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

在化学系化学合成计划的支持下，乔治华盛顿大学的Adelina Voutchkova-Kostal正在研究高效和最少浪费的方法，从含有羰基(C=O)的可再生原料中制备复杂分子。感兴趣的方法涉及化学反应，在该化学反应中，在产物形成过程中，在最终失去之前，羰基控制初始转化的位置。促进理想的“脱碳”反应将依赖于可调粘土催化剂的设计，这种催化剂有望直接适用于小规模和大规模的合成过程。所开发的方法预计将用于精细化学合成、将生物质转化为增值材料，以及未来旨在促进可持续化学经济的制造过程中。该资助项目的更广泛影响将延伸到Voutchkova-Kostal博士和她的同事参与外展和教育活动所积累的社会福利，这些活动包括指导当地的初中生和高中生，以及为全国各地的本科生提供暑期研究经验。除了这些项目将有助于扩大科学、技术、工程和数学(STEM)领域中未被充分代表的群体的参与，所有参与Voutchkova-Kostal研究小组的学生都将获得可移植的技能和在评估化学制造过程的环境影响方面的宝贵经验。通过避免使用传统的有机卤化物原料，脱碳和脱碳偶联反应有可能最大限度地减少卤化废物，允许使用来自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，但此类工艺尚未在有机合成中得到普遍应用。为了解决这一不足，该基金的研究重点是开发一套基于低成本和可调节的Pd-层状双氢氧化物(Pd-LDH)非均相催化剂平台的原子经济和化学选择性的脱碳转化。具体地说，正在进行三种类型的反应：(I)含羰基底物的脱羰基的化学选择方法，(Ii)脱羰的羟醛缩合过程，以及(Iii)Suzuki和Heck交叉偶联反应的脱羰基类似物。传统的均相催化脱羰反应通常需要高负载的贵金属络合物，这使得这种反应的化学选择性很差，而且实施起来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操作的固体负载型催化剂来克服这些挑战，这些催化剂提供了更广泛的应用，作为选择性C-C键形成和去官能化的原子经济策略。从根本上讲，这些研究将有助于合理设计能够在功能上超过同类类似物的负载型催化剂，同时将对环境的影响降至最低。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.