Towards convergent synthesis: Enzymatic and chemical generation of carbonate monomers and polymers.

摘要

Diphenyl carbonate is an attractive monomer for co-polymerization with bisphenol-a to produce the strong, high melting polycarbonate, bisphenol-a polycarbonate. The enzymatic synthesis of diphenyl carbonate via alcoholysis of dimethyl carbonate by phenol is presented. Phenol is a poor nucleophile and conversion to diphenyl carbonate is limited.; Enzyme catalyzed condensation polymerization of carbonate monomers with diols is a more feasible and direct enzymatic route to polycarbonate. Condensation polymerization of vinyl carbonates with diols and triols to make aliphatic and aromatic polycarbonates using enzymes as the sole catalyst at ambient conditions is possible. Weight average molecular weights of up to 8,500 Daltons are achieved. The monomers possess end groups which leave easily during polymerization, but unlike their industrial analogs, this process is performed without the use of acid catalysts, significant energy input, or high temperature or pressure. The effects of the parameters of the polymerization were studied in order to understand the variables that control and limit the system under investigation.; An additional direct route to polycarbonates was investigated as a two step synthesis of an aliphatic polycarbonate. In the first step, a cyclic carbonate was generated in carbon dioxide, using carbon dioxide as both a reactant and a solvent. An enzyme was then used to polymerize the cyclic carbonate. The mechanism of polymerization and the achievable molecular weights using enzymes were both investigated.