NSF/EPA: Biocatalytic Polymer Synthesis in and from Carbon Dioxide for Pollution Prevention

9613166罗素拟议的研究有两个推动力；一个涉及使用二氧化碳(二氧化碳)作为反应物、溶剂或两者，另一个使用酶作为二氧化碳中的多相催化剂，以在低温下选择性地促进所需的反应。在二元醇和二元酯的酶促聚合过程中，将使用二氧化碳作为溶剂，形成聚酯多元醇(带羟基的聚酯)。聚酯多元醇是聚氨酯弹性体的重要组成部分。目前，它们是通过二元醇和二元酸的高温反应生成的。水的持续去除被用来推动反应完成。污染的预防将通过与低温操作相关的能源节约以及通过使用酶和脂肪酶消除循环副产物来实现。这种酶可以在不诉诸高化学计量比失衡的情况下产生二羟基封端材料，从而减少浪费。此外，结合使用酶和压力可调的溶剂(如二氧化碳)，可以生产分子量分布较窄的聚酯。这种材料目前不能用传统的缩聚聚酯合成技术获得。拟议的研究还将对聚合过程的细节进行研究，试图合理地设计一种用于氨基甲酸酯工业的连续合成多元醇聚酯中间体的方法。二氧化碳将作为原料，配合酶催化，合成氨基甲酸二苯酯，双酚A聚碳酸酯(BAPC)的单体，广泛使用的热塑性塑料。目前生产碳酸二苯酯的工艺需要以光气为原料，会产生大量的废盐和有机溶剂。第一步使用二氧化碳生成二烷基碳酸酯，然后进行酶催化的酯交换反应，这两步反应将用于生产碳酸二苯酯。如果成功，这项研究将使用节省能源、最大限度减少浪费并使用环境友好的溶剂的反应物和工艺。

9613166 Russell The proposed research has two thrusts; one involves using carbon dioxide (CO2) as either a reactant, solvent or both, and the other uses enzymes as heterogeneous catalysts in CO2 to promote required reactions selectively at low temperatures. CO2 will be used as the solvent during the enzymatic polymerization of diols and diesters to form polyester polyols (hydroxy-capped polyesters). Polyester polyols are important constituents of polyurethane elastomers. Presently, they are generated via the high temperature reaction of diols with diacids. Constant removal of water is used to drive the reaction to completion. Pollution prevention will be accomplished through energy savings related to low temperature operation, as well as elimination of cyclic byproducts through use of the enzyme, lipase. The enzyme may enable the generation of dihydroxy capped material without resorting to high stoichiometric imbalances, thus reducing waste. In addition, the use of enzymes in concert with a pressure- tunable solvent such as CO2 enables the production of polyesters with narrow molecular weight distributions. Such materials are presently unavailable using conventional condensation polyester synthetic techniques. The proposed research also will investigate the details of the polymerization process in an attempt to rationally design a continuous method for synthesis of polyol polyester intermediates for the urethane industry. CO2 will be used as a raw material, in concert with enzymatic catalysis, in the synthesis of diphenyl carbamate, the monomer for bisphenol A polycarbonate (BAPC), a widely used thermoplastic. Current processes for production of diphenyl carbonate require phosgene as a raw material, generating large quantities of waste salt and organic solvent. A two-step reaction, where CO2 is used in the first step to generate a dialkyl carbonate, followed by an enzymatically catalyzed transesterification, will be used to produce diphenyl c arbonate. If successful, the research will use reactants and processes that save energy, minimize waste and use an environmentally benign solvent.