Presence Of Chloroplatinic Acid Research Articles

A Simple Preparation Route for Bio-Phenol MQ Silicone Resin via the Hydrosilylation Method and its Autonomic Antibacterial Property.

MQ silicone resins represent a broad range of hydrolytic condensation products of monofunctional silane (M units) and tetrafunctional silane (Q units). In this work, a Bio-Phenol MQ silicone resin (BPMQ) was designed and synthesized by the hydrosilylation of hydrogen containing MQ silicone resin and eugenol in the presence of chloroplatinic acid. The structure, thermal property, and antibacterial property against Escherichia coli of the modified MQ silicone resin were investigated. The results showed that BPMQ has been prepared successfully, and the thermal stability of this modified polymer improved significantly because of the introduction of phenyl in eugenol. The temperature at the maximum degradation rate increased from 250 °C to 422.5 °C, and the residual yields mass left at 600 °C were increased from 2.0% to 28.3%. In addition, its antibacterial property against Escherichia coli was also enhanced markedly without adding any other antimicrobial agents. This improved performance is ascribed to special functional groups in the structure of eugenol. The BPMQ polymer is expected to be applied to pressure-sensitive adhesives and silicone rubber products for the biomedical field due to its reinforcing effect and antioxidant quality.

Addition of triorganosilanes to 1-propargyloxy-2-glycidyloxypropane in the presence of chloroplatinic acid

Addition of triorganosilanes to 1-propargyloxy-2-glycidyloxypropane in the presence of chloroplatinic acid

ChemInform Abstract: Regioselectivity of Inter- and Intramolecular Hydrosilylation of the Vinyloxy Group.

Abstract The addition of dialkylethoxysilanes to divinyl ether in the presence of chloroplatinic acid occurs at the terminal carbon atom whereas the regioselect

Reactions of tris(dimethylsilyl)methane and polymers containing si—h groups with various hydroxy compounds under aerobic and mild conditions

AbstractTris(dimethylsilyl)methane, (HMe2Si)CH, reacts with n‐propyl, iso‐propyl, n‐butyl, s‐butyl, iso‐butyl, n‐pentyl, s‐pentyl, n‐hexyl alcohol, and phenol in the presence of chloroplatinic acid (H2PtCl6ċ6H2O) in air to give products (ROMe2Si)3CH (where R is n‐propyl, iso‐propyl, n‐butyl, s‐butyl, iso‐butyl, n‐pentyl, s‐pentyl, n‐hexyl, phenyl). Similar reactions with benzyl alcohol and acetic acid lead to the unexpected products, (PhCH2)2O and HC(Me2SiOSiMe2)3CH, respectively. The compound (n‐BuOMe2Si)3CSiMe2H was made from (n‐BuOMe2Si)3CH by treatment with lithium diisopropylamide, followed by quenching with HMe2SiCl. The homopolymer poly{(4‐chloromethyl)styrene} and copolymers with styrene (in 1:1 and 1:3 mol ratio) were synthesized by free radical polymerization, and (HMe2Si)3C groups were linked to them by nucleophilic substitution reactions between (HMe2Si)3CLi and the chloromethyl groups of the polymer side chains. The resulting functional polymers containing Si—H bonds reacted with various alcohols in the presence of chloroplatinic acid under heterogeneous conditions. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:365–376, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20440

Synthesis of hybrid methacrylate-silicone-cyclohexanepoxide monomers and the study of their UV induced polymerization

The synthesis of two hybrid methacrylate-silicone-epoxycyclohexane monomers is described. These monomers were prepared by sequential hydrosilation reactions attaching first the 4-vinyl-1-cyclohexene 1,2-epoxide, using the Wilkinson catalyst, and then the allyl methacrylate in the presence of chloroplatinic acid as catalyst for the hydrosilation reaction. The reactivity of these monomers was evaluated by RT-FT-IR finding that the methacrylate groups can be photopolymerized concomitantly with the epoxide groups using only a diaryliodonium salt as photoinitiator, in air-free conditions. The addition of a free radical photoinitiator helps to overcome the oxygen inhibition when the radical photopolymerization is performed in air. The films obtained from these monomers were almost totally crosslinked with T g's of 54 and 31 °C for EM2Si and EM4Si, respectively. It was found that the film made with the monomer with a longer siloxane chain exhibited a higher contact angle as a direct result of the higher hydrophobic surface.

