A Comparison of the Mechanism of Hydrolysis of Diphenylketene and Dimethylketene in Diethyl Ether Solution

Article abstract of DOI:10.1039/P29830001381

The spontaneous hydrolysis of diphenylketene in diethyl ether solution at 25 deg C is first order in the ketene concentration and third order in the stoicheiometric water concentration; unlike the hydrolysis of dimethylketene, it is not-auto-catalytic and hydrolysis is negligibly catalised by added carboxylic acids.Added boron trifluoride strongly inhibits the hydrolysis of diphenylketene in ether but powefully catalyses that of dimethylketene; the formation of the strong Broensted acid H2OBF3 (association constant K = 120 +/- 20 l mol^-1 at 25 deg C) underlines these effects.A pK_a value of ca. 0.5 is deduced for this acid and the results as a whole point to the marked inability of diphenylketene , compared with dimethylketene, to accept protons from Broensted acids.Predominantly nucleophilic attack on the ketene is, however, easier for the diphenyl-derivative whose spontaneous hydrolysis varies between ca. 5- and ca. 40-fold faster over the range of stoicheoimetric water concentrations used.

Full text of DOI:10.1039/P29830001381

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