SiCl4 Research Articles

Theoretical study on the SiH4−nCln (n = 0–4) reaction mechanisms for polysilicon production process

Because of the lacking of rate coefficients of reactions in polysilicon production process, the reaction mechanisms of SiH4−nCln (n=0–4) in gas phase were investigated using quantum chemical calculations and transition state theory, which contained 20 species and 117 elementary reactions. By considering of the calculation amount and accuracy, the thermodynamic properties, including enthalpy of formation, entropy and heat capacity of the species were calculated using G3B3 method. The geometry optimization and vibrational frequencies of reactants, transition states, and products were determined at the B3LYP/6-311G(d,p) and MP2/6-311G(d,p) level, while energies were calculated using G3B3, G3MP2 and QCISD(T)/CBS method. The rate coefficients for the reactions without transition states were obtained by the canonical variational transition state theory (CVT), while the rate coefficients for the other reactions with saddle-point transition states were obtained by the conventional transition state theory (TST). The rate coefficients agree with available data from the literatures well. This research provided high accuracy thermodynamic and kinetic data for H–Si–Cl reaction system, which could be used for reactor optimization in polysilicon production.

A Bi-component Cu Catalyst for the Direct Synthesis of Methylchlorosilane from Silicon and Methyl Chloride

A bi-component catalyst comprising CuCl and metallic copper was used in the direct synthesis of methylchlorosilane to study the catalytic synergy between the different copper sources. The catalyst exhibited high activity and high selectivity of dimethyldichlorosilane (M2) in the stirred bed reactor. The effect of the proportion of CuCl used was studied and 10%-30% CuCl gave the best yield of M2. The use of CuCl decreased the induction period of reaction, improved the selectivity in the induction stage, and gave a longer stable stage. These results suggest that bi-component catalyst has advantages in the direct synthesis reaction.

Reduction of Silicon Tetrachloride with Hydrogen in a Chemically Active Plasma

Gas-dynamic and thermal processes occurring in a UHF reactor under optimal conditions for the preparation of silicon have been modeled. The distribution of the gas temperatures, the residence time of the reagents in the high temperature zone, and the rate of quenching of the reaction products have been determined. A mechanism for the formation of silicon with participation of H·, $ SiCl_3^{\cdot } $ , and SiCl2 is proposed.

Hydrogenation of Silicon Tetrachloride in Microwave Plasma

This study investigated the hydrogenation of silicon tetrachloride (SiCl4) in microwave plasma. A new launcher of argon (Ar) and hydrogen (H2) plasma was introduced to produce a non-thermodynamic equilibrium activation plasma. The plasma state exhibited a characteristic temperature related to the equilibrium constant, which was termed “Reactive Temperature” in this study. Thus, the hydrogenation of SiCl4 in the plasma could easily be handled with high conversion ratio and very high selectivity to trichlorosilane (SiHCl3). The effects of SiCl4/Ar and H2/Ar ratios on the conversion were also investigated using a mathematical model developed to determine the optimum experimental parameters. The highest hydrogenation conversion ratio was produced at a H2/SiCl4 molar ratio of 1, with mixtures of SiCl4 and H2 to Ar molar ratio of 1.2 to 1.4. In this plasma, the special system pressure and incident power were required for the highest energy efficiency of hydrogenating SiCl4, while the optimum system pressure varies from 26.6 to 40 kPa depending on input power, and the optimum feed gas (H2 and SiCl4) molar energy input was about 350 kJ·mol−1.

