Dynamics of Mediated Electrochemical Synthesis in Microemulsions

微乳液介导电化学合成动力学

• 批准号: 9632391
• 负责人: James Rusling
• 金额: $ 36万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 2000-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9632391&HistoricalAwards=false
• 关键词: Dynamics; Mediated; Electrochemical; Synthesis; Microemulsions

ABSTRACT CTS-9632391 The goal of this project is to develop a fundamental understanding of how surface dynamics on electrodes and kinetics in microemulsions influence control of reactivity in mediated electrochemical syntheses. Electrochemical studies are used to relate surfactant and reactant adsorption-desorption dynamics on electrode surf aces to catalytic reaction rates. The mediated reactions include carbon-carbon coupling, cyclizations, and olefin production. Catalytic efficiencies of mediators in the bulk fluid using bare carbon electrodes will be compared with those of new catalytic electrodes designed specifically to achieve high reaction rates in microemulsions. Macrocyclic metal complexes that catalyze reactions by efficient inner sphere pathways, such as vitamin B12 and Cobalt-, iron-, and nickel-porphyrins, are used as mediators. Layer-by-layer electrode coating strategies based on polymeric silicon-oxygen-carbon linkages to carbon electrodes are compared with a previously developed polymer deposition method. Electroanalytical methods are used to compare reaction rates in microemulsions and homogeneous organic solvents and catalytic electrodes. Synthetic electrolyses in a stirred batch electrochemical reactor with product analysis are used to assess the practical utility of the systems, and to optimize yields and reactant conversion rates. Compositions of microemulsions and properties of catalytic coatings are tuned for best reaction rates and yields for key reactions. Surface dynamics of reactants and surfactants on electrodes are measured by time-resolved flow voltammetry on bare and catalytic electrodes. Methods and theory developed earlier are employed. Molecular interactions between co-adsorbates will be assessed via Frumkin interaction parameters obtained from wave voltammetry. As possible limiting factors for the rates of mediated reactions, reactant and surfactant exit and entry rates are estimated for the new catalytic films using electroactive probes. Correlations between rates of all surface dynamic events and rates of mediated synthetic reactions are sought. The objective of this work is to provide fundamental guidance for the future design of efficient mediated electrochemical synthetic processes in relatively inexpensive, low toxicity, water-based fluid media. Mediated electrochemical addition reactions are major targets because these atom-economical processes can be utilized to prepare chemicals of many classes, including lactones, pheromones, prostaglandins, C-glycosides, optically active olefins and alcohols, and cyclic molecules. New catalytic surfaces design specifically for microemulsions combined with kinetic control by fluid composition may provide a basis for future cost-effective, environmentally benign processes for the synthesis of high value chemicals.

摘要CTS-9632391 这个项目的目标是发展一个基本的了解如何在电极和微乳液中的动力学表面动力学影响控制介导的电化学合成反应。 电化学研究用于将表面活性剂和反应物在电极表面上的吸附-脱附动力学与催化反应速率联系起来。 介导的反应包括碳-碳偶联、环化和烯烃生产。将使用裸碳电极在本体流体中的介体的催化效率与专门设计用于在微乳液中实现高反应速率的新催化电极的催化效率进行比较。 大环金属配合物，催化反应的有效的内部球途径，如维生素B12和钴，铁，镍卟啉，被用作介体。 基于聚合的硅-氧-碳连接到碳电极的逐层电极涂覆策略与先前开发的聚合物沉积方法进行了比较。 电分析方法用于比较微乳液和均相有机溶剂和催化电极中的反应速率。 在搅拌间歇式电化学反应器中的合成电解与产物分析用于评估系统的实际效用，并优化产率和反应物转化率。 微乳液的组成和催化涂层的性质被调整为最佳反应速率和关键反应的产率。 用时间分辨流动伏安法在裸电极和催化电极上测定了反应物和表面活性剂在电极上的表面动力学。 方法和理论开发较早。 将通过从波伏安法获得的Frumkin相互作用参数评估共吸附物之间的分子相互作用。 作为可能的限制因素介导的反应，反应物和表面活性剂的退出和进入率估计新的催化膜使用电活性探针的速率。 寻求所有表面动态事件的速率和介导的合成反应的速率之间的相关性。 这项工作的目的是提供基本的指导，为未来设计的高效介导的电化学合成过程中相对便宜，低毒性，水基流体介质。 介导的电化学加成反应是主要的目标，因为这些原子经济的方法可以用于制备许多类别的化学品，包括内酯，信息素，野牡丹素，C-糖苷，光学活性烯烃和醇，和环状分子。 新的催化表面的设计，特别是微乳液结合动力学控制的流体组合物，可以为未来的成本效益，环境友好的高价值的化学品的合成过程提供了基础。