A new synthetic route to polycarbonate

Abstract

AbstractA detailed study has been carried out on the new synthetic reaction of poly(p‐xylylene carbonate) from potassium carbonate and p‐xylylene dibromide by using a variety of crown ethers as a catalyst, which was recently found by the present authors. Crown ethers having 18‐member ring showed the best catalytic property of the various crown ethers, and the reaction was conducted in various solvents at 50–160°C by using 18‐crown‐6‐ether. Both the polymer yield and the molecular weight of the polymer increased in proportion to the amount of potassium carbonate, and they increased rapidly and reached constant values with increasing the concentration of 18‐crown‐6‐ether. They also depended significantly upon the reaction temperature as well as the solvent used. A maximum yield with the highest molecular weight was obtained from the reaction at 100–120°C in diglyme solvent. The spectroscopic analysis of the polymer indicated that all the end groups of the resulting polymer had the structure of benzyl bromide. From these results, a plausible mechanism was proposed for the reaction. Similar reactions were also conducted by using several aliphatic dibromides, Br(CH2)xBr, in place of p‐xylylene dibromide. The products were strongly dependent of the value of x: polycarbonate was obtained from dibromides with ≧4, and cyclic carbonates from dibromides with ≦3.