Model studies and a new melt polycondensation route to poly‐bisphenol a–iso/terephthalate (polyarylate)

Alternate syntheses of polyarylate from dimethyl iso/terephthalate (DMI/DMT) and bisphenol‐A (BPA) or bisphenol‐A diacetate (BPAOAc) were investigated using a variety of catalysts. The model exchange of DMT with 4‐t‐butylphenol with loss of methanol proceeded moderately rapidly at rather low temperature (170°C) to produce to mono‐ and di‐t‐butylphenyl terephthalates. Dibutyltin oxide is the preferred catalyst. Alkali metal phenoxides are almost as effective but were less soluble. The model reaction of DMT with 4‐tert‐butylphenyl acetate involving loss of methyl acetate gave comparable results using dibutyltin oxide as catalyst. Based on these model results, polycondensations of DMI/DMT with BPAOAc under optimal conditions, gave polyarylate having an inherent viscosity 0.34 dL g−1 in quantitative yield and light brown color. Polycondensation with BPA was unsatisfactory in terms of yield, molecular weight, and color.