Water-Soluble-Phosphines-Assisted Cobalt Separation in Cobalt-Catalyzed Hydroformylation

The hydroformylation of octene-1 and the removal of Co2(CO)8 and HCo(CO)4 from the reaction products including commercial C9 OXO-product were studied under biphasic conditions using an aqueous solution of different electron-donating sulfonated phosphine RnP(C6H4-m-SO3Na)2 (n = 0, 1, 2; R = Me, Bu, Cp) ligands. Depending on the electronic and steric properties of the phosphines, 6–70 ppm residual cobalt concentrations could be achieved in the organic phase under 10 bar of CO/H2 (1:1) at 75 °C. The formation of several water-soluble-phosphine-substituted cobalt carbonyl species including Co2(CO)6(TPPTS)2, HCo(CO)3(TPPTS), HCo(CO)2(TPPTS)2, and [Co(CO)3(TPPTS)2]+[Co(CO)4]− were identified and monitored by in situ IR and NMR spectroscopy.