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

9613166罗素提议的研究有两个重点；一种是使用二氧化碳（CO2）作为反应物、溶剂或两者兼而有之，另一种是使用酶作为二氧化碳中的多相催化剂，在低温下选择性地促进所需的反应。在二醇和二酯的酶促聚合过程中，二氧化碳将被用作溶剂，以形成聚酯多元醇（羟基覆盖聚酯）。聚酯多元醇是聚氨酯弹性体的重要组成部分。目前，它们是由二醇与二酸的高温反应生成的。不断地除去水来驱动完井反应。污染预防将通过与低温操作相关的节能，以及通过使用酶，脂肪酶来消除循环副产物来完成。该酶可以使生成二羟基盖住的材料，而无需诉诸高的化学计量不平衡，从而减少浪费。此外，使用酶与压力可调溶剂（如CO2）配合使用，可以生产分子量分布较窄的聚酯。这种材料目前无法使用传统的冷凝聚酯合成技术。提出的研究还将调查聚合过程的细节，试图合理设计一种连续合成多元醇聚酯中间体的方法，用于聚氨酯工业。二氧化碳将作为原料，与酶催化作用相结合，用于合成双酚a聚碳酸酯（BAPC）的单体二苯氨基甲酸酯，这是一种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，产生大量的废盐和有机溶剂。通过两步反应，第一步用二氧化碳生成碳酸二烷基，然后用酶催化酯交换反应生成碳酸二苯酯。如果成功，这项研究将使用节省能源、减少浪费和使用环保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.