12 research outputs found
Investigation of the solvent free isomerisation of cis-Mo(CO)4L2 [L = PPh2Et, PPh3, PPh2Me, and P(m-tolyl)3] by diffuse reflectance infrared Fourier transform
Thermal analysis of cis-Mo(CO)4L2 [L= PPh2Et, PPh3, PPh2Me and P(m-tolyl)3] revealed that they undergo cis to trans isomerisation under solventless conditions. For L = PPh3 and P(m-tolyl)3, the reaction occurred in the solid state. For L = PPh2Et and PPh2Me the reaction occurred in the melt and was followed by trans isomer solidification. The rate of the solid state isomerisation of cis-Mo(CO)4 (PPh3)2 was investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and the results showed that the reaction was first order. A thermomicroscopic investigation of cis-Mo(CO)4[P(m-tolyl)3]2 revealed that the isomerisation was surface-initiated.KEY WORDS: Solventless reactions, Molybdenum, Isomerisation, Thermal analysis Bull. Chem. Soc. Ethiop. 2011, 25(2), 209-220
Synthesis and X-ray studies of ruthenium(II) complexes containing hydrazine and benzyl isocyanide ligands
The reaction of the polymeric species [{RuCl2(COD)}x] (1; x > 2; COD = cyclo-octa-1,5-diene) and hydrazine hydrate in methanol under reflux gave a pale pink solution from which the salt [Ru(COD)(N2H4)4][BPh4]2.CH3OH (2) was isolated on addition of NaBPh4. Treatment of 2 in refluxing acetone in the presence of the ligand benzyl isocyanide give a complex of stoichiometry [Ru(NH2N=CMe2)2(PhCH2NC)4][BPh4]2 (3) on the substitution of the labile COD ligand. The two compounds have been characterized by elemental analyses, IR and NMR measurements and single-crystal X-ray diffraction studies. The ruthenium in both compounds has a distorted octahedral coordination geometry. KEY WORDS: Cycloocta-1,5-diene, Hydrazine hydrate, Isocyanide, Ruthenium Bull. Chem. Soc. Ethiop. 2013, 27(3), 405-411.DOI: http://dx.doi.org/10.4314/bcse.v27i3.
<b>Investigation of the solvent free isomerisation of <i>cis</i>-Mo(CO)<sub>4</sub>L<sub>2</sub> [L = PPh<sub>2</sub>Et, PPh<sub>3</sub>, PPh<sub>2</sub>Me, and P(<i>m</i>-tolyl)<sub>3</sub>] by diffuse reflectance infrared Fourier transform spectroscopy and thermal methods</b>
Thermal analysis of <i>cis</i>-Mo(CO)<sub>4</sub>L<sub>2</sub> [L= PPh<sub>2</sub>Et, PPh<sub>3</sub>, PPh<sub>2</sub>Me and P(<i>m</i>-tolyl)<sub>3</sub>] revealed that they undergo <i>cis</i> to <i>trans</i> isomerisation under solventless conditions. For L = PPh<sub>3</sub> and P(<i>m</i>-tolyl)<sub>3</sub>, the reaction occurred in the solid state. For L = PPh<sub>2</sub>Et and PPh<sub>2</sub>Me the reaction occurred in the melt and was followed by <i>trans</i> isomer solidification. The rate of the solid state isomerisation of <i>cis</i>-Mo(CO)<sub>4</sub> (PPh<sub>3</sub>)<sub>2</sub> was investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and the results showed that the reaction was first order. A thermomicroscopic investigation of <i>cis</i>-Mo(CO)4[P(<i>m</i>-tolyl)<sub>3</sub>]<sub>2</sub> revealed that the isomerisation was surface-initiated
Microwave radiation in the modification of iron Fischer-Tropsch catalysts
Potassium-promoted unsupported iron Fischer–Tropsch catalysts have been subjected to microwave radiation treatment as part of the catalyst preparation process. The treatment is applied after the catalysts have been dried and calcined. Solid-state modifications occur which result in changes in the manner and quantity of carbon monoxide adsorbed on the surface as detected by temperature programmed surface reaction (TPSR) with hydrogen. Methane is the essential product of the TPSR runs. The response to microwave treatment is an increase in the methane production at all potassium levels, but the magnitude of the increase is potassium-loading dependent and peaks at a potassium loading of 0.7 wt%. Microwave-induced changes in TPSR characteristics appear to result from selective heating occurring almost immediately on exposure of the catalysts to radiation. Longer duration of microwave exposure does not appear to result in further changes
