Synthesis Of Organosilicon Compounds Research Articles

Dimethylcyclosiloxanes in Mobile Smart Terminal Devices: Concentrations, Distributions, Profiles, and Environmental Emissions.

Dimethylcyclosiloxanes (DMCs) are utilized as vital monomers in the synthesis of organosilicon compounds, integral to the manufacture of mobile smart terminal devices. Toxicological studies have revealed potential endocrine-disrupting activity, reproductive toxicity, neurotoxicity, and other toxicities of the DMCs. This study investigated the concentrations and composition profiles of seven DMCs, including hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and tetradecamethylcycloheptasiloxane (D7), hexadecamethylcyclooctasiloxane (D8), and octadecamethylcyclononasiloxane (D9) in three types of mobile smart terminal device components (silicone rubber, adhesive, and plastics). Environmental emissions of DMCs from silicone rubber materials were also estimated to improve the recognition of their potential fate within the environment. D5-D9 were widely present in silicone rubber and adhesives with detection rates ranging from 91-95.5% and 50-100%, respectively, while D3 and D4 were more frequently detected in plastics, both showing a detection rate of 61.1%. Silicone rubber had the highest total DMCs (∑7DMCs) and a concentration of 802.2 mg/kg, which were dominated by D7, D8, and D9. DMCs detected in adhesives were dominated by D4, D5, and D6. The estimated emission of ∑DMCs released into the environment in China from silicone rubber used in mobile smart terminal devices exceeds 5000 tons per year. Further studies are needed on the presence of DMCs in various commodities and environmental media to assess their ecological and human health impacts, as well as the toxicological effects of D7-D9 for the appropriate regulation of these chemicals.

Synthesis of Organosilicon Polymers Based on Carbamide Formaldehyde Resin

The article presents the synthesis of organosilicon compounds based on industrial secondary raw materials of urea-formaldehyde resin and tetraethoxysilane. The structural characteristics of the synthesized hydrophobic polymer have been studied. Compositions of hydrophobic compositions based on synthesized poly (oligomers) have been developed and tested in concrete mixtures.

Metal-Free Hydrosilylation Polymerization by Merging Photoredox and Hydrogen Atom Transfer Catalysis.

Organosilicon compounds and polymers have found wide applications as synthetic building blocks and functional materials. Hydrosilylation is a common strategy toward the synthesis of organosilicon compounds and polymers. Although transition-metal-catalyzed hydrosilylation has achieved great advances, the metal-free hydrosilylation polymerization of dienes and bis(silane)s, especially the one suitable for both electron-rich and electron-deficient dienes, is largely lacking. Herein, we report a visible-light-driven metal-free hydrosilylation polymerization of both electron-rich and electron-deficient dienes with bis(silane)s by using the organic photocatalyst and hydrogen atom transfer (HAT) catalyst. We achieved the well-controlled step-growth hydrosilylation polymerizations of the electron-rich diene and bis(silane) monomer due to the selective activation of Si-H bonds by the organic photocatalyst (4CzIPN) and the thiol polarity reversal reagent (HAT 1). For the electron-deficient dienes, hydrosilylation polymerization and self-polymerization occurred simultaneously in the presence of 4CzIPN and aceclidine (HAT 2), providing the opportunity to produce linear, hyperbranched, and network polymers by rationally tuning the concentration of electron-deficient dienes and the ratio of bis(silane)s and dienes to alter the proportion of the two polymerizations. A wide scope of bis(silane)s and dienes furnished polycarbosilanes with high molecular weight, excellent thermal stability, and tunable architectures.

A New Strategy for the Synthesis of Organosilicon Compounds of Cyclopropane Derivatives

The one-pot reaction of tetra-substituted cyclopropyl benzyl bromide with tris(trimethylsilyl)methyllithium (TsiLi) and carbon disulfide resulted in 3-(4-((((trimethylsilyl)ethynyl)thio)methyl)phenyl)cyclopropane-1,1,2,2-tetracarbonitrile (3) and 3-(4-((trimethylsilyl)methyl)phenyl)cyclopropane-1,2-dicarbonitrile (4) in excellent yield. The reaction in the absence of carbon disulfide yielded 3-(4-(2,2,2-tris(trimethylsilyl)ethyl)phenyl)cyclopropane-1,1,2,2-tetracarbonitrile (5) in excellent yield at 0°C to room temperature. All structures were characterised by IR, 1H NMR, and 13C NMR spectroscopies. The reaction mechanisms are discussed.

