共查询到20条相似文献,搜索用时 31 毫秒
1.
Thermodynamic assessment of the copper catalyzed direct synthesis of methylchlorosilanes 总被引:1,自引:0,他引:1
The copper catalyzed direct synthesis of methylchlorosilanes is a reaction of enormous complexity. Although, there is a general acceptance about a silylenoide based reaction mechanism, many details of the reaction are not yet fully understood. The present work is a comprehensive thermodynamic study on the reaction system of the direct synthesis. The calculations are based on a broad database containing the elements, all silanes, chlorosilanes, methylsilanes, and methylchlorosilanes with one Si atom, hydrocarbons and chlorinated hydrocarbons as well as other relevant compounds in the system Si-C-H-Cl. A calculation of the reaction between silicon and methylchloride, excluding only SiC as an unlikely reaction product, results in the total decomposition of methylchloride and the formation carbon, methane, hydrogen, trichlorosilane, and silicon tetrachloride. The systematic suppression of certain reaction products from the calculation yields finally into a product distribution close to the experimentally observed ones. The chosen approach to remove certain compounds from the calculation is equivalent to the introduction of unspecific kinetic constraints arising from a hypothetically total and selective blocking of certain reaction pathways. From this, three major kinetically determined reaction pathways are identified: (i) the formation of carbon, hydrocarbons, hydrogen, and hydrogen chloride due to the cleavage of the C-H bond in methyl chloride, (ii) the formation of hydrogen-containing methylchlorosilanes that occurs only in the presence of hydrogen or hydrogen chloride, and (iii) the competition between the thermodynamically favored chlorosilanes and the kinetically favored methylchlorosilanes. The presence of transition metals (regardless whether Cu, Fe, or Ni) during the direct synthesis gives no thermodynamic preference for the formation of methylchlorosilanes. The metals effect is to open a kinetically controlled reaction pathway to the formation of methylchlorosilanes far away from the formation of chlorosilanes or from other thermodynamically more favored compounds. Furthermore, processes related to the induction period, the addition of hydrogen to the direct synthesis, constrained equilibriums between methylchlorosilanes, and the limits of the applied calculation procedure are discussed in detail. 相似文献
2.
Masaki Okamoto 《Research on Chemical Intermediates》2006,32(3):317-330
In the direct synthesis of silicon compounds by reactions of elemental silicon with methyl chloride, methanol and hydrogen
chloride, silylene formed on surface of silicon grains during the reaction is an intermediate. The reaction of surface silylene
with a variety of unsaturated hydrocarbons provides new direct synthesis of organosilanes. In the direct synthesis of methylchlorogermanes
from elemental germanium, surface germylene is not an intermediate, while tetrachlorogermane is synthesized by the direct
reaction of germanium with hydrogen chloride via dichlorogermylene intermediate. Various unsaturated hydrocarbons or organic chlorides added to the system of tetrachlorogermane
synthesis give new methods for the synthesis of organogermanes. 相似文献
3.
Masaki Okamoto 《Research on Chemical Intermediates》2006,32(3-4):317-330
In the direct synthesis of silicon compounds by reactions of elemental silicon with methyl chloride, methanol and hydrogen chloride, silylene formed on surface of silicon grains during the reaction is an intermediate. The reaction of surface silylene with a variety of unsaturated hydrocarbons provides new direct synthesis of organosilanes. In the direct synthesis of methylchlorogermanes from elemental germanium, surface germylene is not an intermediate, while tetrachlorogermane is synthesized by the direct reaction of germanium with hydrogen chloride via dichlorogermylene intermediate. Various unsaturated hydrocarbons or organic chlorides added to the system of tetrachlorogermane synthesis give new methods for the synthesis of organogermanes. 相似文献
4.
Raymond Calas Gerard Deleris Jacques Dunogues Marcel Lefort Christian Simmonet 《Journal of organometallic chemistry》1978,148(2):119-125
The chlorodisilane residue from the industrial synthesis of methylchlorosilanes is cleaved under hydrogen (25 bars) in the presence of HMPT/nickelocene mixture or nickel (resulting from the reduction of dry NiCl2 by Et3SiH) and leads to the formation of methyldichlorosilane (noble product), to the detriment of the methyltrichlorosilane (much less noble). This reaction also gives an appreciable amount of the rare and very useful dimethylchlorosilane. 相似文献
5.
