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 该项目的目标是对电极表面动力学和微乳液动力学如何影响介导电化学合成中的反应性控制有一个基本的了解。 电化学研究用于将电极表面上的表面活性剂和反应物吸附-解吸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。使用裸碳电极的本体流体中介体的催化效率将与专门设计用于在微乳液中实现高反应速率的新型催化电极的催化效率进行比较。 通过有效的内球途径催化反应的大环金属配合物，例如维生素 B12 和钴、铁和镍卟啉，被用作介体。 将基于碳电极聚合物硅-氧-碳键的逐层电极涂层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进行合成电解并进行产物分析，用于评估系统的实用性，并优化产率和反应物转化率。 微乳液的成分和催化涂层的性能经过调整，以获得关键反应的最佳反应速率和产率。 通过时间分辨流动伏安法在裸电极和催化电极上测量电极上反应物和表面活性剂的表面动力学。 采用了早期开发的方法和理论。 共吸附物之间的分子相互作用将通过波伏安法获得的弗鲁姆金相互作用参数进行评估。 作为介导反应速率的可能限制因素，使用电活性探针估计新催化膜的反应物和表面活性剂的退出和进入速率。 寻找所有表面动态事件的速率与介导的合成反应的速率之间的相关性。 这项工作的目的是为未来在相对便宜、低毒的水基流体介质中设计高效介导的电化学合成过程提供基本指导。 介导的电化学加成反应是主要目标，因为这些原子经济的过程可用于制备许多类别的化学品，包括内酯、信息素、前列腺素、C-糖苷、光学活性烯烃和醇以及环状分子。 专为微乳液设计的新型催化表面与流体成分的动力学控制相结合，可以为未来高价值化学品合成的经济高效、环境友好的工艺提供基础。