Synthesis and study of carbon microspheres for use as catalyst support for cobalt
The production of pure carbon spheres was achieved in the absence of a catalyst through the direct pyrolysis of two hydrocarbon sources, acetylene and ethylene. Systematic studies using acetylene as the feedstock indicated that the size distribution of the resulting carbon microspheres can be controlled by pyrolysis temperature, time and feedstock flow rate. The resulting spheres were fully characterised by transmission electron microscopy (TEM) and thermogravimetric analysis. The TEM examination showed that these spheres have a ball-like and chain-like morphology, and the balls have smooth surfaces with a variation in diameter size and distribution determined by the reaction conditions. Carbon microsphere-supported cobalt catalysts were synthesised and have shown good activity in the ethylene hydrogenation reaction
Synthesis and study of carbon microspheres for use as catalyst support for cobalt
The production of pure carbon spheres was achieved in the absence of a catalyst through the direct pyrolysis of two hydrocarbon sources, acetylene and ethylene. Systematic studies using acetylene as the feedstock indicated that the size distribution of the resulting carbon microspheres can be controlled by pyrolysis temperature, time and feedstock flow rate. The resulting spheres were fully characterised by transmission electron microscopy (TEM) and thermogravimetric analysis. The TEM examination showed that these spheres have a ball-like and chain-like morphology, and the balls have smooth surfaces with a variation in diameter size and distribution determined by the reaction conditions. Carbon microsphere-supported cobalt catalysts were synthesised and have shown good activity in the ethylene hydrogenation reaction
Generation of radical species in CVD grown pristine and N-doped solid carbon spheres using H2 and Ar as carrier gases
Solid carbon spheres (CSs, d ≈ 200 nm) were synthesized (yield, <40%) in a vertically oriented chemical vapor deposition (CVD) reactor using acetylene as a carbon source and Ar or H2 as the carrier gas. The CSs synthesized in the presence of H2 exhibited a broader thermal gravimetric derivative curve and a narrower paramagnetic signal than the CSs synthesized in Ar. Post synthesis doping of both types of CSs with nitrogen was achieved by passing acetonitrile at 800 °C for 1 h over the CSs in a CVD reactor. The N-doped CSs (NCSs) synthesized under both H2 and Ar displayed an increase in ID/IG ratios as obtained from Raman spectroscopy and showed an increase in the paramagnetic signal due to the presence of nitrogen induced defects compared to the undoped CSs. The NCSs synthesized in H2 had less graphitic-N (22%) than those produced in Ar (50%). The presence of a higher percentage of pyridinic-N and pyrrolic-N for the NCSs prepared with H2 as carrier gas suggested H2 etching effects on the CSs. Further, the N-doped carbon spheres obtained in the presence of H2 gave a higher N/C ratio (5.0) than in the presence of Ar (3.7). The introduction of edge defects and paramagnetic centers in CSs in the presence of H2 gas without the aid of a metal catalyst opens up a platform for regulating surface and catalytic reactions of CSsEM201
Composites of polyvinyl alcohol and carbon (coils, undoped and nitrogen doped multiwalled carbon nanotubes) as ethanol, methanol and toluene vapor sensors