Recent advances in synthesis of organosilicons via radical strategies

Organosilicon compounds play an important role in the fields of materials science, pharmacy, and organic synthesis. The development of effective approaches for the preparation of these compounds have also become a research focus in organic synthesis. In recent years, free radical synthesis of organosilicons has been vigorously developed, which generally has the advantages of milder synthesis conditions, higher yields and selectivity, and free of precious metal catalysts compared with traditional strategies. This article reviews research progresses in the synthesis of organosilicon compounds by free radical pathways since 2016. In most cases, the radical silylation is achieved based on the reaction of silyl radicals, which are triggered by four routes including peroxide, transition-metal-induced peroxide decomposition, alkali, photocatalysis. The alkyl radicals can also initiate the radical silylation for the generation of C(sp3)Si bonds.

James Mason Crafts

James Mason Crafts (1865-1927), an American mining engineer, is best know for his co-discovery of the Friedel-Crafts reaction, a powerful organic synthesis tool. He did basic work on the synthesis of organo-silicon compounds, determined the atomic weight of silicon, and published extensively on thermometry, on the calibration of thermometers, and proposed naphthalene and benzophenone as new fixed points for the thermometric scale in the range 100° to 400°C.

ChemInform Abstract: Synthesis of Organosilicon Compounds as Synthetic Equivalents of Unstable Active Chemical Species and Their Applications to Highly Selective Synthesis of Heterocycles

Various organosilicon compounds act as synthetic equivalents of unstable active chemical species, especially novel 1, 3-dipolar reagents such as azomethine ylides, thiocarbonyl ylides and related reagents, are designed and synthesized. These compounds activated by a Lewis acid or fluoride ion react with a variety of dipolarophiles and hetero-dipolarophiles in highly regio- and stereospecific mode. It has been found that this methodology can be extended to the design and preparations of tailor-made 1, 3-dipolar reagents. The highly selective synthesis of heterocycles are described.

Synthesis of Organosilicon Compounds by New Direct Reactions

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of organosilicon compounds with a carboranylmethyl radical

The methods of synthesizing C-mono and C, C′-bis [alkoxy(organo)silylmethyl]- o( m)-carboranes by the reaction between the corresponding lithium carboranes and chloromethyl(organo)alkoxysilanes have been developed. Various C-mono- and C, C′-bis[chloro- and hydroxy(organo)silylmethyl]- o( m)-carboranes have been obtained from these compounds and their properties have been studied.

Synthesis of organosilicon compounds containing cyclopentyl, cyclofentenyl, and cyclopentadienyl groups

1. When a mixture of cyclopentadiene and trichlorosilane is heated for a short time in a flow apparatus at 550° and atmospheric pressure, trichloro-2-cyclopenten-1-ylsilane is formed. The same compound is formed also in the liquid-phase catalytic reaction between cyclopentadiene and trichlorosilane. 2. A new method is proposed for the preparation of trichlorocyclopentadienylsilane by the pyrolysis of trichloro(2,3-dichlorocyclopentyl)silanes.

Synthesis of organosilicon compounds. 13. The bromination of o-, m-, and p-(trimethylsilyl)benzoic acids

Synthesis of organosilicon compounds. 13. The bromination of o-, m-, and p-(trimethylsilyl)benzoic acids

Synthesis of organosilicon compounds. XI. On the reaction of p- and m-(trimethylsilyl)chlorobenzene with electrophilic reagents

