Catalyst For Hydrosilylation Reaction Research Articles

Low‐coordinate cobalt(0) N‐heterocyclic carbene complexes as catalysts for hydrosilylation of alkynes

AbstractAmong the great efforts of developing cobalt‐based catalysts for hydrosilylation reactions, cobalt (II) and cobalt(I) complexes are the extensively studied ones. In contrast, explorations on cobalt(0) complexes are relatively rare. Presented herein is the investigation on the catalytic performance of low‐coordinate cobalt(0) N‐heterocyclic carbene (NHC) complexes in the hydrosilylation reaction of alkynes, which disclosed the fine performance of [(CyIDep)Co(η2‐CH2CHSiMe3)2] (CyIDep denotes for a 1,3‐bis(2′,6′‐diethylphenyl)imidazole‐2‐ylidene that bears fused cyclohexyl group on the imidazole backbone) in catalyzing the syn‐addition of a series of symmetric and unsymmetric internal alkynes with H2SiPh2, producing vinylsilanes with high regio‐selectivity. Mechanistic study indicates that the catalytic reaction likely proceeds on a cobalt(0)/cobalt(II) cycle and that the high selectivity is governed by the steric nature of the NHC ligand.

2D Carbon-Supported Platinum Catalysts for Hydrosilylation Reactions

2D carbon structures were prepared by carbonization of biopolymers (starch) via self-propagating high-temperature synthesis process. Electron microscopic, Raman spectroscopic, and X-ray diffraction examinations showed that the structure of the resultant particles corresponded to graphene nanoplatelets. Based on the Raman spectroscopy data, the average number of graphene layers in a graphene nanoplatelets particle was estimated at 2–5. The graphene nanoplatelets synthesized were applied as a support of a platinum-based catalyst (Speier’s catalyst). The resultant supported catalyst was successfully used in the hydrosilylation of 1-hexene with methyldichlorosilane and then separated from the reaction products and reused. The catalytic activity of the supported catalyst was maintained for 4 months.

Highly Efficient and Magnetically Recyclable Pt Catalysts for Hydrosilylation Reactions

Fe3O4@SiO2-APTES-Pt was prepared from 3-aminopropyl triethoxysilane via immobilization on Fe3O4@SiO2, followed by reacted with chloroplatinic acid. The obtained catalyst was characterized by XRD, TEM, FT-IR, XPS and ICP-AES. This catalyst showed extraordinary catalytic performances for hydrosilylation of olefins with triethoxysilane. It was recovered from the reaction medium just by sequestering by a magnet and then reused several times without significant loss in catalytic activity and selectivity.

Study on the anti‐sulfur‐poisoning characteristics of platinum–acetylide–phosphine complexes as catalysts for hydrosilylation reactions

A series of platinum–acetylide–phosphine complexes were synthesized and their anti‐sulfur‐poisoning characteristics investigated. In comparison with Speier's and Karstedt's catalysts, the platinum–acetylide–phosphine complexes exhibited both higher catalytic activity and selectivity for the β‐adduct for the hydrosilylation reactions under the same conditions. Furthermore, the complexes also exhibited a strong ability to resist to sulfur‐poisoning. This indicated that the alkyne ligands containing the silyl group had a strong impact on the hydrosilylation reaction. Copyright © 2014 John Wiley & Sons, Ltd.

ChemInform Abstract: Synthesis of New Iron—NHC Complexes as Catalysts for Hydrosilylation Reactions.

ChemInform Abstract: Synthesis of New Iron—NHC Complexes as Catalysts for Hydrosilylation Reactions.

Synthesis of new iron–NHC complexes as catalysts for hydrosilylation reactions

A series of new piano‐stool iron(II) complexes comprising N‐heterocyclic carbene ligands [Fe(Cp)(CO)2(NHC)]I (NHC = 1,3‐disubstituted imidazolidin‐2‐ylidene) have been synthesized and analyzed by 1H NMR, 13C NMR, IR, elemental analysis and mass spectrometric techniques. These compounds were easily prepared from the reaction of disubstituted imidazolidin‐2‐ylidene with [FeI(Cp)(CO)2] in toluene at room temperature. These complexes were tested in the catalytic hydrosilylation reaction of aldehydes and ketones with phenylsilane in solvent‐free conditions. After a basic hydrolysis step, the corresponding alcohols were obtained in good yields. Copyright © 2013 John Wiley & Sons, Ltd.

Kinetics of the Formation of Poly(Methyldecylsiloxane) by Hydrosilylation of Poly(Methylhydrosiloxane) and 1-Decene

Poly(methylhydrosiloxane) [PMHS], prepared by siloxane equilibration reaction, was used for the hydrosilylation with 1-decene to obtain poly(methyldecylsiloxane) [PMDS]. Pt(0)-1,3- divinyltetramethyldisiloxane complex was used as a catalyst for hydrosilylation reaction. In order to investigate the kinetics of the formation of PMDS, a series of experiments was performed at different reaction temperatures (from 48 to 64 °C) with catalyst concentrations of 7.0 · 10-7 mol of Pt per mol of CH=CH2. All reactions were carried out in bulk, with equimolar amounts of the reacting Si-H and CH=CH2 groups. The course of the reactions was monitored by following the disappearance of the Si-H bands by quantitative infrared spectroscopy. The obtained results show that an induction period occurs at lower reaction temperatures and that the rate of Si-H conversion follows the first-order kinetics.

Iridium complexes as hydrosilylation catalysts

Iridium complexes have been found to be active as catalysts for hydrosilylation reactions, especially for those involving 1,3-dienes and 1-alkynes. For ketones, iridium complexes show maximum activity if one molar equivalent (relative to iridium) of triphenylphosphine is added to the reaction mixture. Iridium complexes are also active catalysts for the hydrosilylation of α,β-unsaturated ketones, although the regioselectivity differs from that obtained with rhodium complexes. Attempts at asymmetric hydrosilylation of keto compounds using iridium complexes resulted in extremely low enantiomeric excesses.