Trimethylchlorosilane, formation

Hexamethyldisiloxane 7 can, furthermore, be used to transform aromatic tri-chloro- or dichloromethyl compounds such as 87 and 89, in nearly quantitative yield, into the corresponding acid chlorides, for example 88 [110], or aldehydes, for example 90, with formation of trimethylchlorosilane 14 [111] (Scheme 2.17). 

DMSO or other sulfoxides react with trimethylchlorosilanes (TCS) 14 or trimefhylsilyl bromide 16, via 789, to give the Sila-Pummerer product 1275. Rearrangement of 789 and further reaction with TCS 14 affords, with elimination of HMDSO 7 and via 1276 and 1277, methanesulfenyl chloride 1278, which is also accessible by chlorination of dimethyldisulfide, by treatment of DMSO with Me2SiCl2 48, with formation of silicon oil 56, or by reaction of DMSO with oxalyl chloride, whereupon CO and CO2 is evolved (cf also Section 8.2.2). On heating equimolar amounts of primary or secondary alcohols with DMSO and TCS 14 in benzene, formaldehyde acetals are formed in 76-96% yield [67]. Thus reaction of -butanol with DMSO and TCS 14 gives, via intermediate 1275 and the mixed acetal 1279, formaldehyde di-n-butyl acetal 1280 in 81% yield and methyl mercaptan (Scheme 8.26). Most importantly, use of DMSO-Dg furnishes acetals in which the 0,0 -methylene group is deuter-ated. Benzyl alcohol, however, affords, under these reaction conditions, 93% diben-zyl ether 1817 and no acetal [67]. 

The formation of trimethylsilyl methanenitronate in the reaction of nitro-methane with trimethylchlorosilane in the presence of pyridine was also postulated without any experimental evidence (173). 

Elimination of trimethylchlorosilane and nitrogen occurs when the (phos-phino)(silyl)diazomethane la is reacted with para-toluenesulfinyl chloride at low temperature. The formation of the four-membered heterocycle 92, obtained in 87% yield, can be rationalized by a multiple-step mechanism involving the formation of the (phosphino)(sulfinyl)carbene 2v. The insertion of the (phosphoryl)(sulfenyl)carbene 91, resulting from a 1,3-oxygen shift from sulfur to phosphorus in 2v, into a carbon-hydrogen bond of a diisopropylamino group readily accounts for the formation of 92.84... 

Example 50 as shown in several examples trimethylchlorosilane (TMCS) acts as a highly efficient catalytic activator for the replacement of a P hjs[R2 amino group by alcohols to form the corresponding esters. Michalski and associates have noticed that compounds can also react as reagents for the replacement of a fluorine ligand by an appropriate alcohol when at least one equivalent of TMCS is used. This reaction is relatively slow. Its driving force is the formation of trimethylfluorosilane [83]. 

The synthetic scheme for functionalized indolines shown in equation 83 assumes formation of a doubly metallated intermediate (335), derived from V,iV-diallyl-2,6-dibromo-p-toluidine, that may be quenched to the dehalogenated toluidine 336, or may undergo cyclization to 337. Quenching of 337 with trimethylchlorosilane in the presence of TMEDA leads to formation of indoline derivatives 338 and 339. Apparently a second cyclization of intermediate 337 to compound 340 is hard to accomplish . 

The action of liquid sodium amalgam on trimethylchlorosilane (34a, 34b) or -bromosilane (207) at room temperature results in the exclusive formation of bis(trimethylsilyl)mercury, [(CH3)3Si]2Hg, which is relatively stable to heat. This compound, however, undergoes decomposition on heating at 100°-160° C for a day to give hexamethyldisilane in quantitative yield (9, 34a, 34b, 207). 

The cleavage of decamethyltetrasilane by sodium-potassium alloy followed by coupling with trimethylchlorosilane gives several lower homologs of methylpolysilanes of both linear and cyclic type (179). Although the formation of linear polysilanes up to the tetrasilane is understood in terms... 

The use of lithium tetramethylpiperidide (LiTMP) as the base, followed by a quench with trimethylchlorosilane, has been shown to effectively silylate iV,iV-d i meth y I amides. With two equivalents of base the reaction occurs on the same methyl group, probably because the first trimethylsilyl group favors the formation of and stabilizes the anion on the same carbon atom.136 137 The process has been extended to thiobenzamide136 and aliphatic amides.137... 

