- CO2 laser excitation of triethylsilane: Time resolved luminescence of diethylsilyl radical
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The infrared multiphoton excitation of triethylsilane in the gas phase, with a pulsed CO2 laser at high intensities (I>700 MW/cm2), produced an intense luminescence. The spectrum and time profile of this luminescence was studied as a function of pressure, and laser frequency. The radiative lifetime of this emission was 357±10 ns, and the quenching rates by Cl2 and NO were determined from lifetime measurements. A reasonable mechanism for the interpretation of this luminescence involves the initial infrared multiphoton decomposition of triethylsilane, followed by the secondary infrared multiphoton excitation of the primary photofragment diethylsilyl radical, which subsequently undergoes relaxation to an excited electronic state. The addition of O2 resulted in a new chemiluminescence at shorter wavelengths, which corresponds to the SiO* chromophore group.
- Papagiannakopoulos,Lazarou
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Read Online
- Oxidation of Triorganosilanes and Related Compounds by Chlorine Dioxide
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Abstract: Oxidation of triethylsilane, tert-butyldimethylsilane, dimethylphenylsilane, triphenylsilane, 1,1,1,2tetramethyl-2-phenyldisilane, tris(trimethylsilyl)silane, hexamethyldisilane, tetrakis(trimethylsilyl)silane, 1,1,3,3tetraisopropyldisiloxane with chlorine dioxide was carried out. The reaction products of studied triorganosilanes with chlorine dioxide in an acetonitrile solution were the corresponding silanols and siloxanes. A mechanism explaining the formation of products and the observed regularities of the oxidation of silanes with chlorine dioxide has been proposed. A thermochemical analysis of some possible pathways in the gas phase using methods G4, G3, M05, and in an acetonitrile solution by the SMD-M05 method was carried out. The oxidation process can occur both with the participation of ionic and radical intermediates, depending on the structure of the oxidized substrate and medium.
- Grabovskiy,Kabal’nova
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p. 2391 - 2402
(2022/01/22)
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- Neutral-Eosin-Y-Photocatalyzed Silane Chlorination Using Dichloromethane
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Chlorosilanes are versatile reagents in organic synthesis and material science. A mild pathway is now reported for the quantitative conversion of hydrosilanes to silyl chlorides under visible-light irradiation using neutral eosin Y as a hydrogen-atom-transfer photocatalyst and dichloromethane as a chlorinating agent. Stepwise chlorination of di- and trihydrosilanes was achieved in a highly selective fashion assisted by continuous-flow micro-tubing reactors. The ability to access silyl radicals using photocatalytic Si?H activation promoted by eosin Y offers new perspectives for the synthesis of valuable silicon reagents in a convenient and green manner.
- Fan, Xuanzi,Xiao, Pin,Jiao, Zeqing,Yang, Tingting,Dai, Xiaojuan,Xu, Wengang,Tan, Jin Da,Cui, Ganglong,Su, Hongmei,Fang, Weihai,Wu, Jie
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supporting information
p. 12580 - 12584
(2019/08/16)
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- Rh(iii)-Catalysed solvent-free hydrodehalogenation of alkyl halides by tertiary silanes
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Efficient catalytic reduction of CDCl3 and other alkyl halides, including persistent organic pollutants, by different tertiary silanes using the unsaturated silyl-hydrido-Rh(iii) complex {Rh(H)[SiMe2(o-C6H4SMe)](PPh3)2}[BArF4] as a pre-catalyst is accomplished. The reactions are performed in a solvent-free manner. On account of experimental evidence, a simplified catalytic cycle is suggested for the hydrodehalogenation of CDCl3.
- Almenara,Azpeitia,Garralda,Huertos
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supporting information
p. 16225 - 16231
(2018/11/30)
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- B(C6F5)3-Catalyzed Selective Chlorination of Hydrosilanes
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The chlorination of Si?H bonds often requires stoichiometric amounts of metal salts in conjunction with hazardous reagents, such as tin chlorides, Cl2, and CCl4. The catalytic chlorination of silanes often involves the use of expensive transition-metal catalysts. By a new simple, selective, and highly efficient catalytic metal-free method for the chlorination of Si?H bonds, mono-, di-, and trihydrosilanes were selectively chlorinated in the presence of a catalytic amount of B(C6F5)3 or Et2O?B(C6F5)3 and HCl with the release of H2 as a by-product. The hydrides in di- and trihydrosilanes could be selectively chlorinated by HCl in a stepwise manner when Et2O?B(C6F5)3 was used as the catalyst. A mechanism is proposed for these catalytic chlorination reactions on the basis of competition experiments and density functional theory (DFT) calculations.
