A two-stage copolycondensation of a mixture of equal parts of isophthalic acid and terephthalic acid first with a',b'-dihydroxyacetophenone (a',b'-DHAP) and then with isomeric c',d'-DHAP was examined at 60 and 80 degreesC. A structurally selective reaction was observed. At 80 degreesC, the preformed oligomers from symmetrically substituted 2',6'-DHAP reacted better with similarly substituted 2',6'- or 3',5'-DHAP to give the copolymers of significantly higher inherent viscosity values than from the reaction with asymmetrically substituted 2',4'-DHAP, whereas at 60 C they did almost equally well with any c',d'-DHAP. Similarly, the reaction of oligomers from 2',4'-DHAP with asymmetrically substituted 2',4'-DHAP or 2,4-dihydroxybenzophenone yielded better results than those from the reaction with 2',6'- or 3',5'-DHAP at both temperatures. The copolycondensations with comonomers of the structure independent of DHAPs were not affected by the preformed oligomers from DHAPs. The results are discussed in terms of the distributions of resulting oligomers determined by gel permeation chromatography. (C) 2003 Wiley Periodicals, Inc.