Silyl chloride

Chemical Grafting. Polymer chains which are soluble in the suspending Hquid may be grafted to the particle surface to provide steric stabilization. The most common technique is the reaction of an organic silyl chloride or an organic titanate with surface hydroxyl groups in a nonaqueous solvent. For typical interparticle potentials and a particle diameter of 10 p.m, steric stabilization can be provided by a soluble polymer layer having a thickness of - 10 nm. This can be provided by a polymer tail with a molar mass of 10 kg/mol (25) (see Dispersants). 

StericaHy hindered silyl ethers such as ferZ-hutyl dimethyl silyl, / fZ-butyldiphenylsilyl, and tricyclohexylsilyl have been proposed as alternatives to trityl ethers. Reaction of sucrose with 3.5 molar equivalents of ferZ-hutyl dimethyl silyl chloride produces the 6,1/6 -tri-O-silyl derivative in good yield (27). 

Sdylation of sucrose with 0.65 equivalents of ferZ-hutyl dimethyl silyl chloride in pyridine gives the corresponding 6 -, 6,6 -di-, and... 

The /-propyldimethylsilyl ester is prepared from a carboxylic acid and the silyl chloride (Et3N, 0°). It is cleaved at pH 4.5 by conditions that do not cleave a tetrahydropyranyl ether (HOAc-NaOAc, acetone-H20, 0°, 45 min - 25°, 30 min, 91% yield). ... 

Pyrroles and indoles can be protected with the r-butyldimethylsilyl group by treatment with TBDMSCl and n-BuLi or NaH. Triisopropylsilyl chloride (NaH, DMF, 0°-rt, 73% yield) has been used to protect the pyrrole nitrogen in order to direct electrophilic attack to the 3-position.It has also been used to protect an indole.This derivative can be prepared from the silyl chloride and The silyl protective group is cleaved with Bu4N F , THF, rt or with CF3COOH. 

Trialkylsilanes are usually formed by the addition of a lithium or Grignard reagent to the silyl chloride, and thus, discussions related to the formation of the silyl acetylene bond will be kept to a minimum. Silyl acetylenes are prepared from the alkynylcopper(I) reagents in the presence of PPh3, Zn or TMEDA in CH3CN at 100°, 36-98% yield. It is interesting to note that the... 

Early work on the chemistry of organosilyl anions/anionoids has been thoroughly reviewed (/). The most frequently employed preparative routes involve either cleavage of a disilane, when HMPA (CAUTION—CANCER SUSPECT AGENT) is normally required as solvent, or reaction of bulky silyl chlorides with lithium metal. 

One-pot tandem sequences involving 1,4-addition and ISOC as the key steps have been developed for the construction of N and 0 heterocycles as well as of carbocycles [44]. In this sequence, the nitronate arising from 1,4-addition to an a, -unsaturated nitro alkene is trapped kinetically using trimethyl silyl chloride (TMSCl). The resulting silyl nitronate underwent a facile intramolecular 1,3-dipolar cycloaddition with the unsaturated tether (e.g.. Schemes 20-22). 

Trimethylsilyl iodide 17, which can be generated in situ by reaction of trimethyl-silyl chloride (TCS) 14 with Nal in acetonitrile [1], converts alcohols 11, in high yields at room temperature, into their iodides 773a, HI, and hexamethyldisiloxane (HMDSO) 7 [1-8, 12]. Likewise esters such as benzyl benzoate are cleaved by Me3SiCl 14/NaI in acetonitrile under reflux [Ij. Reactions of alcohols 11 with trimethylsilyl bromide 16 in chloroform or, for in situ synthesis of 16 from liBr and TCS 14 in acetonitrile and with HMDS 2 and pyridinium bromide perbromide, proceed only on heating in acetonitrile or chloroform to give the bromides 773 b in nearly quantitative yield [3, 8, 12] (Scheme 6.1). 

