Method for making stable, homogeneous melt solutions

Abstract

Stable, homogeneous melt solutions are prepared at temperatures of 200° C. or less from solid mixtures comprising at least one diaryl carbonate, at least one high melting dihydroxy aromatic compound (mp>200° C.), a transesterification catalyst, and optionally a lower melting dihydroxy aromatic compound. Thus, a stable, homogeneous melt solution is obtained from a solid mixture comprising 4,4'-biphenol (mp 282-284° C.) at a temperature of about 200° C. using either diphenyl carbonate or bis(methyl salicyl) carbonate as the diaryl carbonate component. It is shown that formation of the stable, homogeneous melt solutions requires the presence of the transesterification catalyst when substantial amounts of the high melting dihydroxy aromatic compound are present in the initial solid mixture. Solid mixtures comprising a variety of high melting bisphenols; 4,4′-biphenol; 3,3,3,3′-tetramethylspirobiindanbisphenol, and 4,4′-sulfonyidiphenol are converted to stable, homogeneous melt solutions at 200° C., a temperature substantially below the melting points of the high melting bisphenols in their pure states.