Abstract: The subject of the instant invention are polycarbonates based on diphenols of the formula I ##STR1## wherein Y is a single bond, an elkylene- or alkylidene-radical with 1 to 7 carbon atoms, a cycloalkylene- or cycloalkylidene-radical with 5 to 12 carbon atoms, ##STR2## which have weight average molecular weights (M.sub.LS) measured by light scattering of at least 15 000 and which are characterized in having an average of zero to 1.5 mols, preferably 0.3 to 1.0 mols and especially 0.3 to 0.8 mols endgroups per mol polycarbonate.The subject of instant invention is also a process for preparing these polycarbonates according to the interfacial polycondensation method, the polycarbonates thus obtained and the use of the polycarbonates according instant invention for the preparation of compounds and films.

Abstract: Low-molecular polyesters prepared by the condensation of diols and dicarboxylic acid dialkyl esters show a substantially improved capactiy to undergo polycondensation in a susequent polycondensation below the melting point if said low-molecular polyesters are prepared from pressure trans-esterification products by polycondensation in the melt.

Abstract: The contaminating inorganic compounds such as alkali metal salts or alkali metal hydroxides which remain in a polycarbonate solution prepared by reacting phosgene with a dihydroxy-aryl compound are removed by contacting the solution with a molecular sieve.