Development and application of latent hydrosilylation catalysts [2]—Control of catalytic activity of platinum catalyst by polystyrene derivatives having propargyl moieties

A new thermal latent hydrosilylation catalyst on the basis of H₂PtCl₆ and polystyrene derivatives having propargyl moieties is described. The polystyrene derivatives having various propargyl moieties were obtained by the reaction of propargyl alcohols with poly(p‐chloromethylstyrene) or its copolymer with styrene. The polymer‐supported platinum catalysts were prepared by aging H₂PtCl₆ with these polymers in tetrahydrofuran at 30 °C for 12 h. In the presence of the polymers, the hydrosilylation activity of H₂PtCl₆ was found to be controlled thermally in the model reaction of trimethylsilane and triethylvinylsilane. Effective control of the crosslinking reaction of silicone resin was also achieved by using these latent catalyst systems. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 35–42, 2000     

Preparation of styrene–divinyl benzene copolymer-supported platinum complexes and their catalytic properties in hydrosilylation

A new type of catalyst for the hydrosilylation of unsaturated monomers with dichloromethylsilane (DCMS) was prepared, which consisted of thiolmethylene-substituted styrene–divinyl benzene copolymer and platinum. When using DCMS as a hydrosilylation agent, these catalysts showed a high activity in the hydrosilylation of vinyl and acetylene monomers as styrene, alkyl vinyl silanes, acetylene, phenyl acetylene, butyl acrylate. The activities of catalysts were not significantly reduced even after 20 reuse cycles.     

Catalysis of hydrosilylation,part XXII: Polymer-protected immobilized platinum complex catalysts for gas-phase hydrosilylation of acetylene

A platinum catalyst (hexachloroplatinic acid dissolved in ethanol) was immobilized by anchoring via amine and mercapto groups to silica followed by formation of a polymer layer which protected the catalyst against leaching. These catalysts (A and B) as well as precatalysts (S_A-Pt, S_B-Pt) which were not protected by polymer were tested in the gas-phase hydrosilylation reaction of acetylene with trichlorosilane. The catalytic parameters (yield 80%, selectivity 100%) obtained under optimal conditions prove the advantage of catalyst A over 300 h reaction time by the flow method.     

Synthesis of platinum acetylide complexes and their application in curing silicone rubber by hydrosilylation

Eight platinum acetylide complexes have been synthesized and characterized. The catalytic properties of these complexes in curing silicone rubber by hydrosilylation have been tested. Among the complexes tested, trans‐Pt(PPh₃)₂[―C≡CC(CH₃)₂OSi(CH₃)₃] ₂ (2), trans‐Pt(PPh₃)₂[―C≡CC(CH₃)₂OSi(CH₂CH₃)₃]₂ (3), trans‐Pt(PPh₃)₂[―C≡CC(CH₃)₂OSiPh(CH₃)₂]₂ (4), trans‐Pt(PPh₃)₂[―C≡C(C₆H₁₀)OSi(CH₃)₃]₂ (6), trans‐Pt(PPh₃)₂[―C≡C(C₆H₁₀)OSi(CH₂CH₃)₃]₂ (7), and trans‐Pt(PPh₃)₂[―C≡C(C₆H₁₀)OSiPh(CH₃)₂]₂ (8) exhibited sufficiently long pot‐lives (15 days) at room temperature and short silicone rubber curing times of 10–35 min at 100°C or 1–5 min at 120°C. Copyright © 2012 John Wiley & Sons, Ltd.     

Hyperbranched Polymers by Type II Photoinitiated Self‐Condensing Vinyl Polymerization

Type II photoinitiated self‐condensing vinyl polymerization for the preparation of hyperbranched polymers is explored using 2‐hydroxyethyl methacrylate (HEMA) or 2‐(dimethylamino)ethyl methacrylate (DMAEMA), and methyl methacrylate as hydrogen donating inimers and comonomer, respectively, in the presence of benzophenone and camphorquinone under UV and visible light. Upon irradiation at the corresponding wavelength, the excited photoinitiator abstracts hydrogen from HEMA or DMAEMA leading to the formation of initiating radicals. Depending on the concentration of inimers, type of the photoinitiator, and irradiation time, hyperbranched polymers with different branching densities and cross‐linked polymers are formed.

     

N-heterocyclic carbene platinum complexes functionalized with a polyether chain and silyl group: Synthesis and application as a catalyst for hydrosilylation

The synthesis and characterization of new N-heterocyclic carbene platinum(II) complexes functionalized with a polyether chain and silyl group are described. In addition, their application towards the catalytic hydrosilylation of unsaturated carbon–carbon bonds, including alkenes, alkynes, vinyl ether, and unsaturated esters, is reported. These new complexes exhibit both excellent catalytic activity and selectivity for hydrosilylation. The catalytic system can be recycled >27 times.     

