- Sustainable Catalytic Synthesis of Diethyl Carbonate
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New sustainable approaches should be developed to overcome equilibrium limitation of dialkyl carbonate synthesis from CO2 and alcohols. Using tetraethyl orthosilicate (TEOS) and CO2 with Zr catalysts, we report the first example of sustainable catalytic synthesis of diethyl carbonate (DEC). The disiloxane byproduct can be reverted to TEOS. Under the same conditions, DEC can be synthesized using a wide range of alkoxysilane substrates by investigating the effects of the number of ethoxy substituent in alkoxysilane substrates, alkyl chain, and unsaturated moiety on the fundamental property of this reaction. Mechanistic insights obtained by kinetic studies, labeling experiments, and spectroscopic investigations reveal that DEC is generated via nucleophilic ethoxylation of a CO2-inserted Zr catalyst and catalyst regeneration by TEOS. The unprecedented transformation offers a new approach toward a cleaner route for DEC synthesis using recyclable alkoxysilane.
- Putro, Wahyu S.,Ikeda, Akira,Shigeyasu, Shinji,Hamura, Satoshi,Matsumoto, Seiji,Lee, Vladimir Ya.,Choi, Jun-Chul,Fukaya, Norihisa
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p. 842 - 846
(2020/12/07)
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- One-Pot Cooperation of Single-Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization-Hydrosilylation Process
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Realizing the full potential of oxide-supported single-atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one-pot combination of Ru1/CeO2 and Rh1/CeO2 SACs enables a highly selective olefin isomerization-hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double-bond migration and anti-Markovnikov α-olefin hydrosilylation, respectively. First-principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single-pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio-selectivity (>95 %) even from industrially-relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide-supported single-atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes.
- Agostini, Giovanni,Amsler, Jonas,Arenal, Raul,Concepción, Patricia,Kim, Jonglack,Pf?nder, Norbert,Plessow, Philipp,Prieto, Gonzalo,Sarma, Bidyut B.,Studt, Felix,Weidenthaler, Claudia
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supporting information
p. 5806 - 5815
(2020/02/11)
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- Regiodivergent hydrosilylation, hydrogenation, [2π + 2π]-cycloaddition and C-H borylation using counterion activated earth-abundant metal catalysis
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The widespread adoption of earth-abundant metal catalysis lags behind that of the second- and third-row transition metals due to the often challenging practical requirements needed to generate the active low oxidation-state catalysts. Here we report the development of a single endogenous activation protocol across five reaction classes using both iron- and cobalt pre-catalysts. This simple catalytic manifold uses commercially available, bench-stable iron- or cobalt tetrafluoroborate salts to perform regiodivergent alkene and alkyne hydrosilylation, 1,3-diene hydrosilylation, hydrogenation, [2π + 2π]-cycloaddition and C-H borylation. The activation protocol proceeds by fluoride dissociation from the counterion, in situ formation of a hydridic activator and generation of a low oxidation-state catalyst.
- Agahi, Riaz,Challinor, Amy J.,Dunne, Joanne,Docherty, Jamie H.,Carter, Neil B.,Thomas, Stephen P.
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p. 5079 - 5084
(2019/05/24)
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- Dehydrogenative Silylation and Crosslinking Using Cobalt Catalysts
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Disclosed herein are cobalt complexes containing terdentate pyridine di-imine ligands and their use as efficient and selective dehydrogenative silylation and crosslinking catalysts.
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Paragraph 0145
(2014/03/24)
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- COSMETIC TREATMENT METHOD COMPRISING THE APPLICATION OF A COATING BASED ON AN AEROGEL COMPOSITION OF LOW BULK DENSITY
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The present invention relates to a cosmetic treatment method comprising the formation of a coating on keratin fibres characterized in that it comprises: 1) the preparation of an aerogel precursor composition comprising:—at least one organic solvent chosen from acetone, C1-C4 alcohols, C1-C6 alkanes, C1-C4 ethers, which may or may not be perfluorinated, and mixtures thereof and at least one precursor compound that contains:—at least one atom chosen from silicon, titanium, aluminium and zirconium,—at least one hydroxyl or alkoxy function directly attached to the atom chosen from silicon, titanium, aluminium and zirconium by an oxygen atom, and,—optionally an organic group directly attached to the atom chosen from silicon, titanium, aluminium and zirconium by a carbon atom, 2) the removal of the solvent or solvents resulting in the formation of an aerogel composition having a bulk density less than or equal to 0.35 g/cm3, 3) the application to the keratin fibres of the aerogel composition resulting from step 2) or of the aerogel precursor composition resulting from step 1). Advantageously, the molar ratio between the precursor compounds and the solvent is at most 1/20.
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Paragraph 0067
(2014/02/15)
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- COMPOUNDS WITH GUANIDINE STRUCTURE AND USES THEREOF AS ORGANOPOLYSILOXANE POLYCONDENSATION CATALYSTS
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A compound having a guanidine structure and uses thereof as organopolysiloxane polycondensation catalysts are described.
