Jin Feng, M. Garland
Mar 25, 1999
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Journal
Organometallics
Abstract
The homogeneous catalytic hydroformylation of cyclohexene to cyclohexanecarboxaldehyde was studied, starting with Rh4(CO)12 as catalyst precursor in n-hexane as solvent. The reaction conditions were T = 298 K, PH2 = 2.0 MPa (0.018 mol fraction), PCO = 6.0 MPa (0.095 mol fraction), and [C6H10]0 = 0.144 mol fraction. The nominal rhodium concentration was varied in four experiments as [Rh4(CO)12]0 = 3.5 × 10-5, 6.6 × 10-5, 1.7 × 10-4, and 3.3 × 10-4 mol fraction (where the last value represents the approximate solubility limit). In each of the four experiments the time-dependent concentrations of the precursor Rh4(CO)12, the organometallic intermediate C6H11CORh(CO)4, and the organic product C6H11CHO were measured under isobaric and isothermal conditions using in situ high-pressure infrared spectroscopy. Complete conversion of the precursor Rh4(CO)12 to the intermediate C6H11CORh(CO)4 was never observed during the 8 h experiments. Instead, after approximately 30 min, a pseudo steady state was achieved betwee...