The reaction between cuprous chloride CuCl and silicon is the classical model reaction for activation of the contact mass in Direct Synthesis. It had been found by several authors that the reactivity of CuCl strongly depends on its quality and the route of synthesis. In the present study the reactivities of two CuCl charges, prepared from the elements at high temperatures and by reduction in aqueous solution, are compared by means of calorimetric studies. The aqueous route CuCl was found to have a higher reactivity, indicated by lower reaction start temperatures and 100% CuCl conversion with respect to the other charge. It was found that the reactivity depends neither on intrinsic properties (defect concentration) nor on properties that can be derived from microscopical or thermoanalytical characterizations or by X-ray powder diffraction. The initial step of reaction between cuprous chloride and silicon was identified as a solid state reaction. Therefore, the role of the CuCl surface is discussed and a model for the initial step is suggested. 相似文献
6.
Beta-Manganese dioxides' (β-MnO2) hollow octahedra have been prepared by a synergetic redox reaction using cuprous chloride (CuCl) and hydrochloric acid (HCl) as reductants and potassium permanganate (KMnO4) as oxidant through a hydrothermal route. During the process, the self-generated chlorine (Cl2) gas bubbles and HCl's etching appear to be necessary for the formation of MnO2 hollow structure. The catalytic efficiency of the prepared β-MnO2 hollow octahedra was high which has been demonstrated by the catalytic oxidation of methylene blue (MB) dye in the presence of hydrogen peroxide (H2O2) under natural light. 相似文献
7.
Majid Ghashang 《Research on Chemical Intermediates》2014,40(4):1357-1364
A new approach to the synthesis of methyl/benzyl(2-hydroxynaphthalen-1-yl)(aryl)methylcarbamate derivatives based on the reaction of aldehydes, 2-naphthol and methyl/benzyl carbamate, using a catalytic amount of magnesium hydrogen sulfate [Mg(HSO4)2] as an efficient heterogeneous catalyst under solvent-free conditions has been developed. 相似文献
8.
Reactions of organochlorosilanes with chloro-and organogermanes in the presence of aluminum chloride
V. I. Zhun’ I. V. Sbitneva A. N. Polivanov E. A. Chernyshev 《Russian Journal of General Chemistry》2006,76(10):1564-1570
The effect of substituents at the silicon and germanium atoms in reactions of organochlorosilanes with chloro-and organogermanes in the presence of aluminum chloride was studied. The only occurring process is the exchange of the chlorine atoms at Ge for the phenyl groups from Si; an increase in the number of methyl groups or chlorine atoms at Si promotes formation of phenyltrichlorogermane, and an increase in the number of phenyl groups or replacement of the chlorine atom at the Si atom by hydrogen leads to the formation of di-and triphenylchlorogermanes. Neither phenyl nor other radicals are transferred back from Ge to Si in the course of reactions of phenylgermanes with methylchlorosilanes in the presence of aluminum chloride; the only occurring processes are the exchange of the phenyl or methyl radicals bonded to Ge for the Cl atom bonded to Al and the disproportionation of phenylchlorogermanes. 相似文献
9.
Bi‐Quan Su Liang Xian Hai‐Bin Song Li Sheng 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(12):m661-m662
The title copper(I) complex, [CuCl(C11H14N2O3S)2], was synthesized by the redox reaction of cupric chloride with the corresponding thiourea derivative as reducing agent. The CuI coordination environment is trigonal planar, involving two S atoms and one Cl atom. The presence of intramolecular hydrogen bonds leads to the formation of a cis conformation and promotes the stability of the complex. 相似文献
10.
Joan Bosch Mario Rubiralta Montserrat Moral Maria Valls 《Journal of heterocyclic chemistry》1983,20(3):595-605
2-Aryl-4-piperidones have been synthesized by condensation between an aromatic aldehyde and a β-aminoketone ethylene ketal, and further cyclization of the resulting iminoketal with dry hydrogen chloride or anhydrous p-toluensulfonic acid. Alternatively, reaction of the above iminoketals with methyl fluorosulfonate followed by dry hydrogen chloride treatment and acid hydrolysis gives directly N-methyl-4-piperidones. The application of these reactions to the synthesis of some 2-aryl-3-acetylpyrrolidine systems is also described. 相似文献
11.
