R.N. Ram

Oxidation of benzyl alcohol using polymer anchored Ru(III) complex as catalyst

Abstract Polymer-anchored Ru(III) complex was synthesized by sequential attachment of ethylenediamine, salicylaldehyde and ruthenium chloride to chloromethylated styrene–divinylbenzene copolymer with 8% cross-linking. Synthesized catalyst was characterized by different techniques such as FTIR, reflectance UV-VIS spectroscopy, ESR, ESCA, SEM and TGA. Various physico-chemical properties such as moisture content, bulk density, surface area and swelling behaviour in different solvents were also studied. Catalytic activity of this catalyst was tested for oxidation of benzyl alcohol by varying the temperature of the system as well as concentration of substrate and catalyst. Values of energy of activation and entropy of activation have been evaluated from the kinetic data. A probable reaction mechanism has been proposed.

Olefin epoxidation catalysed by Mn(II) Schiff base complex in heterogenised–homogeneous systems

Abstract The polymer supported Mn(II) Schiff base complexes were prepared from crosslinked chloromethylated poly(styrene-divinyl benzene) copolymer beads by sequential modification into a Schiff base bearing ligand. These Schiff base bearing polymer on treatment with a solution of MnCl 2 ·2H 2 O gave the corresponding metal complexes. The polymer supported Mn(II) complexes were characterised by elemental analysis, FT-IR, diffuse reflectance, SEM and thermogravimetric analysis. Physicochemical properties such as surface area, bulk density and swelling behaviour in different solvents were studied. The catalytic activity of the supported metal complexes were studied in the epoxidation of norbornene and cis -cyclooctene using tert -butylhydroperoxide (TBHP) as the terminal oxidant. The influence of various reaction parameters such as temperature, solvent, substrate and catalyst concentration, on conversion and selectivity has been studied.

Synthesis and catalytic activity of Fe(III) anchored to a polystyrene–Schiff base support

Cross-linked styrene-divinylbenzene copolymer was functionalized into bidentate Schiff base bearing ligands. Immobilization of iron(III) on to the polymer matrix resulted in the synthesis of catalytically active metal complexes. These supported catalysts were found to be effective in the epoxidation of cis-cyclooctene and styrene in presence of tert-butylhydroperoxide under mild conditions. The influence of various reaction parameters on conversion and selectivity to products of epoxidation has been discussed.

A study of synthesis, characterization and catalytic hydrogenation by polymer anchored Pd(II)-amino acid complexes

Abstract l -Valine was anchored to 6% and 8% cross-linked poly(styrene-divinyl benzene) resin and its complex with palladium chloride was prepared. The newly synthesized catalysts were characterized by various techniques such as elemental analysis, FT-IR, DRS, SEM and TGA. Physico-chemical properties like surface area, swelling behavior in different solvents, bulk density, etc. have been determined. The polymer supported Pd complexes behave as versatile and recyclable catalysts for the hydrogenation of 1-octene, cyclohexene, acetophenone and nitrobenzene. Kinetics of hydrogenation of 1-octene has been investigated in detail. The influence of different reaction parameters on conversion and selectivity to products are reported.

Synthesis and catalytic property of poly(styrene-co-divinylbenzene) supported ruthenium(III)-2-aminopyridyl complexes

Abstract Chloromethylated styrene-divinylbenzene copolymer beads with 8 and 14% cross-link were chemically modified by a reaction with 2-aminopyridine leading to the incorporation of nitrogen ligating sites on the surface of the polymer. These polymeric ligands, on treatment with a solution of ruthenium(III) chloride, gave the corresponding metal complex. The polymer supported Ru(III) complexes were characterized by elemental analysis, FT-IR, diffuse reflectance, SEM and DTA-TGA methods. The epoxidation of cis -cyclooctene, cyclohexene and styrene was investigated using the supported metal catalysts in presence of tert -butyl hydroperoxide as the terminal oxidant. Cis -cyclooctene gave the corresponding epoxide in a maximum yield of 51% whereas in case of styrene both styrene oxide and secondary oxidation product benzaldehyde were obtained in a combined yield of 95% under similar conditions. Surprisingly with cyclohexene as substrate the major product was 2-cyclohexene-1-one (64%) compared to the epoxide (2 %).

