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Peter Wasserscheid - One of the best experts on this subject based on the ideXlab platform.

  • asymmetric hydrogenation of Methyl Pyruvate in the continuous gas phase using supported ionic liquid phase silp catalysis
    Journal of Molecular Catalysis A-chemical, 2013
    Co-Authors: Martin Schneider, Marco Haumann, Peter Wasserscheid
    Abstract:

    Abstract Based on the recently reported asymmetric hydrogenation of Methyl acetoacetate in a continuous-flow, gas phase reaction using Supported Ionic Liquid Phase (SILP) catalysis, this study deals with the even more challenging asymmetric reduction of the α-keto ester Methyl Pyruvate. Different support materials, ligands and ionic liquids were screened to identify an optimized Ru-based SILP catalyst. With Ru-BINAP dissolved in the ionic liquids 3-hydroxypropylpyridinium bis(trifluoroMethylsulfonyl)imide on silica 100, stable catalyst performance could be obtained for more than 50 h time-on-stream. At 95 °C and with a residence time in the reactor of less than 3 s a stable product yield of 80–84% was obtained with moderate but stable enantiomeric excess of 26–30%.

  • Asymmetric hydrogenation of Methyl Pyruvate in the continuous gas phase using Supported Ionic Liquid Phase (SILP) catalysis
    Journal of Molecular Catalysis A: Chemical, 2013
    Co-Authors: Martin Johannes Schneider, Marco Haumann, Peter Wasserscheid
    Abstract:

    Based on the recently reported asymmetric hydrogenation of Methyl acetoacetate in a continuous-flow, gas phase reaction using Supported Ionic Liquid Phase (SILP) catalysis, this study deals with the even more challenging asymmetric reduction of the α-keto ester Methyl Pyruvate. Different support materials, ligands and ionic liquids were screened to identify an optimized Ru-based SILP catalyst. With Ru-BINAP dissolved in the ionic liquids 3-hydroxypropylpyridinium bis(trifluoroMethylsulfonyl)imide on silica 100, stable catalyst performance could be obtained for more than 50 h time-on-stream. At 95 C and with a residence time in the reactor of less than 3 s a stable product yield of 80-84% was obtained with moderate but stable enantiomeric excess of 26-30%.© 2013 Elsevier B.V. All rights reserved.

Pieralberto Tarasconi - One of the best experts on this subject based on the ideXlab platform.

  • new Methyl Pyruvate thiosemicarbazones and their copper and zinc complexes synthesis characterization x ray structures and biological activity
    Journal of Inorganic Biochemistry, 2001
    Co-Authors: Marisa Belicchi Ferrari, Pieralberto Tarasconi, Franco Bisceglie, Giorgio Pelosi, Roberto Albertini, Silvana Pinelli
    Abstract:

    Abstract By reacting thiosemicarbazides substituted on the aminic nitrogen with both alkyl or aryl groups, and Methyl Pyruvate a new group of MethylPyruvate thiosemicarbazones (Hmpt) derivatives was obtained. These ligands were then treated with copper and zinc inorganic salts. All isolated compounds were characterized using spectroscopic methods. The single crystal structural analysis of the ligands Me–Hmpt·0.5H 2 O 1 , Et–Hmpt·H 2 O 2 , Ph–Hmpt 5 , Meph–Hmpt 6 showed that only compound 6 presents significant deviation from planarity. The X-ray structure of [Zn(Me–Hmpt)Cl 2 ]·H 2 O 8 showed that in this complex Me–Hmpt behaves as a neutral ligand SNO terdentate and that the penta coordination is achieved by chloride ions according to spectroscopic and elemental analyses. On the basis of the analytical data the same behavior is proposed for the other zinc complexes. All the ligands in copper complexes seem to be monodeprotonated; nevertheless the same SNO behavior is expected. Tests on cell proliferation of human leukemic cell line U937 showed that the copper complex Cu(Et–mpt)Cl·H 2 O is the most active compound among those reported even though it is not able to induce apoptosis.