Selectivity of contact mass. Since the most important products in the synthesis of organochlorosilanes are diorganodichlorosilanes, it is natural that the increase of their yield receives much attention. The selective formation of diorganodichlorosilanes when organic chlorine derivatives interact with contact mass is connected with the purity of the reactants, silicon above all. High yield of dimethyldichlorosilane in the direct synthesis of methylchlorosilanes largely depends on the presence of noticeable quantities of aluminum in contact mass. The yield of dimethyldichlorosilane in the presence of aluminum as a rule decreases due to the formation of trimethylchlorosilane in the reaction with pure (semiconductor) silicon in the presence of copper trimethylchlorosilane is virtually not formed. 

The formation of trimethylchlorosilane due to the reduction of the quantity of dimethyldichlorosilane and the absence of trimethylchlorosilane in reactions based on pure silicon seem to testify that trimethylchlorosilane is a product of dimethyldichlorosilane disproportioning, which occurs in the conditions of synthesis under the influence of impurities (first of all, aluminum and its compounds) ... 

The reaction of dimethyldichlorosilane disproportioning under the influence of aluminum chlorides sharply accelerates on the surface of copper in the presence of methylchloride. In this connection, the process of direct synthesis can encounter the conditions in which the formation of trimethylchlorosilane due to dimethyldichlorosilane disproportioning occurs at noticeable speed, and the quantity of trimethylchlorosilane in the mixture formed can be increased to 20%. At the same time, another reaction accelerates on the surface of copper reacting with methylchloride, the methylation of dimethyldichlorosilane with methylchloride in the presence of aluminum or zinc ... 

Trimethylchlorosilane reacts with alcohols or phenols much more slowly, and at certain quanitities of phenol or alcohol does not participate in the reaction altogether. Methyl alcohol cannot be used to separate azeotropic mixture, because in this case there is an active secondary reaction between methyl alcohol and liberated hydrogen chloride with the formation of methylchloride and water. Water hydrolyses the reaction prod-... 

Electron-impact ionization of trimethylchlorosilane in an ICR mass spectrometer resulted in the formation of the trimethylsilyl cation, which could be detected for as long as a 800 mseconds (33). On collision it... 

These condensation reactions often lead to the formation of isomers. Structural isomerism of bis(silyl)hydrazines was first observed in 1964.19-24 In the absence of strong steric or electronic constraints, the bis(silyl)hy-drazines such as bis(trimethylsilyl)hydrazine give in a thermoneutral reaction essentially equal amounts of the N,N- and N,N -isomers at equilibrium.7 23 Wannagat et al. found that the reaction of hydrazine with trimethylchlorosilane at room temperature results only in the formation of N,N -bis(trimethylsilyl)hydrazine, whereas the same reaction in boiling solvents leads to a mixture of N,N- and /V,/V -bis(trimcthylsilyl)hydrazine. Both could be separated by preparative gas chromatography. Their struc-... 

Gas Chromatography-Mass Spectrometry. Prepare methoxime derivatives by heating the extract from the thin-layer chromatographic plate with 100 xl of an 8% solution of methoxyamine hydrochloride in dry pyridine at 60° for 30 minutes, and evaporate in a rotary film evaporator. Silylate by dissolving the residue in 100 Lll of chloroform, adding 100 Lll of A,0-bis(trimethylsilyl)acetamide and 20 Lll of trimethylchlorosilane, then seal, and heat for 2 hours at 60°. When only 5a-estrane-3P,17a-diol is to be confirmed the methoxime formation can be omitted. Prepare a 2-cm column of Sephadex LH-20 in a Pasteur pipette with a cotton wool plug, using a... 

Except THF alone, all of the chosen mixtures showed a sufficient conductivity. But when using them for electrolysis of trimethylchlorosilane, either the solvent or the supporting electrolyte is not stable, thus leading to the formation of hexamethyldisiloxane instead of hexamethyldisilane. With TMEDA MezSiCl reacts to an insoluble, white complex that can not be electrolyzed. 