Reaction of p-(trimethylsilyl)- (IV) and m-(trimethylsilyl)chlorobenzene (V) with various electrophilic reagents was examined. Bromination, nitration with acetyl nitrate, and Friedel-Crafts acylation of IV respectively afforded p-bromo-chlorobenzene, p-chloro-nitrobenzene, and p-chloro-acylphenone. Nitration of V resulted in substitution of the chlorine in paraposition with a nitro group to produce 2-(trimethylsilyl)-4-chloro-nitrobenzene (VII), which was reduced to 2-(trimethylsilyl)-4-chloroaniline (VIII) and further decomposed by acid to p-chloroaniline. Bromination and Friedel-Crafts acylation of V do not result in substitution of the chlorine in para-position and desilylation occurs in meta-position to produce m-bromo-chlorobenzene and m-chloro-acylphenone. Such a reaction does not occur in other meta-substituted (trimethylsilyl)benzenes. It is assumed that such independence of the substituent position from the +M effect of the functional group and desilylation by electrophilic reagents occurring solely by the + I effect of the trimethylsilyl group would appear as the +M effect of the functional group becomes smaller.

Synthesis of organosilicon compounds with phenylene carbonic and phenylene siloxane groups and their thermal analysis

1. 1. From di-(methylphenyl)- p-phenylene-disilanes, in which the silicon atoms were combined with bromine, vinyl radicals or hydrogen atoms, silophenylenes of the following general formula were obtained ▪ where A is an oxygen bridge or group (CH 2) n , n from 1 to 3. 2. 2. The heating curves of the silophenylenes obtained which were recorded in air in a Kurnakov pyrometer, showed that the 1,4- bis-(tetramethylphenyldisiloxy)-benzene compound in which, in addition to the phenylene bridge, two siloxane groups are contained, has the highest initial degradation temperature.

Synthesis of organosilicon compounds with phenylene carbon links

Synthesis of organosilicon compounds with phenylene carbon links

Studies in IVth group organometallic chemistry. IX: Synthesis of organosilicon compounds and polymers containing the p‐Phenylene Group

AbstractA number of oligomeric p‐phenylenesilanes containing 2‐6 silicon atoms per molecule and a series of low molecular weight poly‐p‐phenylenesilanes (n = 10‐30) have been prepared by Wurtz‐type condensation reactions involving appropriate combinations of p‐chlorophenyl‐ and chloro‐silanes. The polymeric products have been characterized by infrared spectroscopy, analytical and thermogravimetric data, and number‐average molecular weights, the low value of which is presumably caused by participation of the solvent (toluene) in the reaction. The polymers started to lose weight at temperatures varying from 310 to 485°.

Synthesis of organosilicon compounds containing phenylenesiloxane molecular chains

1. A linear organosilicon compound with a phenylenesiloxane chain and a cyclic phenylenebis(hydroxyphenylsilyl) dioxide was synthesized. 2. A bisheterocyclic compound was isolated.

Synthesis of organo silicon compounds from p-dibromobenzene

1. The reaction of magnesium with p-dibromobenzene and chlorotrimethylsilane was investigated and it was shown that there is simultaneous formation of p-bromophenyltrimethylsilane and p-bistrimethylsilylbenzene in the proportions of 4.4∶1. 2. The new compounds, p-bromophenylchloromethylphenylsilane and p-bromophenylethoxymethylphenylsilane, were synthesized.

Synthesis of orga nosilicon compounds containing the methacryloyl group

1. By reaction between potassium methacrylate and alkoxy(chloromethyl)silanes five new organosilicon compounds were obtained: ettioxy- and butoxy-(methacryloyloxymethyl)dimethylsilanes, diethoxy- and dibutoxy-(methacryloyloxymethyl) methylsilanes, and tributoxy(methacryloyloxymethyl)silane. 2. An investigation was made of the heterofunctional cocondensation of ethoxy(methacryloyloxymethyl)-methylsilanes with diacetoxydimethylsilane and its polymerization products and with acetoxytrimethylsilane. It was shown that the process proceeds with formation of ethyl acetate and methacryloyl organosilicon compounds. 3. Four new organosilicon compounds were prepared by this reaction: 1,5-bis(methacryloyloxymethyl)-hexamethyltrisiloxane, 1,7-bis(methacryloyloxymethyl)octamethyltetrasiloxane, 1,9-bis(methacryloyloxymethyl)-decamethylpentasiloxane, and 3 -(methacryloyloxymethyl)heptamethyltrisiloxane.

有機珪素化合物の合成 (第3報)

有機珪素化合物の合成 (第3報)

有機珪素化合物の合成 (第1報)

有機珪素化合物の合成 (第1報)