Determination of 18O Exchange Accompanying Basic Hydrolysis of p-Toluamide and N,N-Dimethyl-p-toluamide

Article abstract of DOI:10.1021/jo00241a006

The base-catalyzed hydrolysis and ¹⁸O-exchange rate constants for p-toluamide (IV) and N,N-dimethyl-p-toluamide (V) have been determined under pseudo-first-order conditions as a function of -> at T = 100 deg C, μ = 1.0 M.Both sets of rate constants are linearly dependent on ->, and therefore the ratio of k_ex/k_hyd for IV and V does not change as a function of ->.For IV and V the ratios are 3.5 +/- 0.2 and 0.11 +/- 0.007 respectively.The fact that V shows substantial exchange suggests that the original formulation of the Deslongchamps stereoelectronic theory needs to be reassessed with respect to the conformational equilibration of the anionic tetrahedral addition intermediate produced from N,N-dimethylbenzamide and OH^-.