Tuning the coordination microenvironment of Co sites embedded in porous organic polymer for the hydroformylation of diisobutylene

Abstract

Hydroformylation is one of the most important routes for the synthesis of high-value-added fine chemicals, which usually relies on metal rhodium and cobalt. Diisobutylene is a chemical intermediate of great interest in the chemical industry, which could serve as a fine feedstock to prepare environmentally friendly plasticizers through the hydroformylation route. At present, the hydroformylation of diisobutylene is mainly based on homogeneous cobalt-based catalytic systems, suffering from a complicated recycling process and harsh reaction conditions. Herein, by regulating the coordination microenvironment of Co species, three Co@POPs heterogeneous catalysts, marked as Co@POPs-DVB, Co@POPs-PPh₃&DVB and Co@POPs-PPh₃, were successfully designed and synthesized. Co@POPs-PPh₃&DVB showed a superior catalytic performance with a 45.6% yield and a 78.4% selectivity for the main products (isononanal and isononanol), which was better than the homogeneous Co(acac)₂:PPh₃ system that offered a 29.1% yield and a 53.1% selectivity. Additionally, Co@POPs-PPh₃&DVB could maintain a high activity and selectivity for at least 5 cycles without losing activity. Various characterizations indicated that the unique structure and microenvironment of Co@POPs-PPh₃&DVB promoted the formation of HCo(CO)₃(P-frame) active species, which was the dominant active species for the hydroformylation of diisobutylene.