Enantioselective Double Aldol Reactions Involving the Sequential Activation of Silicon Tetrachloride by Chiral Phosphine Oxides

This account summarizes our recent studies on the development of phosphine oxide-catalyzed enantioselective double aldol reactions that extend hypervalent silicon chemistry by using a ­Lewis base catalyst. Chiral phosphine oxides repeatedly activate silicon ­tetrachloride and form hypervalent silicon complexes, thereby promoting sequential activation of substrates and realizing enantioselective double aldol reactions. The account describes several relevant applications of these reactions. 1 Introduction 2 General Concept of Sequential Catalysis by a Lewis Base 2.1 Lewis Base Catalysis with Chlorosilanes 2.2 Phosphine Oxides as Lewis Base Catalysts 3 Branched-Type Double Aldol Reactions 3.1 Enantioselective Branched-Type Double Aldol Reactions Catalyzed by Phosphine Oxides 3.2 Mechanism of the Branched-Type Double Aldol Reactions 3.3 Applications of the Branched-Type Double Aldol ­Reactions in Enantioselective Syntheses of 2,3-Dihydro­pyran-4-ones 4 Linear-Type Double Aldol Reactions 4.1 Enantioselective Linear-Type Double Aldol Reactions Catalyzed by Phosphine Oxides 4.2 Mechanism of the Linear-Type Double Aldol Reactions 4.3 Application of the Double Aldol Reactions to the Total Synthesis of (–)-Ericanone 5 Conclusions

A novel low temperature vapor phase hydrolysis method for the production of nano-structured silica materials using silicon tetrachloride

Download options Please wait... Supplementary files Supplementary information PDF (4894K) Article information DOI https://doi.org/10.1039/C3RA47018K Article type Paper Submitted 26 Nov 2013 Accepted 09 Jan 2014 First published 17 Jan 2014 Download Citation RSC Adv., 2014,4, 8703-8710 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions A novel low temperature vapor phase hydrolysis method for the production of nano-structured silica materials using silicon tetrachloride X. Chen, J. Jiang, F. Yan, S. Tian and K. Li, RSC Adv., 2014, 4, 8703 DOI: 10.1039/C3RA47018K To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Xuejing Chen Jianguo Jiang Feng Yan Sicong Tian Kaimin Li

Universal self-assembly of organosilanes with long alkyl groups into silicone nanofilaments

Recently, a new group of nanostructures called “silicone nanofilaments (SNs)” were prepared via polymerization of organosilanes with small alkyl groups. Organosilanes with long alkyl groups tend to form self-assembled monolayers and cannot form SNs because of their bulky steric hindrance. Here we report the one-step self-assembly of organosilanes with long alkyl groups into SN coatings at room temperature by using tetraethyl orthosilicate (TEOS) or tetrachlorosilane (TCS) as the molecular spacer. The SNs should grow according to a “limiting growth” mechanism via a “seeding-asymmetric growth-further growth” process. The growth of SNs could be controlled simply by the composition of the precursor and the water concentration (Cwater) in toluene. All the precursors studied can form SNs successfully under proper conditions, indicating universality of this method. The wettability of the SN coatings ranges from hydrophilic to superhydrophobic and even to superamphiphobic. Moreover, these coatings are transparent and can be easily applied onto various substrates besides the glass slide. This facile fabrication of SNs using organosilanes with long alkyl groups will shed light on their application in generating unique nanostructures besides self-assembled monolayers.

Synthesis and characterization of luminescent properties of ceramics derived from polysilylcarbodiimides

The luminescence properties related to the thermal polymer/ceramic conversion behavior of silicon dicarbodiimide {SDC, [Si(N=C=N)2]n} have been investigated. SDC was synthesized by the non-oxidic sol–gel condensation reaction of silicon tetrachloride with bis(trimethylsilyl)carbodiimide. As-synthesized SDC showed no luminescence under UV light, while heat-treated SDC showed an appreciable photoluminescence (PL) and the maximum visible PL emission intensity was achieved by heat treatment at 400°C. Even after the heat treatment up to 970°C, the SDC preserved most of the N=C=N groups to keep whitish gray color without distinct free carbon formation, and emitted visible blue luminescence. The 400°C-heat treated SDC exhibited the intense luminescence excited at 281 and 379 nm wavelengths, while there was no PL emission excited by the N=C=N group-derived host absorption at 214 nm. The PL properties of the heat-treated SDCs could be correlated with their preservation of the local structure including N=C=N groups and defects formation during the heat treatment. Moreover, Eu3+-modified SDC was prepared by the same sol–gel method using Eu(III) chloride as the Eu3+-source. The results of FT-IR and 29Si NMR spectroscopic analyses revealed a complex formation between the Eu(III) chloride and bis(trimethylsilyl)carbodiimide. As a result, the Eu3+-modified SDC exhibited a characteristic PL red emission at around 600 nm attributed to the f-f-transition of Eu3+.