- Chulsky, Karina,Dobrovetsky, Roman
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supporting information
p. 4744 - 4748
(2017/04/11)
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- DMF-activated chlorosilane chemistry: Molybdenum-catalyzed reactions of R3SiH, DMF and R′3SiCl to initially form R′3SiOSiR′3 and R3SiCl
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The room temperature reactions between R3SiH (R3?=?Et3, PhMe2, Ph2Me) and R′3SiCl (R′3?=?Me3, PhMe2, Ph2Me), with an excess of dimethylformamide (DMF) in the presence of (Me3N)Mo(CO)5 as a catalyst, result in the initial formation of R3SiCl, R′3SiOSiR′3 and Me3N as detected by 29Si, 13C, 1H NMR spectroscopy and GC/MS. As the reaction proceeds, the more so if the reaction temperature is raised, mixed disiloxanes R3SiOSiR′3 and ultimately lesser amounts of R3SiOSiR3 may be detected. A mechanism involving the activation of chlorosilanes by the nucleophilic DMF is proposed to produce transient imminium siloxy ion pairs, [Me2N[dbnd]CHCl]+[R′3SiO]? ? [Me2N[dbnd]CH(OSiR′3)]+Cl? which react with R3SiH to form Me2NCH2OSiR′3 and R3SiCl. A secondary reaction of Me2NCH2OSiR′3 with R′3SiCl produces the symmetrical disiloxane R′3SiOSiR′3 and ClCH2NMe2. The final stage of the reaction is the reduction of ClCH2NMe2 by R3SiH, a reaction which is reported for the first time. The newly created chlorosilane R3SiCl can become involved in the initial DMF activation chemistry thereby forming the other disiloxanes observed as the reaction proceeds.
- Gonzalez, Paulina E.,Sharma, Hemant K.,Pannell, Keith H.
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p. 376 - 381
(2017/06/30)
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- An Isolable Potassium Salt of a Borasilene–Chloride Adduct
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Among the variety of isolable compounds with multiple bonds involving silicon, examples of compounds that contain silicon–boron double bonds (borasilenes) still remain relatively rare. Herein, we report the synthesis of the potassium salt of a chloride adduct of borasilene 1 ([2]?), which was obtained as an orange crystalline solid. Single-crystal X-ray diffraction analysis and reactivity studies on [2]? confirmed the double-bond character of the Si=B bond as well as the reduced Lewis acidity, which is due to the coordination of Cl? to the boron center. A thermal reaction of [2]? afforded a bicyclic product by formal intramolecular C?H insertion across the Si=B bond of 1, which was corroborated by a theoretical study.
- Suzuki, Yuko,Ishida, Shintaro,Sato, Sota,Isobe, Hiroyuki,Iwamoto, Takeaki
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supporting information
p. 4593 - 4597
(2017/04/11)
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- [...] compound
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PROBLEM TO BE SOLVED: To provide a method of manufacturing a dichloromonohydrosilane compound that is capable of manufacturing a dichloromonohydrosilane compound useful as a synthesis raw material for various silane compounds such as a silane coupling agent or a functional silicone oil by using inexpensive and easily available monohydrosilane compound at a low cost since it does not require a special reaction device for conducting reactions under pressure.SOLUTION: There is provided a method of manufacturing dichloromonohydrosilane compound represented by the general formula (3) HSiRCl, where Ris an unsubstituted or a substituted monovalent hydrocarbon group having a substituent at other than α position of a silicon atom, by reacting a trichloroorganosilane compound represented by the general formula (1) RSiCl, where Ris as defined above, and a monohydrosilane compound represented by the general formula (2) HSiRCl, where Ris an unsaturated or a substituted monovalent hydrocarbon group and m is 1, 2 or 3.
