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dc.contributor.authorSutar, Alekha Kumar-
dc.date.accessioned2014-09-23T11:32:44Z-
dc.date.available2014-09-23T11:32:44Z-
dc.date.issued2008-
dc.identifierPh.Den_US
dc.identifier.urihttp://hdl.handle.net/123456789/1501-
dc.guideGupta, K. C.-
dc.description.abstractThe purpose of the present investigations was to determine, whether there is any difference between the activities of supported and unsupported metal ions complexes used as catalyst. Although, extensive investigations on supported catalysts have been reported, but most of these systems are complicated to be compared with present investigations. These systems have included different supports and not only the complexes of macromolecules but also included labile metal ions complexes; hence, their properties and activity are different than polymer supported metal ions complexes of Schiff base ligands. The application of polymers as a support for the catalyst is a logical transition from inorganic supports to polymeric supports to get a homogeneously distributed catalysts on flexible polymeric support than heterogeneously distributed catalyst on brittle and rigid inorganic supports. In polymer support, the cross-linking and degree of functionalization have further rationalized the application of polymers to control the degree of metal ions loading and stability for their applications in drastic conditions. The metal ions complexes anchored on rigid supports hardly behave like solution, but metal ions complexes on polymer supports have shown high activities, composition, configuration comparable to metal ions complexes in solution specially with highly cross-linked polymers. The highly cross-linked polymers have shown low porosity, which reduced the degree of swelling and loading of metal ions; hence, polymer supports with low degree of cross-linking has been used in present investigations. In addition to the effect of polymer support, the activity of metal ions complexes also varies with the structures and the coordination affinity of Schiff base 11 ligand; hence, in the present investigations, the metal ions complexes of different Schiff base ligands have been synthesized and anchored on polymer supports after derivatization. To analyze the effect of type of metal ions on catalytic activity of polymer anchored Schiff base ligands, the polymer anchored Schiff base ligands were loaded with five different metal ions and characterized for their structures and activity in oxidation of phenol and epoxidation of cyclohexene in presence of hydrogen peroxide as oxidant The activity of metal ions complexes of polymer anchored Schiff base ligands was compared with unsupported metal ions complexes. The first set of catalyst dealt with synthesis of unsupported and polymer supported iron(lll), cobalt(ll), copper(ll), nickel(ll), and zinc(ll) ions complexes of N,N'-bis (o-hydroxy acetophenone) ethylenediamine Schiff base ligand (HPED) and their characterization for structures and activity in oxidation of phenol and epoxidation of cyclohexene in presence of hydrogen peroxide at constant temperature. The N, N'-bis (o-hydroxy acetophenone) ethylenediamine Schiff base (HPED) was synthesized refluxing o-hydroxy acetophenone and ethylenediamine in methanol. The polymer supported HPED Schiff base was synthesized by reacting amino derivatized HPED Schiff base with cross-linked polymer beads. The HPED Schiff base was characterized by i.r, uv and elemental analysis for their structures and compositions. The amount of HPED Schiff base ligand loaded on 1 g of chloromethylated polystyrene beads was 2.31 mmol. The efficiency of complexation (%EC) of metal ions on unsupported and polymer supported HPED Schiff base ligand was also analyzed using atomic absorption spectrometer. The efficiency of complexation of polymer supported HPED Schiff base ligand was more than in unsupported HPED Schiff base ligand. The unsupported and polymer supported metal ions complexes were characterized for their structures, composition and stability by i.r. UV, elemental and thermal analysis. TG and DTG analysis was used to determine the complexation of metal ions and their thermal stability in comparison to unsupported and polymer supported HPED Schiff base. To analyze the effect of polymer support, the synthesized unsupported and polymer supported metal ions complexes of HPED Schiff base were used as catalyst in oxidation of phenol and epoxidation of cyclohexene and their activity was evaluated in substrate conversion and product selectivity for catechol and epoxy cyclohexane. The polymer supported metal ions complexes of HPED Schiff base were more catalytic and selective in oxidation of phenol and