Poly(silarylene–siloxane)polyimides from allyl‐terminated oligoimides and hydride‐functional silarylene–siloxanes via hydrosilylation polymerization

AbstractThis research was focused on the design and execution of new synthetic routes to low‐temperature‐curable poly(silarylene–siloxane)polyimides. The synthesis of individual oligoimide and silarylene–siloxane blocks was followed by hydrosilylation polymerization to produce crosslinked copolymers. The silarylene–siloxane and polyimide blocks were structurally characterized by IR and 1H NMR spectroscopy and size exclusion chromatography. The high‐temperature resistance of the copolymers was evaluated through the measurement of heat distortion temperatures (THD's) via thermomechanical analysis and by the determination of the weight loss at elevated temperatures via thermogravimetric analysis. Glass‐transition temperatures (Tg's) of the silarylene–siloxane segments were measured by differential scanning calorimetry. Hydrosilylation curing was conducted at 60 °C in the presence of chloroplatinic acid (H2PtCl6). The copolymers displayed both high‐temperature resistance and low‐temperature flexibility. We observed Tg of the silarylene–siloxane segment as low as −77 °C and THD of the polyimide segment as high as 323 °C. The influence of various oligoimide molecular weights on the properties of copolymers containing the same silarylene–siloxane was examined. The effect of various silarylene–siloxane molecular weights on the properties of copolymers containing the same oligoimide was also examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4922–4932, 2005

1,3-Bis[2-(ethynyldimethylsilyl)vinyl]tetramethyldisiloxane and Macrocyclic Polyunsaturated Siloxanes on Its Basis

Hydrosilylation of diethynyldimethylsilane with tetramethyldisiloxane in the presence of chloroplatinic acid give rise to a mixture of three stereoisomers of 1,3-bis[2-(ethynyldimethylsilyl)vinyl]tetramethyldisiloxane: trans-trans, gem-trans, and gem-gem. Hydrolysis of chloro[2-(ethynyldimethylsilyl)vinyl]dimethylsilane provides the trans-trans isomer of 1,3-bis[2-(ethynyldimethylsilyl)vinyl]tetramethyldisiloxane exclusively. Reactions of an organomagnesium derivative of the disiloxane with dichlorodiorganylsilanes allowed synthesis of novel polyunsaturated macrocyclic siloxanes. The 1H, 13C, and 29Si NMR spectra of the products were studied.

Preparation and Properties of C60-Polysiloxane Hybrids

C60-polysiloxane hybrids were prepared by the reaction of triethoxysilylated C60 (TES-C60) with methylpolysiloxane (MPS) or α,ω -dihydroxypolydimethylsiloxane (STPDS). TES-C60 was synthesized by hydrosilylation using triethoxysilane and C60 in the presence of chloroplatinic acid. TES-C60 was mixed with MPS and heated to provide a bulk body of C60 containing polysiloxane hybrid in a Si/C60 molar ratio of 1000:500. The formation of this hybrid is based on the hydrolytic polycondensation of TES-C60 and MPS to fix C60 into the silica matrix by a chemical bond. TES-C60 and STPDS also provide an isolatable thin film of C60 containing polysiloxane hybrid by an ethanol-forming condensation reaction. Because no gelation was observed when only STPDS was aged, it is thought that TES-C60 serves as a cross-linking point in gel formation.

