Trimethylsilane Research Articles

Palladium-Catalyzed Conversion of Benzylic and Allylic Halides into α-Aryl and β,γ-Unsaturated Tertiary Amides by the Use of a Carbamoylsilane

[reaction: see text] Treatment of allylic and benzylic halides with N,N-dimethylcarbamoyl(trimethyl)silane in the presence of tetrakis(triphenylphosphine)palladium(0) affords tertiary amides, which arise from the replacement of the halogen by the N,N-dimethylcarbamoyl group.

Photochemical synthesis of ultrafine organosilicon particles from trimethyl(2-propynyloxy)silane and carbon disulfide

Under light irradiation at 313 nm with a medium-pressure mercury lamp, a gaseous mixture of trimethyl(2-propynyloxy)silane (TMPSi) and carbon disulfide (CS 2) produced sedimentary aerosol particles. From measurement of monitor (He–Ne laser) light intensity scattered by the aerosol particles, it was shown that the nucleation process of the aerosol particles was accelerated with increasing partial pressure of TMPSi. Analysis of FT-IR and X-ray photoelectron spectra (XPS) of the sedimentary aerosol particles revealed that excited CS 2 molecules reacted with TMPSi at C C to initiate nucleation reaction of the particle formation. Several chemical species originated from CS 2 were incorporated into the polymerization reactions between TMPSi and CS 2 in forming >C S and C S chemical bonds.

An Effective Method for the Synthesis of Carboxamides by Using Tetrakis(pyridine-2-yloxy)silane as a Mild Coupling Reagent

Abstract Tetrakis(pyridin-2-yloxy)silane [Si(OPy)4] is easily prepared by trans-silylation between silicon tetrachloride and trimethyl(pyridin-2-yloxy)silane in the molar ratio of 1:4. This novel reagent is effectively employed as a mild dehydrating reagent in forming various carboxamides from the corresponding carboxylic acids and amines that involve secondary or tertiary alkyl substituted ones in good to high yields without using any basic promoters such as tertiary amines or 4-(dimethylamino)pyridine.

Simultaneous analysis of Thebaine, 6-MAM and six abused opiates in postmortem fluids and tissues using Zymark ® automated solid-phase extraction and gas chromatography–mass spectrometry

Opiates are some of the most widely prescribed drugs in America and are often abused. Demonstrating the presence or absence of opiate compounds in postmortem fluids and/or tissues derived from fatal civil aviation accidents can have serious legal consequences and may help determine the cause of impairment and/or death. However, the consumption of poppy seed products can result in a positive opiate drug test. We have developed a simple method for the simultaneous determination of eight opiate compounds from one extraction. These compounds are hydrocodone, dihydrocodeine, codeine, oxycodone, hydromorphone, 6-monoacetylmorphine, morphine, and thebaine. The inclusion of thebaine is notable as it is an indicator of poppy seed consumption and may help explain morphine/codeine positives in cases where no opiate use was indicated. This method incorporates a Zymark ® RapidTrace™ automated solid-phase extraction system, gas chromatography/mass spectrometry, and trimethyl silane (TMS) and oxime-TMS derivatives. The limits of detection ranged from 0.78 to 12.5 ng/mL. The linear dynamic range for most analytes was 6.25–1600 ng/mL. The extraction efficiencies ranged from 70 to 103%. We applied this method to eight separate aviation fatalities where opiate compounds had previously been detected.

Convenient Syntheses of 1,1,1,3,3,3‐Hexafluoro‐2‐organyl‐propan‐2‐ols and the Corresponding Trimethylsilyl Ethers.

A new convenient synthetic procedure to obtain various 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers has been worked out starting from anhydrides or activated esters of carboxylic acids and trimethyl(trifluoromethyl)silane in the presence of tetramethylammonium fluoride. Conditions for the selective formation of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols as well as the trimethylsilyl derivatives have been found.

