Relative rates of ferrocenylmethyl benzoate solvolyses in formic and acetic acid

Relative rates of ferrocenylmethyl benzoate solvolyses in formic and acetic acid 

A kinetic study of the acetolysis of trityl acetate was carried out earlierJ The measured specific rates were about 300 times higher than the predicted valuesJ A possible explanation, consistent with the powerful catalysis by mineral acids of solvolyses in aqueous-organic solvents, is that the actual reactant in acetic acid is not the neutral acetate but an equilibrium concentration of the faster reacting protonated species, a general idea suggested previously.  

However, the most unusual feature is the observation of lower solvolysis rates in formic acid than in acetic acid. Table 9.5.1 contains V(ionizing power) and N (nucleophilicity) values for formic acid, acetic acid, and 100 and 96% 

Solvent r-Butyl chloride scale 2-Adamantyl tosylate scale  

Because water and ethanol are of comparable nucleophilicity, its change in EtOH-H20 mixtures is small (ref. 78) interpolated from the data for 100, 90, and 80% EtOH (from ref. 76). 

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