- A magnetically recyclable superparamagnetic silica supported Pt nanocatalyst through a multi-carboxyl linker: Synthesis, characterization, and applications in alkene hydrosilylation
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To simplify separation procedures, improve the reusability and decrease the loss of Pt, two Pt catalysts anchored on superparamagnetic silica (Fe3O4@SiO2-EDTA@Pt and Fe3O4@SiO2-DTPA@Pt) were prepared for the first time. The stable magnetic properties made them easily recyclable using a magnet rather than filtration, decantation or centrifugation. After 12 catalytic runs for both 30-50 nm Pt catalysts, the yield of 1-heptylmethyldichlorosilane was still up to 90%. The average loss of Pt in each reaction was only 0.87% for Fe3O4@SiO2-EDTA@Pt and 0.66% for Fe3O4@SiO2-DTPA@Pt owing to the strong interaction between Pt and carboxyl. The unprecedented activity and selectivity of the two Pt nanoparticle catalysts were observed in the hydrosilylation of alkenes. The turnover number in the reaction between 1-hexene and methyldichlorosilane using 5 × 10-8 mol of the Pt approached 662733 for Fe3O4@SiO2-EDTA@Pt and 579947 for Fe3O4@SiO2-DTPA@Pt over 12 h. The corresponding hydrosilylation products in excellent yields were obtained when we employed a broad range of alkenes as substrates, including 5 isomerous hexenes and 14 important industry raw materials. Fe3O4@SiO2-DTPA@Pt showed a better activity. They have potential for catalyzing more reactions and replacing the current homogeneous Pt catalysts in industry.
- Li, Laiming,Li, Youxin,Yan, Jincong,Cao, Hang,Shao, Dongyun,Bao, James J.
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- Mild niobium-catalyzed [2 + 2 + 2] cycloaddition of sila-triynes: Easy access to polysubstituted benzosilacyclobutenes
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A new and efficient synthesis of highly sensitive benzosilacyclobutenes has been developed. For the first time, these compounds can be synthesized in very high yields by a mild, unprecedented intramolecular niobium-catalyzed [2 + 2 + 2] cycloaddition of easily accessible tetrasubstituted sila-triynes. An easy access to highly functionalized benzosilacyclobutenes enlarging the number of potential applications in organic and material chemistry is described.
- Simon, Cdric,Amatore, Muriel,Aubert, Corinne,Petit, Marc
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Read Online
- PROCESS FOR THE STEPWISE SYNTHESIS OF SILAHYDROCARBONS
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The invention relates to a process for the stepwise synthesis of silahydrocarbons bearing up to four different organyl substituents at the silicon atom, wherein the process includes at least one step a) of producing a bifunctional hydridochlorosilane by a redistribution reaction, selective chlorination of hydridosilanes with an ether/HCI reagent, or by selective chlorination of hydridosilanes with SiCI4, at least one step b) of submitting a bifunctional hydridochloromonosilane to a hydrosilylation reaction, at least one step c) of hydrogenation of a chloromonosilane, and a step d) in which a silahydrocarbon compound is obtained in a hydrosilylation reaction.
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Page/Page column 65; 67; 82
(2021/12/08)
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- Preparation, characterization and evaluation of a series of heterogeneous platinum catalysts immobilized on magnetic silica with different acid ligands
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Platinum was immobilized on magnetic silica gel by means of boronic, nitric, carboxylic or sulfuric acid ligands to give four heterogeneous Pt nano-catalysts, designated as Fe3O4@SiO2-BA@Pt, Fe3O4@SiO2-NA@Pt, Fe3O4@SiO2-CA@Pt and Fe3O4@SiO2-SA@Pt, respectively. Particles of these mono-dispersible Pt catalysts were 10–20?nm in size and could be separated for recycling by means of a magnet. Fe3O4@SiO2-BA@Pt (0.174?mmol/g Pt) showed the best catalytic activity and selectivity, which were better than Speier’s catalyst. Its turnover numbers were up to 1.7 × 106 and 1.1 × 106 for hydrosilylation of 1-hexene or styrene, respectively. This material could also catalyze the hydrosilylation of a broad range of alkenes and alkynes as substrates and methyldichlorosilane or triethoxysilane as silanes. Similar yields of 1-hexyl-methyldichlorosilane at the first and eighth runs (96.5% and 95.2%, respectively), together with a final Pt content of 0.171?mmol/g indicated the outstanding stability of Fe3O4@SiO2-BA@Pt under the catalytic reaction conditions.