We investigate the chemical sensing behavior of composites prepared with polyvinyl alcohol and carbon materials (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and carbon nanocoils). We determine the sensitivity of thin films of these composites for ethanol, methanol and toluene vapor, comparing their conductance and capacitance responses. The composite that exhibits highest sensitivity depends on specific vapor, vapor concentration and measured electrical response, showing that the interactivity of the carbon structure with chemical species depend on structural specificities of the carbon structure and doping. © 2011 American Scientific Publishers. All rights reserved
Synthesis Of C 60-containing Polymers By Ring-opening Metathesis Co-polymerization Of A C 60-cyclopentadiene Cycloadduct And N-(cycloheptyl)-endo-norbornene-5, 6-dicarboximide And Their Application In A Photovoltaic Device
A C 60-cyclopentadiene cycloadduct and N-(cycloheptyl)-endo- norbornene-5,6- dicarboximide were utilized as co-monomers in ring-opening metathesis polymerization (ROMP) reactions to afford a series of polymers containing C 60 in varying ratios. The polymerization reactions were catalyzed by the Grubbs second-generation ruthenium catalyst, and the co-polymers formed were investigated by spectroscopic and thermal techniques. The photovoltaic behavior of the new materials was studied by the construction of a simple sandwich-type photovoltaic cell. Under irradiation we concluded that the C 60 in the copolymers simultaneously accelerated both the charge separation in the polymer and the charge recombination between the electrons in the TiO2 and the electrolyte. Copyright © Taylor & Francis Group, LLC.213198212Giacalone, F., MartÃn, N., (2006) Chem. Rev., 106, p. 5136Wang, C., Guo, Z.-X., Fu, S., Wu, W., Zhu, D., (2004) Prog. Polym. Sci., 29, p. 1079Geckeler, K.E., Samal, S., (1999) Polym. Int., 48, p. 743Prato, M., (1997) J. Mater. Chem., 7, p. 1097Shi, S., Khemani, K.C., Li, Q.C., Wudl, F., (1992) J. Am. Chem. Soc., 114, p. 10656Song, T., Goh, S.H., Lee, S.Y., (2003) Polymer, 44, p. 2563Ma, C.-C.M., Sung, S.-C., Wang, F.-Y., Chiang, L.Y., Wang, L.Y., Chiang, C.-L., (2001) J. Polym. Sci., Part B: Polym. Phys., 39, p. 2436. , and references cited thereinImahori, H., Hagiwara, K., Akiyama, T., Aoki, M., Taniguchi, S., Okada, T., Shirakawa, M., Sakata, Y., (1996) Chem. Phys. Lett., 263, p. 545Yu, G., Gao, Y., Hummelen, J.C., Wudl, F., Heeger, A.J., (1995) Science, 270, p. 1789Sariciftci, N.S., Smilowitz, L., Heeger, A.J., Wudl, F., (1992) Science, 258, p. 1474. , 7Imahori, H., Sakata, Y., (1999) Eur. J. Org. Chem., p. 2445Gust, D., Moore, T.A., Moore, A.L., (2001) Acc. Chem. Res., 34, p. 40Roncali, (2005) J. Chem. Soc. Rev., 34, p. 483Bazaco, R.B., Segura, J.L., Seoane, C., (2009) Collect. Czech. Chem. Commun., 74, p. 857Hiorns, R.C., Cloutet, E., Ibarboure, E., Khoukh, A., Bejbouji, H., Vignau, L., Cramail, H., (2010) Macromolecules, 43, p. 6033Hilf, S., Kilbinger, A.F.M., (2009) Macromolecules, 42, p. 1099Sharma, G.D., Balraju, P., Mikroyannidis, J.A., Stylianakis, M.M., (2009) Sol. Energy Mater. Sol. Cells, 93, p. 2025Jin, Y., Jee, J., Kim, H., Song, S., Park, S.H., Kim, J., Kang, S.-W., Suh, H., (2009) Synth. Met.,., 159, p. 1529Mozer, A.J., Sariciftci, N.S., (2006) C.R. Chimie, 9, p. 568Sakai, J., Taima, T., Saito, K., (2008) Org. Electron., 9, p. 582Zhang, N., Schricker, S.R., Wudl, F., Prato, M., Maggini, M., Scorrano, G., (1995) Chem. Mater., 7, p. 441Ball, Z.T., Sivula, K., Fréchet, J.M.J., (2006) Macromolecules, 39, p. 70De La Escosura, A., MartÃnez-DÃaz, M.V., Torres, T., Grubbs, R.H., Guldi, D.M., Neugebauer, H., Winder, C., Sariciftci, N.S., (2006) Chem. Asian J., 1-2, p. 148Sivula, K., Ball, Z.T., Watanabe, N., Fréchet, J.M.J., (2006) Adv. Mater., 18, p. 206Liu, X., Basu, A., (2006) J. Organomet. Chem., 691, p. 5148Gómez, F.J., Chen, J., Wang, D., Waymouth, R.R.M., Dai, H., (2003) Chem. Commun., p. 190Liu, Y., Andronov, A., (2004) Macromolecules, 37, p. 4755Mamo, M.A., Coville, N.J., Van Otterlo, W.A.L., (2007) Fullerenes, Nanotubes and Carbon Nanostructures, 15, p. 341. , 15Trnka, T.M., Grubbs, R.H., (2001) Acc. Chem. Res., 34Morgans, G.L., Ngidi, E.L., Madeley, L.G., Khanye, S.D., Michael, J.P., De Koning, C.B., Van Otterlo, W.A.L., (2009) Tetrahedron, 65, p. 10650Scalzullo, S.M., Uislam, U., Morgans, G.L., Michael, J.P., Van Otterlo, W.A.L., (2008) Tetrahedron Lett., 49, p. 7403Panayides, J.