US Patent 7863404 Method of making isosorbide polycarbonate

A polycarbonate is provided that contains repeat units derived from isosorbide and a residue derived from an activated diaryl carbonate. The polycarbonate has 1H-NMR peaks associated with the repeat units derived from isosorbide. The polycarbonate contains no more than a maximum allowable amount of sorbitol-derived color bodies. If these color bodies are present in the polycarbonate it has a 1H-NMR peak associated with the color bodies. The maximum allowable amount of color bodies are present when the integrated area of the 1H-NMR peak associated with the color bodies divided by the integrated areas of the 1H-NMR peaks associated with the repeat units derived from isosorbide is 0.025.