  • thiosemicarbazones as co ordinating agents part 5 zinc complexes derived from Methyl Pyruvate and pyridoxal thiosemicarbazone
    Journal of The Chemical Society-dalton Transactions, 1992
    Co-Authors: Marisa Belicchi Ferrari, Giovanna Gasparri Fava, Corrado Pelizzi, Pieralberto Tarasconi
    Abstract:

    Reaction of zinc chloride or acetate with two ligands, Methyl Pyruvate thiosemicarbazone (Hmpt) and pyridoxal thiosemicarbazone (H2L), lead to the formation of five novel complexes which have been characterized by spectroscopic methods. The crystal structure of three compounds: [Zn(Hpt)2]1, [Zn(Hept)Cl2]2 and [{Zn(HL)Cl}2]·2H2O 3(H2pt = pyruvic acid thiosemicarbazone, Hept = ethyl Pyruvate thiosemicarbazone) have been determined by X-ray methods from diffractometer data and refined by least squares to R 0.054 (1), 0.034 (2) and 0.029 (3) for 1205, 1590 and 2134 observed reflections respectively. All the zinc complexes seem to be influenced significantly by the nature of the solvent and, consequently by the resulting pH. The transesterificated (Hept) and hydrolysed (H2pt) forms of the original ligand (Hmpt) have been selectively isolated depending on the experimental conditions. In 1 the co-ordination geometry about zinc is distorted octahedral while in 2 and 3 the metal is five-co-ordinated, the geometry about zinc being better described as intermediate between an ideal square pyramid and trigonal bipyramid.

  • synthesis spectroscopic and structural characterization of chlorobis Methyl Pyruvate thiosemicarbazone copper i and chlorobis triphenylphosphine Methyl Pyruvate thiosemicarbazone copper i toluene solvate 2 1
    Inorganica Chimica Acta, 1991
    Co-Authors: Marisa Belicchi Ferrari, Giovanna Gasparri Fava, Maurizio Lanfranchi, Corrado Pelizzi, Pieralberto Tarasconi
    Abstract:

    Abstract Two new compounds, chlorobis(Methyl Pyruvate thiosemicarbazone)copper(I), [Cu(Hmpt)2Cl] (A), and chlorobis(triphenylphosphine)(Methyl Pyruvate thiosemicarbazone)copper(I) toluene solvate (2/1), [Cu(PPh3)2(Hmpt)Cl]·0.5C7H8 (B) have been synthesized and characterized using spectroscopic studies and single-crystal X-ray diffraction methods at 293 K. Compound A crystallizes in space group C2/c, with a = 14.695(1), b = 13.775(1), c = 10.251(1) A, β = 113.38(1)°, V= 1904.7 A3; compound B crystallizes in space group P 1 , with a=17.871(7), b=10.681(2), c=11.695(7) A, α=74.90(1), β=86.65(4), γ=83.66(2)°, V=2141 A3. The crystal structures were solved by the heavy-atom method for A and by direct methods for B and refined to R values of 0.053 for both compounds. In A the copper and chlorine atoms lie on a crystallographic two-fold axis and the trigonal coordination around copper involves, besides chlorine, two sulfur atoms from two Hmpt molecules. In B the copper is tetrahedrally four-coordinated involving a chlorine atom, a sulfur atom from the Hmpt molecule and the phosphorus atoms of the two PPh3 molecules. In both compounds the ligand is neutral, monodentate through the sulfur atom and shows the configuration Z E Z about the C(2)N(3), C(1)N(2) and C(2)C(3) bonds (with respect to possible donating centres O(1), N(3) and S). The main vibrational bands are also reported and discussed.

Marisa Belicchi Ferrari - One of the best experts on this subject based on the ideXlab platform.

  • new Methyl Pyruvate thiosemicarbazones and their copper and zinc complexes synthesis characterization x ray structures and biological activity
    Journal of Inorganic Biochemistry, 2001
    Co-Authors: Marisa Belicchi Ferrari, Pieralberto Tarasconi, Franco Bisceglie, Giorgio Pelosi, Roberto Albertini, Silvana Pinelli
    Abstract:

    Abstract By reacting thiosemicarbazides substituted on the aminic nitrogen with both alkyl or aryl groups, and Methyl Pyruvate a new group of MethylPyruvate thiosemicarbazones (Hmpt) derivatives was obtained. These ligands were then treated with copper and zinc inorganic salts. All isolated compounds were characterized using spectroscopic methods. The single crystal structural analysis of the ligands Me–Hmpt·0.5H 2 O 1 , Et–Hmpt·H 2 O 2 , Ph–Hmpt 5 , Meph–Hmpt 6 showed that only compound 6 presents significant deviation from planarity. The X-ray structure of [Zn(Me–Hmpt)Cl 2 ]·H 2 O 8 showed that in this complex Me–Hmpt behaves as a neutral ligand SNO terdentate and that the penta coordination is achieved by chloride ions according to spectroscopic and elemental analyses. On the basis of the analytical data the same behavior is proposed for the other zinc complexes. All the ligands in copper complexes seem to be monodeprotonated; nevertheless the same SNO behavior is expected. Tests on cell proliferation of human leukemic cell line U937 showed that the copper complex Cu(Et–mpt)Cl·H 2 O is the most active compound among those reported even though it is not able to induce apoptosis.