主链含有冠醚基团的聚硅氧烷及其铂配合物的催化硅氢化性能

报道了一种合成主链含有冠醚基团的聚硅氧烷的方法.首先,从适当的冠醚出发,合成带有两个烯基侧链的双套索冠醚,再与含氢硅单体进行硅氢加成.合成两端带有烷氧硅基的含冠醚基的硅单体,然后与八甲基环四硅氧烷共聚合,得到标题聚硅氧烷.后者与氯亚铂酸钾反应,得到相应的铂配合物,该配合物对于烯烃与三乙氧基硅烷的硅氢加成反应具有催化活性.     

Synthesis of Hyperbranched Polysaccharide by Thermally Induced Cationic Polymerization of 1,6-Anhydrohexopyranose

The thermally induced cationic polymerizations of 1,6-anhydro-β-D -glucopyranose ( 1a ), 1,6-anhydro-β-D -mannopyranose ( 1b ) and 1,6-anhydro-β-D -galactopyranose ( 1c ) as a latent cyclic AB₄-type monomer were carried out using (S-2-butenyl)tetramethylenesulfonium hexafluoroantimonate ( 2 ) as an initiator. The solution polymerization in propylene carbonate proceeded without gelation to produce the water-soluble hyperbranched polysaccharides ( 3a-c ) with controlled molecular weights and narrow polydispersities. The degree of branching (DB), estimated by the methylation analysis of 3a-c , was in the range of 0.38 – 0.49. The thermally induced cationic polymerization of 1a-c using 2 is a facile method leading to a hyperbranched polysaccharide with a high DB value.     

C~6~0乙醇胺铂配合物的合成及其催化硅氢化性能

C~6~0与乙醇胺反应,然后与亚氯铂酸钾络合,制得了含配位氮原子的富勒烯铂配合物。该配合物能有效地催化烯烃与三乙氧基硅烷的硅氢化反应,并对苯乙烯有独特的催化性能,以近100%的区域选择性得到α-加成产物。还对催化机理进行了初步的探讨。     

Use of carboxylated polyethylene glycol as promoter for platinum‐catalyzed hydrosilylation of alkenes

Several carboxylated polyethylene glycols as promoters were applied in the platinum‐catalyzed hydrosilylation of alkenes, and polyethylene glycol maleic acid monoester as a promoter for hydrosilylation was investigated. It was found that an improvement of the selectivity was achieved in the presence of carboxylated polyethylene glycol, and the β‐adduct as major product was obtained. Additionally, the effect of alkenes and silanes employed on the selectivity was investigated; better selectivity could be achieved when (EtO)₃SiH was used as the hydride than ClMe₂SiH. Copyright © 2011 John Wiley & Sons, Ltd.     

超支化聚酰胺负载铂纳米簇杂化膜催化苯加氢反应

制备了一系列不同结构的超支化聚酰胺及其负载铂纳米簇杂化膜催化剂,研究了该催化剂对苯液相加氢反应的催化性能。利用透射电子显微镜、傅里叶变换红外光谱仪、X-射线衍射和X-射线光电子能谱等对铂纳米簇以及负载催化剂的结构进行了表征。结果表明：铂纳米颗粒分散均匀,粒径为3～5 nm;催化剂中的Pt与超支化聚酰胺上的N和O之间存在...     

Synthesis of Conjugated Hyperbranched Polytriazoles Containing Truxene Units by Click Polymerization

It has been a challenge to synthesize high molecular weight and soluble conjugated hyperbranched poly(1,2,3‐triazole)s (hb‐PTAs). In this paper a series of soluble hyperbranched polytriazoles, whose number‐average molecular weight (M_n) and polydispersity index ranged in (1.2–3.3)×10⁴ and 1.7–3.0, respectively, were synthesized with A₂+B₃ approach. In the polymerization process, diazides A1 – A4 and triyne B1 were used as A₂ and B₃ monomers; Cu(I)‐catalyst, THF and water were used as their reaction system. At room temperature the final molecular weight could be controlled through reaction time, so finally we obtained soluble conjugated hyperbranched poly(1,2,3‐triazole)s hb‐PTAs (1–4 ). The polymers were soluble in common organic solvents, and all emitted blue light; the films of polymers emitted yellow and blue light, due to the difference in the aggregation of their chromophoric units in the solid state. The thermal properties of the final copolymers were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

The hydrosilylation of propylene

The reactions of separate and competitive hydrosilylation of propylene with HSiCl₃, MeSiHCl₂, Me₂SiHCl, and MePh₂SiH in the presence of the Speier catalyst (SC) with different additives and a catalyst obtained from SC and propylene were studied. A mutual influence of the hydrosilanes in the competitive reactions was found. The influence of various additives to SC on the process was considered. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2048–2051, October, 1998.     

