Organosilicon Research Articles

Study of the impurity composition of silicon tetrachloride by gas chromatography-mass-spectrometry

Silicon tetrachloride is a sought-after substance in the semiconductor and optoelectronics industries. High demands placed on its purity entail the need for detail information about the impurities present. The impurity composition of silicon tetrachloride obtained by different technologies (chlorination of diatomite and charcoal, disproportionation of trichlorosilane and chlorination of isotopically enriched silicon) was studied using the method of chromatography-mass spectrometry. Study of the possibility of using a DB-5MS 30 m × 0.32 mm × 0.25 μm capillary column with methylsiloxane as a stationary liquid phase to separate impurities revealed that most of the identified substances are eluted in the form of separate chromatographic peaks, which simplifies their determination. The exceptions are impurities N2, O2, Ar, as well as CO2, SiF4, and CHClF2, HCl, H2S. They were registered using the characteristic peaks of the mass spectra. To identify impurities, experimental mass spectra were compared to data from the NIST library and those known from the literature. Information on the impurity composition of SiCl4 has been expanded. It contains permanent gases, aliphatic and chlorine-containing hydrocarbons, chlorides of elements, sulfur-containing substances, and organosilicon compounds. A total of 30 compounds are identified, 19 being discovered for the first time. The mass spectrum of C2H6Cl4OSi2, which is absent in the literature, was obtained and described. For the first time, data on the impurity composition of isotopically enriched silicon tetrachloride have been obtained. A comparative analysis of the impurity composition of the samples under study was carried out and the impurities characteristic of each of them were determined. The data obtained in the study can be used in developing the technology for deep purification of silicon tetrachloride and in characterization of SiCl4 by manufacturing enterprises.

On-Surface Synthesis of Silole and Disila-Cyclooctene Derivatives.

The incorporation of Si atoms into organic compounds significantly increases a variety of functionality, facilitating further applications. Recently, on-surface synthesis was introduced into organosilicon chemistry as 1,4-disilabenzene bridged nanostructures were obtained via coupling between silicon atoms and brominated phenyl groups at the ortho position on Au(111). Here, we demonstrate a high generality of this strategy via syntheses of silole derivatives and nanoribbon structures with eight-membered sila-cyclic rings from dibrominated molecules at the bay and peri positions on Au(111), respectively. Their structures and electronic properties were investigated by a combination of scanning tunneling microscopy/spectroscopy and density functional theory calculations. This work demonstrates a great potential to deal with heavy group 14 elements in on-surface silicon chemistry.

On‐Surface Synthesis of Silole and Disila‐Cyclooctene Derivatives

AbstractThe incorporation of Si atoms into organic compounds significantly increases a variety of functionality, facilitating further applications. Recently, on‐surface synthesis was introduced into organosilicon chemistry as 1,4‐disilabenzene bridged nanostructures were obtained via coupling between silicon atoms and brominated phenyl groups at the ortho position on Au(111). Here, we demonstrate a high generality of this strategy via syntheses of silole derivatives and nanoribbon structures with eight‐membered sila‐cyclic rings from dibrominated molecules at the bay and peri positions on Au(111), respectively. Their structures and electronic properties were investigated by a combination of scanning tunneling microscopy/spectroscopy and density functional theory calculations. This work demonstrates a great potential to deal with heavy group 14 elements in on‐surface silicon chemistry.

Activation of water at disiladicarbene: from the perspective of modification of silicon surface with organo-silicon compounds

Activation of water at disiladicarbene: from the perspective of modification of silicon surface with organo-silicon compounds

Enantioselective Vinylogous Mukaiyama‐Michael Reaction of Silyl Ketene Acetals to α,β‐Unsaturated 2‐Acyl Imidazoles to Construct 1,7‐dioxo Compounds

AbstractThe synthesis of chiral 1,7‐dioxo compounds via Sc(III)‐pybox catalyzed vinylogous Mukaiyama‐Michael reaction of vinyl ketene silyl acetals with α,β‐unsaturated 2‐acyl imidazoles has been described. This innovative approach to the formation of chiral 1,7‐dioxo compounds illustrates excellent regio‐, and enantioselectivities, demonstrating a broad substrate scope. So far, to the best of our knowledge, this is the first example of a metal‐catalyzed asymmetric vinylogous Mukaiyama‐Michael reaction using vinyl ketene silyl acetals.

Evolved enzyme breaks silicon-carbon bond

Evolved enzyme breaks silicon-carbon bond

Silyl Radical Generation from Silylboronic Pinacol Esters through Substitution with Aminyl Radicals.

