Mechanistic Studies of the Decarbonylation of Carboxylic Acids using Palladium Catalysts

Linear α-olefins are widely used in industry as feedstock for consumer products such as surfactants, lubricants, and polymers. Currently, commercial production of these commodity chemicals relies on petrochemical sources, which have long-term sustainability and environmental implications. However, the potential of biomass as a more sustainable antidote to the diminishing stock of fossil fuels has been demonstrated. This has led to a surge in research into bio-derived carboxylic acids and their derivatives due to their ready availability in nature, relatively cheaper cost and ability to generate valuable olefins. In this project, we are seeking to develop an active and efficient catalyst for producing linear α-olefins from bio-derived carboxylic acid derivatives under mild reaction conditions. Using density functional theory (DFT), we are studying the reaction mechanism for the decarbonylation of 3-phenylpropanoyl chloride by palladium complexes to produce styrene without the possibility of olefin isomerization. Using Pd(PtBu3)2 and Pd(PPh3)4 as catalysts, we seek to understand the effect of the ligand on styrene formation. Our results show that oxidative addition is a facile process for both phosphine systems. The choice of ligand and halide abstraction from the oxidative addition product affect styrene formation via the barriers to decarbonylation and β-Hydride elimination. Our results suggest that a lower coordinate Pd center leads to more favorable barriers