Hydrogenation of nitrobenzene using polymer anchored Pd(II) complexes as catalyst

Abstract Polymer anchored metal complex catalysts of Pd(II) were synthesized using styrene divinyl benzene (PS–DVB) co-polymer of two different crosslinking (2% and 8%) by sequential attachment of chloromethyl group, bidentate ligand and treating the functionalized polymer with the metal chloride solution. The supports and the catalysts were characterized using conventional techniques as well as the spectroscopic methods such as UV-Vis reflectance, IR and DTA-TG analysis. Other physico chemical properties such as bulk density, moisture content, surface area by BET method and swelling of the catalysts in different solvents have also been studied. The morphology of the catalysts was seen using scanning electron microscope. A probable structure of the catalyst formed on polymer matrix was proposed on the basis of the above studies. The synthesized catalysts were tested for their catalytic activity for the hydrogenation of nitrobenzene as a model reaction. The influence on the rate of various factors such as the amount of catalysts, concentration of the substrate and temperature of the system has been studied. The recycling efficiency of catalysts has also been studied.

Preparation characterization and catalytic activity of polymer supported Ru(III) complexes

Abstract Chloromethylated styrene-divinyl benzene copolymer with different types of cross-link was treated with glycine for the introduction of the ligand. The polymer modified with ligand was kept in contact with RuCl 3 to form the metal complex on the surface of the polymer. The catalysts thus prepared were characterised by techniques such as IR, UV-Vis reflectance spectroscopy and DTA-TG analysis. Other physico-chemical properties such as surface area, moisture content, bulk density and swelling were also studied. The morphology of the catalysts was observed by scanning electron microscope. The catalysts were tested for the hydrogenation of nitrobenzene as a model reaction. The influence of various parameters such as concentration of catalyst and substrate, temperature and different solvents on the rate of the reaction has been studied.

Bromamine-T mediated aziridination of olefins with a new / polymer supported Manganese II complex as catalyst

Chloromethylated styrene-divinyl benzene of 8% cross-link was functionalized using o-phenylene diamine and finally it . was treated with Mn II for the formation of metal complex on the surface. The metal content was estimated using atomic absorption spectroscopy. The thermal stability of the catalyst was seen by the use of DTA-TG analyses and the catalyst was found to be stable up to ; 1258C. The modern spectroscopic methods such as FT-IR, ESR were used in order to confirm the . probable structure of the catalyst. The catalytic activity of this supported Mn II -complex was investigated for aziridination of olefins with bromamine-T as the source of nitrogen. The catalyst was found to be effective in this reaction and could be reused with no substantial loss of activity for up to three cycles. q 2000 Elsevier Science B.V. All rights reserved. .

Surface characterization and catalytic activity of polymer-anchored Ru(III)–schiffbase complex

Abstract A polymer-anchored Ru(III)–schiffbase complex was synthesized by chloromethylation of styrene-divinylbenzene copolymer with 14% cross-linked (AM-24) followed by sequential attachment of ethylenediamine and salicylaldehyde and finally, treatment with an ethanolic solution of metal salt. It was characterized using various techniques such as FTIR, reflectance UV–Vis spectroscopy, SEM, Electron Spin Resonance (ESR), ESCA and TGA. Various other physico-chemical properties such as bulk density, surface area, moisture content and swellability in different solvents have also been studied. Catalytic activity of the synthesised complex was investigated for hydrogenation of styrene and oxidation of benzylalcohol. Reaction kinetics was studied by varying different parameters. Results were compared with that of unbound metal complex and higher catalytic activity was found in case of supported catalyst. Catalytic behaviour under repeated catalytic cycles was studied. A probable reaction mechanism has been proposed.

Hydrogenation of 1-hexene using polymer supported Pd(II) complex catalyst

Abstract Polymer supported Pd(II) complex catalyst was synthesised by chloromethylation of styrene-divinylbenzene copolymer (XAD-2), with sequential attachment of ethylenediamine and salicylaldehyde, followed by treatment with an ethanolic solution of palladium chloride. The synthesised catalyst, named 2PS, was characterised by various techniques, such as UV-vis reflectance spectroscopy, IR, SEM, TGA and ESR. Other physico-chemical properties, such as surface area (by the BET method), moisture content, bulk density and swelling by different solvents, have been studied. The catalytic activity of the catalyst was investigated for hydrogenation of 1-hexene by varying different parameters, such as temperature, amount of the catalyst and concentration of 1-hexene.