Virgil Percec Tamaz Guliashvili Anatoliy V. Popov Ernesto Ramirez‐Castillo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(9):1935-1947
A variety of conditions, including catalysts [CuCl, CuI, Cu2O, and Cu(0)], ligands [2,2′‐bipyridine (bpy), tris(2‐dimethylaminoethyl)amine (Me6‐TREN), polyethyleneimine, and hexamethyl triethylenetetramine], initiators [CH3CHClI, CH2I2, CHI3, and F(CF2)8I], solvents [diphenyl ether, toluene, tetrahydrofuran, dimethyl sulfoxide (DMSO), dimethylformamide, ethylene carbonate, dimethylacetamide, and cyclohexanone], and temperatures [90, 25, and 0 °C] were studied to assess previous methods for poly(methyl methacrylate)‐b‐poly(vinyl chloride)‐b‐poly(methyl methacrylate) (PMMA‐b‐PVC‐b‐PMMA) synthesis by the living radical block copolymerization of methyl methacrylate (MMA) initiated with α,ω‐di(iodo)poly(vinyl chloride). CH3CHClI was used as a model for α,ω‐di(iodo)poly(vinyl chloride) employed as a macroinitiator in the living radical block copolymerization of MMA. Two groups of methods evolved. The first involved CuCl/bpy or Me6‐TREN at 90 °C, whereas the second involved Cu(0)/Me6‐TREN in DMSO at 25 or 0 °C. Related ligands were used in both methods. The highest initiator efficiency and rate of polymerization were obtained with Cu(0)/Me6‐TREN in DMSO at 25 °C. This demonstrated that the ultrafast block copolymerization reported previously is the most efficient with respect to the rate of polymerization and precision of the PMMA‐b‐PVC‐b‐PMMA architecture. Moreover, Cu(0)/Me6‐TREN‐catalyzed polymerization exhibits an external first order of reaction in DMSO, and so this solvent has a catalytic effect in this living radical polymerization (LRP). This polymerization can be performed between 90 and 0 °C and provides access to controlled poly(methyl methacrylate) tacticity by LRP and block copolymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1935–1947, 2005 相似文献
12.
The effect of the addition of hydrogen chloride on the photolysis of carbon tetrachloride in the presence of cyclohexane has been investigated in a companion paper. The data enable the rate constant ratio k8/(k5)1/2 to be determined. Since k?8 is well established, k5 can be estimated from known thermochemical data. The validity of the thermochemical derivation is checked by applying it to trifluoromethyl radicals. The photolysis of bromotrichloromethane and carbon tetrachloride in the presence of hydrogen chloride has been investigated over a range of temperatures. From these results and assuming reaction (5) has no activation energy, Arrhenius parameters for reaction (8) have been determined: The activation energies for the reaction of methyl, trichloromethyl, and trifluoromethyl radicals with hydrogen chloride are compared, and at first sight surprising results are rationalized in terms of relative electronegativity. 相似文献
13.
Davoodnia Abolghasem Heravi Majid M. Rezaei-Daghigh Leila Tavakoli-Hoseini Niloofar 《中国化学》2010,28(3):429-433
A green and improved method for the synthesis of β‐amido ketones through one‐pot multi‐component reaction of an enolizable ketone, aryl aldehyde, acetonitrile or benzonitrile in the presence of trimethylsilyl chloride using 3‐methyl‐1‐(4‐sulfonic acid)butylimidazolium hydrogen sulfate [(CH2)4SO3HMIM][HSO4], a Br?nsted‐acidic ionic liquid, as an effective and recyclable catalyst is described. The present methodology offers several advantages such as simple procedure with an easy work‐up, relatively short reaction time, and good to excellent yields. 相似文献
14.
