TY - JOUR
T1 - Metalloporphyrin-catalyzed homogeneous oxidation in supercritical carbon dioxide
AU - Birnbaum, Eva R.
AU - Le Lacheur, Richard M.
AU - Horton, April C.
AU - Tumas, William
N1 - Funding Information:
We thank Dr. Mark McCleskey for assistance with high pressure UV–Vis spectroscopy, and Dr. Jay Labinger, Prof. John Bercaw, and Prof. Harry Gray (Caltech) for helpful discussions. This work is part of the Los Alamos Catalysis Initiative and was predominantly funded by Los Alamos National Laboratory Directed Research and Development grants. We also acknowledge the EPA Risk Reduction and Engineering Lab (RREL) for funding for portions of this work. LA-UR-97-3883.
PY - 1999/2/19
Y1 - 1999/2/19
N2 - We report results from a study of the reactivity of the halogenated porphyrins tetrakis(pentafluorophenyl)porphyrinato iron(III) chloride [Fe(TFPP)Cl] and β-octabromo-tetrakis(pentafluorophenyl)porphyrinato iron(III) chloride [Fe(TFPPBr8)Cl] with dioxygen and cyclohexene in supercritical carbon dioxide. A lower limit for the solubility of the iron porphyrins in sc CO2 was determined. Both halogenated metalloporphyrins were active catalysts for oxidation of cyclohexene to epoxide and allylic oxidation products in sc CO2. In 12 h at 80°C, up to 350 and 580 turnovers were observed for Fe(TFPP)Cl and Fe(TFPPBr8)Cl, respectively. We have also explored several organic solvent reactions at high temperature and pressure to benchmark relative activity and selectivity. Activity is higher in organic solvent, but accompanied by substantial oxidation of, or reaction with the solvent. Selectivity for epoxidation with Fe(TFPPBr8)Cl is higher in sc CO2 than in organic solvents, with up to 34% cyclohexene oxide produced.
AB - We report results from a study of the reactivity of the halogenated porphyrins tetrakis(pentafluorophenyl)porphyrinato iron(III) chloride [Fe(TFPP)Cl] and β-octabromo-tetrakis(pentafluorophenyl)porphyrinato iron(III) chloride [Fe(TFPPBr8)Cl] with dioxygen and cyclohexene in supercritical carbon dioxide. A lower limit for the solubility of the iron porphyrins in sc CO2 was determined. Both halogenated metalloporphyrins were active catalysts for oxidation of cyclohexene to epoxide and allylic oxidation products in sc CO2. In 12 h at 80°C, up to 350 and 580 turnovers were observed for Fe(TFPP)Cl and Fe(TFPPBr8)Cl, respectively. We have also explored several organic solvent reactions at high temperature and pressure to benchmark relative activity and selectivity. Activity is higher in organic solvent, but accompanied by substantial oxidation of, or reaction with the solvent. Selectivity for epoxidation with Fe(TFPPBr8)Cl is higher in sc CO2 than in organic solvents, with up to 34% cyclohexene oxide produced.
KW - Metallophorphyrins
KW - Oxidation
KW - Supercritical carbon dioxide
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U2 - 10.1016/S1381-1169(98)00172-1
DO - 10.1016/S1381-1169(98)00172-1
M3 - Article
AN - SCOPUS:0344507541
VL - 139
SP - 11
EP - 24
JO - Journal of Molecular Catalysis A: Chemical
JF - Journal of Molecular Catalysis A: Chemical
SN - 1381-1169
IS - 1
ER -