Synthesis and characterization of uniform silica nanoparticles on nickel substrate by spin coating and sol–gel method

Spin coating and sol–gel methods are proposed for the preparation of silica nanoparticles on a nickel substrate using silicon tetrachloride, 2-methoxyethanol, and four different types of alkaline solutions. The effects of the type of alkaline solution, concentration of silica solution, and speed of spin coating on the properties of silica nanoparticles are investigated systematically. Uniform spherical shape of silica nanoparticles on Ni with the smallest size are obtained with sodium carbonate among the alkaline solutions after stirring at 70°C for 6h and spin-coating at 7000rpm. Physical and electrochemical properties of the silica particles are investigated.

Multifunctional Silicon Surfaces: Reaction of Dichlorocarbene Generated from Seyferth Reagent with Hydrogen-Terminated Silicon (111) Surfaces

Insertion of dichlorocarbene (:CCl2), generated by decomposition of the Seyferth reagent PhHgCCl2Br, into the Si-H bond of a tertiary silane to form a Si-CCl2H group is an efficient homogeneous, molecular transformation. A heterogeneous version of this reaction, between PhHgCCl2Br and a silicon (111) surface terminated by tertiary Si-H bonds, was studied using a combination of surface-sensitive infrared and X-ray photoelectron spectroscopies. The insertion of dichlorocarbene into surface Si-H bonds parallels the corresponding reaction of silanes in solution, to produce surface-bound dichloromethyl groups (Si-CCl2H) covering ∼25% of the silicon surface sites. A significant fraction of the remaining Si-H bonds on the surface was converted to Si-Cl/Br groups during the same reaction, with PhHgCCl2Br serving as a halogen atom source. The presence of two distinct environments for the chlorine atoms (Si-CCl2H and Si-Cl) and one type of bromine atom (Si-Br) was confirmed by Cl 2p, Br 3d, and C 1s X-ray photoelectron spectroscopy. The formation of reactive, halogen-terminated atop silicon sites was also verified by reaction with sodium azide or the Grignard reagent (CH3MgBr), to produce Si-N3 or Si-Me functionalities, respectively. Thus, reaction of a hydrogen-terminated silicon (111) surface with PhHgCCl2Br provides a facile route to multifunctional surfaces possessing both stable silicon-carbon and labile silicon-halogen sites, in a single pot synthesis. The reactive silicon-halogen groups can be utilized for subsequent transformations and, potentially, the construction of more complex organic-silicon hybrid systems.

Study of Materials for Drugs Delivery: cis-[PtCl2(NH3)2] Hydrolysis on Functionalized SiO2(100) Surfaces

The hydrolysis of the cis-platin drug on a SiO2(100) hydrated surface was investigated by computational modeling. The cisplatin molecule presents weak interactions with the neighbouring OH groups of the hydrated surface. The cisplatin hydrolysis is not favourable on the SiO2(100) surface. Consequently, the adsorption properties of SiO2(100) are improved considering the surface's modification with K, Mg, or NH2 functional species. In general, the system is more stable and the molecule-surface distance is reduced when cisplatin is adsorbed on the promoted surfaces. The hydrolysis is a favourable process on the SiO2(100) functionalized surfaces. The cisplatin hydrolysis is most favoured when the surface is functionalized with the NH2 specie. The electron density exchange plays a main role in the adsorption process. cis-[PtCl2(NH3)2] and cis-[PtCl(NH3)2]+ are adsorbed on the functionalized surface via Cl–N and Cl–Si interactions, while the cis-[Pt(NH3)2]2+ complex is adsorbed through Pt–O, Pt–Si, and Pt–H interactions. After adsorption, the strength of the N–Si, Si–O, and N–H superficial bonds of the functionalized SiO2(100) changes favouring the interaction between the molecule and their complexes with the surface.

