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首页> 外文会议>International Conference on Carbon Dioxide Utilization; 20050620-23; Oslo(NO) >Direct synthesis of dimethyl carbonate with supercritical carbon dioxide: Characterization of a key organotin oxide intermediate
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Direct synthesis of dimethyl carbonate with supercritical carbon dioxide: Characterization of a key organotin oxide intermediate

机译：用超临界二氧化碳直接合成碳酸二甲酯：关键有机锡氧化物中间体的表征

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摘要

The direct synthesis of dimethyl carbonate (DMC) using carbon dioxide as solvent and reagent for its fixation to methanol was explored with di-n-butyldimethoxystannane in order to get insight into the reaction mechanism for activity improvement. Catalytic runs including recycling experiments allowed isolation and characterization by NMR, IR, and single-crystal X-ray diffraction of a new tin complex containing 10 tin atoms. This compound could be prepared independently and is considered as a resting species. The yield of DMC is highest under 20 MPa pressure that fits with a monophasic supercritical medium in agreement with fluid phase equilibria calculations. In line, preliminary kinetics and initial rate determination show a positive order in carbon dioxide and a first-order dependence on the stannane. The initial rates were lower with the deca-tin complex than with the stannane precursor, but the turnover numbers (TONs) were higher. Water, the co-product of the reaction, was found to reversibly poison the active centers. Its in situ trapping had a beneficial effect. This study provides new mechanistic clues as to the reactive species and DMC formation. Further kinetics work is in progress to determine the rate-limiting step(s) at the initial stage of the reaction for more active catalyst design.
机译：用二正丁基二甲氧基锡烷探索了使用二氧化碳作为溶剂和固定在甲醇上的试剂直接合成碳酸二甲酯（DMC）的方法，以了解提高活性的反应机理。包括再循环实验在内的催化运行，可以通过NMR，IR和包含10个锡原子的新锡配合物的单晶X射线衍射进行分离和表征。该化合物可以独立制备，被认为是静止物种。 DMC的产率在20 MPa压力下最高，这与单相超临界介质相符，与液相平衡计算相符。同时，初步动力学和初始速率测定显示二氧化碳呈正序，且对锡烷具有一阶依赖性。与锡烷前体相比，十加锡配合物的初始速率较低，但周转率（TONs）较高。发现水是反应的副产物，可逆地毒害活性中心。它的原位捕获具有有益的作用。这项研究为反应物种和DMC的形成提供了新的机制线索。正在进行进一步的动力学工作，以确定反应初始阶段的限速步骤，以设计更具活性的催化剂。

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