-L., Pathak, R., Panagiotopoulos, H., Davids, H., Fernandes, M.A., De Koning, C.B., Van Otterlo, W.A.L., (2007) Tetrahedron, 63, p. 4737Panayides, J.-L., Pathak, R., De Koning, C.B., Van Otterlo, W.A.L., (2007) Eur. J. Org. Chem., 4953Coyanis, E.M., Panayides, J.-L., Fernandes, M.A., De Koning, C.B., Van Otterlo, W.A.L., (2006) J. Organomet. Chem., 691, p. 5222Yadav, D.B., Morgans, G.L., Aderibigbe, B.A., Madeley, L.G., Fernandes, M.A., Michael, J.P., De Koning, C.B., Van Otterlo, W.A.L., (2011) Tetrahedron, 67, p. 2991Contreras, A.P., Tlenkopatchev, M.A., Del Mar López-González, M., Riande, E., (2002) Macromolecules, 35, p. 4677For related work concerning N-alkylated norbornene dicarboximides and their application in ROMP, see the following representative publications:Matson, J.B., Grubbs, R.H., (2010) Macromolecules, 43, p. 213Hilf, S., Grubbs, R.H., Kilbinger, A.F.M., (2008) J. Am. Chem. Soc., 130, p. 11040Vargas, J., Santiago, A.A., Gaviño, R., Cerda, A.M., Tlenkopatchev, M.A., (2007) Express Polym. Lett., 1, p. 274Santiago, A.A., Vargas, J., Gaviño, R., Cerda, A.M., Tlenkopatchev, M.A., (2007) Macromol. Chem. Phys., 208, p. 1085Hilf, S., Kilbinger, A.F.M., (2007) Macromol. Rapid Commun., 28, p. 1225Thomas, C.C., Ezat, K., Lian, R.H., (2006) Macromolecules, 39, p. 5639Castle, T.C., Khosravi, E., Hutchings, L.R., (2006) Macromolecules, 39, p. 5639Madan, R., Anand, R.C., Varma, I.K., (1997) J. Polym. Sci.: Part A: Polym. Chem., 35, p. 2917Rotello, V.M., Howard, J.B., Yadav, T., Conn, M.M., Viani, E., Giovane, L.M., Lafleur, A.L., (1993) Tetrahedron Lett., 34, p. 1561Wilson, S.R., Yurchenko, M.E., Schuster, D.I., Khong, A., Saunders, M., (2000) J. Org. Chem., 65, p. 2619Schwenninger, R., Müller, T., Kräutler, B., (1997) J. Am. Chem. Soc., 119, p. 9317Nie, B., Rotello, V.M., (1996) J. Org. Chem., 61, p. 1870Yurovskaya, M.A., Trushkov, I.V., (2002) Russ. Chem. Bull. Int. Ed., 51, p. 367Hudhomme, P., (2006) C.R. Chimie, 9, p. 881Taylor, R., (2006) C.R. Chimie, 9, p. 982Yli-Kauhaluoma, J., (2001) Tetrahedron, 57, p. 7053Goh, H.W., Goh, S.H., Xu, G.Q., (2002) J. Polym. Sci. Part A: Polym. Chem., 40, p. 1157Zhang, X., Sieval, A.B., Hummelen, J.C., Hessen, B., (2005) Chem. Commun., p. 1616Geckeler, K.E., Hirsch, A., (1993) J. Am. Chem. Soc., 115, p. 3850Suzuki, T., Li, Q., Khemani, K.C., Wudl, F., (1992) J. Am. Chem. Soc., 114, p. 7301Li, W.J., Liang, W.J., (2007) Spectrochim. Acta Part A, 67, p. 1346Tang, B.Z., Leung, S.M., Peng, H., Yu, N.-T., Su, K.C., (1997) Macromolecules, 30, p. 2848Chu, C.-C., Ho, T.-I., Wang, L., (2006) Macromolecules, 39, p. 5657Xiao, S., Li, Y., Li, Y., Li, H., Zhuang, J., Liu, Y., Lu, F., Zhu, D., (2004) Tetrahedron Lett., 45, p. 3975Kraus, A., Mullen, K., (1999) Macromolecules, 32, p. 4214Camp, A.G., Lary, A., Ford, W.T., (1995) Macromolecules, 28, p. 7959Chiang, L.Y., Wang, L.Y., Kuo, C.-S., (1995) Macromolecules, 28, p. 7574Dai, L., Mau, A.W.H., Griesser, H.J., Spurling, T.H., (1995) J. Phys. Chem., 99, p. 17302MacHado, W., Athayde, P., Mamo, M.A., Van Otterlo, W.A.L., Coville, N.J., Hümmelgen, I.A., (2010) Org. Electron., 11, p. 1736Mamo, M.A., MacHado, W.S., Van Otterlo, W.A.L., Coville, N.J., Hümmelgen, I.A., (2010) Org. Electron., 11, p. 1858De Freitas, J.N., Mamo, M.A., Maubane, M., Van Otterlo, W.A.L., Coville, N.J., Nogueira, A.F., (2012) J. Power Sources, , DOI 10.1016/j. jpowsour.2012.04.066Ohmori, Y., Itoh, E., Miyairi, K., (2006) Thin Solid Films, 499, p. 36