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Paragraph 0041
(2020/10/21)
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- S-F and S-C activation of SF6 and SF5 derivatives at rhodium: Conversion of SF6 into H2S
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The degradation of SF6 and SF5 organyls by S-F and S-C bond-activation reactions at [{Rh(μ-H)(dippp)}2] under mild conditions is reported. Fluorido and thiolato species were identified as products or intermediates, and were characterized by X-ray diffraction analysis and multinuclear NMR spectroscopy. An unprecedented cyclic process for the conversion of the potent greenhouse gas SF6 into H2S was developed. Activation of the stable greenhouse gas SF6: The rhodium hydrido complex [{Rh(μ-H)(dippp)}2] effected defluorination at the sulfur atom of SF6 and organic SF5 compounds under mild conditions. The reduction of SF6 in the presence of HSiEt3 led exclusively to the thiolato complex [Rh2(μ-H)(μ-SSiEt 3)(dippp)2] and FSiEt3 (see Scheme). A cyclic process was developed for the conversion of SF6 into H2S.
- Zamostna, Lada,Braun, Thomas,Braun, Beatrice
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supporting information
p. 2745 - 2749
(2014/03/21)
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- Hexachloroethane: a highly efficient reagent for the synthesis of chlorosilanes from hydrosilanes
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A new and efficient chlorination protocol is presented for the preparation of chlorosilanes from hydrosilanes. A variety of chlorinating agents in combination with palladium(II) chloride as the catalyst are examined. Among them, hexachloroethane is found to be the best choice, furnishing the desired product in good to quantitative yields under mild conditions. Various hydrosilanes are used as starting materials to explore the scope of this reaction.
- Pongkittiphan, Veerachai,Theodorakis, Emmanuel A.,Chavasiri, Warinthorn
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body text
p. 5080 - 5082
(2009/12/01)
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- High oxidation state rhodium and iridium bis(silyl)dihydride complexes supported by a chelating pyridyl-pyrrolide ligand
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New rhodium and iridium complexes containing the bidentate ligand 3,5-diphenyl-2-(2-pyridyl)pyrrolide (PyPyr) were prepared. The bis(ethylene) complex (PyPyr)Rh(C2H4)2 (3) reacted with HSiEt 3, HSiPh3, and HSitBuPh2 to produce the 16-electron Rh(V) bis(silyl)dihydrides (PyPyr)Rh(H)2(SiEt 3)2 (8), (PyPyr)Rh-(H)2(SiPh3) 2 (9), and (PyPyr)Rh(H)2(SitBuPh 2)2 (10), respectively. The analogous Ir(V) bis(silyl)dihyride (PyPyr)Ir(H)2(SiPh3)2 (11) has also been synthesized. X-ray crystallography reveals that 9-11 adopt a coordination geometry best described as a bicapped tetrahedron. Silane elimination from 9 and 10 occurred in the presence of either HSiEt3 or PPh3. Mechanistic studies of the silane exchange process involving 10 and free HSiEt3 (to give 8) indicate that this process occurs by rate-limiting reductive elimination of HSitBuPh2 from 10 to generate a 14-electron Rh(III) intermediate of the type (PyPyr)Rh(H)(Si tBuPh2).
- McBee, Jennifer L.,Escalada, Jose,Tilley, T. Don
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body text
p. 12703 - 12713
(2010/01/30)
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- Reduction of alkyl halides by triethylsilane based on a cationic iridium bis(phosphinite) pincer catalyst: Scope, selectivity and mechanism
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A highly efficient procedure for the reduction of a broad range of alkyl halides by triethylsilane based on a cationic iridium bis(phosphinite) pincer catalyst has been discovered and developed. This reduction chemistry is chemoselective and has unique selectivities compared with conventional radical-based processes and the aluminum trichloride/ triethylsilane (AlCl 3/Et3SiH) and triphenylmethyl tetrakis[pentafluorophenyl] borate/triethylsilane {[Ph3C] [B(C6F5) 4]/Et3SiH} systems. Reductions use three equivalents of triethylsilane relative to the halide and can be carried out with very low catalyst loadings and in a solvent-free manner, which may provide an environmentally attractive and safe alternative to many currently practiced methods for reduction of alkyl halides. Mechanistic studies reveal a unique catalytic cycle. The cationic iridium hydride 2,6-bis[di-(tert-butyl) phosphinyloxy)phenyl-(hydrido)iridium, (POCOP)IrH+ {POCOP= 2,6-[OP(t-Bu)2]2C6H3} binds and activates the silane. This complex serves as a potent silylating reagent to generate silyl halonium ions, Et3SiXR+, which are reduced by the neutral iridium dihydride to yield alkane product and regenerate the cationic (POCOP)IrH+, thus closing the catalytic cycle. All key intermediates have been identified by in situ NMR monitoring and kinetic studies have been completed. An application of this reduction system to the catalytic hydrodehalogenation of a metal chloride complex is also described.
