Cyclic polyesters: 5. Cyclics prepared by poly(decamethylene terephthalate) ring-chain reactions
1997; Elsevier BV; Volume: 38; Issue: 7 Linguagem: Inglês
10.1016/s0032-3861(96)00687-8
ISSN1873-2291
AutoresS. Caroline Hamilton, J.A. Semlyen,
Tópico(s)Synthetic Organic Chemistry Methods
ResumoCyclic oligomers of poly(decamethylene terephthalate) (PDT) were prepared successfully and cleanly from a ring-chain equilibrium reaction in dilute solution of chlorobenzene. A variety of catalysts were investigated for this purpose. The reactions were monitored up to equilibrium and the molar cyclization equilibrium constants Kx deduced. Satisfactory yields of cyclics [O(CH2)10OCO C6H4CO]x were obtained, together with a higher molar mass linear polymer. Mass spectroscopic investigation showed that no monomeric ring was formed in the PDT reaction. The individual cyclics with x = 2–14 corresponding to 36–252 skeletal bonds were completely resolved using PL-gel mixed-E gel permeation chromatographic columns. The lower mass cyclics (x = 2–5) were cleanly extracted and then characterized. The yield of cyclics in ring-chain equilibrates corresponding to a solvent/polymer dilution ratio of 301, 601 and 1001 were ca 11%, ca 30% and ca 50%, respectively. The Kx values for PDT cyclics were used to compare the statistical conformations of the corresponding PDT chains in chlorobenzene with an aliphatic polyester, poly(decamethylene adipate), which was studied previously.
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