Structural elucidations of T8 and Q8 silsesquioxane cages containing two types of pendant group using 29Si NMR spectroscopy

The products from the reaction of octahydrosilsesquioxane (T8-H) with different molar ratios of phenol and undec-1-ene or methyl 3,3-dimethylpent-4-enoate (MDP) in the presence of chloroplatinic acid have been analysed by 29Si NMR spectroscopy. The distribution of the two different pendant groups leads to tetrad patterns where the relative chemical peak intensities reflect the selectivity for particular patterns of substitution. As well as analysing the cause of these tetrad patterns we also discuss how the regioselectivity of hydrosilylation can be determined.Key words: T8, Q8, silsesquioxane, 29Si NMR, hydrosilylation, tetrad pattern, regioselectivity, statistical modelling.

Polyethylene oxide—polysiloxane branched copolymers and networks

The hydrosilylation of vinyl methyl and divinyl ethers of oligoethylene glycols with polyhydridosiloxanes in the presence of chloroplatinic acid is accompanied by side processes, namely, polymerization of vinyl ethers and homodehydrocondensation of polyhydridosiloxanes. The electrical conductivity of ∼1M solutions of lithium triflate or bis(trifluoromethylsulfonyl) imide in the resulting hydrosilylation products is ∼10−5 S cm−1.

Synthesis of (diorgano)chloro(4-chlorobutoxy)silanes

Some novel (diorgano)chloro(4-chlorobutoxy)silanes were obtained by the reaction of dichlorodiorganosilanes with tetra hydrofuran in the presence of chloroplatinic acid.

Hydrosilylation of Olefins with Allyldichlorosilane: A Convenient Route to Allyl Group Containing Organodichlorosilanes

The hydrosilylation of olefins with allyldicholorosilane in the presence of chloroplatinic acid diluted with isopropanol gave allylalkyldichlorosilanes, retaining the allyl group. When the olefin was used in fivefold excess or more relative to allyldichlorosilane, allylalkyldichlorosilanes were obtained in good yields (63–89%), and the formation of double hydrosilylation products was reduced to less than 6%. The isomerization of allylsilane to 1-propenylsilane was suppressed by lowering reaction temperatures below 100°C. This hydrosilylation of olefins with allyldichlorosilane is a good synthetic route to an allyl group containing organodichlorosilanes.

Synthesis and reactivity of germyliron complexes [Ph 2HGeFe(η 5-C 5H 5)(CO) 2] and [RH 2GeFe(η 5-C 5H 5)(CO) 2] (R = Ph or 2,4,6-Me 3C 6H 2)

The new complexes [Ph 2HGeFe(η 5-C 5H 5)(CO) 2] ( 1) and [RH 2GeFe(η 5-C 5H 5)(CO) 2] (R = Ph or Mes, 2a or 2b) were prepared by a substitution reaction, from the corresponding arylhalohydrogermanes and the iron salt. Their characterization by IR, 1H and 13C NMR and mass spectroscopy is reported. They are easily transformed into the mono- or di-halogermyl compounds by action of N-chlorosuccinimide. Treatment of 1 with lithium reagents (LDA or tBuLi) leads to an initial deprotonation of the cyclopentadienyl ring with migration of the germyl group. The intermediate iron salt was quenched by MeI producing MeFe(η 5-C 5H 4GeHPh 2)(CO) 2. Hydrogermylation reactions with phenylacetylene or methylethynylketone were performed in the presence of chloroplatinic acid and yielded mainly the α-isomer of the adduct.

ChemInform Abstract: Hydrosilylation of Ethynylsilanes with Dimethyl(2‐thienyl)silane.

AbstractThe ethynylsilanes (II) react with dimethyl(2‐thienyl)silane (I) in the presence of chloroplatinic acid, producing the β‐trans‐ (III) and α‐isomers (IV).

Chain branching of poly(dimethylsiloxane): A competitive side reaction of the hydrosilylation reaction

AbstractPoly(dimethylsiloxane) (PDMS) fitted at both chain ends with dimethylsilyl functions was heated at 90 and 110°C in the presence of chloroplatinic acid. A chain‐branching reaction was observed yielding very‐high‐molecular‐weight species. The phenomenon, which occurs as well in solution as in the bulk, is temperature dependent. This reaction can exist as a side reaction of the hydrosilylation reaction between PDMS (1) and 1,4‐bis(dimethylvinylsilyl)benzene (2) or tetraallyloxyethane (5) when dimethylsilyl functions are in excess. However, it does not take place in hydrosilylations in which mole ratios 1/2 equal to unity or higher are applied.