- Yang, Jian,Brookhart, Maurice
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scheme or table
p. 175 - 187
(2009/10/01)
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- The synthesis of chlorosilanes from alkoxysilanes, silanols, and hydrosilanes with bulky substituents
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We have found that commercially important trialkylchlorosilanes can readily be synthesized by the reaction of alkoxysilanes, silanols, and hydrosilanes with aqueous concentrated hydorochloric acid. Treatment of trialkylalkoxysilanes bearing the bulky alkyl substituents, such as the i-Pr, sec-Bu, tert-Bu, and cyclo-Hex group, with 35% aqueous hydrochloric acid afforded the corresponding trialkylchlorosilanes in excellent yields. Similar treatment of trialkylsilanols with 35% aqueous hydrochloric acid also gave trialkylchlorosilanes in almost quantitative yields. The reaction of methyltrichlorosilane and dimethyldichlorosilane with alkyl-Grignard reagents bearing a bulky alkyl group, followed by treatment of the resulting mixtures with aqueous concentrated hydrochloric acid, produced the respective dialkylmethyl- and alkyldimethylchlorosilanes in high yields. Treatment of trialkylhydrosilanes with concentrated hydrochloric acid in the presence of a palladium catalyst afforded trialkylchlorosilanes in high yields.
- Masaoka, Shin,Banno, Tadashi,Ishikawa, Mitsuo
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p. 174 - 181
(2007/10/03)
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- Production processes for triorganomonoalkoxysilanes and triorganomonochlorosilanes
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A silane containing a bulky hydrocarbon group or groups R therein and having the formula (III) [in-line-formulae]R3-(x+y)(R1)x(R2)ySi(OR3) [/in-line-formulae] can be produced by reacting a silane of the formula (I) [in-line-formulae](R1)x(R2) ySiCl3-(x+y)(OR3) [/in-line-formulae] with a Grignard reagent of the formula (II) [in-line-formulae]RMgX [/in-line-formulae] Further, a tri-organo-chlorosilane of the formula (XIIa) [in-line-formulae](R1)(R2)(R3)SiCl [/in-line-formulae] can be produced by reacting a tri-organo-silane of the formula (XIa) [in-line-formulae](R1)(R2)(R3)SiZ1 [/in-line-formulae] with hydrochloric acid. Furthermore, a tri-organo-monoalkoxysilane of the formula (XXIII) [in-line-formulae]R3-(x+y)(R1)x(R2)ySi(OR3) [/in-line-formulae] can be produced when a silane of the formula (XXI) [in-line-formulae](R1)x(R2)ySiCl4-(x+y) [/in-line-formulae] is reacted with a Grignard reagent of the formula (XXII) [in-line-formulae]RMgX [/in-line-formulae] with addition of and reaction with an alcohol or an epoxy compound during the reaction.
