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: In this article, a simple physical-vapor-infiltration (PVI) method was applied to prepare highly ordered Fe-containing mesoporous silica SBA-15.
Abstract: A simple physical-vapor-infiltration (PVI) method was applied to prepare highly ordered Fe-containing mesoporous silica SBA-15. The loading amount of Fe in SBA-15 was very high (up to 24 mol%) and can be tuned by using different PVI time. The liquid phase selective oxidation of styrene with H 2 O 2 has been used to characterize their catalytic properties, the major product is benzaldehyde and the minor is styrene oxide. Independent of the Fe contents and the heat treatment temperature, the selectivity for benzaldehyde in the reaction at a mild temperature of 50 °C are all above 91%. At elevated temperature of 70 °C, the conversion rate of styrene increases beyond 36% and more significantly the selectivity for benzaldehyde can reach as high as 99%. Comparatively, another two different schemes (simple wet impregnation and incorporation using silane coupling agent) have been also applied to synthesize Fe-containing SBA-15 samples. Under the same condition, the styrene conversion on these two samples are both very low with minor product of phenylacetaldehyde and other styrene oxides.
40 citations
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TL;DR: In this paper, the coupling of microwave energy with solvent-free phase-transfer catalysis was studied for the oxidation of cyclohexene and styrene, and parallel oxidations were successfully employed by using a special microwave set-up.
Abstract: The coupling of microwave energy with solvent-free phase-transfer catalysis was studied for the oxidation of cyclohexene and styrene. The former Noyori oxidation system (Science, 1998, 281, 1646) was restudied under the aforementioned conditions and optimised. In addition, parallel oxidations were successfully employed by using a special microwave set-up.
35 citations
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TL;DR: In this paper, the authors used a robust biosorption system consisting of a bacterial biofilm, Arthrobacter viscosus, supported on zeolite NaY.
Abstract: The goal of this study is the preparation of new heterogeneous catalytic materials to be used in oxidation reactions under mild conditions through the valuation of heavy metals in wastewater. The samples used in the immobilization of chromium complexes were prepared from a dichromate solution of 100 mgCr L � 1 . The zeolite CrNaY was prepared from a robust biosorption system consisting of a bacterial biofilm, Arthrobacter viscosus, supported on zeolite NaY. The biofilm performs the reduction of Cr(VI) to Cr(III) and this cation is retained in the zeolite by ion exchange. The immobilization of chromium complexes with heterocyclic ligands in the supercages of Y zeolite was performed by the in situ synthesis with three different ligands, 3-methoxy-6-chloropyridazine (A), 3-piperidino-6-chloropyridazine (B) and 1-(2pyridylazo)-2-naphthol (C). A sample loaded with Cr from a liquid solution with the same initial concentration was prepared as a reference through the traditional direct ion-exchange method and coordinated with ligand (A). The resulting catalysts were fully characterized by different techniques (FTIR, XRD, TGA, SEM, Raman, cyclic voltammetric studies and chemical analysis) and the results confirmed that the Cr complexes were immobilized in supercages of NaY. Catalytic studies were performed in liquid phase for the cyclohexene oxidation, at 40 8C, using tert-butyl hydroperoxide (TBHP) as the oxidizing agent. All the prepared catalysts exhibited catalytic activity for the oxidation reaction.
28 citations
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TL;DR: In this paper, an environmentally benign oxidation of alcohols and alkenes over transition metal substituted phosphomolybdates with molecular oxygen as an oxidant and TBHP as an initiator was carried out.
Abstract: Environmentally benign oxidation of alcohols and alkenes over transition metal substituted phosphomolybdates with molecular oxygen as an oxidant and TBHP as an initiator was carried out. The influence of different parameters on the conversion as well as the selectivity was investigated. All the catalysts showed good catalytic activity with excellent selectivity for the desired products as well as a higher TON. The system not only catalyzes the reaction but also avoids the use of organic solvents as it was carried out under solvent free conditions. Moreover, the catalysts could be recovered and reused four times without a significant loss in their activity and selectivity. A probable reaction mechanism was also proposed for the oxidation of alcohols and alkenes.
27 citations
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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.
Abstract: The [RuII(trpy)(pic)(H2O)]+ (1) was synthesized and characterized by analytical, spectral (UV–Vis and IR), molar conductivity, magnetic moment and electrochemical studies. Complex 1 catalyzes the epoxidation of styrene and stilbenes in presence of tert-butyl hydroperoxide (t-BuOOH) in dichloromethane at room temperature. No epoxide formation was observed in presence of the radical trapping agent (benzoquinone). A mechanism involving formation of [Ru–O(t-Bu)–O] type of radicaloid intermediate as an active intermediate responsible for epoxide formation is proposed for the catalytic epoxidation process.
27 citations
References
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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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422 citations