As expected, 3-Li reacts readily with electrophiles protonation with cyclopentadiene or treatment with trimethylchlorosilane gave 3-H and 3-TMS, respectively (Schemes 1 and 2). Surprisingly, the reactions with 1,2-dibromoethane or diaryldichlorosilane gave rise to the formation of the cyclotrisilane 1 in moderate yield. Other silicon containing ring systems should be accessible via reaction with bis-electrophiles. 

During the search for homogeneous systems in which the tetravalent perhalotellurium compounds would undergo addition to an alkene, trimethylchlorosilane, acetyl chloride, or acetyl bromide were found to be a convenient source of halogens for the conversion of tellurium dioxide to a tellurium tetrahalide88. Addition of twice the stoichiometrically required amount of cyclohexene to a solution of tellurium tetrahalide, thus generated in either acetic acid, dichloromethane or ethanol-free chloroform leads to the formation of (fra i-2-halocyclo-hexyl)tellurium trihalides in ca. 70% yield. When dry methanol is used as solvent, trans-2-... 

Conversion to the corresponding amides with ammonia, primary or secondary amines proceeds by adding two equivalents of amine (to trap excess hydrogen chloride), refluxing with one equivalent of amine in aromatic solvents, or reacting with dialkylaminotrimethylsilane under formation of the volatile trimethylchlorosilane. The latter method has advantages especially in the preparation of sterically hindered amides like acetic acid r-butylamide. ... 

The following reagents and respective amounts are needed 1.5 L of acetonitrile, 1400 g (39 mol) of silver perrhenate [AgRe04], 1080 mL (85 mol) of trimethylchlorosilane [ClSi(CH3)3], 600 mL (4.3 mol) of tetramethyltin.The quick formation of the reactive intermediate species is indicated by the spontaneous precipitation of silver chloride after the silver perrhenate and the trimethylchlorosilane are mixed together. Yield 780-880 g (80-90%). 

In attempt to dilute bromoalkyl residues in the bonded layers, modification with mixtures of alkylchlorosilane-bromoalkylchlorosilane (Table 4) was performed. This process is similar to that employed in the so- called multiphase generation. Alkylsilanes taken in excess were believed to result in formation of bonded layer with isolated bromoalkyl groups. However, experimental evidence shows that even with a huge excess of trimethylchlorosilane bromomethylchlorosilane reacts with silica surface by the island-like mechanism. This result is most likely related to enhanced reactivity of bromoalkylchloro-silanes compared to alkylchlorosilanes. To put it in other words, alkylchlorosilane fails to interfere in formation of bonded layer by bromoalkyl groups (Table 4). 

The residue is dissolved in 2 ml of redistilled tetrahydrofuran (THF) containing 10 mg per 100 ml of coprostan-3 -ol (COP) as internal standard. (Blowout pipettes must not be used because moisture is detrimental to the formation of trimethyl silyl ethers.) The solution is transferred by capillary pipette to a 15-ml conical centrifuge tube, and the flask is rinsed out with 0.5 ml of fresh THF. Hexamethyldisilazane (0.3 ml) and trimethylchlorosilane (0.1 ml) are added. The tube is then stoppered, thoroughly mixed, and allowed to stand at room temperature overnight. 

Generation of enol silyl ethers from acyclic ketone precursors can be accomplished using the same kind of reagents. Depending on the reaction conditions, stereoselective formation of either the ( )- or the (Z)-isomer of the enol silyl ethers has been reported (Scheme 11). An in situ method of generating the enolate anion with lithium dialkylamides in the presence of trimethylchlorosilane leads to enhanced selection for the kinetically preferred enol silyl ether (e.g. 34a). Lithium r-octyl-r-butylamide (LOBA) is... 

The use of other nucleophiles has not been as well explored. Trimethylchlorosilane will react244,368 with insertion of one or two molecules of dimethylsilanone. The formation of comparable amounts of 1 1 and 1 2 adducts of Me3SiCl to Me2Si=0368 in the presence of excess Me3SiCl (equation 203) suggests that the insertion into the Si-O bond is easier than that into the Si-Cl bond in keeping with the notion that the reaction is essentially a nucleophilic attack onto the silanone silicon atom. 

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