Effect of pH on ether, ester, and carbonate hydrolysis in high-temperature water

We examined the hydrolysis of dibenzyl ether, benzyl t-butyl ether, methyl t-butyl ether, methylbenzoate, and diphenylcarbonate in high-temperature liquid water, both with and without added acid or base. The apparent reaction order for H⁺ did not exceed 0.2 for any of the compounds investigated. This result indicates that hydrolysis of these compounds in high-temperature water (HTW) does not follow the kinetics expected for specific acid catalysis (H ⁺ reaction order = 1.0), as does the hydrolysis at ambient temperatures. Rather, the greater thermal energy in the HTW system allows protonation by water molecules to become faster than protonation by H ⁺ at near-neutral conditions. Because the water-catalyzed path is faster, the occurrence of these acid-catalyzed reactions in HTW with no added acid is not due to the elevated value of K_w, the ion product. This finding contradicts the conventional wisdom in this field.