Macrocyclic terephthalate esters

In 1930, in one of many pioneering studies, Carothers showed that certain condensation polymers could be cyclic or macrocyclic rather than exclusively linear. In addition to this very important observation, he showed that thermolysis in vacuo of certain polymers could also yield macrocyclic materials. Quite a number of papers have been published on this subject since that time, especially dealing with the chemistry of phthalate " , isophthalate " ", and terephthalate esters Many of these structures are tabulated at the end of this... 

Tetraphenoxyl titanates such as 4-isopropyl-, 2-isopropyl-6-t-butyl-, and 2-di-t-butyl-have been prepared and used as catalysts for the rapid depolymerization and repolymerization of macrocyclic oligomers. In this manner macrocyclic co-esters consisting of (butylene terephthalate-co-ethylene terephthalate) were re-polymerized to molecular weights of up to 120,000 daltons. 

Polymerization of a oligo(Butylene Terephthalate-co-Ethylene Terephthalate) Macrocyclic Co-ester... 

Macrocyclic(butylene terephthalate-co-ethylene terephthalate) co-ester (8.91 mmol) containing about 95 mol% butylene terephthalate was charged into a vial and then heated to 190°C at 1 torr for 5 minutes in an oil bath. This mixture was then treated with 0.30 mol% of the Step 1 product. The mixture was re-heated to the melt phase at 190°C for 10 minutes and polymerized for 15 minutes. Thereafter the polymer began to crystallize, and a white solid product was isolated. 

Macrocyclic oligomer precursors of polycarbonates, PET, polymers of amides, etherketones, and ethersulfones are candidates for further study of macrocyclic oligomer polymerization thermodynamics [6]. Research extends to cyclic arylates (cyclic aryl-aryl esters) and cyclic alkyl aryl esters going back to isolating a cyclic trimer of poly(ethylene-terephthalate) in 1954 [13]. Much of the work on macrocyclic oligomers as precursors to high-MW macromolecules starts with spiro(bis)indane (SBI) biphenyl monomer to produce macrocyclic carbonates. 

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