Synthesis of aromatic polycarbonates by an anhydrous catalytic solution process. I. The phosgene–phenol interaction

A two-step, catalytic, anhydrous solution process was developed for the preparation of the polycarbonate of 2,2-bis(p-hydroxyphenyl)propane (bisphenol-A). It involves the preparation of the dichloroformate of bisphenol-A followed by its condensation with bisphenol-A in the presence of magnesium metal. Attempts were also made to develop a one-step, catalytic solution process. The reaction of bisphenol-A with phosgene, in the presence of aluminum chloride, a very powerful catalyst, led to polymers with reduced viscosities as high as 0.35. Higher viscosities were not obtained due to the lack of a suitable, nonreactive solvent.