Synthesis of polymers in aqueous solutions: heterogeneous oxidation of poly(amide-sulphide) in water

Abstract. The heterogeneous oxidation of N-(2-phenylthioethyl)benzamide in a dispersion of water was performed with twice the amount of hydrogen peroxide at 60 C for 72 h as a model reaction of the oxidation of poly(amide-sulphide) (polymer 1), and the corresponding N-[2-(phenylsulphoxy)-ethyl]benzamide and N-[2-(phenylsulphonyl)ethyl]benzamide were ob-tained in 5 % and 95 % yields respectively. This suggests that the alkyl phenyl sulphide group was easily oxidized with time via the alkyl phenyl sulphoxide group into the alkyl phenyl sulphone group. On the other hand, when heterogeneous oxidation of diphenyl sulphide in a dispersion of water was carried out with twice the amount of hydrogen peroxide at 60 C for 72 h, the cor-responding diphenyl sulphoxide and diphenyl sulphone were obtained in 77 % and 23 % yields, respectively. Therefore, the oxidation rate of the diphenyl sulphide group was much slower than that of the alkyl phenyl sulphide group, and the heterogeneous oxidation of diphenyl sulphide with excess hydrogen peroxide in a dispersion of water primarily produced diphenyl sulphoxide under the same conditions. On the basis of these model reactions, the heterogeneous oxidation of polymer 1, which was prepared by the polyaddition of bis(4-mercaptophenyl)sulphide with m-phenylenebis(2-oxazoline), was performed with one to three times the amount of hydrogen peroxide in a dispersion of water at 60 C, and the Tg of the resulting polymers gradually increased with reaction time from 111 C to 165 C. When the oxidization was carried out with three times the amount of hydrogen peroxide for 48 h, the polymer with major structure, poly(amide-sulphone) (polymer 3), was obtained. Polymer 3 was also easily prepared by the oxidization of polymer 1 with equivalent amounts of sodium periodate in a dispersion of water at 60 C for 48 h. 1