1 / 49

Molybdenum Catalysis

Molybdenum Catalysis. Group Seminar 9-27-2012 Grant Margulieux. Hydrogenation Hydrodesulfurization Ketone/Aldehyde Reduction and Hydrogenation Hydrosilylation Olefin Epoxidation Methanol Oxidation N 2 Reduction Alkylidene Metathesis. Homogeneous Olefin Hydrogenation.

minya
Télécharger la présentation

Molybdenum Catalysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Molybdenum Catalysis Group Seminar 9-27-2012 Grant Margulieux

  2. Hydrogenation Hydrodesulfurization Ketone/Aldehyde Reduction and Hydrogenation Hydrosilylation Olefin Epoxidation Methanol Oxidation N2 Reduction Alkylidene Metathesis

  3. Homogeneous Olefin Hydrogenation Catalyst resistant to H2S and dibenzothiophene poisoning Biphasic mercury test performed to rule out nanoparticle chemistry Bricelli P.J., J. Organomet. Chem. 2009

  4. Hydrogenation with Group VI Carbonyl Hydrides Cr found to be most active for homogeneous hydrogenation, followed by Mo and W Fuchikami T., Ubukat Y., Tet. Let. 1991

  5. Heterogeneous Olefin Hydrogenation Mo(CO)6 encaged in zeolites hydrogenation of butadiene at RT at 0.20 atm, 2:1 ratio of H2/butadiene Zeolite LiY is a particularly acidic Zeolite, followed by NaY, then KY BlascoT., Sanchez-Sanchez M., Chem. Comm. 2000 Okamoto Y., J. Chem. Soc. Chem. Commun. 1988

  6. Stoichiometric Olefin Hydrogenation Mo-N 1.77A BoncellaJ. M., Ortiz C. G., Chem. Comm. 2000

  7. Hydrodesulfurization Essential industrial catalyst MoS2 used to desulfonate natural gas and petroleum products Reduces SO2 emissions from combustion of all hydrocarbon fuels Converts thiols and sulfides to H2S, thiophenes to H2S and alkanes Hydrogenates ethylene and propylene, isomerizes trans-butene to cis butene Thiophenes- sulfur containing heterocycles Daage, M.; Chianelli, R. R., J. of Catalysis, 1994 Topsøe, H.; Clausen, B. S.; Massoth, F. E., Hydrotreating Catalysis, Science and Technology, Springer-Verlag: Berlin, 1996

  8. Hydrodesulfurization Rim-Edge Model elucidated to explain why amorphous powders had substantially higher activity that microcrystalline powders Annealing amorphous MoS2 powder at increasing temperatures leads to an increase in basal plane surface area and number of layers. Amorphous XRD powder diffraction decreasing, TEM images of crystals increasing in size. Hydrodesulfurization activity decreases with annealing temperature. Daage, M.; Chianelli, R. R., J. of Catalysis, 1994 Polyakov M., Poisot M., GrunertW., J. of Catalysis, 2008

  9. Hydrodesulfurization Kinetics measured by mass spec under a continuous flow of H2 at 30 atm. Rim and edge densities extrapolated form powder XRD. Both hydrogenation and desulfurization rates increase with amorphology of microcrystalline catalyst. Daage, M.; Chianelli, R. R., J. of Catalysis, 1994

  10. Hydrodesulfurization Mo-S bonds easier to reduce in non-linear structure. HCL gas exposed to MoS2 microcrystals, hydrodesulfurization activity increases. Photodefleciton Spectroscopy measures the bending of light due to optical absorption. Used for measuring surface absorption and profiling thermal properties in layer materials. Daage, M.; Chianelli, R. R., J. of Catalysis, 1994 http://www.photonics.cusat.edu/Research_Photothermal%20Deflection.html

