Syntheses of Poly(butylene succinate) by Means of Non-Toxic Catalysts

The usefulness of bismuth, calcium, magnesium and zinc salts for the preparation of poly(butylene succinate), PBSu, was studied. Two different approaches were compared. Firstly, 1,4-butanediol (or in a few experiments ethanediol) dimethyl succinate were condensed at temperatures up to 240°C in the presence of Bi2O3. Regardless of the feed ratio, only low molar mass polyesters having two diol endgroups were obtained. Secondly, 1,4-butanediol and succinic anhydride were polycondensed in refluxing decalin with azeotropic removal of water. BiCL3, BiBr3, BiI3, and Bi-triflate were used as catalyst and the monomer/catalyst ratio was varied. The highest molar masses were achieved with BiCl3. Analogous polycondensations catalysed with ZnCl2, Zn-triflate, MgCl2, Mg-triflate and CaCl2 were unsuccessful. Yet the BiCl3, decalin method was also successfully applied to the combination of succinic anhydride and 1,5-pentanediol.