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Page/Page column 23
(2008/06/13)
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- Continuous and batch organomagnesium synthesis of ethyl-substituted silanes from ethylchloride, tetraethoxysilane, and organotrichlorosilane for production of polyethylsiloxane liquids. 2. Continuous one-step synthesis of ethylethoxy- and ethylchlorosilanes
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Development of a continuous one-step manufacturing process for ethylethoxy- and ethylchlorosilanes is described. The methodology of synthesis of ethyl-substituted silanes has been improved. The important factors for the successful synthesis have been determined. Among them are (1) the replacement of some tetraethoxysilane 3 by ethyltrichlorosilane 10, (2) the optimum concentration of 3 and 10, (3) the excess of the granulated magnesium (the supply rate 50-110 g h-1), and, finally, (4) the columnar apparatus with the stirrer, resulting in high yields of di-and triethylsilanes, low duration of synthesis, and high selectivity of Grignard reagent. Continuous one-step synthesis has been assimilated into industry (up to a scale 7-40 kg h-1 of magnesium) for production of oligoethylsiloxanes with low (5-20%) and high content (up to 40%) of the terminal triethylsiloxy groups. The rules for R/D process of the Grignard synthesis are described.
- Klokov, Boris A.
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p. 234 - 240
(2013/09/07)
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- Simultaneous Dehalogenation of Polychloroarenes and Chlorination of HSiEt3 Catalyzed by Complexes of the Groups 8 and 9
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The catalytic activity of the complexes FeCl2(PPh3)2, RuHCl (PPh3)3, RuH2(CO)(PPh3)3, RuHCl(CO)(AsPh3)3, RuHCl(CO) (PiPr3)
- Diaz, Julia,Esteruelas, Miguel A.,Herrero, Juana,Moralejo, Luisa,Olivan, Montserrat
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p. 187 - 192
(2007/10/03)
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- Azetidine, pyrrolidine and piperidine derivatives as 5HT1 receptor agonists
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PCT No. PCT/GB95/02759 Sec. 371 Date Jul. 28, 1997 Sec. 102(e) Date Jul. 28, 1997 PCT Filed Nov. 27, 1995 PCT Pub. No. WO96/17842 PCT Pub. Date Jun. 13, 1996A class of substituted azetidine, pyrrolidine and piperidine derivatives are selective agonists of 5-HT1-like receptors, being potent agonists of the human 5-HT1D alpha receptor subtype whilst possessing at least a 10-fold selective affinity for the 5-HT1D alpha receptor subtype relative to the 5-HT1D beta subtype; they are therefore useful in the treatment and/or prevention of clinical conditions, in particular migraine and associated disorders, for which a subtype-selective agonist of 5-HT1D receptors is indicated, whilst eliciting fewer side-effects, notably adverse cardiovascular events, than those associated with non-subtype-selective 5-HT1D receptor agonists.
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- Continuous and batch organomagnesium synthesis of ethyl-substituted silanes from ethylchloride, tetraethoxysilane, and organotrichlorosilane for production of polyethylsiloxane liquids. 1. Batch one-step synthesis of ethylethoxysilanes and ethylchlorosilanes
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Development of batch one-step manufacturing process for ethylethoxy- and ethylchlorosilanes is desribed. The methodology of synthesis of ethyl-substituted silanes has been improved. The important factors for the successful synthesis have been determined. Among them are the replacement of the part tetraethoxysilane 3 by ethyltrichlorosilane 10, the optimum concentration of 3 and 10 resulting in high yield of triethylsilanes, low duration of synthesis, and high selectivity of Grignard reagent. Batch one-step synthesis has been assimilated into industry (up to a scale 240 kg of magnesium) for production of oligoethylsiloxanes with the high content (>40%) of a terminal triethylsiloxy group. The rules for R/D process of the Grignard synthesis are described.
- Klokov, Boris A.
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- Stepwise organomagnesium synthesis of mixtures of ethyletoxysilanes and ethylchlorosilanes
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Mixture of ethylethoxy- and ethylchlorosilanes was prepared in a toluene solution by successive reaction of magnesium with a mixture of ethyl chloride and tetraethoxysilane and then with a mixture of ethyl chloride and tetrachlorosilane.
- Klokov
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p. 1863 - 1865
(2007/10/03)
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- Reducing System Trialkylsilane-Transition Metal Acetylacetonate. III. Reduction of Unsaturated Monocarboxylic Acid Chlorides
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Reactions of triethylsilane with acryloyl, methacryloyl, and crotonoyl chlorides in the presence of transition metal (Fe, Co, Ni, Cr, Mn) acetylacetonates yield trialkylchlorosilane and the corresponding unsaturated aldehyde, acid, and triethylsilyl carboxylate. The catalytic activity of the metal acetylacetonates in the reaction of triethylsilane with acryloyl chloride decreases in the order Fe(acac)3 > Co(acac)3 > Ni(acac)2 > Cr(acac)3 >Co(ocac)2 > Mn(acac)3. The reactivity of unsaturated acid chlorides RCOC1 in the reduction decreases in the order R = CH3CH=CH > CH2=C(CH3) > CH2=CH.