UV‐activated hydrosilylation: a facile approach for synthesis of hyperbranched polycarbosilanes

A facile approach for synthesis of hyperbranched polycarbosilane from AB₂ monomer via UV‐activated hydrosilylation is presented in this communication. The polymerization process was monitored using real‐time FTIR spectroscopy and the resulting hyperbranched polycarbosilanes were characterized using ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR and SEC/MALLS. It is found that hyperbranched polycarbosilane can be synthesized from methyldiallylsilane via UV‐activated hydrosilylation with bis(acetylacetonato)platinum(II) as catalyst. The polymerization activated by UV irradiation was much faster than that under thermal conditions. The similar degree of branching, average number of branch units and the exponent of the Mark–Houwink equation demonstrate that the hyperbranched polycarbosilane synthesized via UV‐activated polyhydrosilylation possesses almost the same branching structure as that synthesized via thermal‐activated polyhydrosilylation. Copyright © 2009 John Wiley & Sons, Ltd.     

Development and application of a latent hydrosilylation catalyst. IX. Control of the catalytic activity of a platinum catalyst by polymers bearing amine moieties

A new thermal‐latent hydrosilylation catalyst consisting of H₂PtCl₆ and polymers bearing amine moieties is described. In the presence of aminated polymers, the catalytic activity of H₂PtCl₆ was suppressed remarkably in the model reaction of triethylsilane with trimethylvinylsilane, whose effect was remarkably higher in comparison with monomeric amines. On heating, however, sufficient catalytic activity was attained where the activation temperature was dependent on the amine content in the polymer and polymer structure. Furthermore, this catalyst system was applied to the curing process of silicone resin to confirm the thermal‐latent character of the catalyst. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 804–809, 2000     

Platinum(II) complexes bearing bulky Schiff base ligands anchored onto mesoporous SBA‐15 supports as efficient catalysts for hydrosilylation

Reported herein is an easy‐to‐prepare novel heterogeneous catalyst of platinum complexes bearing binary ligands of bidentate naphthalenolimine and cyclo‐1,5‐octadiene that are anchored onto mesoporous silica SBA‐15. The presence of the binary ligands not only stabilized the platinum, but also enabled the platinum atoms to form nanoclusters with diameters of ca 1 nm, and led to high platinum loading (8.69 wt%). Moreover, the platinum catalyst exhibited high catalytic activity towards hydrosilylation of terminal alkenes and styrene with silanes under mild and solvent‐free conditions, with excellent regioselectivity.     

聚γ-(β-氰乙基)胺丙基硅氧烷铂配合物的合成与催化性能

γ-氨丙基三乙氧基硅烷与丙烯腈反应，得到γ-(β-氰乙基)胺丙基三乙氧基硅烷。后者用气相法二氧化硅固载，再与氯亚铂酸钾反应，合成了聚γ-(β-氰乙基)胺丙基硅氧烷铂配合物。研究了它对不饱和烃与三乙氧基硅烷的硅氢加成反应的催化特性。     

A novel fumed silica-supported nitrogenous platinum complex as a highly efficient catalyst for the hydrosilylation of olefins with triethoxysilane

A novel fumed silica-supported nitrogenous platinum complex was conveniently prepared from cheap γ-aminopropyltriethoxysilane via immobilization on fumed silica in toluene, followed by a reaction with hexachloroplatinic acid. The title complex was characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It was found that the complex is an efficient and stable catalyst for the hydrosilylation of olefins with triethoxysilane. The title platinum complex could be separated by simple filtration and reused several times without any appreciable loss in the catalytic activity.     

Catalysis of hydrosilylation: Part XXIV. H2PtCl6 in cyclohexanone as hydrosilylation catalyst—what is the active species in this catalytic system?

A cyclohexanone solution of H₂PtCl₆ was examined to find the catalytic species responsible for the hydrosilylation of the olefinic C=C bond. Similarly to other H₂PtCl₆–solvent systems (e.g. Speier's and Karstedt's catalysts), the real catalyst appeared to be colloidal platinum formed in situ by stepwise reduction [Pt(IV)→Pt(O)] and dechlorination of the platinum precursor. The role of cyclohexanone seems to be to form sufficiently stable platinum complexes to avoid rapid platinum precipitation and aggregation. The studies of H₂PtCl₆–solvent systems are of practical importance since these compounds are widely used catalyst precursors for hydrosilylation on an industrial scale.