Direct synthesis of trimethyl(2-phenoxyethyl)silanes from aromatic fluorides

A direct synthesis of trimethyl(2-phenoxyethyl)silanes from the corresponding aromatic fluorides and 2-(trimethylsilyl)ethanol was developed. A variety of substituents were tolerated and a substitution reaction using 1-bromo-3-chloro-5-fluorobenzene was demonstrated.

One‐Pot Synthesis of 1‐Aryl‐3‐methyl‐1,3‐dienes Using Methallyl(trimethyl)silane and Aldehydes and Their Low Temperature (Z)→(E) Isomerization Induced by Sulfur Dioxide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Adhesion study of tetra methyl cyclo tetra siloxanes (TMCTS) and tri methyl silane (3MS)-based low- k films

Chemical vapor deposited (CVD) low- k films using tri methyl silane (3MS) precursors and tetra methyl cyclo tetra siloxanes (TMCTS) precursors were studied. Films were deposited by means of four processes, namely, O 2, O 2 + He process and CO 2, CO 2 + O 2 process for 3MS and TMCTS precursors, respectively. Interfacial adhesion energy ( G c), of low- k/Si samples, as measured by a 4-point bending test displayed a linear relationship with film hardness and modulus. Fractography studies indicated two possible failure modes with the primary interface of delamination being either at low- k/Si or Si/epoxy interface. In the former, once delamination initiated at the low- k/Si interface, secondary delamination at the Si/epoxy and epoxy/low- k interfaces was also observed. Films with low hardness (<5 GPa) displayed a low G c (<10 J/m 2) with an adhesive separation of Si/epoxy, epoxy/low- k, and low- k/Si interfaces. Whereas, films of high hardness (>5 GPa) displayed interfacial energies in excess of 10 J/m 2 with separation of Si/epoxy and epoxy/low- k interfaces, thus indicating excellent adhesion between the Si and low- k films. Films with high hardness have less carbon in the system causing it to be more “silicon dioxide” like and exhibiting better adhesion with the Si substrate.

Comparative Study of Trimethyl Silane and Tetramethylcyclotetrasiloxane-Based Low-k Films

In this work, chemical vapor deposited low- films using trimethylsilane (3MS) as the linear precursors and tetramethylcyclotetra siloxanes (TMCTS) as the cyclic precursors are studied. There are four processes studied: , process and , process for 3MS and TMCTS precursors, respectively. Films deposited by the 3MS and TMCTS processes displayed similarities in the relationship between the Fourier transform infrared spectroscopy peak ratios, dielectric constants, refractive indexes, hardness, and modulus. The dielectric constant was found to have a linear relationship with hardness and modulus and inversely proportional with the peak ratio for both precursors. It is believed that the introduction of a methyl group in the film has reduced the covalency of the Si-O bond thus reducing its dielectric constant in comparison with silica. In this work, the 3MS based low- films appear to have slightly wider process windows compared to the TMCTS based low- films. The linear precursors (3MS) in both and process and cyclic precursors (TMCTS) in both and processes yielded similar hardness and modulus values for the same range of dielectric constants. In terms of the films electrical properties and stability, all films indicate mild stress where the 3MS system showed lower values of stress, good thermal stability, breakdown voltage, and leakage current values that are comparable to silica.

Protection of aluminum alloys from filiform corrosion by low-temperature plasma interface engineering