  • thiosemicarbazones as co ordinating agents part 5 zinc complexes derived from Methyl Pyruvate and pyridoxal thiosemicarbazone
    Journal of The Chemical Society-dalton Transactions, 1992
    Co-Authors: Marisa Belicchi Ferrari, Giovanna Gasparri Fava, Corrado Pelizzi, Pieralberto Tarasconi
    Abstract:

    Reaction of zinc chloride or acetate with two ligands, Methyl Pyruvate thiosemicarbazone (Hmpt) and pyridoxal thiosemicarbazone (H2L), lead to the formation of five novel complexes which have been characterized by spectroscopic methods. The crystal structure of three compounds: [Zn(Hpt)2]1, [Zn(Hept)Cl2]2 and [{Zn(HL)Cl}2]·2H2O 3(H2pt = pyruvic acid thiosemicarbazone, Hept = ethyl Pyruvate thiosemicarbazone) have been determined by X-ray methods from diffractometer data and refined by least squares to R 0.054 (1), 0.034 (2) and 0.029 (3) for 1205, 1590 and 2134 observed reflections respectively. All the zinc complexes seem to be influenced significantly by the nature of the solvent and, consequently by the resulting pH. The transesterificated (Hept) and hydrolysed (H2pt) forms of the original ligand (Hmpt) have been selectively isolated depending on the experimental conditions. In 1 the co-ordination geometry about zinc is distorted octahedral while in 2 and 3 the metal is five-co-ordinated, the geometry about zinc being better described as intermediate between an ideal square pyramid and trigonal bipyramid.

  • synthesis spectroscopic and structural characterization of chlorobis Methyl Pyruvate thiosemicarbazone copper i and chlorobis triphenylphosphine Methyl Pyruvate thiosemicarbazone copper i toluene solvate 2 1
    Inorganica Chimica Acta, 1991
    Co-Authors: Marisa Belicchi Ferrari, Giovanna Gasparri Fava, Maurizio Lanfranchi, Corrado Pelizzi, Pieralberto Tarasconi
    Abstract:

    Abstract Two new compounds, chlorobis(Methyl Pyruvate thiosemicarbazone)copper(I), [Cu(Hmpt)2Cl] (A), and chlorobis(triphenylphosphine)(Methyl Pyruvate thiosemicarbazone)copper(I) toluene solvate (2/1), [Cu(PPh3)2(Hmpt)Cl]·0.5C7H8 (B) have been synthesized and characterized using spectroscopic studies and single-crystal X-ray diffraction methods at 293 K. Compound A crystallizes in space group C2/c, with a = 14.695(1), b = 13.775(1), c = 10.251(1) A, β = 113.38(1)°, V= 1904.7 A3; compound B crystallizes in space group P 1 , with a=17.871(7), b=10.681(2), c=11.695(7) A, α=74.90(1), β=86.65(4), γ=83.66(2)°, V=2141 A3. The crystal structures were solved by the heavy-atom method for A and by direct methods for B and refined to R values of 0.053 for both compounds. In A the copper and chlorine atoms lie on a crystallographic two-fold axis and the trigonal coordination around copper involves, besides chlorine, two sulfur atoms from two Hmpt molecules. In B the copper is tetrahedrally four-coordinated involving a chlorine atom, a sulfur atom from the Hmpt molecule and the phosphorus atoms of the two PPh3 molecules. In both compounds the ligand is neutral, monodentate through the sulfur atom and shows the configuration Z E Z about the C(2)N(3), C(1)N(2) and C(2)C(3) bonds (with respect to possible donating centres O(1), N(3) and S). The main vibrational bands are also reported and discussed.

Doble Mukesh - One of the best experts on this subject based on the ideXlab platform.

Sumit Bhaduri - One of the best experts on this subject based on the ideXlab platform.

