Reaction isoentropic

In the isoenthalpic and isoentropic reaction series, the isoenthalpic and isoentropic activation parameters, respectively, may be defined as a special case of isokinetic values. Values of this kind are certainly more reliable than the usual ones in all cases when the isokinetic behavior has been proved, or, better, when it cannot be rejected. In dubious cases, when it cannot be disproved with any reliability but yet would cause a reduction of the overall accuracy, we recommend the calculation of both isokinetic and unconstrained parameters. In... 

Two extreme situations should be noted. If p =0, then 8AG = — 78A5, and the reaction series is entirely entropy controlled it is said to be isoenthalpic. If I/p = 0, then 8AG = 8A//, and the series is enthalpy controlled, or isoentropic. All of these relationships apply also to equilibria, but we will be concerned with kinetic quantities. 

For the theory of LFER s, two consequences follow (a) The reaction constant p should depend on T according to eq. (18), and (b) values of AH and AS should obey the pertinent relationship as well as log k. The experimental evidence seems to be in accord with the first postulate (9, 17). Sometimes the simple proportionality to T" was claimed (124), corresponding to the isoentropic series but this is only a particular case, of course. 

Hydrolysis of 5-arylidenebarbiturates (5) proceeds according to Scheme ll.24 Kinetic studies revealed the isoentropic character of this reaction.362 363... 

We have assumed that the reaction of ozone with the homologies series of />paraffins is isoentropic and the difference in their reactivity is determined by the energies of C-H-bonds. In order to eliminate random factors we have applied the relative rate constants on example of y>hexane Eq. (9) ... 

Many correlations between the complexation enthalpy and the Gibbs energy of complexation have been proposed, for example the SbCls complexes [78], the diiodine complexes [4] or the hydrogen-bonded complexes [84]. They have been explained either by a quasi-isoentropic behaviour of the complexation reaction or by an enthalpy-entropy compensation effect (Equation 1.90) ... 

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