- Li, Laiming,Li, Youxin,Assefa, Aschenaki,Bao, James J.
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p. 779 - 787
(2019/08/12)
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- Silicon-hydrogen addition reaction (by machine translation)
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The invention relates to the field of organic chemistry, in order to solve the addition reaction catalyst with hydrogen in the presence of the problem, the invention provides a method for addition reaction, in order to olefin and three b oxygen radical hydrogen silicane as raw materials, in order to b [(1 - mPEG - 3 - alkyl 2 - diphenyl [...] halide) rhodium chloride] as the catalyst, heating 50 - 90 °C stirring for 4 - 6 hours, filtration, vacuum distillation fraction of, hydrogen addition product is obtained. This method of mild reaction conditions, security, high reaction conversion rate, β addition product selectivity is strong, it is convenient to separate the products and the catalyst, the catalyst can be recycled. (by machine translation)
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Paragraph 0066; 0067
(2018/04/21)
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- Hydrosilylation reaction using recyclable platinum compound as catalyst
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The present invention relates to the field of organic chemistry. In order to solve the problems existing in catalysts for a hydrosilylation reaction, the present invention provides a hydrosilylation reaction method. The method comprises the steps of using an olefin and triethoxysilane as raw materials and taking bis[(1-mPEG-3-alkyl-2-diphenylphosphinous imidazolium halide)platinum dichloride] as acatalyst, performing heating to 50-90 DEG C, performing a stirring reaction for 4-6 hours, performing filtration, performing vacuum distillation, and collecting fractions to obtain a hydrosilylationproduct. The reaction conditions of the method are mild and safe, the reaction conversion rate is high, the selectivity of a beta addition product is high, separation of the products and the catalystis convenient, and the catalyst can be recovered and reused.
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Paragraph 0066-0067
(2018/04/21)
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- Preparation of polycarboxylic acid-functionalized silica supported Pt catalysts and their applications in alkene hydrosilylation
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A series of novel immobilized platinum catalysts was prepared by loading Pt onto silica particles modified with polycarboxylic acid groups such as diethylenetriaminepentaacetic acid (DTPA), nitrolotriacetic acid (NTA) and succinic acid (SA). The three modified heterogeneous Pt catalysts were characterized using infrared spectroscopy (IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and atomic absorption spectroscopy (AAS). The residual H2PtCl6 solutions were characterized using ultraviolet spectroscopy (UV). The polycarboxylic acid-functionalized silica supported Pt catalysts were used to catalyze alkene hydrosilylation and 1-hexene was chosen as a model alkene. The data indicated that the catalytic performance was strongly dependent on the properties of the polycarboxylic acid group bonded to the silica particles. Among them, DTPA-functionalized silica supported Pt (SiO2-DTPA-Pt) showed the best catalytic activity and reusability. Furthermore, some hydrosilylation reactions between other linear alkenes (1-heptene, 1-octene, 1-decene, 1-do-decene, 1-tetra-decene, 1-hexa-decene, 1-octa-decene, styrene or cis-hex-2-ene), or ring type alkenes (norbornene) with methyldichlorosilane could be catalyzed in the presence of these three Pt catalysts. Their high activities were more than 90%, and their selectivities were more than 99%, which were apparently better than homogeneous Pt catalysts. In addition, reactions with cyclohexene were also successfully catalyzed by the Pt catalysts. These results indicate that the polycarboxylic acid-functionalized silica gel supported Pt catalysts have potential value in industrial hydrosilylation reactions.