epoxidation of cyclohexene. The iron(lll) ions complexes of unsupported and polymer supported HPED Schiff base have shown highest activity in comparison to unsupported and polymer supported other metal ions complexes of HPED Schiff base. The conversion of phenol was 58.2 wt% and 70.0 wt% in presence of unsupported and polymer supported iron(lll) ions complexes of HPED Schiff base, whereas, conversion of cyclohexene was 72.5 wt% and 87.3 wt% respectively. The selectivity for catechol was 70.0 wt% and 92.4 wt% in oxidation of phenol and selectivity for epoxy cyclohexane was 85.2 wt% and 97.6 wt% in epoxidation of cyclohexene, which clearly indicated that polymer supported iron(lll) ions complexes were more catalytic than unsupported iron(lll) ions complexes of HPED Schiff base. The activity of metal ions complexes of HPED Schiff base was also characterized in term of turn over number (TON) and energy of activation (Ea) for oxidation of phenol and epoxidation of cyclohexene, which varied with metal ions IV complexes of unsupported and polymer supported HPED Schiff base and with type of metal ions. The energy of activation was lowest with polymer supported iron(lll) ions complexes of HPED Schiff base, which was 25.0 k J mol"1 and 9.30 k J mol"1 respectively in oxidation of phenol and epoxidation of cyclohexene. The activity of recycled supported metal ions complexes of HPED Schiff base was also evaluated, which shown almost constant activity up to six recycles; hence, indicated high stability for metal ions complexes on polymer support without leaching of metal ions. To analyze the effect of diamine in Schiff base ligands on loading of metal ions and their catalytic activity, the unsupported and polymer supported metal ions complexes N, N'-bis (o-hydroxy acetophenone) hydrazine (HPHz) and N, N'-bis (o-hydroxy acetophone) propylene diamine (HPPn) Schiff base ligands were prepared refluxing o-hydroxy acetophone with hydrazine and 1,2-propylenediamine. The amino functionalized HPHz and HPPn Schiff base ligands were loading on polymer beads, which shown 3.44 mmol and 3.484 mmol loading of HPHz and HPHz Schiff base ligands on 1 g of polymer beads. The i.r., uv and thermal analysis was used for characterization of HPHz and HPPn Schiff base ligands and their loading on polymer beads. The unsupported and polymer supported HPHz and HPPn Schiff base ligands were loaded with iron(ll), cobalt(ll), copper(ll), nickel(ll) and zinc(ll) ions and characterized by i.r., uv and elemental analysis for their structures and to evince the complexation of metal ions with unsupported and polymer supported HPHz and HPPn Schiff base ligands. The unsupported and polymer supported HPPn Schiff base ligand has shown high loading of metal ions than unsupported and polymer supported HPHz Schiff base ligand. The u.v. analysis and magnetic properties of metal ions complexes of HPHZ and HPPn Schiff base ligands have indicated octahedral geometry (dsp3) for iron(lll) ions, square planar geometry (dsp2) for cobalt(ll), copper(ll) and nickel(ll) ions and tetrahedral geometry (sp3) for zinc(ll) ions complexes with unsupported and polymer supported HPHz and HPPn Schiff base ligands.The spectral analysis has indicated that the geometry of unsupported and polymer supported metal ions complexes of HPHz and HPPn Schiff base complexes was identical, but shown different activity due to the presence of different diamines in these Schiff base ligands. The metal ions complexes of unsupported and polymer supported HPHz and HPPn Schiff base ligands were characterized for their activity and selectivity in oxidation of phenol and epoxidation of cyclohexene using hydrogen peroxide as oxygen donor at constant temperature. Like metal ions complexes of HPED Schiff base ligand, the polymer supported metal ions complexes of HPHz and HPPn Schiff base ligands have shown high activity and selectivity in oxidation of phenol and epoxidation of cyclohexene. The activity and selectivity of unsupported and polymer supported metal ions complexes of HPHz Schiff base was lowest than metal ions complexes of HPED and HPPn Schiff base ligands. The polymer supported iron(lll) ions complexes of HPHz Schiff base ligand have shown 64.0 wt% conversion of phenol, whereas, polymer supported iron(lll) ions complexes of HPED and HPPn Schiff base ligands have shown 70.0 wt% and 73.0 wt% conversion of phenol under constant concentration (0.05 mol dm"3) of catalysts, phenol and hydrogen peroxide. Similar trend was observed in conversion of cyclohexene. The iron(lll) ions complexes of polymer supported HPHz Schiff base ligand has shown different selectivity for catechol and epoxy cyclohexane than polymer supported VI iron(lll) ions complexes of HPED and HPPn