A novel strategy was developed to generate silyl radicals from silylboronic pinacol esters (SPEs) through nucleohomolytic substitution of boron with aminyl radicals. We successfully applied this strategy to obtain diverse organosilicon compounds using SPEs and N-nitrosamines under photoirradiation without any catalyst. The ability to access silyl radicals offers a new perspective for chemists to rapidly construct Si-X bonds.

Directed evolution of enzymatic silicon-carbon bond cleavage in siloxanes.

Volatile methylsiloxanes (VMS) are man-made, nonbiodegradable chemicals produced at a megaton-per-year scale, which leads to concern over their potential for environmental persistence, long-range transport, and bioaccumulation. We used directed evolution to engineer a variant of bacterial cytochrome P450BM3 to break silicon-carbon bonds in linear and cyclic VMS. To accomplish silicon-carbon bond cleavage, the enzyme catalyzes two tandem oxidations of a siloxane methyl group, which is followed by putative [1,2]-Brook rearrangement and hydrolysis. Discovery of this so-called siloxane oxidase opens possibilities for the eventual biodegradation of VMS.

Preparation and Characterization of Composites Based on ABS Modified with Polysiloxane Derivatives.

In this study, organosilicon compounds were used as modifiers of filaments constituting building materials for 3D printing technology. Polymethylhydrosiloxane underwent a hydrosilylation reaction with styrene, octadecene, and vinyltrimethoxysilane to produce new di- or tri-functional derivatives with varying ratios of olefins. These compounds were then mixed with silica and incorporated into the ABS matrix using standard processing methods. The resulting systems exhibited changes in their physicochemical and mechanical characteristics. Several of the obtained composites (e.g., modified with VT:6STYR) had an increase in the contact angle of over 20° resulting in a hydrophobic surface. The addition of modifiers also prevented a decrease in rheological parameters regardless of the amount of filler added. In addition, comprehensive tests of the thermal decomposition of the obtained composites were performed and an attempt was made to precisely characterize the decomposition of ABS using FT-IR and optical microscopy, which allowed us to determine the impact of individual groups on the thermal stability of the system.

UV-LASER adjuvant-surfactant-facilitated delivery of mobile dsRNA to tomato plant vasculature and evidence of biological activity by gene knockdown in the potato psyllid.

Double-stranded RNA (dsRNA) biopesticides are of interest for the abatement of insect vectors of pathogenic bacteria such as 'Candidatus Liberibacter', which infects both its psyllid and plant hosts. Silencing of genes essential for psyllids, or for Liberibacter, is anticipated to lead to mortality or impeded bacterial multiplication. Foliar delivery is preferred for biopesticide application; however, the cuticle impedes dsRNA penetration into the vasculature. Here, conditions were established for wounding tomato leaves using ultraviolet light amplification by stimulated emissions of radiation (UV-LASER) to promote dsRNA penetration into leaves and vasculature. UV-LASER treatment with application of select adjuvants/surfactants resulted in vascular delivery of 100-, 300- and 600-bp dsRNAs that, in general, were correlated with size. The 100-bp dsRNA required no pretreatment, whereas 300- and 600-bp dsRNAs entered the vasculature after UV-LASER treatment only and UV-LASER adjuvant/surfactant treatment, respectively. Of six adjuvant/surfactants evaluated, plant-derived oil combined with an anionic organosilicon compound performed most optimally. Localization of dsRNAs in the tomato vasculature was documented using fluorometry and fluorescence confocal microscopy. The biological activity of in planta-delivered dsRNA (200-250 bp) was determined by feeding third-instar psyllids on tomato leaves post UV-LASER adjuvant/surfactant treatment, with or without psyllid cdc42- and gelsolin dsRNAs. Gene knockdown was quantified by quantitative, real-time polymerase chain reaction with reverse transcription (RT-qPCR) amplification. At 10 days post the ingestion-access period, knockdown of cdc42 and gelsolin expression was 61% and 56%, respectively, indicating that the dsRNAs delivered to the tomato vasculature were mobile and biologically active. Results indicated that UV-LASER adjuvant/surfactant treatments facilitated the delivery of mobile, biologically active dsRNA molecules to the plant vasculature. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Metal and metal oxide particles as modifiers for effective layer melting and Z-axis strength in 3D printing

This work concerns research on the use of inorganic chemical compounds Fe2O3, Fe3O4, and Al and organosilicon modifiers used as additives controlling the properties of PLA for material extrusion in 3D printing technology. The addition of inorganic compounds reduces the temperature at the beginning of the composite decomposition, which is related to the presence of metal and metal oxides. An effect of inhibition of catalytic activity was also noticed as a result of the addition of organosilicon compounds. An increase in the melt flow index parameter was observed, making improving the extrusion and 3D printing process possible. The presence of inorganic additives results in a better fusion of the print paths, which leads to reduced structure defects and better interlayer adhesion. The tensile strength of the obtained composite samples decreases with the increase in the concentration of the metal and metal oxides. The addition of organosilicon substances increases the tensile strength regardless of the inorganic compound concentration. The highest increase in tensile strength was obtained for the PLA/12.5% Fe3O4/OSS-5OD-3TMOS sample and it was 24.35% compared to the sample without the addition of organosilicon compounds. The use of organosilicon additives resulted in an increase in the water contact angle.

