CAREER: SusChEM: Development of Manganese Hydrosilylation Catalysts for Silicone Curing

在这个由化学系化学催化计划资助的项目中，亚利桑那州立大学的莱恩·特罗维奇教授正在研究如何从丰富的金属(如锰)中制造催化剂，这些催化剂可以用来制备有机硅聚合物。聚合物是长链分子，它们的许多性质来自于链之间的纠缠和相互作用。聚合物已经成为我们日常生活中无处不在的材料，影响到大多数行业，包括农业和食品、健康和安全以及交通运输。半个多世纪以来，有机硅聚合物一直用于各种消费产品，包括隐形眼镜、软管和医疗植入物。大多数广泛用于有机硅制备和固化的催化剂都是以贵金属为基础的，如铂或铱，这些相对有毒的元素由于在地壳中的丰度较低，获得成本较高。用于有机硅制备的锰基催化剂的开发将有可能取代贵金属催化剂的使用，这将是可持续化学方面的重大进步。特罗维奇教授也在努力提高学生和公众对绿色化学的熟悉程度。他正在为当地高中生开发一个可持续发展研讨会，并将提供基于该项目的视频，以实现广泛传播。作为绿色化学承诺的顾问委员会成员，他正在参与正在进行的活动，通过更新课程和实验室经验，向本科生和研究生介绍可持续化学的高级主题。特罗维奇教授还与凤凰城公共图书馆合作组织科学咖啡馆讨论。在这个项目中，亚利桑那州立大学的Ryan J.trovitch教授正在开发可持续的锰氢硅化催化剂，这种催化剂将显示出与广泛使用的贵金属催化剂相当的活性和选择性。相对于第二和第三排过渡金属，锰在催化应用中仍未得到充分利用，因为它倾向于参与单电子反应途径。最近的研究结果表明，多齿、氧化还原非无害的螯合配体通过可逆地转移电子并在整个催化过程中部分解离，使锰催化的羰基硅氢加成反应成为可能。在这一发现的基础上，特罗维奇教授正在研究锰催化的氢硅化反应的几个方面，包括可用作铂催化剂替代品的锰烯烃氢硅化催化剂，将聚酮与多氢硅烷或多氢硅氧烷交联的新的羰基硅氢反应途径，以及合成硅氧烷网络的脱氢硅烷反应途径。通过电子结构测定和机理研究，通过合理地修饰配体结构，开发出了用于烯烃硅氢化、硅酮氢化和硅氢化脱氢的高活性锰催化剂。该项目的成功完成将改变目前对锰催化的认识，同时揭示高密度氧化还原非无害螯合物利用的潜在优势。

In this project funded by the Chemical Catalysis Program of the Chemistry Division, Professor Ryan Trovitch of Arizona State University is studying ways to make catalysts from abundant metals, such as manganese, that can be used to prepare silicone polymers. Polymers are long chain molecules that derive many of their properties from the entanglements and interactions between the chains. Polymers have become ubiquitous materials in our daily lives, impacting most industries, including agriculture and food, health and safety, as well as transportation. For more than half a century, silicone polymers have been used in a variety of consumer products including contact lenses, flexible tubing, and medical implants. Most catalysts that are widely employed in silicone preparation and curing are based on precious metals such as platinum or iridium, relatively toxic elements that are costly to obtain due to their low abundance in the Earth's crust. The development of manganese-based catalysts for silicone preparation would have the potential to supplant precious metal catalyst use, which would represent a significant advance in sustainable chemistry. Professor Trovitch is also working to enhance student and public familiarity with green chemistry. He is developing a sustainability workshop for local high school students, and videos based upon this program will be made available to achieve broad dissemination. As an Advisory Board Member of the Green Chemistry Commitment, he is participating in ongoing initiatives to introduce undergraduate and graduate students to advanced topics in sustainable chemistry through updated coursework and laboratory experiences. Professor Trovitch is also organizing Science Cafe discussions in collaboration with the Phoenix Public Library. In this project, Prof. Ryan J. Trovitch of Arizona State University is developing sustainable manganese hydrosilylation catalysts that will exhibit comparable activity and selectivity to widely used precious metal catalysts. Relative to second and third row transition metals, manganese remains underutilized in catalytic applications due to its propensity to participate in one-electron reaction pathways. Recent results have shown that polydentate, redox non-innocent chelate ligands enable manganese-catalyzed carbonyl hydrosilylation by reversibly transferring electrons and partially dissociating throughout catalysis. Building on this discovery, Professor Trovitch is studying several aspects of manganese-catalyzed hydrosilylation reactions including manganese olefin hydrosilylation catalysts that can serve as replacements for ones based upon platinum, novel carbonyl hydrosilylation pathways to crosslink polyones with polyhydrosilanes or polyhydrosiloxanes, and dehydrogenative silylation pathways to the synthesis of siloxane networks. Via electronic structure determinations and mechanistic studies, highly active manganese catalysts for olefin hydrosilylation, carbonyl hydrosilylation, and dehydrogenative silylation are being developed by judiciously modifying their ligand frameworks. Successful completion of this project will transform current knowledge of manganese catalysis while revealing potential advantages of high-denticity redox non-innocent chelate utilization.