CYCLIC POLYESTERS .6. PREPARATION AND CHARACTERIZATION OF 2 SERIES OFCYCLIC OLIGOMERS FROM SOLUTION RING-CHAIN REACTIONS OF POLY(ETHYLENE-TEREPHTHALATE)

Solution ring-chain reactions of poly(ethylene terephthalate) (PET) we re carried out using a high boiling solvent, 1-methyl naphthalene and catalyst. At a dilution of 1/10 (w/w polymer/solvent) and catalyst con centration of 0.5% (w/w), a reaction with tetraisopropyl orthotitanate , gave cyclics at a yield of 3 wt%, with dibutyltin bis (2-ethyl-hexan oate) the yield was ii wt%, and with zinc acetate it was 20 wt%. Incre asing the dilution of the reaction to 1/30 (w/w polymer/solvent) using zinc acetate as catalyst, increased the yield of the cyclics to 30 wt %. The cyclics were analysed using PL-gel mixed-E gel permeation chrom atographic columns, and by H-1 nuclear magnetic resonance spectroscopy , fast atom bombardment mass spectrometry, and liquid chromatography t andem mass spectrometry. The cyclic compounds (CO.C6K4.CO.O.CH2.CH2.O) (x), where x = 3-13, 30-130 skeletal bonds), were identified together with a series of ring compounds (CO.C6H4.CO.O.CH2.CK2.O)(x)CH2.CH2.O, (where x = 2-7) which were also found to be present. This latter serie s has not been previously reported. (C) 1997 Elsevier Science Ltd.