ГИДРОФОБНЫХ ПОВЕРХНОСТНЫХ СОЕДИНЕНИЙ МЕТАЛЛОВ ТВЕРДОТЕЛЬНЫМ СИНТЕЗОМ С ПРИМЕНЕНИЕМ КРЕМНИЙГИДРИДНЫХ РЕАГЕНТОВ

A study of the formation of hydrophobic properties of dispersed metal samples (Ni, Fe, Cu, Al) obtained by different methods was carried out. The methods used are based on chemical processes, including chemisorption and reduction, during the interaction of a solid with gaseous modifier substances. The time dependence in the interval 24-216 (h) of the sorption of water (a) from saturated vapor on samples of copper powder (PMS-1) coated with ammonium preparations (Triamon and Alkamon) was studied. For the first time, the dependence of the sorption rate da/dt for the named samples was obtained and approximated by an equation based on the Gaussian function. Using XPS spectroscopy, structural changes in the surface of modified dispersed aluminum (PAP-2) were revealed upon interaction with water vapor. The binding energies of the O1s oxygen peaks (531.2; 531.5 eV), reflecting this interaction, were determined and assigned. There is no noticeable oxidation of aluminum on the surface. It was revealed that after 10 days of interaction with saturated water vapor, the proportion of aluminum atoms on the surface of the powder modified with vapors of organosilicon liquid based on ethyl hydride siloxane increases. It is assumed that the observed effect is due to the “pushing out” of water molecules from the hydrophobized surface during prolonged treatment, which is confirmed by the graph of the experimental dependence a=f(t). The higher hydrophobicity of metal products of solid- state hydride synthesis compared to industrial nickel and copper powders modified from the gas phase with known water-repellent agents based on ammonium and organosilicon compounds was experimentally confirmed. An explanation was proposed for the decrease in nonlinear effects in the time dependences of a(t) for dispersed metals – products of solid-state hydride synthesis.

Recent developments in difunctionalization of unsaturated hydrocarbons with organosilicon reagents.

Organosilicon compounds have attracted considerable attention because of their special biological activities. Direct difunctionalization of unsaturated hydrocarbons with organosilicon reagents for the efficient construction of synthetically valuable silicon-functionalized compounds are featured with a high step and atom economy, which could form carbon-silicon/carbon-carbon bonds or carbon-silicon/carbon-hetero bonds in one step. This review summarizes the recent advances on this topic based on different unsaturated hydrocarbons along with typical examples and mechanisms.

INTERRELATION OF BIOLOGICAL ACTIVITY AND CALCULATED PARAMETERS OF NITRILSILANES AND NITRILSILOXANES

The processes of oil production, transport, refining are time-bound, which is fraught with sludge and storage, which is the cause of microbiological corrosion. The geometric, electronic and energy parameters of previously synthesized organosilicon nitriles and the manifestation of their antimicrobial activity are studied, and some regularities of their physicochemical properties are established. It was found that heteroatomic compounds containing silicon atoms in their composition have a high and effective fungicidal activity, inhibiting the growth of fungi and plants, as well as minimal toxicity. It has been established that the effect of the studied compounds can last up to several weeks, in contrast to the currently used drugs of biological action during the storage and transportation of petroleum oils. The results of the physicochemical parameters of a number of nitrilesilanes and nitrilesiloxanes calculated by the DFT method with the B3LYP/6-31G(d,p) functional are presented. The studied compounds are highly reactive, and in this work the biological activities of a number of organosilicon nitriles have been experimentally established. Based on the calculated and experimental data obtained, the relationship between the energies of the boundary molecular orbitals (depending on the electronic structure) and the antimicrobial properties of the presented nitrile silanes and nitrile siloxanes were established. It has been shown that a number of studied organosilicon compounds, especially nitrile siloxanes, are superior in bactericidal activity to the biocide sodium pentachlorophenolate. When compiling a 3D function graph, the average deviation of the results of mathematical calculations from the results of a biological experiment was a maximum of 23%. It has been established that the most effective of the given compounds of a number of organosilicon nitrile silanes and nitrile siloxanes can be widely used in industry and can be recommended as biocidal additives for lubricating oils and other lubricating and cutting fluids and materials.

