CAS: Atom-Economical Decarbonylative Processes Using Low-Cost Heterogeneous Catalysts

在化学系化学合成项目的支持下，乔治华盛顿大学的Adelina Voutchkova-Kostal正在研究用含有羰基（C=O）基团的可再生原料制备复杂分子的高效和最小浪费的方法。感兴趣的方法涉及化学反应，其中羰基控制初始转化的位置，然后在产物形成过程中最终丢失。促进所需的“脱碳化”反应将依赖于可调粘土基催化剂的设计，这种催化剂有望直接适用于小型和大规模的合成过程。预计所开发的方法将用于精细化学合成、将生物质转化为增值材料以及旨在促进可持续化学经济的未来制造过程。该资助项目的更广泛影响将扩展到社会效益，这是由Voutchkova-Kostal博士和她的同事参与外展和教育活动所产生的，这些活动包括对当地中学生和高中生的指导，以及为来自全国各地的本科生提供暑期研究经验。除了这些有助于扩大科学、技术、工程和数学（STEM）领域代表性不足群体参与的项目之外，所有参与Voutchkova-Kostal研究小组的学生都将获得可转移技能和评估化学制造过程对环境影响的宝贵经验。通过避免传统的有机卤化物起始材料，脱碳和脱碳偶联反应有可能最大限度地减少卤化废物，允许使用可再生生物质来源的醛，并促进新的选择性C-C键形成反应。尽管有这些优点，但这种工艺尚未在有机合成中得到普遍应用。为了帮助解决这一不足，该基金的研究重点是开发一套基于低成本和可调的pd层状双氢氧化物（Pd-LDH）多相催化剂平台的原子经济性和化学选择性脱碳转化。具体来说，目前正在进行三种类型的反应：(i)含羰基底物的脱羰化的化学选择方法，（ii）脱羰化醛醇缩合过程，以及（iii） Suzuki和Heck交叉偶联反应的脱羰类似物。传统的基于均相催化的脱碳化学通常需要高负荷的贵金属配合物，这使得这种反应的化学选择性很差，而且既昂贵又环境不可持续。相比之下，正在探索的方法旨在通过使用易于处理的固体负载催化剂来克服这些挑战，这些催化剂提供了脱碳的广泛使用，作为选择性C-C键形成和去功能化的原子经济策略。在基础层面上，这些研究将有助于合理设计负载催化剂，使其在功能上优于均相类似物，同时最大限度地减少对环境的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemical Synthesis program in the Division of Chemistry, Adelina Voutchkova-Kostal of George Washington University is studying efficient and minimally wasteful methods to prepare complex molecules from renewable starting materials containing carbonyl (C=O) groups. The methods of interest involve chemical reactions in which the carbonyl group controls the site of the initial transformation before it is ultimately lost during the course of product formation. Promoting the desired 'decarbonylative' reactions will rely on the design of tunable clay-based catalysts which are anticipated to be directly applicable to both small and large-scale synthetic processes. The methodology developed is expected to find use in fine chemical synthesis, the conversion of biomass to value-added materials, and in future manufacturing processes aimed at facilitating a sustainable chemical economy. The broader impacts of the funded project will extend to societal benefits accrued by the participation of Dr. Voutchkova-Kostal and her coworkers in outreach and educational activities that include the mentoring of middle and high school students from the local area and the provision of summer research experiences for undergraduate students from across the country. In addition to these programs, which will help to broaden the participation of underrepresented groups in science, technology, engineering, and mathematics (STEM) fields, all students engaging with the Voutchkova-Kostal research group will gain transferrable skills and valuable experiences in the evaluation of the environmental impacts of chemical manufacturing processes.By their avoidance of traditional organohalide starting materials, decarbonylation and decarbonylative coupling reactions have the potential to minimize halogenated waste, allow for the use of aldehydes from renewable biomass sources, and facilitate new selective C-C bond forming reactions. Notwithstanding these advantages, such processes have yet to find universal application in organic synthesis. To help to address this deficiency, the funded research focuses on the development of a suite of atom-economical and chemoselective decarbonylative transformations based on a low-cost and tunable Pd-layered double hydroxide (Pd-LDH) heterogeneous catalyst platform. Specifically, three types of reaction are being pursued: (i) chemoselective methods for decarbonylation of carbonyl group-containing substrates, (ii) decarbonylative aldol condensation processes, and (iii) decarbonylative analogs of the Suzuki and Heck cross-coupling reactions. The high-loading of precious metal complexes typically required for conventional homogenous catalysis-based decarbonylation chemistry, makes such reactions poorly chemoselective and both expensive and environmentally non-sustainable to implement. By contrast, the approach being explored aims to overcome these challenges by the use of easy-to-handle solid supported catalysts that offer expanded use of decarbonylation as an atom-economical strategy for selective C-C bond formation and defunctionalization. At a fundamental level, the studies will help to enable the rational design of supported catalysts that can outperform homogeneous analogues in function, while minimizing environmental impact.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.