Abstract: Disclosed is a process for preparation of a polyarylate having a degree of polymerization of at least 50 by polymerizing an admixture comprised of 4-dialkylaminopyridine, an acid anhydride, bisphenol-A and a mixture of isophthalic acid and terephthalic acid by the steps of(1) subjecting the admixture to a pressure in the range of 500 to 1400 mm of Hg and a temperature in the range of 20.degree. to 150.degree. C. while maintaining a degree of polymerization of substantially 1.0,(2) subjecting the admixture to a pressure in the range of 500 to 1400 mm of Hg and a temperature in the range of 285.degree. to 350.degree. C. to achieve a degree of polymerization in the range of 2 to 7,(3) subjecting the admixture to a pressure in the range of 100 to 400 mm of Hg and a temperature in the range of 285.degree. to 350.degree. C. to achieve a degree of polymerization in the range of 7 to 15,(4) subjecting the admixture to a pressure in the range of 100 to 400 mm of Hg and a temperature in the range of 330.degree. to 400.

Abstract: A process for preparing a polymer having repeating units corresponding to the structure ##STR1## wherein y is in the range of 0.005 to 0.15, x is in the range of 0.02 to 0.25, n is at least 200, and R a divalent aromatic radial. The polymer is prepared by reacting a diiodoaromatic compound and elemental sulfur.