DIPEA-induced Si-H Activation of Siloxane for Hydrosilylation Polymerization via Metal-Free Photocatalysis

Although metal-free hydrosilylation of siloxanes is essential for the industrial preparation of organosilicon compounds due to its unique advantages, such as the avoidance of the use and residue of precious...

X-type silyl ligands for transition-metal catalysis.

Given the critical importance of novel ligand development for transition-metal (TM) catalysis, as well as the resurgence of the field of organosilicon chemistry and silyl ligands, to summarize the topic of X-type silyl ligands for TM catalysis is highly attractive and timely. This review particularly emphasizes the unique σ-donating characteristics and trans-effects of silyl ligands, highlighting their crucial roles in enhancing the reactivity and selectivity of various catalytic reactions, including small molecule activation, Kumada cross-coupling, hydrofunctionalization, C-H functionalization, and dehydrogenative Si-O coupling reactions. Additionally, future developments in this field are also provided, which would inspire new insights and applications in catalytic synthetic chemistry.

Organocatalytic enantioselective construction of Si-stereocenters: recent advances and perspectives.

Silicon-stereogenic chiral organosilanes have found increasing applications in synthetic chemistry, medicinal chemistry, and materials science. In this context, various asymmetric catalytic methods have been established for the diverse synthesis of silicon-stereogenic silanes. In particular, asymmetric organocatalysis is emerging as an important and complementary synthetic tool for the enantioselective construction of silicon-stereocenters, along with the rapid development of chiral-metal catalyzed protocols. Its advent provides a powerful platform to achieve functionalized silicon-stereogenic organosilanes with structural diversity, and should lead to great development in chiral organosilicon chemistry. In this Tutorial Review, we highlight these latest achievements from two aspects: desymmetrizations of prochiral tetraorganosilanes and dynamic kinetic asymmetric transformations of racemic organosilanes by employing five organocatalytic activation modes. The advantages, limitations and synthetic value of each protocol, as well as the synthetic opportunities still open for further exploration, are also discussed.

The role of silicon in drug discovery: a review.

This review aims to highlight the role of silicon in drug discovery. Silicon and carbon are often regarded as being similar with silicon located directly beneath carbon in the same group in the periodic table. That being noted, in many instances a clear dichotomy also exists between silicon and carbon, and these differences often lead to vastly different physiochemical and biological properties. As a result, the utility of silicon in drug discovery has attracted significant attention and has grown rapidly over the past decade. This review showcases some recent advances in synthetic organosilicon chemistry and examples of the ways in which silicon has been employed in the drug-discovery field.

Photo-initiated thiol-ene reaction of multi-functional thiol and olefinic organosilicon compounds leading to porous polymers: Solution polymerization and photolithography

Photo-initiated thiol-ene reaction between multi-functional thiol compounds and unsaturated organosilicon compounds in ethanol/dimethyl sulfoxide mixed solvent successfully yielded porous polymers. The morphology of the porous polymer was formed by connected particles, whose diameters ranged from 1 to 6 μm. An increase in the number of thiol group of multi-functional thiol compounds decreased the particle size and increased the Young's modulus of the porous polymers. Porous polymers absorbed various organic solvents and showed high water repellency. Photolithography based on the thiol-ene reaction led to the patterning by the porous polymers.

Gold nanoparticles supported on reduced graphene oxide as green catalyst for solventless hydrosilylation process

The hydrosilylation reaction is a versatile process that is used to synthesize a variety of organosilicon compounds. However, the traditional metal oxide catalysts used for this reaction suffer from low activity and selectivity. In this study, we synthesized and characterized a gold nanoparticles (AuNPs)-reduced graphene oxide (rGO) catalyst for the hydrosilylation reaction. The AuNPs-rGO catalyst was synthesized by a one-pot method using trisodium citrate (Na3C6H5O7) as a reducing and capping agent. The catalyst was characterized by XRD, FESEM, and FTIR. The hydrosilylation reaction was carried out under solventless conditions using dimethylphenylsilane as the substrate. The AuNPs-rGO catalyst was found to be highly active and selective for the hydrosilylation reaction, yielding a 100% conversion of the substrate to disiloxane in 3 hours. The results of this study demonstrate the potential of AuNPs-rGO catalysts for the hydrosilylation reaction and suggest that they could be used to develop more efficient and sustainable processes for the synthesis of organosilicon compounds.