Molecular Structure and Deviations from the Bro***nsted Relation.

Reaction scheme for the chlorination of ammoniacal water

“…Other evidence is that inorganic bases such as phosphate (HP042") do not enhance NHC12 decay in the absence of HOC1 (28), suggesting OCT would not directly catalyze NHC12 decay. ÓCT, however, is a well-known a nucleophile (31)(32)(33), indicating that it may be near impossible to calculate ab initio the reactivity of OCT to the proton on NHC12.…”

Linear Free Energy Relationships.

“…By selecting one reaction series as a standard, e.g., A, equation 10 may be considered composed of two parts log (ki/kO)A 3 xi (11) dependent only on the change in the variable x, and gzBTA/gzATB = GzAB (12) dependent only on the nature of and the conditions employed for reaction series B and its susceptibility to changes in x relative to that for the standard reaction series A.…”

“…Of 56 reaction series common to both treatments, Bekkum, Verkade and Wepster find 34% having correlation coefficients better than 0.998, 77% better than 0.99 and 89% better than 0.98; while Jaff6, for these reaction series, finds 29% better than 0.99, 59% better than 0.98, but none better than 0.998, in fact only 6% of the 371 reactions covered shorn this high precision. That this marked improvement is due to the removal of deviations due to variable p-substituent influences is shown by the computation of sigmavalues for other m-substituents (Table IV, numbers [11][12][13][14][15][16][17][18][19]. The standard deviations obtained are no larger than might be expected and do not greatly exceed those for substituents "H" and "p-NOn" (Table V) calculated from reaction series correlated using the primary values of these substituents.…”

“…Limitation of structural variations is still important. Deviations from a wide correlation for the dehydration of acetaldehyde hydrate have been identified as due to abnormal resonance stabilization in the anions of "pseudoacids" not present in carboxylate and phenolate anions (12,16). Imidazole and hydroxylamine prove to be exceptional in the general base catalysis of the aminolysis of phenyl acetate (140), probably because functions other than base strength are involved.…”

“…Since the logarithm of an equilibrium constant (K) is proportional to the standard free-energy change (AF°) accompanying the reaction log K = -(AF«/2.3RT) (2) and the logarithm of a rate constant (k), according to the transition state theory (cf. 91a), is proportional to the standard free-energy of activation (AF*) c o n t e n t i s The combination of equations 8 and 9 leads to a linear free-energy correlation between reaction series A and B, equivalent to the generalized equation 1. log (¿íA,)b = rxu x los ( Wa (io) By selecting one reaction series as a standard, e.g., A, equation 10 may be considered composed of two parts log (*i/*o)a sa X, (11) dependent only on the change in the variable x, and 0 ß /0 ß = G*AB (12) dependent only on the nature of and the conditions employed for reaction series B and its susceptibility to changes in x relative to that for the standard rec o n t e n t i s The alternative analysis of free energy changes in terms of potential energy changes and quotients of the appropriate partition functions does not lead to experimentally determinable quantities. Although these are ultimately the theoretical quantities that are desired, the present discussion is not advanced by their use.…”