Nickel Catalysts for the Dehydrative Decarbonylation of Carboxylic Acids to Alkenes

详细信息    查看全文

• 作者：Alex John ; Maria O. Miranda ; Keying Ding ; Büsra Dereli ; Manuel A. Ortuño ; Anne M. LaPointe ; Geoffrey W. Coates ; Christopher J. Cramer ; William B. Tolman
• 刊名：Organometallics
• 出版年：2016
• 出版时间：July 25, 2016
• 年：2016
• 卷：35
• 期：14
• 页码：2391-2400
• 全文大小：557K
• 年卷期：0
• ISSN：1520-6041

文摘

Combining high-throughput experimentation with conventional experiments expedited discovery of new first-row nickel catalysts for the dehydrative decarbonylation of the bioderived substrates hydrocinnamic acid and fatty acids to their corresponding alkenes. Conventional experiments using a continuous distillation process (180 °C) revealed that catalysts composed of Ni^II or Ni⁰ precursors (NiIb>2b>, Ni(PPhb>3b>)b>4b>) and simple aryl phosphine ligands were the most active. In the reactions with fatty acids, the nature of the added phosphine influenced the selectivity for α-alkene, which reached a maximum value of 94%. Mechanistic studies of the hydrocinnamic reaction using Ni(PPhb>3b>)b>4b> as catalyst implicate a facile first turnover to produce styrene at room temperature, but deactivation of the Ni(0) catalyst by CO poisoning occurs subsequently, as evidenced by the formation of Ni(CO)(PPhb>3b>)b>3b>, which was isolated and structurally characterized. Styrene dimerization is a major side reaction. Analysis of the reaction mechanism using density functional theory supported catalyst regeneration along with alkene formation as the most energetically demanding reaction steps.