Yazar "Özkar, Saim" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • Küçük Resim
    Öğe
    New route to synthesis of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Heck and Suzuki cross-coupling reactions
    (Wiley, 2009) Durap, Feyyaz; Metin, Önder; Aydemir, Murat; Özkar, Saim; 0000-0003-0899-1948; 0000-0003-1622-4992
    Herein we report a new method for the synthesis and characterization of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Suzuki coupling and Heck reactions of aryl bromides with phenylboronic acid and styrene, respectively, under mild conditions. The PVP-stabilized palladium(0) nanoclusters with a particle size of 4.5 +/- 1.1 nm were prepared using a new method: refluxing a mixture of potassium tetrachloropalladate(II) and PVP in methanol at 80 degrees C for 1 h followed by reduction with sodium borohydride. Palladium(0) nanoclusters prepared in this way were stable in solution for weeks, could be isolated as solid materials and were characterized by TEM, XPS, UV-vis, and XRD techniques. The PVP-stabilized palladium(0) nanoclusters were active catalysts in Heck and Suzuki coupling reactions of arylbromides with styrene and phenylboronic acid affording stilbenes and biphenyls, respectively, in high yield. Recycling experiments showed that PVP-stabilized palladium(0) nanoclusters could be used five times with essentially no loss in activity in the Heck and Suzuki coupling reactions. Copyright (C) 2009 John Wiley & Sons, Ltd.
  • [ X ]
    Öğe
    Ruthenium(0) nanoclusters supported on hydroxyapatite: Highly active, reusable and green catalyst in the hydrogenation of aromatics under mild conditions with an unprecedented catalytic lifetime
    (Royal Society of Chemistry, 2010) Zahmakıran, Mehmet; Tonbul, Yalçın; Özkar, Saim; 0000-0003-4520-2602
    The preparation of ruthenium(0) nanoclusters supported on hydroxyapatite and their characterization by a combination of complementary techniques are described. The resultant ruthenium(0) nanoclusters provide high activity and reusability in the complete hydrogenation of aromatics under mild conditions (at 25 °C and with 42 psi initial H2 pressure). © 2010 The Royal Society of Chemistry.
  • Küçük Resim
    Öğe
    Synthesis and characterization of new (N-diphenylphosphino)-isopropylanilines and their complexes: crystal structure of (Ph2P=S)NH-C6H4-4-CH(CH3)2 and catalytic activity of palladium(II) complexes in the Heck and Suzuki cross-coupling reactions
    (Wiley, 2010) Aydemir, Murat; Baysal, Akın; Gürbüz, Nevin; Özdemir, İsmail; Gümgüm, Bahattin; Özkar, Saim; Çaylak, Nagihan; 0000-0001-7294-6792; 0000-0003-3201-3597; 0000-0001-6325-0216
    Three new (N-diphenylphosphino)-isopropylanilines, having isopropyl substituent at the carbon 2- (1) 4- (2) or 2,6- (3) were prepared from the aminolysis of chlorodiphenylphosphine with 2-isopropylaniline,4-isopropylaniline or 2,6-diisopropylaniline, respectively, under anaerobic conditions. Oxidation of 1,2 and 3 with aqueous hydrogen peroxide, elemental sulfur or gray selenium gave the corresponding oxides, sulfides and selenides (Ph2P=E)NH-C6H4-2-CH(CH3)(2), (Ph2P=E)NH-C6H4-4-CH(CH3)(2) and (Ph2P=E)NH-C6H4-2,6-[CH(CH3)(2)](2), where E = O, S, or Se, respectively. The reaction of [M(cod)Cl-2] (M = Pd, Pt; cod = 1,5-cyclooctadiene) with two equivalents of 1,2 or 3 yields the corresponding monodendate complexes [M((Ph2P)NH-C6H4-2-CH(CH3)(2))(2)Cl-2], M = Pd 1d, M = Pt 1e, [M((Ph2P)NH-C6H4-4-CH(CH3)(2))(2)Cl-2], M = Pd 2d, M = Pt 2e and [M((Ph2P)NH-C6H4-2,6-(CH(CH3)(2))(2))(2)Cl-2], M = Pd 3d, M = Pt 3e, respectively. All the compounds were isolated as analytically pure substances and characterized by NMR, IR spectroscopy and elemental analysis. Furthermore, representative solid-state structure of [(Ph2P=S)NH-C6H4-4-CH(CH3)(2)] (2b) was determined using single crystal X-ray diffraction technique. The complexes 1d-3d were tested and found to be highly active catalysts in the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes, respectively. Copyright (C) 2009 John Wiley & Sons, Ltd.
