Development of a Catalytic Protocol for Alkane Dehydrogenation by C–H Activation at Iridium(III)

通过在铱 (III) 上活化 C–H 来开发烷烃脱氢催化方案

• 批准号: 9395276
• 负责人: Kelly Kim
• 金额: $ 5.63万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9395276
• 关键词: Aerobic; Alcohols; Aldehydes; Alkanes; Alkenes; Amides; Biological; Carbon; Catalysis; Chemicals; Coke; Complex; Dependence; Development; Electronics; Electrons; Esters; Future; Goals; Health; High temperature of physical object; Human; Hydrocarbons; Industrialization; Insertional Activations; Investigation; Iridium; Ketones; Ligands; Ligation; Mediating; Mediator of activation protein; Metals; Methods; Modification; Molecular; Natural regeneration; Octanes; Organic Synthesis; Oxidants; Oxygen; Predisposition; Preparation; Problem Solving; Process; Production; Protocols documentation; Reaction; Research; Scheme; Scientist; System; Temperature; Transition Elements; base; career; catalyst; chemical synthesis; cold temperature; computer studies; dehydrogenation; drug discovery; improved; novel; novel strategies; planetary Atmosphere; skills

PROJECT SUMMARY Inexpensive and abundant, unactivated alkanes are ideal precursors for the production of commodity chemicals. Common starting materials in industrial processes and ubiquitous motifs in complex molecules, alkenes can be produced from more readily available alkanes through transition-metal-catalyzed dehydrogenation. While heterogeneous catalysis has proven useful in industrial dehydrogenation of low-carbon alkanes, applications in chemical synthesis have been limited due to high temperatures, susceptibility to catalyst-deactivating coking, and low selectivity with longer-chain alkane substrates. In contrast, homogeneous catalytic reactions generally proceed under milder conditions and can be effective in the dehydrogenation of higher alkanes. Extensive research has revealed pincer-ligated Ir compounds to be the optimal catalysts, and recent studies have implicated Ir(III) complexes as promising candidates capable of circumventing many limitations of established Ir(I) systems. This application describes the development of a novel protocol for catalytic alkane dehydrogenation by pincer- ligated Ir(III) complexes using the most economical oxidant available, molecular oxygen. The research strategy builds on the previously demonstrated capabilities of a (NCN)Ir(III) complex for mediating alkane dehydrogenation and for regenerating under aerobic conditions. To date, catalysis has remained elusive due to the instability of the Ir(III) complex in the presence of oxygen at the high temperatures required for dehydrogenation. Computational studies suggest that ligation of the Ir(III) metal center with electron-poor pincer ligand frameworks will lower the energy barrier to dehydrogenation. Based on the conclusions drawn from these experimental and computational investigations, the central hypothesis of this research plan is that catalytic dehydrogenation can be realized by reducing the reaction temperature through strategic modification of the pincer ligand supporting the Ir(III) metal center. The specific aims of this application are: 1) synthesis of novel Ir(III) pincer complexes for alkane dehydrogenation, 2) Ir(III)-catalyzed alkane dehydrogenation under aerobic conditions, and 3) dehydrogenation of functionalized organic substrates. The development of a method for Ir(III)-catalyzed alkane dehydrogenation under aerobic conditions will contribute a novel olefin preparation strategy invulnerable to many limitations of current processes while using an environmentally friendly oxidant. The results of this project will greatly impact the preparation of olefin- containing commodity chemicals and complex molecules relevant to human health or intermediates thereto.

项目概要 廉价且丰富的未活化烷烃是生产商品的理想前体 化学品。工业过程中常见的起始材料和复杂分子中普遍存在的图案， 可以通过过渡金属催化从更容易获得的烷烃生产烯烃 脱氢。虽然多相催化已被证明可用于低碳工业脱氢 烷烃，由于高温、易受环境影响，在化学合成中的应用受到限制。 催化剂失活焦化，以及长链烷烃底物的低选择性。相比之下，同质 催化反应通常在较温和的条件下进行，可以有效地脱氢 高级烷烃。广泛的研究表明钳状连接的铱化合物是最佳的催化剂，并且 最近的研究表明 Ir(III) 配合物是有希望的候选者，能够规避许多 已建立的 Ir(I) 系统的局限性。 该申请描述了一种通过钳式催化烷烃脱氢的新方案的开发 使用最经济的氧化剂分子氧连接 Ir(III) 配合物。研究策略 建立在先前展示的 (NCN)Ir(III) 配合物介导烷烃的能力之上 脱氢和在有氧条件下再生。迄今为止，由于催化作用仍然难以捉摸 Ir(III) 配合物在氧存在和高温下的不稳定性 脱氢。计算研究表明 Ir(III) 金属中心与贫电子的连接 钳配体框架将降低脱氢的能垒。根据得出的结论 根据这些实验和计算研究，本研究计划的中心假设是 通过策略改造降低反应温度可实现催化脱氢 支持 Ir(III) 金属中心的钳配体的结构。该应用的具体目标是：1）合成 用于烷烃脱氢的新型 Ir(III) 钳配合物，2) Ir(III) 催化的烷烃脱氢反应 有氧条件，3) 功能化有机底物的脱氢。 开发有氧条件下 Ir(III) 催化烷烃脱氢方法 贡献了一种新颖的烯烃制备策略，在使用时不受当前工艺的许多限制的影响 一种环境友好型氧化剂。该项目的成果将对烯烃的制备产生重大影响。 含有与人类健康相关的商品化学品和复杂分子或其中间体。