Solvothermal synthesis of disordered mesoporous materials based on a Si–N framework in ionic liquids

Silicon–nitrogen network based porous materials have been synthesized by a novel method based on the preparation of silicon diimide gel by the ammonolysis of silicon tetrachloride using an ionic liquid as solvent followed by a heating process. The resulting materials contain ionic liquid molecules occluded inside the framework, which can be remove by heat treatment at 600°C under flowing ammonia leading to microporous and mesoporous materials with high surface areas. The pore size of the materials is tailored by the variation of the experimental conditions.STEM investigations reveal a disordered porous structure with pores with an average diameter of 10nm in the mesoporous samples. A N/Si molar ratio higher than 2 is obtained for all the ammonia-calcined materials and FTIR and XPS measurements indicate a high number of Si–NH groups, both in the bulk and on the materials surface.

Facile Access to Mono- and Dinuclear Heteroleptic N-Heterocyclic Silylene Copper Complexes

Reaction of the heteroleptic N-heterocyclic chlorosilylene L(Cl)Si: (1; L = PhC(NtBu)2) with [Cu(tmeda)(CH3CN)][OTf] (2; tmeda = N,N,N′,N′-tetramethylethylenediamine, OTf = OSO2CF3 (triflate)) affords the Cu(I) complex [L(Cl)Si:→Cu(tmeda)][OTf] (3) in high yield as the first example of a heteroleptic N-heterocyclic silylene copper complex. Similarly, the reaction of L(OtBu)Si: (4; L = PhC(NtBu)2) with 2 affords [L(OtBu)Si: → Cu(tmeda)][OTf] (5) and that of L(NMe2)Si: (6) with 2 leads to [L(NMe2)Si:→Cu(tmeda)][OTf] (7). Complex 3 shows a rather strong interaction in the solid state between the O atom of the triflate anion and the three-coordinate Cu(I) center with a Cu···O distance of 2.312 A. In contrast, complex 7 features only a weak interaction (ca. 3.28 A), while in complex 5 the cation and anion are fully separated. Strikingly, the reaction of the chelating oxo-bridged silylene :Si(L)(μ2-O)(L)Si: (8) with the copper source [Cu(CH3CN)4][OTf] (9) affords the dinuclear complex salt [Cu2{η1:η1-LSi(μ2-O)S...

Effects of zero-valent metals together with quartz sand on the mechanochemical destruction of dechlorane plus coground in a planetary ball mill

Mechanochemical destruction by grinding with additives in high energy ball milling has been identified as a good alternative to traditional incineration for the disposal of wastes containing halogenated organic pollutants. Despite CaO normally used as an additive, recently Fe+SiO2 has been used to replace CaO for a faster destruction. In the present study, zero-valent metals (Al, Zn, besides Fe) together with SiO2 were investigated for their efficiencies of prompting the destruction of dechlorane plus (DP). Aluminum was found of be the best with a destruction percentage of nearly 99% for either syn- or anti-DP after 2.5h milling. In comparison, only 88/85% and 37/32% of syn-/anti-DP were destroyed when using zinc and iron after the same time, respectively. The detected water soluble chloride was lower than the stoichiometric amount containing in the original DP samples, due to the Si–Cl bond formed during the process. The potential fate of C and Cl present in DP is in the form of inorganic carbon, inorganic Cl and formation of Si–Cl bonds, respectively. The results suggested that Al+SiO2 is promising in the mechanochemical destruction of chlorinated organic pollutants like DP.

Hybrid Silicon Nanocrystal/Poly(3-hexylthiophene-2,5-diyl) Solar Cells from a Chlorinated Silicon Precursor

Freestanding silicon nanocrystals (Si NCs) synthesized by a nonthermal plasma from silicon tetrachloride (SiCl4) were successfully employed in hybrid Si NC/poly(3-hexylthiophene-2,5-diyl) (P3HT) bulk-hetrojunction (BHJ) solar cells. The weight fraction of Si NCs in P3HT greatly influences device performance. As the weight fraction increases up to 50 wt %, short-circuit current dramatically increases, while open-circuit voltage (Voc) and fill factor (FF) do not change significantly. The improvement in device performance is attributed to both increased probability of exciton dissociation in P3HT and an enhancement in the light conversion of wavelengths where P3HT is a poor absorber. These results demonstrate an alternative approach to synthesizing Si NCs from SiCl4 instead of silane (SiH4) for optoelectronic devices.