Hydrosilylation of the CC triple bond by phenyl- and thienyl-silanes

The effects of the structures of the hydrosilane and the acetylene derivative, catalyst, temperature and solvent on the yields and ratio of isomers during the hydrosilylation of phenylacetylene, 2-(ethynyl)thiophene, 2-(propargyl)thiophene, methyl propiolate, propargyl alcohol and its methyl ether, and propargyl amines by phenyl- and thienyl-hydrosilanes have been studied. The yields of the reaction products upon hydrosilylation of HCCX compounds by dimethyl(2-thienyl)silane in the presence of chloroplatinic acid at 50°C decrease in the following sequence of substituents X: ▪

Selective redistribution reactions of organosilanes in the presence of chloroplatinic acid

Tetrasubstituted silanes of the general formula R 2SiR′ 2 undergo redistribution reactions quite selectively in the presence of SiHCl 3 and chloroplatinic acid. It is the smallest and seemingly the least hindered of the R groups on the tetrasubstituted silane which exchange most readily with a chloro group on trichlorosilane.

Physico-chemical study of the reaction of 1,1,5,5-tetraphenyl-3,7-dimethyl-3,7-dihydrocyclotetra-siloxane with 1,1,5,5-tetraphenyl-3,7-dimethyl-3,7-butadienecyclotetrasiloxane

A study was made of the reaction of hydride poly-addition of 1,1,5,5-tetraphenyl-3,7-dimethyl-3,7-dihydrocyclotetrasiloxane to 1,1,5,5-tetraphenyl-3,7-dimethyl-3,7-divinylcyclotetrasiloxane in melt in the presence of chloroplatinic acid. Independent of process conditions, poly-addition takes place in two stages and results in the formation of a crystalline polymer with a glass temperature of 338°K and a melting point of 433°K. The supermolecular structure of this polymer is characterized by spherulitic formations. Interplanar distances of the new crystalline polymer were calculated. The reaction of these monomers in solution in hexane also results in the formation of a crystalline polymer with higher crystallinity. The activation energy of the first stage of poly-addition calculated from the displacement of peaks of heat liberation under conditions of non-isothermal heating at different rates is 104·9 × 10 3 J/mole.

Reactions of methylated cyclopropanes and olefins with chloroplatinic acid. I. Diacylation and pyrylium ion formation

In contrast to cyclopropane itself, simple methyl-substituted cyclopropanes do not produce platinum insertion products upon reaction with chloroplatinic acid in acetic anhydride. Instead, the major products are aromatic heterocyclic cations, the pyrylium ions, which are formed as the result of diacylation of the cyclopropane ring and subsequent dehydration and ring closure to the aromatic heterocycle. Similar products are formed from the diacylation of certain olefins in the presence of chloroplatinic acid in anhydride solvents. The combination of solvent and substrate variations has led to a proposed mechanism for these reactions which demonstrates the essential and unique mole of platinum. In particular, the specific pyrylium ions produced are formed as a consequence of initial activation of the least-substituted cyclopropane ring bond by insertion of platinum, followed by acylation of platinum-bonded carbon, proton loss to a β,γ-unsaturated carbonyl, a second acylation, and, finally, ring closure.

Synthesis of silicon–substituted azonitriles and their use in preparing caulks

A silicon-substituted azonitrile, has been synthesized by the hydrosilation of 5-hexene-2-one azine with methyldichlorosilane in the presence of chloroplatinic acid, followed by hydrocyanation with anhydrous HCN, and subsequent oxidation with chlorine. The azonitrile is an initiator for radical polymerizations. It is especially useful for the preparation of low molecular weight polymers that, after treatment with acetic anhydride, cure at room temperature in the presence of atmospheric moisture. The preparation of a series of room temperature- vulcanizable materials based on a tetrafluoroethylene/methyl vinyl ether copolymer is described.