Linear Free-Energy Relationships in the Protonation Equilibria and Acid-Base Catalysed Reaction of 4-Substituted Benzohydroxamic Acids

摘要

As part of our investigations on the structure-reactivity relationships in protonation and hydrolysis of hydroxamic acids, we have now studied a series of 4-substituted benzohydroxamic acids (4-X-C_6H_4.CO.NH(OH), with X=H, Me, OMe,Cl,Br,F and NO_2) in aqueous sulfuric acid. Good correlation was observed pointing out the validity of the Hammett equation. The protonation constant, ionizationn constant and rate constant for acid- and base-catalysed hydrolysis reactions seems are to be related in a linear free-energy (LEER) fashion.