Polycarbonates
The diol often used for this reation is Bisphenol A, produced from the reaction of phenol and acetone. The phenols are better leaving groups that aliphatic alcohols - and so are more reactive in transesterification reactions. A polycarbonate has similar properties to polystyrene or perspex (PMMA), but the polycarbonate is stronger and more rigid and has higher impact resistance - ideal as a polymer for safety use - such as in motorcycle crash helmets. Polycarbonate is produced as follows:
