REACTIVITY PATTERNS OF N-METHYLBENZHYDROXAMATES .1. STUDIES OF METHYL TRANSFER BETWEEN N-METHYLBENZHYDROXAMATES AND ARENESULFONATES

The rates of methyl transfer between benzohydroxamates and sulfonates show large beta-nuc values (ca. 0.8) indicating much charge transfer to the C atom, similar to the results of N,N-dialkylaminofluorene anions. A small alpha effect shows that even in methyl substrates, with certain leaving groups, the effect is displayed. Investigation of the beta-1g shows that from the leaving group side of the reaction it is a normal S(N)2 reaction. Correlation of the reactivity with computed gas phase ionization potentials shows that desolvation of anions is probably not important. These results suggest an alpha-effect model that explains the larger size of the effect at carbonyl groups in terms of greater solvation of the charge transferred to the O atom.