Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
A New Acidity Function, T0, in Acid-catalyzed Reactions
Haruo TakayaNaoyuki TodoTadasuke Hosoya
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1969 Volume 42 Issue 10 Pages 2748-2755


In acid-catalyzed reaction systems a new acidity function, T0, which is related to the first-order rate constant, k1 by the equation log k1=CT0 was defined by T0=−log (aH+/awh5h1f\ eweq) and was theoretically calculated in much the same manner as in Glueckauf’s treatments on a salt solution but with the additional assumption that the character of a hydrated univalent activated complex is represented by that of a hydrated alkali metal cation. The calculated results show that T0 in hydrochloric acid can be represented by:
This equation shows that if the hydration number (the water molecules bound with an activated complex) of an activated complex, h1, increases by one, the corresponding increment of T0 becomes −2.4logaw. It was also shown that the value of fAH+fBfAfBH+ is not always constant, but depends on the hydration numbers of the AH+ and BH+ species as well as on the acid concentrations. The factors affecting the acidity function, T0, were compared with those affecting the activity of water. The applicability of the T0 was examined by means of the observed logk1 value reported by Bunnett.

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