An improved process for preparing mono-condensation derivatives of adipic acid with fewer steps and better purity is disclosed. In particular, this process comprises: (a) forming relatively concentrated and pure cyclic monomeric adipic anhydride by depolymerization and concentration starting from polymeric adipic anhydride; and (b) adding a condensation reactant having an active hydrogen, e.g., a primary or secondary amine, to said cyclic monomeric adipic anhydride to form the corresponding mono-condensation derivative of adipic acid.