  11. Catalytic CO2 Reduction M=Cr, W CO and PPH3 retards formate production [PPN][HW(13CO)5] used as catalyst, no 13CO seen in formate [HCO2M(CO)5]- and [HM(CO)5]- seen through FTIR No D2 Study Darensbourg D.J., Valles C., J. Am. Chem. Soc. 1984

  12. Acyl Reduction Darensbourg M. Y., Kao, S.C., Organometallics 1984

  13. Aldehyde Reduction Reaction Conditions: 4 equiv [Et4N][HMo2(CO)10], 4 equivHOAc, refluxing THF Darensbourg M. Y., Kao, S.C., Organometallics 1984 Gibson D. H., El-Omrani Y.S., Organometallics. 1985

  14. Ketone Reduction M = Cr, Mo,W Mo(CO)6 has highest activity at lowest temperatures (70° C) Marko L., Nagy-Magos Z., J. Organomet. Chem. 1985

  15. Proposed Mechanism of Ketone Reduction with Cr(CO)6 Reaction slows with excess CO Accelerates whenH2 pressure increased Accelerates when concentration of NaOMe is increased Marko L., Nagy-Magos Z., J. Organtomet. Chem. 1985

  16. The Fate of the Catalyst Darensbourg M. Y., Darensbourg D. J., Tooley P., J Am. Chem. Soc 1986

  17. The Fate of the Catalyst Darensbourg M. Y., Darensbourg D. J., Tooley P., J Am. Chem. Soc 1986

  18. The Fate of the Catalyst Darensbourg M. Y., Darensbourg D. J., Tooley P., J Am. Chem. Soc 1986

  19. Ketone Hydrogenation Proposed Mechanism Darensbourg M. Y., Darensbourg D. J., Tooley P., J Am. Chem. Soc 1986

  20. Aldehyde and Ketone Reduction with Group VI Carbonyl Hydrides Fuchikami T., Ubukat Y., Tet. Let. 1991

  21. J Hydrosilylation with Group VI Carbonyl Hydrides Mo gave highest activity, followed by W and Cr. Fuchikami T., Ubukat Y., Tet. Let. 1991

  22. Transfer Hydrogenation in Water pH 5-6, lower pH catlyzs reaction In D2O studies D washes into Mo-H, and both positions on the iPrOH Kuo L.Y., Weakley T. Organometallics 2001

  23. Group 6 Hydride Kinetics Kinetic measurements by lo temp HNMR of Cp’s and Phosphines along with stopped flow reactor measuring UV absorption of Trityl hydride and Trityl cation. 3rd Row metals most hydridic Effect of changing the metal is much less than changing the ligands Cp* more hydridic than Cp, large increase in hydricity for phosphines over CO. Bullock R.M., Cheng T.C.J. Am. Chem. Soc. 1998

  24. Bullock Ketone Hydrogenation Catalyst Mo-C bonds 2.56, 2.65A Mo-P 2.49 A Bullock R.M., Cheng T.C. Chem. Comm. 1999

  25. Ketone Hydrogenation Under Mild Conditions Bullock R.M., Voges M.H., J. Am. Chem. Soc. 2000

  26. Hydrosilylationof Ketones Catalyst crashes out of silylated products Mo catalyst less active Bullock R.M., Dioumaev V., Nature. 2000

  27. Hydrosilylationof Ketones Bullock R.M., Dioumaev V., Nature. 2000

  28. Group 6 Hydrosilylation: The Early Years Mo(CO)6 5.0% HF aqueous workup Products assigned by NMR and GC Schmidt, T. Tet. Lett. 1994

  29. Molly Oxo Hydrosilylation Classically electron withdrawing benzaldehydes had high conversions Royo B., Fernandes A., Chem. Comm. 2004

  30. The Molly Shotgun Approach Synthesized new and known Mo Oxo’s to test catalytic competence, 1 is superior to all for hydrosilylation. Tested against range of ketones and aldehydes. Electron withdrawing benzaldehydes gave highest conversions in most cases. 6,7,8 known for olefin epoxidation Royo B., Reis P., Dalton Trans. 2006

