PREPARATION OF BIS(CHLOROFORMATE)S FOR USE IN CYCLIZATION REACTIONS

Cyclic oligomeric carbonates are prepared by a hydrolysis/condensation reaction from aromatic bis(chloroformate)s. Three methods for conveni ent preparation of bis(chloroformate)s have been developed: (1) use of diethylaniline to scavenge HCI, in a modification of an earlier proce dure; (2) low pH, low temperature interfacial condensation of bispheno ls with phosgene; and (3) use of Ca(OH)(2) in interfacial condensation with phosgene. Reaction parameters which control formation of monomer ic bis(chloroformate)s versus higher oligomerization include temperatu re, pH, and rate of phosgene addition. For water-soluble bisphenols su ch as hydroquinone, the phase ratio of water to CH2Cl2 can also be imp ortant.