AbstractSimple and rapid route for Meerwein arylation reaction using iron powder or a mixture of tin/tin chloride has been developed. In the presence of iron powder, different aryl diazonium salts reacted with methyl vinyl ketone, acrylates, and isopropenyl acetate. Production of oximes was detected as the main product with acrylates or in a mixture with β-aryl methyl ketones in the case of methyl vinyl ketone. The in situ produced HNO2 from an excess of NaNO2/HCl was trapped by alkyl aryl radical to form oximes in the E configuration form. The presence of tin/tin chloride mixture in the reaction of the aryl diazonium salts with methyl vinyl ketone produced Michael products along with β-aryl methyl ketones. The predicted α-aryl methyl ketones from the reaction of isopropenyl acetate with the diazotized anilines were obtained using iron or tin/tin chloride mixture. 相似文献
15.
The synthesis of dimethyl carbonate by oxidative carbonylation of methanol over CuCl/SiO2-TiO2 catalysts has been investigated in a slurry reaction system. The γ-Cu2(OH)3Cl crystals were detected by X-ray diffraction on the catalysts after reaction. It was revealed that γ-Cu2(OH)3Cl was formed by CuCl reacting with O2 and by-product water. The catalytic tests showed that γ-Cu2(OH)3Cl was largely inactive for this reaction, may be attributed to its high stability that resisted the Cu+/Cu2+ redox cycle. 相似文献
16.
A. D. Bulanov P. G. Sennikov A. Yu. Sozin A. Yu. Lashkov O. Yu. Troshin 《Russian Journal of Inorganic Chemistry》2011,56(4):510-512
The possibility of the reduction of hexafluorodisiloxane by calcium hydride in the synthesis of silane from silicon tetrafluoride
has been studied. This reaction is shown to be not decisive for oxygen contamination of silane. The most likely reason for
the appearance of impurity Si2OH6 in “fluoride” silane is the Ca(OH)2-catalyzed reaction of silane with trace water. The concentration of impurity Si2OH6 in silane at the stage of synthesis may be efficiently decreased by the preliminary purging of calcium hydride with a hydrogen
(grade A) flow. 相似文献
17.
The temperature-programmed-activation (TPA) of CuSi, CuSi(H) (prepared using CuCl and CuCl 2H2O, respectively), and CuSi copromoted with zinc and tin have been investigated. The main effect of promotion was to increase the activation temperature suggesting that zinc may inhibit the transfer of chlorine from CuCl to surface silicon atoms. The sample prepared using hydrated cuprous chloride initially exhibited reduced activity for the Direct Reaction relative to CuSi, apparently, due to oxidation of the contact mass surface inhibiting the formation of -Cu3Si. 相似文献
18.
Hossein Fakhraian Akbar Mirzaei 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):511-518
A liquid–liquid phase-transfer-catalyzed (PTC) Michaelis-Becker reaction was adopted in the preparation of dialkyl methyl phosphonate (R = Me, iPr, nBu, and iBu). This was performed by the reaction of an appropriate dialkyl hydrogen phosphonate with methyl iodide in the presence of benzyl triethyl ammonium chloride and sodium hydroxide as PTC and base, respectively. A liquid–liquid two-phase system (H2O/CH2Cl2) introduced a suitable situation for the preparation of dialkyl methyl phosphonates with bulky alkyl groups (R = iPr, nBu, and iBu), but with R = Me, the hydrolysis of dimethyl hydrogen phosphonate (reagent) reduced the yield to 22%. In this case, a solid–liquid PTC-free system was successfully applied and yield of over 80% was obtained. 相似文献
19.
Robert Vícha 《Tetrahedron》2005,61(1):83-88
The preparation of non-symmetrical ketones by the reaction of acyl chlorides and the corresponding Grignard reagents in the presence of catalytic amounts of metal halides is described. The composition of catalyst has a great influence on the yield of the required ketone as well as on side product formation. For each catalytic system, the yield of ketone and the number of side products changes with the time of addition of the Grignard reagent. We examined the influence of both factors in our model reaction of adamantane-1-carbonyl chloride with ethylmagnesium bromide and discussed the possible mechanisms from this point of view. We have found ZnCl2, MnCl2, AlCl3 and CuCl to be active catalytic components and developed very efficient, cheap and fast methods for the preparation of alkyl adamantyl ketones. The procedure was also tested for the synthesis of other alkyl aryl ketones. 相似文献