Density Functional Investigation On Mechanism Of Hydroformylation Catalyzed By Rh-complex

In present paper, hydroformylation of ethene, ethyne, propyne, propenal catalyzed by the modified Rh catalyst HRh(CO)2(PH3) and asymmetric hydroformylation of vinyl formate catalyzed by Rh-complex with CHIRAPHOS-type ligand were investigated from a computational view. The competitive hydrogenation of ethyne, propenal and propyne were also calculated at the same level in order to further advance the mechanism. Moreover, solvent effect on hydroformylation of enthene was also carried out with Onsager model.To begin with addition of reactant to the active catalyst and then C=C bond insertion into Rh-H bond, catalytical cycle of hydroformylation followed PH3 addition, CO insertion, H2 oxidative addition and reductive elimination steps; hydrogenation proceeded with H2 oxidative addition and reductive elimination. Except for olefin and PH3 addition steps, the transition states for the other steps were all located in our work. Combining the results from each elementary step, there were a number of possible pathways for hydroformylation and hydrogenation of above reactants. Except for ethyne hydroformylation and hydrogenation, H2 oxidative addition was rate-limited step for both hydroformylation and hydrogenation for other reactions with relative higher energy barrier than other steps.Solvent effects on hydroformylation of ethene were calculated via self-convergence reaction field (SCRF) with Onsager model under condition of non-solvent, cyclohexane (C6H12, ε=2.02), benzene (C6H6, ε=2.25), tetrahydrofuran (THF,ε=7.43), dichloromethane (CH2Cl2, ε=8.93), methanol (CH3OH, ε=32.61) and water (H2O, ε=78.36) respectively. The results show that geometry parameters and energy changed with different solvents and the activating free energies fell down with ε value increasing. Therefore, water with ε=78.36 as solvent for hydroformylation of...