An-Najah National University

An-Najah Blogs


  • Tuesday, April 1, 2003
  • Osmium(VIII)-Catalyzed Oxidation of Some Cyclic Amines by Potassium Hexacyanoferrate(III) in Alkaline Media: a Kinetics and Mechanistic Study
  • Published at:Not Found
  • Reactions of morpholine, piperidine, and piperazine with Os(VIII)-catalyzed hexacyanoferrate(III) in alkaline media to produce the corresponding lactam have been studied at constant temperature and ionic strength. The reactions followed first-order kinetics with respect to [amine] and [Os(VIII)] but were independent of [Fe(CN)6 3-] and [OH-]. The effects of introduced electrolytes, potassium hexacyanoferrate(II), relative permitivity, and temperature have also been studied. A mechanism accounting for these results has been proposed.
    Chemistry of Heterocyclic Compounds, Volume 39, Number 4 / April, 2003

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  • Friday, March 1, 2002
  • Kinetics and mechanisms of oxidation of 1-octene and heptanal by crown ether-solubilized potassium permanganate in non-aqueous solvents
  • Published at:TRANSITION METAL CHEMISTRY Volume: 27 Issue: 2 Pages: 223-227 Published: MAR 2002
  • The kinetics of oxidation of 1-octene and heptanal by 18-crown-6-ether-solubilized KMnO4 in benzene and CH2Cl2 have been investigated. In benzene, the oxidation of 1-octene is first order with respect to the oxidant and zero order with respect to the substrate, whereas in CH2Cl2 the reaction is first order with respect to both substrate and oxidant. The reaction of heptanal followed different kinetics being first order with respect to both substrate and oxidant, regardless of whether benzene or CH2Cl2 was employed as the solvent. The values of activation energy E-a, standard enthalpy DeltaH*, standard entropy change DeltaS*, and standard free energy DeltaG*, for the reaction, are reported. Mechanistic pathways for the studied reactions are also proposed.
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  • Monday, January 1, 2001
  • Oxidation of some Alicyclic Amines by Potassium Hexacyanoferrate (III) in Alkaline Medium: A Kinetic and Mechanistic Study
  • Published at:Not Found
  • Oxidation of some alicyclic amines (morpholine, piperazine and piperidine) by potassium hexacyanoferrate(???) in basic medium has been investigated at 35°C. Stoichiometric results showed that four moles of hexacyanoferrate(III) were consumed per mole of piperidine or morpholine whereas piperazine consumed eight moles of the oxidant to produce the corresponding lactams. Kinetic studies indicated that piperidine and morpholine also followed different kinetics from that of piperazine, being first order in the amine concentration and independent of the concentrations of hexacyanoferrate(???) and hydroxide ion, while in the case of piperazine, the reaction was first order in both oxidant and substrate concentrations and zero order with respect to the concentration of hydroxide ion. The changes in reaction rate due to changing ionic strength of the medium as well as other factors has also been investigated. The activation parameters of the oxidation process have been evaluated and a mechanism consistent with th
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  • Thursday, July 22, 1999
  • Poly(siloxane)-supported decacarbonyldimanganese(0) catalyst for terminal olefin hydrosilylation reactions: the effect of the support on the catalyst selectivity, activity and stability
  • Published at:Not Found
  • A new class of supported carbonyl manganese catalyst was prepared by treating the dimeric decacarbonyldimanganese(0), Mn2(CO)10, with insoluble aminated poly(siloxane) surface. Solid state FT-IR spectra indicated that the supported catalyst is a dimeric complex that is substituted with two amine ligands, one at each Mn atom. The supported manganese complex was investigated as catalyst for the hydrosilylation reaction of terminal olefins. Contrary to the homogeneous Mn2(CO)10 catalytic system, the supported manganese complex was completely selective toward the hydrosilylation reaction with no detectable olefin isomerization or other side-reaction products. Furthermore, the catalyst was selective to produce the linear hydrosilylation product rather than the branched one. No lowering in catalyst activity due to the support was observed. A good proportion of the catalyst activity after separation and reuse was retained for at least four times. Highly reproducible catalytic activity measurements were obtained with
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  • Friday, January 1, 1999
  • Terminal Olefin Isomerization Reactions Catalyzed By Poly(Siloxane)-Supported Ru3(Co)12 : The Effect Of The Support On The Catalyst Selectivity, Activity And Stability
  • Published at:مجلة جامعة الأزهر بغزة - سلسلة العلوم الطبيعية، المجلد (1) ديسمبر 1999
  • Dodecacarbonyltriruthenium(0), Ru3(CO)12, 1, has been chemically anchored to the aminated polysiloxane surface, 2. The resulting supported ruthenium complex, 3, was evaluated as catalyst for the olefin isomerization reactions. Contrary to its homogeneous catalyst counterpart, 1, the supported catalyst 3 showed exceptionally high selectivity towards 1-octene isomerization, and trans-2-octene was the sole product of the reaction mixture. The olefin isomerization reaction was markedly activated by the presence of the tertiary silane (EtO)3SiH. No hydrosilylation reaction products were detected. Preliminary kinetic study indicated catalysis by lower nuclearity catalytic species, where the cluster fragments during the reaction process. The effects of different reaction parameters on the rate of the reaction have been investigated.
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Waheed J. Jondi
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