- Pukhnarevich,Koval'skaya,Ushakova,Tsykhanskaya,Kopylova,Voronkov
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p. 1257 - 1259
(2007/10/03)
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- Concurrent preparation of dimethylchlorosilane and triorganochlorosilane
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Dimethylchlorosilane and a triorganochlorosilane of the formula: R1 R2 R3 SiCl wherein R1, R2, and R3 are independently selected from monovalent hydrocarbon groups are concurrently prepared by reacting dimethyldichlorosilane with a SiH bond-containing silane compound of the formula: R1 R2 R3 SiH in the presence of a Lewis acid catalyst. The method is especially effective for concomitant preparation of dimethylchlorosilane and trimethylchlorosilane or t-butyldimethylchlorosilane in an inexpensive, simple, safe manner and in high yields.
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- Triorganomonohalogenosilane
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A triorganomonohalogenosilane is prepared by reacting a triorganomonohydrosilane represented by the following general formula (I): with a halogenated allyl compound represented by the following general formula (II): STR1 in the presence of metal palladium, or a salt or complex of palladium to replace the hydrogen atom directly bonded to the silicon atom of the triorganomonohydrosilane with a halogen atom. In Formula ( I ), the substituents R1 's directly bonded to the silicon atom may be identical to or different from one another and each represents a monovalent organic group. In Formula (II), the substituents R2 's may likewise be identical to or different from one another and each represents a hydrogen atom or a monovalent alkyl group and X represents a chlorine atom, a bromine atom or an iodine atom.
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- Process for preparing cyclopentadienyl group-containing silicon compound or cyclopentadienyl group-containing germanium compound
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Disclosed is a process for preparing a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, comprising reacting (i) a lithium, sodium or potassium salt of a cyclopentadiene derivative with (ii) a silicon halide compound or a germanium halide compound in the presence of a cyanide or a thiocyanate. The cyanide or the thiocyanate is preferably a copper salt. According to the process of the invention, a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, which is very useful for the preparation of a metallocene complex catalyst component, can be prepared in a high yield for a short period of time.
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- 1,3-disilacyclobutanes and the method for producing thereof
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The present invention relates to a process for preparing 1,3-disilacyclotutanes by pyrolyzing alkoxytrisilaalkaness at a temperature of from 400° C. to 800° C. at the atmospheric pressure or under the vacuum. This is a new synthetic route of 1,3-disilacyclobutanes which employs readily available starting materials without using alkaline metals or magnesium, affords very good yields, produces very clean product mixtures separable by distillation, and tolerates functionality on silicon.
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- Electrochemical Oxidation of Hydrosilanes. A Synthetic Approach to Halosilanes and Disilanes
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Electrolytic oxidation of dimethylphenylsilane (1) in the presence of CuCl2 or CuCl afforded chlorodimethylphenylsilane in high yields (>90percent), while similar electrolysis of 1 in the presence of BF4- ions afforded fluorodimethylphenylsilane in 90percent yield. 1,2-Diphenyltetramethyldisilane was obtained from 1 in 48percent yield by the electrolysis with a Pt-Cu electrode system.A "paired" electrolysis of methyldiphenylsilane on the anode and chloromethyldiphenylsilane on the cathode afforded 1,2-dimethyltetraphenyldisilane in 64percent yield.
- Kunai, Atsutaka,Kawakami, Toshihiro,Toyoda, Eiji,Sakurai, Tomohiro,Ishikawa, Mitsuo
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p. 1945 - 1948
(2007/10/02)
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- CHLORINE AND HYDROGENTRANSFER BY METAL CARBONYL INTERMEDIATES
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The reduction of 1,1,1,5-tetrachloropentane by toluene in the presence of the Fe(CO)5 or M(CO)6 (M = Cr, Mo, W) in conjunction with triphenylphosphine was investigated.It was shown that the chlorine-containing metal carbonyl intermediates formed in the process take part in the transfer of the chlorine atom to the benzyl radicals.It was shown that HMn(CO)5 is not the main intermediate responsible for the transfer of hydrogen by the chloroalkyl radicals, which are formed during the reduction of 1,3,3,5-tetrachloropentane by triethylsilane in the presence of Mn2(CO)10.