  • Kinetic and Scanning Transmission Electron Microscopy Investigations on a MCM-41 Supported Cluster Derived Enantioselective Ruthenium Nanocatalyst
    ACS Catalysis, 2011
    Co-Authors: Arindam Indra, Sumit Bhaduri, Mukesh Doble, Goutam Kumar Lahiri
    Abstract:

    The asymmetric hydrogenation of Methyl Pyruvate to Methyl lactate, by cinchonidium functionalized MCM-41 supported [Ru4(μ-H)3(CO)12]− as the precatalyst has been studied kinetically and by scanning transmission electron microscopy (STEM). Existence of an induction time and two competitive equilibriums are inferred from the time monitored conversion data. Steady state approximation gives a poor fit, but a kinetic model (Eley−Rideal) consisting of a fast equilibrium between Methyl Pyruvate and the catalyst, a slow one between the catalyst and dihydrogen, and a rate determining reaction between the latter and Methyl Pyruvate, accurately simulates the time monitored conversion profiles. The model suggests that on increasing the Methyl Pyruvate concentration there is a change in the stoichiometry of the equilibrium between the catalyst and the Methyl Pyruvate. The change in enantioselectivity with time can also be accurately simulated by assuming enantiomeric excess to be proportional to the rate constant for ...

  • MCM-41-supported platinum carbonyl cluster-derived catalysts for asymmetric and nonasymmetric hydrogenation reactions
    Journal of Catalysis, 2006
    Co-Authors: Susmit Basu, Sumit Bhaduri, Mukesh Doble, Maitri Mapa, Chinnakonda S. Gopinath, Goutam Kumar Lahiri
    Abstract:

    Anionic platinum carbonyl cluster ([Pt 12 (CO) 24 ] 2- ) was ion-paired with the 3-chloropropyltrimethoxysilyl-ammonium group chemically bound to the surface of MCM-41. The materials undergo quick decarbonylation and have been characterized before decarbonylation by IR and UV-vis spectroscopy and after decarbonylation by XPS and TEM. They have been used as catalysts for the hydrogenations of Methyl Pyruvate, acetophenone, nitrobenzene, benzonitrile, and ethylacetoacetate. The support and the quaternary ammonium groups have significant effects on surface platinum concentration, crystallite size, and observed activity. In the hydrogenation of the prochiral substrates Methyl Pyruvate or acetophenone, the cinchonidine-based catalyst gives significant enantioselectivity under optimum conditions. A kinetic model that includes an enantioselective product-formation step and a hydrogen pressure-dependent step for the deactivation of the enantioselective sites gives reasonable agreement between predicted and observed enantioselectivity. The model is also in accordance with the XPS and TEM data.

  • A MCM-41-supported platinum carbonyl cluster-derived asymmetric hydrogenation catalyst
    Journal of Catalysis, 2005
    Co-Authors: Susmit Basu, Sumit Bhaduri, Chinnakonda S. Gopinath, Himadri Paul, Goutam Kumar Lahiri
    Abstract:

    Abstract Anionic platinum carbonyl cluster has been ion paired with cinchonidium groups that are chemically bound to the surface of MCM-41 and fumed silica. In the hydrogenation of Methyl Pyruvate or acetophenone the fumed silica-based catalyst gives zero enantioselectivity, but under optimum conditions enantiomeric excesses of >90 and ∼ 40 % , respectively, are obtained with the MCM-41-based catalyst.

  • asymmetric hydrogenation of Methyl Pyruvate using platinum carbonyl cluster supported on an anion exchanger as the catalyst
    Catalysis Letters, 2000
    Co-Authors: Sumit Bhaduri, Goutam Kumar Lahiri, Pradip Munshi, Doble Mukesh
    Abstract:

    Anionic platinum carbonyl clusters supported on quaternary amine functionalized cross-linked polystyrene, i.e., anion exchangers, are effective precatalysts for the hydrogenation of Methyl Pyruvate to Methyl lactate. Kinetic data has been obtained for anion exchangers with different quaternary groups. Highest observed rate constant and enantioselectivity are obtained with cinchonine funtionalized resin. The kinetic data also indicates saturation kinetics. The decarbonylated used catalyst could be recarbonylated to give a material spectroscopically (infrared) equivalent to freshly anchored cluster.

  • Carbonyl cluster derived polystyrene supported platinum for asymmetric hydrogenation of α-ketoesters
    Journal of The Chemical Society Chemical Communications, 1992
    Co-Authors: Sumit Bhaduri, Vishnu S. Darshane, Krishna Sharma, Doble Mukesh
    Abstract:

    Ion-pairing of anionic carbonyl clusters with cinchona alkaloid groups on cross-linked polystyrene is a viable method for the synthesis of asymmetric catalysts for the hydrogenation of Methyl Pyruvate.