Base catalysis of nucleophilic aromatic substitution. The reactions of primary and secondary amines with nitrophenyl phosphates

Abstract

The aromatic nucleophilic displacement of methyl phosphate dianion from the anion of methyl 4-nitrophenyl phosphate by dimethylamine and piperidine is compared with the corresponding displacement of inorganic phosphate, as the trianion, from the dianion of 4-nitrophenyl phosphate. The latter reaction is known to show a change in the rate-determining step with increasing base concentration, and the reaction at high base concentration is quantitatively closely similar to that of the diester. The results are interpreted in terms of the two-step mechanism for nucleophilic aromatic substitution, and it is shown that both steps are subject to catalysis by hydroxide ion.