- Il'inskaya, L. V.,Kuznetsov, V. F.,Gasanov, R. G.
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p. 823 - 826
(2007/10/02)
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- Process for reducing silicon, germanium and tin halides
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A process for reducing halogen-containing compounds of silicon, germanium or tin with lithium hydride in the presence of tetrahydrofuran wherein the lithium hydride is first heated in the tetrahydrofuran and then the halogen-containing compound is added.
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- New hexacoordinate silicon complexes, the process for their preparation and their application
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The present invention relates to new hexacoordinate silicon complexes, the process for their preparation and their application. These new complexes correspond to the general formula I: STR1 in which: A represents an alkali metal or alkaline earth metal except for magnesium, and n=0 or 1.
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- Method for producing chlorosilanes
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A method for producing chlorosilanes, which are useful in a wide range of industrial field as an intermediate for organosilicon products such as silicone rubbers, silicone oils, silicone resins, etc. as well as a raw material for the production of organic chemicals such as medicines, agricultural chemicals, dyestuffs, etc., represented by the general formula, STR1 wherein R1 and R4, which may be the same or different, represent an alkyl group having from 1 to 5 carbon atoms, a chloromethyl group, an ethynyl group or a halogen atom; R2 and R3, which may be the same or different, represent an alkyl group having from 1 to 3 carbon atoms; R5 and R6, which may be the same or different, represent an alkyl group having from 1 to 2 carbon atoms; and R7 represents an alkyl group having from 1 to 18 carbon atoms, which comprises reacting a disiloxane represented by the general formula, STR2 wherein R1, R2, R3, R4, R5 and R6 are as defined above, or a silanol represented by the general formula, STR3 wherein R2, R3 and R7 are as defined above, with phosgene in the presence or absence of a tertiary amide.
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- REACTION OF THIOACETALS WITH TRIETHYLSILANE IN THE PRESENCE OF LEWIS ACIDS AND REDUCED NICKEL
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1,1-Di(alkylthio)alkanes, 1,3-oxathiolanes, 1,3-dithiolanes, and ortho thioesters are cleaved by triethylsilane in the presence of catalytic amounts of zinc iodide or reduced nickel.In the presence of zinc iodide the acyclic dithioacetals and ortho thioester are converted into alkyl sulfides and triethyl(alkylthio)silanes by cleavage of the carbon-sulfur bond.The analogs of the cyclic acetals are cleaved by triethylsilane only in the presence of reduced nickel, while regiospecific cleavage of the heterocycle at the carbon-oxygen bond is observed in 1,3-oxathiolanes.The cleavage of the 1,3-dithiolanes takes place by a more complicated mechanism with the formation of the disilyl ether of ethanediol, hexaethyldisilylthiane, and triethyl(alkylthio)silanes.The cyclic ortho thioester reacts with triethylsilane both at zinc iodide and at reduced nickel with the formation of the products from preferential cleavage of the exocyclic bond.
- Kirilyuk, B. A.,Mel'nitskii, I. A.,Golub, N. M.,Kiladze, T. K.,Kantor, E. A.,Rakhmankulov, D. L.
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p. 1754 - 1758
(2007/10/02)
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- ARRHENIUS PARAMETERS FOR THE REACTION OF tert-BUTOXYL RADICALS WITH TRIETHYLSILANE
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Absolute rate constants for the reaction of tert-butoxyl radicals with triethylsilane have been measured in solution by a new indirect method using laser flash photolysis technique.Arrhenius parameters obtained in the temperature range 251-315 K are log (A/M-1s-1)=8.85+/-0.50 and Ea=2.91+/-0.32 kcal mol-1.The discrepancies with the previously obtained gas-phase data are discussed.