Formation of a 1,4-Diamino-2,3-disila-1,3-butadiene Derivative

A 1,4-diamino-2,3-disila-1,3-butadiene derivative of composition (Me2-cAAC)2(Si2Cl2) (Me2-cAAC = :C(CMe2)2(CH2)N-2,6-iPr2C6H3) was synthesized by reduction of the Me2-cAAC:SiCl4 adduct with KC8. This compound is stable at 0 °C for 3 months in an inert atmosphere. Theoretical studies reveal that the silicon atoms exhibit pyramidal coordination, where the Cl-Si-Si-Cl dihedral angle is twisted by 43.3° (calcd 45.9°). The two silicon-carbon bonds are intermediates between single and double Si-C bonds due to twisting of the C-Si-Si-C dihedral angle (163.6°).

Enantioselective Morita–Baylis–Hillman reaction catalyzed by a chiral phosphine oxide

An application of a hypervalent silicon complex, generated from a chiral phosphine oxide catalyst and silicon tetrachloride, to the enantioselective organocatalytic Morita–Baylis–Hillman reaction is described. A chloride anion liberated from the hypervalent silicon complex smoothly generated a γ-chloro silyl enol ether that subsequently reacted with an aldehyde to afford the Baylis–Hillman adducts in good yields and with good enantioselectivities.

ChemInform Abstract: Reactions of a Stable Dialkylsilylene and Their Mechanisms

AbstractReview: 131 refs.

Large-scale preparation of SiBN ceramic fibres from a single source precursor

Large-scale production of SiBN ceramic fibres was achieved by the pyrolysis of N-methylpolyborosilazane. This precursor was prepared by a three-step synthesis starting from hexamethyldisilazane (HMDS), silicon tetrachloride (STC), boron trichloride (BTC), and methylamine. To prove the feasibility of the synthesis on both the large and laboratory scales, the structure and composition of the as-synthesised polymer was characterised by Fourier transform infrared (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy and elemental analysis (EA). Differential scanning calorimetry (DSC) showed that the obtained large-scale polymer had a wide glass transition temperature range (32°C to 50°C) and a low transition temperature (40.41°C), making it suitable for melt spinning. Both the large- and lab-scale synthesised polymers were successfully processed into polymer green fibres by a melt spinning process under an inert atmosphere, as the synthesised polymer is air and moisture sensitive. Endless and crack-free green fibres above 1000m in length were successfully collected on a rotating spool, followed by cross-linking and thermolysis up to 1000°C in an ammonia atmosphere. The SiBN ceramic fibres are amorphous up to 1600°C in a nitrogen atmosphere. The presented results emphasise a feasible approach to highly thermally stable SiBN ceramic fibres on a large scale starting from a greatly flexible single-source precursor.

Size Controlled Synthesis of Silicon Nanocrystals Using Cationic Surfactant Templates

Alkyl-terminated silicon nanocrystals (Si NCs) are synthesized at room temperature by hydride reduction of silicon tetrachloride (SiCl₄) within inverse micelles. Highly monodisperse Si nanocrystals with average diameters ranging from 2 to 6 nm are produced by variation of the cationic quaternary ammonium salts used to form the inverse micelles. Transmission electron microscopy imaging shows that the NCs are highly crystalline, while FTIR spectra confirm that the NCs are passivated by covalent attachment of alkanes, with minimal surface oxidation. UV-vis absorbance and photoluminescence spectroscopy show significant quantum confinement effects, with moderate absorption in the UV spectral range, and a strong blue emission with a marked dependency on excitation wavelength. The photoluminescence quantum yield (Φ) of the Si NCs exhibits an inverse relationship with the mean NC diameter, with a maximum of 12% recorded for 2 nm NCs.