Preparation and polymerization of bisphenol A cyclic oligomeric carbonates

Abstract

A selective, high-yielding procedure for the preparation of Bisphenol A cyclic oligomeric carbonates via a triethylamine-catalyzed hydrolysis/ condensation reaction of bis (chlorof ornate) is described. The reaction produces cyclic oligomers in 80-90% yield, along with about 15 % high molecular weight polymer, but with almost total exclusion of linear oligomers. The structure of the amine catalyst controls the selectivity of cyclic vs linear vs polymer formation. Use of other amine catalysts can lead to different products. Use of pyridine as catalyst, for example, affords linear oligomers in 99% yield, with very low yields of cyclics. Polymerization of the cyclic oligomers to polycarbonate with Mv = 50 000-300 000 is achieved by heating at 300 °C for 15 min in the presence of various basic catalysts. The preparation of authentic oligomeric linear and cyclic materials is also described.

Synthesis and characterization of new bi-functional monomers based on germarylene or silarylene units: 4,4′-(R1R2-silylene)bis(phenyl chloroformates) and 4,4′-(R1R2-germylene)bis(phenyl chloroformates)

“…• C [18,19] or used as a toluene solution [15]. The new bi-functional monomers were obtained following the route already described [13].…”

Cyclic oligomer chemistry

“…15 The mixture of cyclic oligomeric carbonates indeed provided the melting point depression that was desired, and had a broad melting range, starting to soften at about 200 8C, becoming completely molten and flowing freely at 250 8C (capable of stirring magnetically). The cyclic oligomers have M w of about 1200-1500 Da and M w /M n of about 1.5.…”

“…15 BPA was protected as the mono-triethylsilyl ether, and then functionalized it as the chloroformate. Subsequent manipulations provided linear dimer, trimer, tetramer, and pentamer PCs.…”

“…Because HPLC analyses can be carried out on crude, unpurified reaction mixtures with very little workup, we had an efficient tool for elucidating the selectivity of cyclization reactions. 15 Other authors have used gel permeation or size-exclusion chromatography (GPC or SEC), which does not readily resolve individual oligomers. Recently, many authors have used MALDI-TOF mass spectral analysis, but again, crude reaction mixtures cannot be used, and a significant amount of work is needed to ascertain whether all the components of a mixture fly at comparable rates.…”

Catalytic Reactions of Living Polymers: Density Functional Study of Reactivity of Phenol and Phenoxides with the Cyclic Tetramer of Polycarbonate

“…4 The tetramer should then reproduce much of the local bonding behavior found in a single polymer chain, and cyclic oligomers in general are useful intermediates for the preparation of high molecular weight polycarbonate. 5 Ring-opening polymerization, ROP, 6 is often initiated by nucleophilic attack, giving rise to a "living" polymer. 7 The present work describes density functional calculations of the reaction of the cyclic tetramer with the molecules phenol, lithium phenoxide (LiOPh), and sodium phenoxide (NaOPh).…”