  31. Propylene Oxidation Main ingredient in synthetic rubbers, adhesives and paints Nitrile rubber Ulmans Encyclopedia of Industrial Chemistry, Acrolein and Methacrolein Kuhn F. E., Jain K. R., Herrmann W. A., Coord. Chem. Rev. 2006

  32. Asymmetric Mo Olefin epoxidation- What Has failed Good conversions of styrenes to epoxides 40-70%, low ee’s1-20% Kuhn F. E., Jain K. R., Herrmann W. A., Coord. Chem. Rev. 2006

  33. Asymmetric Mo Olefin epoxidation- The Trail of Tears Continues Mo polyoxo’s generated by oxidizing carbonyls off in situi with t-butyl hydroperoxide Kuhn F. E., Jain K. R., Herrmann W. A., Coord. Chem. Rev. 2006

  34. Olefin Epoxidation with Chiral Ligands Thrown In Epoxidation of allylic alcohols works with VO(OiPr)3 , Zr(O-tBu)4 , Hf(O-tBu)4 Yamamoto H., Barlan A., Basak A. Andew. Chem. Int. Ed.2006 Yamamoto H., Li Z., Zhang W., Andew. Chem. Int. Ed.2008 Yamamoto H., Li Z., J. Am. Chem. Soc. 2010

  35. Organic Chemists to the Rescue Can do 1°, 2°, 3° aliphatic olefins with ee’s>50%. No functional group tolerance THP=Trityl hydroperoxide TBHP=t-Buytl hydroperoxide CHP= Cumene hydroperoxide Yamamoto H., Barlan A., Basak A. Andew. Chem. Int. Ed.2006

  36. Possible Epoxidation Mechanism Calhorda M., Alonso J., Organometallics 2007

  37. Calculated Resting State of Catalyst No numbers on differences in energy. Monomeric solutions did not converge Calhorda M., Alonso J., Organometallics 2007

  38. Methanol Oxidation with MoO3 IR Source He flow 3.6% MeOH 5.0% O2 Mass Spec Detector Cavity heated to 450-700 C Pressed MoO3 catalyst Chung J. S., Miranda R., Bennett C.O., J. Catalysis 1988

  39. Methanol Oxidation with MoO3 Increasing O2 % decreases dimethyl ether, methyl formate, and dimethoxy methane production Observed Mo-O-Mo bonds being depleted at lower temperatures, Mo=O bonds being depleted at higher temps. Chung J. S., Miranda R., Bennett C.O., J. Catalysis 1988

  40. Possible Mechanism Measurements from IR emission of well known bands for Mo-O-Mo and Mo=O Chung J. S., Miranda R., Bennett C.O., J. Catalysis 1988

  41. Byproduct Formation Chung J. S., Miranda R., Bennett C.O., J. Catalysis 1988

  42. Mo Catalyzed Hydrazine Production from N2 Mg helps reduce Mo center by forming stronger Ti-Mg reductant PR3 acts as ligand for Mo, decreases degradation time Ti(III) acts as reducing agent to get to Mo(III) First report of catalytic N2activation. Bazhenova, T.A.; Shilov, A.E. Coord. Chem. Rev.1995, 144, 69-145.

  43. Mo Catalyzed N2 Reduction/Hydrogenation: Schrock System Each synthesized “intermediate” found to be catalytically competent Yandulov, D.V.; Schrock, R.R. Science2003, 301, 76.

  44. Mo Catalyzed N2 Reduction/Hydrogenation: Nishibayashi System Arashiba, K.; Miyake, Y.; Nishibayashi, Y. Nature Chem.2011, 3, 120.

  45. Olefin Metathesis

  46. Z Selective Olefin Metathesis

  47. Hydrogenation Hydrodesulfurization Ketone/ Aldehyde Reduction and Hydrogenation Hydrosilylation Olefin Epoxidation Methanol Oxidation N2 Reduction Olefin Metathesis

More Related