermediate polyethers...

In the case of PO (monomer 1) copolymerisation with THF (monomer 2) in the presence of hydroxyl groups, the reactivity constants of copolymerisation r and r are ... 

Numerical reactivity constants can be derived from equation 2 by inserting empirical values of a and 7 with the restriction that a > 7 because 7/a is a measure of the extent of bond formation in the transition state. (7/a = 1 for complete bond formation.)... 

TjPt = nucleophilic reactivity constant (for the entering ligand)... 

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