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Molybdenum(VI) Complexes and Palladium Nanoparticles in Ionic Liquid-Liquid Biphasic and Supported Ionic Liquid phase (SILP) Catalysis, and Green Catalytic Processes using Polymeric Ionic Liquids (PILs

Ghazali-Esfahani, Saeideh | 2013

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 45032 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Bagherzadeh, Mojtaba
  7. Abstract:
  8. In this thesis, ionic liquids and polymeric ionic liquids were investigated as solvent and support for immobilization of molybdenum and palladium catalysts. Three newly synthesized room temperature ionic liquids containing molybdate anion, [DMIm][MoO2(NCS)4], [RPy][MoO2(NCS)4] (R = butyl or decyl), and previously reported [BMIm][MoO2(NCS)4] were used as catalysts for the reduction of sulfoxides. For facilitating the recyclability of the catalysts, the ionic liquid solvents, [RMIm][PF6] and [RPy][PF6] (RMIm=1-n-alkyl-3-methylimidazolium, RPy= 1-n-alkylpyridinium), were applied to immobilize molybdenum catalysts. These catalysts showed high catalytic activity for sulfoxide reduction in this liquid-liquid biphasic catalytic system using toluene as organic solvent and PPh3 as reducing agent. This system was reuse for 8 times with no loss of catalytic activity. Then, [BMIM]2[MoO2(NCS)4] and [DMIM]2[MoO2(NCS)4] were also immobilized on ionic liquid-modified silica to obtained molybdenum-supported ionic liquid phase catalysts. These heterogeneous catalysts showed notable catalytic activity for the reduction of sulfoxides into sulfides with triphenylphosphine (PPh3). The molybdenum liquid salts immobilized on the supported ionic liquid phase could be reused at least for three catalytic cycles without significant loss of activity. The next part of thesis consists of the investigation of some cross-linked ionic polymers based on styrene-functionalized imidazolium salts with chloride, hexafluorophosphate, or tetrafluoroborate anion as catalyst for the cycloaddition of carbon dioxide to epoxides affording cyclic carbonates. The polymer with the chloride anion is an efficient catalyst for this reaction using no solvent. The cross-linked polymer was insoluble in organic solvents and is highly stable and therefore could be easily recycled and reused. Continuing our study on green catalytic system using polymeric ionic liquid, the polymer prepared by radical polymerization of 1,3-bis(4-vinylbenzyl)imidazolium chloride ([bvbim]Cl) as ionic monomer, was used for immobilization of palladium nanoparticle. The immobilized palladium nanoparticle efficiently catalyzed Suzuki coupling reaction of different aryl halide with phenyl bronic acid in water. The catalyst was reused for 4 times. TEM images proved that nanoparticles were stable on the surface of polymeric support even after 4 recycling tests. Finally, new polymeric material was synthesized by copolymerization of styrene and [bvbim]Cl as imidazolium liquid salt with two styrenic arms. This copolymer was used to stabilize palladium nanoparticle. The catalytic activity has been evaluated for the Heck reaction, without using solvents, proving an excellent performance in terms of both activity and recyclability.
  9. Keywords:
  10. Sulfoxides ; Carbon Dioxide ; Ionic Liquids ; Triphenylphosphine ; Supported Ionic Liquid Phase ( SILP)Catalysis System ; Polymeric Ionic Liquid (PIL) ; Cycloaddition Reaction ; Palladium Nanoparticle ; Epoxide

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