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

The hydroformylation of octene-1 and the removal of Co-2(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/H-2 (1:1) at 75 degrees C. The formation of several water-soluble-phosphine-substituted cobalt carbonyl species including Co-2(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.