- Shao, Dongyun,Li, Youxin
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p. 20379 - 20393
(2018/06/11)
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- The first alkene-platinum-silyl complexes: Lifting the hydrosilation mechanism shroud with long-lived precatalytic intermediates and true Pt catalysts
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The synthesis, characterization, and exploratory chemistry of two classes of alkene-platinumsilyl complexes, which have been postulated as hydrosilation intermediates, are described in this report. The unique dimeric complexes 1, [R3Si(u-Cl)(η2-COD)Pt]2 {R3Si = Et3Si, MeCl2Si, Me2ClSi, "(EtO)3Si", PhMe2Si, and (Me3SiO)Me2Si: COD = cycloocta-1,5-diene}, and the bis-silyl complexes 2, (η4-COD)Pt-(SiR3)2 (R3Si = Cl3Si, MeCl2Si, Me2ClSi, and PhMe2Si), are formed from the sequential reaction of 2 and 4 equiv of the corresponding hydrosilanes, respectively, with Pt(COD)Cl2 in the presence of a small excess of COD. Complexes 1 are stable for many days in solution at room temperature but decompose via slow elimination of chlorosilane. Some of the bis-silyl compounds 2 are stable for extended periods under inert atmosphere and especially below 0 °C, either in the solid state or in solution (in the presence of a small excess of free COD). Complexes 2 display catalytic activity as discrete, molecular, and mononuclear species for hydrosilation and isomerization reactions. Compound 2c (R3Si = MeCl2Si) MeCl2Si) was fully characterized via multinuclear NMR spectroscopy and x-ray crystal structure analysis. The facile H-transfer rather than Si-transfer to bound COD provides experimental support for the sequence of insertive steps in the Chalk-Harrod catalytic cycle, at least for Pt-catalyzed hydrosilation.
- Roy, Aroop K.,Taylor, Richard B.
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p. 9510 - 9524
(2007/10/03)
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- Dehydrohalogenative coupling reaction of organic halides with silanes
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The present invention relates to methods for making the compounds of formula I which is a dehydrohalogenative coupling of hydrochlorosilanes of formula II with organic halides of formula III in the presence of a Lewis base catalyst. R3CH2SiR1Cl2??(I) HSiR1Cl2??(II) R2CH2X??(III) In formulas I and II, R1represents a hydrogen, chloro, or methyl; in formula III, X represents a chloro or bromo; in formula III, R2can be selected from the group consisting of a C1-17alkyl, a C1-10fluorinated alkyl with partial or full fluorination, a C1-5alkenyl groups, a silyl group containing alkyls, (CH2)nSiMe3-mClmwherein n is 0 to 2 and m is 0 to 3, aromatic groups, Ar(R′)1wherein Ar is C6-14aromatic hydrocarbon, R′ is a C1-4alkyl, halogen, alkoxy, or vinyl, and q is 0 to 5, a haloalkyl group, (CH2)pX wherein p is 1 to 9 and X is a chloro or bromo; or an aromatic hydrocarbon, Ar CH2X wherein Ar is C6-14aromatic hydrocarbon and X is a chloro or bromo. in formula I, R3is the same as R2in formula III and further, R3can also be (CH2)pSiR1Cl2or ArCH2SiR1Cl2when R2in formula III is (CH2)pX or ArCH2X, because of the coupling reaction of X with the compound of formula II.
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- Redistribution of dichlorosilanes and dihydridosilanes. Synthesis of chloro hydridosilanes
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The redistribution of dichlorosilanes RSi(CH3)Cl2 and dihydridosilanes RSi(CH3)H2, prepared by reduction of the homologues dichlorosilanes, in the presence of a quaternary ammonium salt is presented. The influence of the nature of R (fluoroalkyl chain RFCH2CH2 with RF = CF3, C4F9, C8F17, alkyl chain R = C6H13 or aromatic R = C6H5) and of the temperature on the rate of the reaction is studied. The equilibrium constants and free enthalpies are calculated and discussed taking into account the nature of R. The new products described were characterized from I.R, 1H, 19F and 29Si NMR spectroscopies.
- Benouargha,Boulahia,Boutevin,Caporiccio,Guida-Pietrasanta,Ratsimihety
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- Macrocyclic polyether compounds
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Macrocyclic polyether "crown" compounds of the formula EQU1 WHEREIN T is a C2 -C3 alkylene, A is EQU2 R being H or C1 -C18 alkyl, R2 and R3 being independently C1 -C18 alkyl, C2 -C4 alkenyl, or C6 -C14 aryl; Q and Z are independently 1,2-arylene (or saturated derivatives thereof) or substituted 1,2-arylene (or saturated derivatives thereof); a is 0, 1, 2, or 3; b is an integer from 3 to 20; y is 1 or zero; x1, x2, x3, and x4 are integers independently selected to give a 15-60 atom ring. Such crown compounds are generally useful in the formation of complexes with ionic metal compounds, thus making it possible to use certain chemical reagents in media wherein they are normally insoluble.
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