Benzoic oxygen exchange with

The rate of oxygen exchange of a series of substituted benzoic acids was also studied by Gragerov and Ponomarchuk (1959) (see Table 7) who attempted to correlate the rate of exchange with the dissociation constants of the acids without much success. The rates of exchange (Gragerov and Ponomarchuk, 1959) fall in the following order ... 

Bender et al.136 have measured the rate of incorporation of, 80 from enriched water into several substituted benzoic acids. The catalyst was 0.07 M HC1, and the solvent 33% dioxan-water. The rate coefficients for exchange at 80°C are given in Table 14, which also contains a comparison of these rate coefficients with those for the hydrolysis of the corresponding ethyl esters, measured by Timm and Hinshelwood128 in 60% acetone and 60% ethanol. As noted earlier by Roberts and Urey, the absolute rates are very similar for the two reactions. Also, as expected, the exchange rate of benzoic acid, with two equivalent oxygen atoms, is almost exactly twice as fast as that of ethyl benzoate, with only one ( h.vdM< xch is 5.2 for the ester). 

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