Selective oxidation of alkenes catalysed by ruthenium(II) complexes containing coordinated perchlorate
TL;DR: In this paper, the selective homogeneous oxidation of cyclohexene with TBHP and H2O2 as oxidizing agents was investigated. And the results showed that TBHP was more effective than H 2 O 2 as an oxidizing agent.
Abstract: Ruthenium(II) perchlorate complexes, [Ru(dppm)3(ClO4)]ClO4 1, [Ru(dppe)3(ClO4)]ClO4 2, and [Ru(dpae)3(ClO4)]ClO4 3, catalyse the selective homogeneous oxidation of alkenes with TBHP and H2O2 as oxidizing agents. Oxidation of cyclohexene with TBHP gave 2-cyclohexene-1-ol, 2-cyclohexenone and 1-(tert-butylperoxy)-2-cyclohexene. The homogeneous liquid phase oxidation of cyclohexene with TBHP shows appreciable solvent effect. Styrene on oxidation with TBHP gave benzaldehyde as the major product and styrene oxide as the minor product. Oxidation with H2O2 is radical-initiated and gives low conversion to products. TBHP and H2O2 are compared for their oxidizing ability and TBHP is more effective than H2O2 as an oxidizing agent. Linear and long chain alkenes are not efficiently oxidized. Cyclooctene and trans-stilbene are oxidized to the corresponding epoxides.
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TL;DR: The Keggin-type Cs salt of a mono Mn(II)-substituted phosphotungstate (Cs5[PMnW11O39]) was synthesized from H3PW12O40, MnCl2 and CsCl.
Abstract: The Keggin-type Cs salt of a mono Mn(II)-substituted phosphotungstate (Cs5[PMnW11O39]) was synthesized from H3PW12O40, MnCl2 and CsCl. The complex was characterized in solution as well as in the solid state by spectroscopic, magnetic and electrochemical techniques. The complex crystallized in tetragonal phase. X-ray structural analysis shows two types of disorder in which the Mn and W atoms are distributed over the 12 positions, and the Mn atom could not be distinguished from the 11 W atoms distributed equally over the 12 addenda atoms in the Keggin structure. The catalytic activity of the complex was evaluated for non-aqueous oxidation of styrene using molecular oxygen. The complex gave >99.0% selectivity towards benzaldehyde and could be reused.
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TL;DR: In this article, a mechanism involving formation of [RuII(trpy)(pic)(H2O)]+ (1) type of radicaloid intermediate as an active intermediate responsible for epoxide formation is proposed for the catalytic epoxidation process.
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TL;DR: In this paper, a series of structurally controllable multi-Ru-bridged polyoxometalates, K5NaH10[{Ru4(H2O)n}(WO2)4(AsW9O33)4]·mH 2O {1, 1-dehyd-373K, 1 dehyd-473k, 1dehyd573K; n = 4, m = 36; n= 4,m = 6; n
Abstract: Five-coordinate geometry around ruthenium with highly exposed active sites has attracted intensive scientific interest due to its superior properties and extensive applications. Herein, we report a series of structurally controllable multi-Ru-bridged polyoxometalates, K5NaH10[{Ru4(H2O)n}(WO2)4(AsW9O33)4]·mH2O {1, 1-dehyd-373K, 1-dehyd-473K, 1-dehyd-573K; n = 4, m = 36; n = 4, m = 6; n = 4, m = 0; n = 0, m = 0} fabricated through a feasible assembly strategy using arsenotungstate {2, KNa12H17Cl2(As4W40O140)·29H2O} as a structure-directing unit. Systematic characterization methods identified that the six-coordinate geometry can successfully transform into five-coordinate geometry about active sites (Ru) by removing aqua ligands under high reaction temperatures. All the multi-Ru-bridged polyoxometalates demonstrated strong stability and catalytic effectiveness in the transformation of 1-(4-chlorophenyl)ethanol to 4′-chloroacetophenone under very mild conditions. 1-dehyd-573K, specifically, achieves the best catalytic effectiveness with a turnover frequency (TOF) = 25 100·h−1 owing to its unique five-coordinate geometry on the Ru sites. To our knowledge, 1-dehyd-573K outperforms other POM-based catalysts in the oxidative catalysis of 1-(4-chlorophenyl)ethanol. The heterogeneous polyoxometalates were also proven to be strongly reusable, with their structural integrities well maintained after multiple-cycle catalytic reactions.
19 citations
TL;DR: In this article, the first review regarding the biorecovery of metals and their further reutilization as heterogeneous catalysts is presented, focusing on two broad areas: the bioresorption of chromium by a combined biosorption system consisting of bacteria supported on zeolites and the catalytic reutilisation of the metal-loaded zeolite in the oxidation of organic compounds, in both gaseous and liquid phase.
Abstract: Wastewater pollution with heavy metals is an issue of great environmental concern. The future development of clean technologies for the treatment of wastewater loaded with heavy metals entails environment friendly and sustainable processes that may allow simultaneously the recovery of the metals and their reutilization as value-added catalysts to be used in environmental applications. This is the first review regarding the biorecovery of metals and their further reutilization as heterogeneous catalysts. In this regard, metallic residues that generally would be considered as a waste at the end of the treatment process can be reutilized and transformed into value-added catalysts to be used in environmental applications. This review is focused in two broad areas: the biorecovery of chromium by a combined biosorption system consisting of bacteria supported on zeolites and the catalytic reutilization of the metal-loaded zeolites in the oxidation of organic compounds, in both gaseous and liquid phase. A...
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TL;DR: In this article, an efficient Co-ZSM-11 catalyst has been synthesized for benzaldehyde production by the selective styrene oxidation, which presents a higher reaction rate about 30% with respect to those found in literature and a higher selectivity towards benzaldehyde about 80% at optimal conditions.
16 citations
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01 Jan 1980
TL;DR: Ion Pairs and ion pair extraction as mentioned in this paper, the nature of phase transfer catalysis ion pairs in organic media Extraction of Ion Pairs from Aqueous Solution Crown Ethers, Cryptates, and Other Chelating Agents as Extractants Solid-Liquid Anion Exchange Mechanism of Phase Transfer Catalysis Mechanistic Investigations Empirical Catalyst Evaluations Unusual and Polymer Supported Catalysts Practical Applications of PTC Applications General Experimental Procedures Formation of Halides Preparation of Nitriles Ester Formation Miscellaneous Displacements Thiols and Sulfides Prepar
Abstract: Ion Pairs and Ion Pair Extraction Introduction: The Nature of Phase Transfer Catalysis Ion Pairs in Organic Media Extraction of Ion Pairs from Aqueous Solution Crown Ethers, Cryptates, and Other Chelating Agents as Extractants Solid-Liquid Anion Exchange Mechanism of Phase Transfer Catalysis Mechanistic Investigations Empirical Catalyst Evaluations Unusual and Polymer Supported Catalysts Practical Applications of Phase Transfer Catalysis General Experimental Procedures Formation of Halides Preparation of Nitriles Ester Formation Miscellaneous Displacements Thiols and Sulfides Preparation of Ethers N-Alkylations C-Alkylation of Activated CH-Bonds Alkylation of Ambident Anions Isomerizations and H/D Exchange Additions across Multiple CC-Bonds Addition to C=O and C=N Bonds b'-Eliminations Hydrolysis Reactions Generation and Conversion of Phosphonium and Sulfonium Ylides Nucleophilic Aromatic Substitution Miscellaneous Reactions Organometallic PTC Applications a'-Eliminations Reduction Reactions Oxidation Reactions References Subject Index.
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