employed at a level of from 50 mole percent to 55 mole percent based on the total moles of 4 4 39 dihydroxybiphenyl 4 4 39 dihydroxyphenylether and diphenyl carbonate during transesterification a vacuum can be used in combination with agitation such as achieved with the use of an extruder reactor or stirrer to facilitate the removal of phenol the 4 4 39 dihydroxybiphenyl is preferably present at a level of from about 50 mole percent to about 80 mole percent based on the total moles of 4 4 39 dihydroxybiphenyl and 4 4 39 dihydroxyphenylether reacted to form the polycarbonate more preferably the 4 4 39 dihydroxybiphenyl is present at a level of from 60 mole percent to 75 mole percent and most preferably is present at a level of 70 mole percent thereof and the 4 4 dihydroxyphenylether is preferably present at a level of from about 20 mole percent to 50 mole percent based on the total moles of 4 4 39 dihydroxybiphenyl and 4 4 39 dihydroxyphenylether reacted more preferably at a level of from 25 mole percent to 40 mole percent and most preferably at a level of about 30 mole percent thereof in order that those skilled in the art will be better able to practice the present invention the following examples are given by way of illustration and not by.