Copolycondensations of bisphenols with aggregates of isophthalic acid and terephthalic acid activated by tosyl chloride/dimethylformamide/pyridine in different manners

Abstract

A mixture of isophthalic acid (IPA) and terephthalic acid (TPA) was activated by a tosyl chloride/dimethylformamide/pyridine (Py) condensing agent in two steps via the treatment of a mixture of the initially activated IPA/TPA with additional TPA followed by the activation of TPA with the agent. The resulting mixture showed a solubility in Py different from that obtained by the activation of them all at once; the difference might be due to different structures of the aggregates of the activated IPA and TPA at the same composition of the diacids. The structures of the aggregates were evaluated on the basis of melting points and the IR spectra of a mixture of dimethyl esters of IPA and TPA produced by the quenching of the reaction mixtures with methanol. The mixture obtained by two-step activation showed lower melting points and spectral changes due to enhanced associations of the esters with respect to the mixture prepared by the activation of them all at once. The aggregates were also examined in terms of the distributions of IPA and TPA in thermotropic copolyesters prepared from methylhydroquinone and chlorohydroquinone by their transition temperatures and 13 C NMR.

Copolycondensation of various compositions of isophthalic acid and terephthalic acid with hydroquinones or bisphenols by tosyl chloride/dimethylformamide/pyridine

“…In agreement with our previous procedure,7 a mixture of TsCl (13 mmol) and DMF (10 mmol) in Py (10 mL), prepared and aged at room temperature for 30 min, was reacted with a mixture of IPA (3.5–1.5 mmol) and TPA (1.5 and 3.5 mmol) in Py (10 mL) at room temperature and 80 °C in an oil bath for 10 min each. After being removed from the oil bath, the mixture was reacted with methanol (10 mL) for 30 min.…”

“…The reaction of IPA and TPA by TsCl/DMF/Py may proceed as shown in Scheme 7. Several molecules of IPA and/or TPA randomly interact among themselves and/or with each other through hydrogen bonding among the carboxyl groups and form associates [(IPA) m /(TPA) n (I IPA/TPA )].…”

The effect of compositions and combinations of the reactants upon the copolycondensation of isophthalic acid/terephthalic acid with a combination of hydroquinones and bisphenols by tosyl chloride/dimethylformamide/pyridine

“…Instead of the copolymer solubility, it was assumed to be caused by the associated structures of the activated IPA and TPA, which might control the contents of a BP in the associates, and were examined from distributions of the oligomers resulting from a BP 4. Also, the structures were examined from solubility in Py and melting points and IR spectra of the mixtures of dimethyl esters of IPA and TPA obtained after quenching the possible IPA/TPA associates with methanol 5. It was expected that the resulting oligomers might interact with each other to form their aggregates, and their structures might also influence the content of a BP in the aggregates.…”

“…4 Also, the structures were examined from solubility in Py and melting points and IR spectra of the mixtures of dimethyl esters of IPA and TPA obtained after quenching the possible IPA/TPA associates with methanol. 5 It was expected that the resulting oligomers might interact with each other to form their aggregates, and their structures might also influence the content of a BP in the aggregates. Therefore, in the copolycondensation with two kinds of BPs, relative contents of BPs in the oligomer aggregates as well as the activated IPA/ TPA associates might be changed by the kind and relative amounts of BPs employed, and could be estimated from sequence distributions of BPs in the resultant copolymers.…”

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“…The results have been discussed in terms of the sequence distributions in the resultant copolymers, suggesting that the next comonomers should more randomly react with the preformed oligomers 7, 8. In connection with thermotropic polyarylates, many copolyarylates of various combinations of monomers have been prepared to depress their transition temperatures to improve their processability, but structural analyses of them by NMR have seldom been performed 9, 10…”