Species other than Hydrogen Ions in Aqueous Solution

Catalysis by Species other than Hydrogen Ions in Aqueous Solution 

The possibility of detecting an isotope effect on proton transfer from an undissociated acid only arises for the A-SE2 mechanism. The 

Gold and Waterman (1968a) considered the small discrepancy between their experimental points and the predictions of equation (57) in terms of the transfer effect alone. Equation (144) was modified to give  

Equation (145) gave the best fit to the data for the assumption of Y = 0-96, i.e. quite a small transfer effect. However, this calculation by Gold and Waterman (1968a) disregarded the deviation from the rule of the geometric mean. In the case of hydrogen ion-catalysed reactions we have remarked that a correction for this effect is hard to evaluate because of its unknown size for the hydrogen ion. In the li  

the calculation in Table 4 with and without consideration of the breakdown of the rule of the geometric mean (i.e. by equations (57) and (148)) should place the importance of this factor in perspective. The case considered here is one in which this effect can be properly computed and is also one in which it exerts a particularly large influence because the ratio H/ D is large. Even so the difference between the predictions of equations (57) and (148) is small compared with the accuracy normally attainable in all but the most exact kinetic studies. 

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VI. Catalysis by Species other than Hydrogen Ions in Aqueous Solution. . 312... 

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