Realistic Modelling of Organometallic Reactivity in Solution: Computational Studies on the Mechanism of Methanolysis of Palladium-Acyl Bonds

溶液中有机金属反应性的真实模拟：钯酰基键甲醇分解机理的计算研究

• 批准号: EP/F020163/1
• 负责人: Stuart Macgregor
• 金额: $ 32.47万
• 依托单位: Heriot-Watt University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FF020163%2F1
• 关键词: Realistic; Modelling; Organometallic; Reactivity; Solution

Methoxycarbonylation is a process that converts cheap, widely available feedstocks (alkenes, carbon monoxide and methanol) into commercially-important intermediates for the chemicals industry. This process uses Pd-based catalysts and the best example is the reaction of the simplest alkene, ethene, to give the intermediate methyl methacrylate, which is used in the synthesis of plastics. More recently, alkenes such as vinyl acetate have been shown to undergo methoxycarbonylation to generate intermediates that are themselves useful as green solvents (low-volatility/biodegradable) or as monomers for the formation of biodegradable polymers. These have the potential to replace traditional materials such as polystyrene or polythene. Methoxycarbonylation of butadiene promises a new route to adipic acid, one of the co-monomers involved in the manufacture of nylon. As yet the methoxycarbonylation of vinyl acetate and butadiene have not been optimised and greater insight into these reactions is required before effective industrial processes are in place.A key issue that remains to be solved in the methoxycarbonylation reaction is the detailed mechanism by which the products are released - the so-called methanolysis step. There a several possibilities for this process, however, it is extremely difficult to obtain information on this from experiment as the reaction itself is incredibly fast. In these circumstances the use of computational modelling comes into its own, as this can readily provide information on the energies of the species involved in reactivity. The methanolysis reaction is, however, very complicated and is strongly dependent on the precise nature of the reacting species and the nature of the solvent being used. To obtain reliable modelling data these factors must be taken into account, a fact that makes the task of modelling these systems very challenging.This proposal seeks to use high level computational modelling to assess the mechanism of the methanolysis on the simplest methoxycarbonylation system - ethene/CO/MeOH - and the most effective Pd catalysts. Our approach will be to employ hybrid calculations where the catalyst and reacting molecules are dealt with at a high level of theory (density functional theory) but the solvent molecules (many 10s or hundreds) are treated at a lower level of theory based on classical force fields. Through this approach the effect of the solvent on the reactivity at the Pd catalyst will be taken into account and we aim to provide extremely reliable data to define the preferred mechanism. We will test our approach by comparing with an alternative catalyst which displays a different reactivity, thus giving a stringent test of our modelling approach.Once we have defined the correct way to treat these complicated reactions - as well as the mechanism by which methanolysis occurs - we will be in a position to tackle the new reactions of vinyl acetate and butadiene. We hope to provide sufficient insight into these processes that experimental chemists will be able to design new improved catalysts for more efficient methoxycarbonylation of these feedstocks on an industrial scale.

甲氧基羰基化是将廉价且广泛使用的原料（烯烃、一氧化碳和甲醇）转化为化学工业中具有商业价值的中间体的过程。该过程使用钯基催化剂，最好的例子是最简单的烯烃乙烯的反应，生成用于塑料合成的中间体甲基丙烯酸甲酯。最近，乙酸乙烯酯等烯烃已被证明可以进行甲氧基羰基化，生成中间体，这些中间体本身可用作绿色溶剂（低挥发性/可生物降解）或用作形成可生物降解聚合物的单体。这些有可能取代聚苯乙烯或聚乙烯等传统材料。丁二烯的甲氧基羰基化开辟了一条生产己二酸的新途径，己二酸是尼龙制造中涉及的共聚单体之一。迄今为止，乙酸乙烯酯和丁二烯的甲氧基羰基化尚未得到优化，在有效的工业流程到位之前，需要对这些反应有更深入的了解。甲氧基羰基化反应中仍有待解决的一个关键问题是产物生成的详细机制。释放 - 所谓的甲醇分解步骤。这个过程有多种可能性，但是，由于反应本身非常快，因此从实验中获得有关信息非常困难。在这些情况下，计算模型的使用就发挥了作用，因为这可以很容易地提供有关参与反应的物种的能量的信息。然而，甲醇分解反应非常复杂，并且很大程度上取决于反应物质的精确性质和所用溶剂的性质。为了获得可靠的建模数据，必须考虑这些因素，这一事实使得对这些系统进行建模的任务非常具有挑战性。本提案旨在使用高级计算建模来评估最简单的甲氧基羰基化系统 - 乙烯/的甲醇分解机制。 CO/MeOH - 和最有效的 Pd 催化剂。我们的方法将采用混合计算，其中催化剂和反应分子在高水平的理论（密度泛函理论）下处理，但溶剂分子（数十或数百）在基于经典力的较低理论水平上处理字段。通过这种方法，将考虑溶剂对 Pd 催化剂反应性的影响，我们的目标是提供极其可靠的数据来定义优选的机制。我们将通过与显示不同反应性的替代催化剂进行比较来测试我们的方法，从而对我们的建模方法进行严格的测试。一旦我们定义了处理这些复杂反应的正确方法 - 以及甲醇分解发生的机制 -我们将能够解决乙酸乙烯酯和丁二烯的新反应。我们希望对这些过程提供足够的了解，使实验化学家能够设计新的改进催化剂，以便在工业规模上更有效地对这些原料进行甲氧基羰基化。

项目成果

Reactivity of the Latent 12-Electron Fragment [Rh(P i Bu 3 ) 2 ] + with Aryl Bromides: Aryl?Br and Phosphine Ligand C?H Activation

潜在 12 电子片段 [Rh(P i Bu 3 ) 2 ] 与芳基溴化物的反应性：Aryl?Br 和膦配体 C?H 活化

• DOI: 10.1002/chem.201000554
• 发表时间: 2010
• 期刊: Chemistry - A European Journal
• 作者: Townsend N

Comparison of the photochemistry of organometallic N-heterocyclic carbene and phosphine complexes of manganese.

有机金属N-杂环卡宾和锰膦配合物的光化学比较。

• DOI: 10.1039/c1cc14467g
• 发表时间: 2011
• 期刊: Chemical communications (Cambridge, England)
• 作者: Batool M