This study investigates the filiform corrosion resistance of chromate-free coating systems fabricated on aluminum alloys by low-temperature plasma interface engineering. The aluminum alloys investigated include AA2024-T3 ([2B]), AA7075-T6 ([7B]), Alclad AA2024-T3 ([2A]), plate stock AA2124-T851([2P]), plate stock AA7050-T7451 ([7P]), and ion vapor deposition (IVD) Al-coated AA2024-T3 ([2I]), IVD Al-coated plate stock AA2124-T851([2PI]), IVD Al-coated plate stock AA7050-T7451 ([7PI]). Direct current (DC) cathodic plasma processes including plasma treatment and plasma deposition were used to create the water-insensitive adhesion of organic coatings to aluminum alloys. With appropriate application to aluminum alloys, DC cathodic plasma coatings of trimethylsilane (TMS) combined with argon plasma post-treatment provided tenacious and water-insensitive adhesion between the water-borne, chromate-free spray primers and aluminum substrates. These chromate-free coating systems, when tested by filiform corrosion test, showed superb resistance to filiform corrosion. Filiform corrosion test was found to be a good measure of water sensitivity of the coating interfaces.

The First Cu(I)‐Mediated Nucleophilic Trifluoromethylation Reactions Using (Trifluoromethyl)trimethylsilane in Ionic Liquids.

The new ionic liquids (5a–8a) were used as reaction media for nucleophilic trifluoromethylation reactions of trifluoromethyl(trimethyl)silane with (1) aryl, allyl, benzyl, and alkyl halides in Cu(I)-mediated C–C bond formation reactions, and (2) carbonyl functionalities catalyzed with Ph3P or CsF. In addition, conversion of benzyl bromide as a model compound to benzyl fluoride was examined in 6a using CsF as the fluorinating reagent. The morpholinium-based ionic liquid (6a) stood out as an efficient solvent system comparable to organic solvents and superior to the other new ionic liquids prepared in this work as well as to [bmim]+[PF6]−. Neat reactions of N-methyloxazolidine (1), N-methylmorpholine (2), N-methylimidazole (3) or N-methyltriazole (4) with 2-(2-ethoxyethoxy)ethyl bromide (BrCH2CH2OCH2CH2OCH2CH3, 9) or 2-bromoethyl methyl ether (BrCH2CH2OCH3, 10) at 75 or 105 °C gave the N-(2-ethoxyethoxy)ethyl- or N-methoxyethyl-substituted oxazolidinium, morpholinium, imidazolium and triazolium quaternary bromides (1a–4a, 1b–4b) which were metathesized with LiN(SO2CF3)2 to form the respective room-temperature liquid bis(trifluoromethanesulfonyl)amides 5a–8a and 5b–8b in high yields with transition or melting points 310 °C as determined by thermogravimetric analyses (TGA). Densities range between 1.29 and 1.53 g cm−3 at 25 °C.

Convenient syntheses of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers

A new convenient synthetic procedure to obtain various 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers has been worked out starting from anhydrides or activated esters of carboxylic acids and trimethyl(trifluoromethyl)silane in the presence of tetramethylammonium fluoride. Conditions for the selective formation of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols as well as the trimethylsilyl derivatives have been found.

A Radiochemical Study of Reactions of Diethylsilylium Ions with Trimethyl(tert-butylamino)silane in Gas and Liquid Phases

The reaction of diethylsilylium ions with trimethyl(tert-butylamino)silane in gas and liquid phases was studied radiochemically. In contrast to the reactions of carbocations with amines, with diethylsilylium ions the proton transfer channel is not realized at all. As in the reactions of diethylsilylium ions with benzene, alcohols, and ethers, the reaction with the aminosilane is accompanied by rearrangement of the silylium ion. Formation of the condensation complex with trimethyl(tert-butylamino)silane is complicated by both its geometry and electron density distribution, despite the fact that formation of the condensation complex in this case is more exothermic than with the nucleophiles studied previously (benzene, alcohol, ether).

Copper(II) Trifluoromethanesulfonate Catalyzed Addition of a Carbamoylsilane to Aldehyde Imines

The addition of N,N-dimethylcarbamoyl(trimethyl)silane to aldehyde-derived N-methylimidines is catalyzed by copper(II) trifluoromethanesulfonate. Alter hydrolysis, N,N-dimethyl-α-(N-methylamino)amides are formed, isolatedas their ethyl carbamate derivatives.