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- PROCESS FOR THE PREPARATION OF HALOALKYLALKOXYSILANCS AND HALOALKYLHALOSILANES
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This invention involves a process for the preparation of haloalkylalkoxysilanes and haloalkylhalosilancs. The process comprises reacting an alkoxyhydridosilane or a halohydridosilanc silane with an alkenylhalide compound in the presence of a catalytic amount of an iridium containing catalyst. When a halohydridosilane is the silane rcactant. the resulting haloalkylhalosilane may be alkoxylatcd by reaction with a C1-C6, alcohol, In another aspect of the invention, the reacting is conducted under a reduced oκygen atmosphere to improve the catalyst activity and the yield of the resulting haloalkylhalosilane or halυalkylalkυx vsi lane.
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Page/Page column 17-19
(2009/10/22)
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- Highly selective dehydrogenative silylation of alkenes catalyzed by rhenium complexes
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Rhenium(I) complexes of type [ReBr2(L)(NO)(PR3) 2] (L = H2 (1), CH3CN (2), and ethylene (3); R = iPr (a) and cyclohexyl (Cy; b)) catalyze dehydrogenative silylation of alkenes in a highly selective ma
- Jiang, Yanfeng,Blacque, Olivier,Fox, Thomas,Freeh, Christian M.,Berke, Heinz
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experimental part
p. 2121 - 2128
(2009/09/30)
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- Hydrosilylation of ethylene
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Hydrosilylation of ethylene with trialkoxysilanes in the presence of Pt(0) complexes as catalysts affords ethyltrialkoxysilanes in almost quantitative yields. No impurities of vinyltrialkoxysilanes were detected. Experiments and ab initio calculations showed that the Pt(0) catalysts are considerably more active in ethylene hydrosilylation than Pt(II) catalysts. Pleiades Publishing, Inc., 2006.
- Chernyshev,Belyakova,Knyazev,Turkel'taub,Parshina,Serova,Storozhenko
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p. 225 - 228
(2008/02/08)
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- Process for making haloalkylalkoxysilanes
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A haloalkylalkoxysilane is prepared by reacting an olefinic halide with an alkoxysilane in which the alkoxy group(s) contain at least two carbon atoms in the presence of a catalytically effective amount of ruthenium-containing catalyst. The process can be used to prepare, inter alia, chloropropyltriethoxysilane which is a key intermediate in the manufacture of silane coupling agents.
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- Method of preparing an organosilicon compound
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A method of preparing an organosilicon compound comprising effecting a hydrosilylation reaction between (a) unsaturated compounds with terminal unsaturated groups and (b) silane compounds described by formula HSiR0mW3-m, where W is selected from the group consisting of C1 to C6 alkoxy groups, C6 to C10 aryloxy groups, and halogen atoms, R0 is an organic group, and m is 0, 1, or 2 in the presence of (c) a platinum catalyst and (d) an auxiliary catalyst selected from the group consisting of (1) silyl esters of acids derived from oxo acids of sulfur; (2) amide compounds having N-Si bonds; (3) urea compounds; (4) silyl esters of carbamic acid; (5) phosphoric acid compounds; and (6) cyclic compounds selected from the group consisting of (i) hydroxypyridine compounds, (ii) 8-hydroxyquinoline compounds, (iii) oxazolidinone compounds, and (iv) N-hydroxysuccinimide compounds.
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- Method of preparing an organosilicon compound
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A method of preparing an organosilicon compound comprising effecting a hydrosilylation reaction between (a) unsaturated compounds with terminal unsaturated groups and (b) silane compounds described by formula HSiR0mW3?m, where W is selected from the group consisting of C1to C6alkoxy groups, C6to C10aryloxy groups, and halogen atoms, R0is an organic group, and m is 0, 1, or 2 in the presence of (c) a platinum catalyst and (d) an auxiliary catalyst selected from the group consisting of (1) silyl esters of acids derived from oxo acids of sulfur; (2) amide compounds having N—Si bonds; (3) urea compounds; (4) silyl esters of carbamic acid; (5) phosphoric acid compounds; and (6) cyclic compounds selected from the group consisting of (i) hydroxypyridine compounds, (ii) 8-hydroxyquinoline compounds, (iii) oxazolidinone compounds, and (iv) N-hydroxysuccinimide compounds.
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- Process for preparing low-chloride or chloride-free alkoxysilanes
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A process for preparing an alkoxysilane with an acidic chloride content of less than 10 ppm by weight, comprising: reacting a chlorosilane with an alcohol in a water-free and solvent-free phase to form a product mixture containing alkoxysilane and residual acidic chloride, with removal of resultant hydrogen chloride from the product mixture, then adding liquid or gaseous ammonia, in an amount corresponding to a stoichiometric excess, based on the content of acidic chloride, to form an ammonia-containing product mixture, treating the ammonia-containing product mixture at a temperature between 10 and 50 DEG C., wherein the ammonia and acidic chloride undergo neutralization, to form a crude product, and optionally, then separating off a salt formed in the course of neutralization, from the crude product, and recovering the alkoxysilane by distilling the crude product.
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