Schiff base ligands. Although unsupported and polymer supported cobalt(ll), copper(ll), nickel(ll) and zinc(ll) ions complexes of HPHz Schiff base ligand have shown low activity than iron(lll) ions complexes of unsupported and polymer supported HPHz Schiff base ligand but their trends were like iron(lll) ions complexes of unsupported and polymer supported HPHz Schiff base ligand. The catalytic activity of unsupported and polymer supported metal ions complexes of HPHz and HPPn Schiff base was evaluated at different concentrations of phenol/ cyclohexene, catalyst and hydrogen peroxide. The metal ions complexes of HPHz Schiff base ligand has shown low activity and selectivity for catechol and epoxy cyclohexane in comparison to metal ions complexes of HPPn Schiff base ligand, which clearly indicated that the structure of diamine in HPHz and HPPn Schiff base ligands have influenced the activity of metal ions complexes as catalyst in addition to the effect of polymer support. The Schiff base ligand structure has also influenced the rate of oxidation and epoxidation and turn over number in these reactions. The value of these kinetic parameters has been found to be low with metal ions complexes of HPHz Schiff base ligand. The energy of activation for oxidation and epoxidation reaction was lowest with metal ions complexes of HPPn Schiff base ligand than HPHz Schiff base ligand. The unsupported and polymer supported metal ions complexes of N, N'-bis (2-hydroxy naphthaldehde) ethylenediamine (HNED) and N, N'-bis (2-hydroxy naphthaldehde) propylenediamine Schiff base (HNPPn) ligands were also prepared to determine the effect of polymer support and the structure of Schiff base ligand. These metal ions complexes were characterized for their structures and catalytic Vll activity in oxidation of phenol and epoxidation of cyclohexene in comparison to metal ions complexes of HPED and HPPn Schiff base ligands, which were having a different aldehyde than used in HNED and HNPh Schiff base ligands. The unsupported HNED and HNPn Schiff base ligands were prepared reacting 2-hydroxy naphthaldehyde with ethylenediamine and 2-propylene diamine and polymer supported analogues of HNED and HNPn Schiff base ligands were prepared by reacting aminofunctionalized Schiff base ligands with chloromethylated polystyrene beads in methanol. The structure of unsupported and polymer supported HNED and HNPn Schiff base ligands and their metal ions complexes were characterized by i.r. , uv and elemental analysis. The thermal stability of unsupported and polymer supported HNED and HNPn Schiff base ligands and their metal ions complexes was analyzed by TG and DTG analysis. The loading of metal ions was higher on polymer supported HNED and HNPn Schiff base ligands than unsupported Schiff base ligands. Although loading of metal ions on HNED and HNPn Schiff base was comparable to HPED and HPPn Schiff base ligands, but metal ions complexes of HNED and HNPn Schiff base ligands were having different properties and activities in comparison to metal ions complexes of HPED and HPPn Schiff base ligands as confirmed from their activity and selectivity in oxidation of phenol and epoxidation of cyclohexene. The low activity of metal ions complexes of HNED and HNPn Schiff base ligands than metal ions complexes of HPED and HPPn Schiff base ligands in oxidation of phenol and epoxidation of cyclohexene was attributed to the presence of naphthalene ring in Schiff base ligands, which reduced their activities in oxidation of phenol and epoxidation of cyclohexene. The energy of activation for oxidation and Vlll epoxidation reactions in presence of metal ions complexes of HNED and HNPn Schiff base ligands has been found to be high in comparison to the metal ions complexes of HPED and HPPn Schiff base ligands. These investigations have clearly indicated that the activity of metal ions complexes was influenced significantly on anchoring the metal complexes of Schiff base ligands on polymer supports and using different Schiff base ligands. The activity of polymer anchored Schiff base ligand was also influenced by using different metal ions. Amongst the selected metal ions complexes of Schiff base ligands, the iron(lll) ions complexes have shown high activity in synthesized Schiff base ligands.en_US
dc.language.isoenen_US
dc.subjectCHEMISTRYen_US
dc.subjectPOLYMER ANCHORED METAL COMPLEXESen_US
dc.subjectCATALYTIC ACTIVITYen_US
dc.subjectHIGHLY CROSS-LINKED POLYMERSen_US
dc.titleSYNTHESIS OF POLYMER ANCHORED METAL COMPLEXES AND EVALUATION OF THEIR CATALYTIC ACTIVITYen_US
dc.typeDoctoral Thesisen_US
dc.accession.numberG13997en_US
Appears in Collections:DOCTORAL THESES (chemistry)

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