One-pot synthesis of 1-aryl-3-methyl-1,3-dienes using methallyl(trimethyl)silane and aldehydes and their low temperature ( Z)→( E) isomerization induced by sulfur dioxide

2-Methylprop-2-ene-1-sulfonyl fluorides can be easily prepared via the ene reaction of methallylsilanes and SO 2. In the presence of a base, aldehydes and 2-methylprop-2-ene-1-sulfonyl fluorides give 1,3-( E) and ( Z)-dienes. Their ( Z)→( E) isomerization by classical means fails or leads to their polymerization. It is shown that SO 2 can isomerize 1-aryl-3-methyl-1,3-dienes at low temperature, without formation of sulfolenes (cheletropic addition/elimination). Preliminary mechanistic studies suggest that SO 2 adds to 1,3-dienes forming 1,4-diradical intermediates that are responsible for the ( Z)→( E) isomerizations.

The Synthesis of Salts and Esters of Perfluorinated Dithio‐ and Thiocarboxylic Acids from Carbon Disulfide and Carbonyl Sulfide Reacting with RFSiMe3/F‐.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Initial adsorption and C-incorporation of organosilanes at Si(0 0 1) investigated by temperature-programmed desorption

Temperature-programmed desorption (TPD) has been used to study the initial adsorption and C-incorporation of organosilanes [monomethylsilane (MMS), dimethylsilane (DMS) and trimethylsilane (TMS)] at Si(0 0 1) surfaces. Hydrogen was the only desorbing species observed in the TPD spectra from organosilanes. Organosilane molecules adsorb dissociatively on the Si(0 0 1) surfaces at room temperature. TPD spectra from DMS- and TMS-adsorbed Si surfaces present carbon-related hydrogen (H 2) desorption peaks from the initial adsorption. The carbon-incorporation ratio was found to be larger in the order of TMS > DMS > MMS, with the sticking probability of molecules being almost identical for the three organosilane molecules.

Perfluoroorganosilver(I) Compounds

AbstractFor Abstract see ChemInform Abstract in Full Text.

First Example of Trifluoromethylation in the Ecdysteroid Series. Synthesis of (20RS)‐20‐O‐Hydro‐20‐trifluoromethylpoststerone.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Creation of Polymerizable Species in Plasma Polymerization

Plasma polymerization of trimethylsilane (TMS) was carried out and investigated in a direct current (dc) glow discharge. The formation of TMS plasma glow was carefully examined with optical photography as compared with an Ar dc glow discharge. It was found that there exists a significant difference in the nature of glow and how the glow is created in TMS glow discharge, which polymerizes or causes deposition, and that of monatomic gas such as Ar, which does not polymerize or deposit. In dc Ar discharge, the negative glow, which is the most luminous zone in the discharge, develops in a distinctive distance away from the cathode surface, and the cathode remains in the dark space. In a strong contrast to this situation, in TMS dc discharge, the primary glow that is termed as cathode-glow in this paper appears at cathode surface, while a much weaker negative glow as a secondary glow was observed at the similar location to where the Ar negative glow appears. The deposition results of plasma polymers and gas phase composition data of TMS in a closed reactor acquired by ellipsometry and residual gas analyzer (RGA) measurements clearly indicated that the cathode-glow in TMS glow discharge is mainly associated with chemically reactive species that would polymerize or form deposition, but the negative glow is related to species from simple gases that would not polymerize or deposit. Based on the glow location with respect to the cathode, it was deduced that the cathode-glow is due to photon emitting species created by molecular dissociation of the monomer that is caused by low energy electrons emanating from the cathode surface. The negative glow is due to the ionization and the formation of excited neutrals of fragmented atoms caused by high-energy electrons. Polymerizable species that would cause deposition of material (plasma polymers) are created mainly by the fragmentation of monomer molecules by low energy electrons, but not by electron-impact ionization of the monomer.