  • Küçük Resim
    Öğe
    Synthesis and characterization of transition metal complexes of thiophene-2-methylamine: X-ray crystal structure of palladium (II) and platinum (II) complexes and use of palladium(II) complexes as pre-catalyst in Heck and Suzuki cross-coupling reactions
    (Wiley, 2009) Aydemir, Murat; Baysal, Akın; Durap, Feyyaz; Gümgüm, Bahattin; Özkar, Saim; Yıldırım, Leyla Tatar; 0000-0001-7294-6792; 0000-0003-0899-1948
    The reactions of thiophene-2-(N-diphenylphosphino)methylamine, Ph2PNHCH2-C4H3S, 1 and thiophene-2-[N,N-bis(diphenylphosphino)methylamine], (Ph2P)(2)NCH2-C4H3S, 2, with MCl2(cod) (M = Pd, Pt; cod = 1,5-cyclooctadiene) or [Cu(CH3CN)(4)]PF6 yields the new complexes [M(Ph2PNHCH2-C4H3S)(2)Cl-2], M = Pd 1a, Pt 1 b, [Cu(Ph2PNHCH2-C4H3S)(4)]PF6, 1c, and [M(Ph2P)(2)NCH2-C4H3S)Cl-2], M = Pd 2a, Pt 2b, (Cu[(Ph2P)(2)NCH2-C4H3S](2))PF6, 2c, respectively. The new compounds were isolated as analytically pure crystalline solids and characterized by (31)p-, C-13-, H-1-NMR and IR spectroscopy and elemental analysis. Furthermore, the solid-state molecular structures of representative palladium and platinum complexes of bis(phosphine)amine, 2a and 2b, respectively, were determined using single crystal X-ray diffraction analysis. The palladium complexes were tested as potential catalysts in the Heck and Suzuki cross-coupling reactions. Copyright (C) 2009 John Wiley & Sons, Ltd.
  • Küçük Resim
    Öğe
    Synthesis, Characterization, Crystal and Molecular Structure of 1,5-Dihydro-2H-cyclopenta[1,2-b:5,4-b′]dipyridin-2-imine
    (Wiley-V C H Verlag Gmbh, 2007) Baysal, Akın; Durap, Feyyaz; Gümgüm, Bahattin; Yıldırım, Leyla T.; Ülkü, Dinçer; Boğa, Ayşe Dilek; Özkar, Saim; 0000-0001-7294-6792; 0000-0003-0899-1948
    The reaction of 1,5-diliydro-2H-cyclopenta[1,2-b:5,4-b'ldipyridin-2-one (3) with an alkylamine (butvlamine, hexylamine or ethylenediamine) yields, quite unexpectedly and in the absence of catalyst, the novel compound 1,5-dihydro-2H-cyclopentafl,2-b:5.4-b']dipyridin-2-imine (4) as the sole, analytically pure, solid product, which was fully characterized. The structure of 4 was unequivocally solved by single-crystal X-ray-diffraction analysis. The compound crystallizes in a monoclinic cell (space group P 2(1/c)). with two molecules in the asymmetric unit. held together by intermolecular H-bonds. Compound 4 could be interesting as a bi- or even tridentate ligand, and exhibits a strong fluorescence upon excitation at 310 nm. A mechanism, based on the observed C-N bond cleavage, is proposed.
  • Küçük Resim
    Öğe
    Tungsten(VI) oxide supported rhodium nanoparticles: Highly active catalysts in hydrogen generation from ammonia borane
    (Pergamon-Elsevier Science LTD, 2021) Akbayrak, Serdar; Tonbul, Yalçın; Özkar, Saim
    Herein, we report the use of tungsten(VI) oxide (WO3) as support for Rh0 nanoparticles. The resulting Rh0/WO3 nanoparticles are highly active and stable catalysts in H2 generation from the hydrolysis of ammonia borane (AB). We present the results of our investigation on the particle size distribution, catalytic activity and stability of Rh0/WO3 catalysts with 0.5%, 1.0%, 2.0% wt. Rh loadings in the hydrolysis reaction. The results reveal that Rh-0/WO3 (0.5% wt. Rh) is very promising catalyst providing a turnover frequency of 749 min-1 in releasing 3.0 equivalent H2 per mole of AB from the hydrolysis at 25.0 C-circle. The high catalytic activity of Rh-0/WO3 catalyst is attributed to the reducible nature of support. The report covers the results of kinetics study as well as comparative investigation of activity, recyclability, and reusability of colloidal(0) nanoparticles and Rh-0/WO3 (0.5 % wt. Rh) catalyst in the hydrolysis reaction.