- Chatgilialoglu, Chryssostomos
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p. 511 - 514
(2007/10/02)
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- The Mechanism of the Reaction between Silyl Radicals and Chloroethylenes: A Case Study of the Et3Si-C2Cl4 Reaction
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The photolysis and radiolysis of C2Cl4 solutions in Et3SiH were studied at 298 K.The main products, Et3SiCl and C2Cl3H, are formed in equal yields and via a free radical chain mechanism, as indicated by the high quantum yields (ca.500) and G values (ca.1600).The reactions C2Cl3+Et3SiH->C2Cl3H+Et3Si (3) and Et3Si+C2Cl4->Et3SiCl+C2Cl3 (4) constitute the chain propagation step.Competitive studies yield k4/k11 of 0.18+/-0.01 (2?) where Et3Si+t-BuCl->Et3SiCl+t-Bu (11).The mechanistic implications and consequences of the observation that the reaction of Et3Si radicals with C2Cl4 results almost exclusively in Cl transfer rather than addition are discussed, and the conclusions are generalized for similar reactions of other chloroethylenes.
- Horowitz, Abraham
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p. 318 - 321
(2007/10/02)
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- Sulfosilylation of Carbonyl Compounds and Trimethylsilyl Enol Ethers with Trimethylsilyl Chlorosulfonate
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Aldehydes and ketones 3 react with trimethylsilyl chlorosulfonate (1a) to yield trimethylsilyl 2-oxosulfonates 5.The course of this sulfosilylation is discussed briefly.The sulfosilylation of trimethylsilyl carboxylates 7 and trimethylsilyl ketene acetals 14 results in formation of 2-(trimethylsiloxysulfonyl)carboxylates 8 and 15.
- Hofmann, Karin,Simchen, Gerhard
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- Silyl Halides from (Phenylseleno)silanes. Reaction with Oxiranes and Alcohols To Give Hydrolytically Stable Silyl Ethers.
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The preparation of (phenylseleno)silanes and their reactions with halogens (Cl2, Br2, I2) to give silyl halides and diphenyl diselenide are described.Highly hindered tert-butyldimethyl and tert-butyl diphenylsilyl halides were easily prepared.The reaction of silyl bromides and iodides with oxiranes followed by diazabicyclononane treatment gave allylic alcohol silyl ethers.Tertiary alcohols reacted rapidly with silyliodides to give hydrolytically stable silyl ethers.Treatment of the silyl ethers with tetra-n-butylammonium fluoride gave the free alcohols withoutrearrangement or isomerization.
- Detty, Michael R.,Seidler, Mark D.
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p. 1283 - 1292
(2007/10/02)
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- Liquid-Phase Reactions of CCl3 Radicals with Trimethylsilane and Triethylsilane
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The γ-radiation-induced chain reactions in liquid solution of silane (R'3SiH) in CCl4-c-C6H12(RH) mixtures were investigated over the temperature range 303-423 K for R' = Me and 335-423 K for R' = Et.In both systems the main products are R'3SiCl, CHCl3, and RCl.By kinetic analyses of product distribution, the rate constants of hydrogen abstraction from the two silanes by CCl3 radicals were competitively determined vs. hydrogen abstraction from cyclohexane.The relative rate constants combined with the known Arrhenius parameters of the reference systems gave the following Arrhenius parameters for the reaction CCl3 + R'3SiH -> CHCl3 + R'3Si: log A4 (L mol-1 s-1) = 8.49 and E4 = 8.70 kcal mol-1 when R' = Me, and log A4 = 8.62 and E4 = 8.06 when R' = Et.These results indicate that alkyl-substituted silanes are considerably more reactive than Cl3SiH in the H-atom transfer reactions with CCl3 radicals.This observation is rationalized in terms of the polar effects of the alkyl substituents.
- Baruch, G.,Horowitz, A.
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p. 2535 - 2539
(2007/10/02)
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- Process for the preparation of hydrogenosilanes
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A process for preparing hydrogenosilanes by hydrogenating disilanes, especially halogenated disilanes, under relatively mild reaction conditions is disclosed. The hydrogenation is effected in the presence of a catalytic system containing an aprotic compound and a nickel catalyst which consists essentially of finely divided nickel and is obtained by preliminary or in situ reduction of a nickel compound.
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