The 0-silylation reaction of alcohols is important as a protection method of hydroxyl groups. 0-Silylations of liquid or crystalline alcohols with liquid or crystalline silyl chlorides were found to be possible in the solid state. For example, when a mixture of powdered L-menthol (26), ferf-butyldimethylsilyl chloride (27), and imidazole (28) was kept at 60 °C for 5 h, 0-tert-butyldi-methylsilyl L-menthol (29) was obtained in 97% yield [8] (Scheme 4). Similar treatments of 26 with the liquid silyl chlorides, trimethyl- (30a) and triethylsilyl chloride (30b), gave the corresponding 0-silylation products 31a (89%) and 31b (89%), respectively, in the yields indicated [8] (Scheme 4). However, 0-silylation of triisopropyl- (30c) and triphenylsilyl chloride (30d) proceeded with difficultly even at 120 °C and gave 31c (57%) and 31d (70%), respectively, in relatively low yields. Nevertheless, when the solvent-free silylation reactions at 120 °C were carried out using two equivalents of 30c and 30d, 31c (77%) and 31d (99%) were obtained, respectively, in relatively high yields. 

Alcohol Silyl chloride Yield (%) of silyl ether... 

The solvent-free 0-silylation can also be applied to liquid alcohols. Treatment of liquid alcohols 32-36 with various silyl chlorides at 60 °C for 5 h gave the corresponding 0-silyl ethers in good yields (Table 7). In this case, the steric bulkiness of the alcohol and reagent do not present any significant problem, except in the case of tertiary alcohols. 

Another convenient procedure for hydrochlorination involves adding trimethylsilyl chloride to a mixture of an alkene and water. Good yields of HC1 addition products (Markovnikov orientation) are formed.3 4 These conditions presumably involve generation of HC1 by hydrolysis of the silyl chloride, but it is uncertain if the silicon plays any further role in the reaction. 

General Considerations. The following chemicals were commercially available and used as received 3,3,3-Triphenylpropionic acid (Acros), 1.0 M LiAlH4 in tetrahydrofuran (THF) (Aldrich), pyridinium dichromate (Acros), 2,6 di-tert-butylpyridine (Acros), dichlorodimethylsilane (Acros), tetraethyl orthosilicate (Aldrich), 3-aminopropyltrimethoxy silane (Aldrich), hexamethyldisilazane (Aldrich), tetrakis (diethylamino) titanium (Aldrich), trimethyl silyl chloride (Aldrich), terephthaloyl chloride (Acros), anhydrous toluene (Acros), and n-butyllithium in hexanes (Aldrich). Anhydrous ether, anhydrous THF, anhydrous dichloromethane, and anhydrous hexanes were obtained from a packed bed solvent purification system utilizing columns of copper oxide catalyst and alumina (ether, hexanes) or dual alumina columns (tetrahydrofuran, dichloromethane) (9). Tetramethylcyclopentadiene (Aldrich) was distilled over sodium metal prior to use. p-Aminophenyltrimethoxysilane (Gelest) was purified by recrystallization from methanol. Anhydrous methanol (Acros) was... 

The tris(trimethylsilyl)silyl ligands can be easily modified by reactions with silyl chlorides, as shown with a series of phenylated species Mes Ph SiCl (n = 0-3). Furthermore, triisopropyl, thexyldimethylsilyl, or tert-butyldimethylsilyl substitution are all easily possible.190 The crystallographic characterization of some of the alkali metal derivatives indicates a direct correlation between ligand size and resulting structural parameters. 

The reaction of bis(silanethiolato) complexes of group 10 metals with transition metal complexes gives the corresponding multinuclear complexes accompanied by the elimination of the silyl chloride (Scheme 14).117,118... 

Interestingly, deprotonation of the 3-oxo-pyrrolo[l,2-f]oxazole 277 with r-BuLi at —78°C took place at the C-5 position. Addition of an electrophile provided the substituted products 278 in good yields. Stannyl and silyl chlorides, dimethyl sulfate, ketones, and benzaldehyde were successfully used as electrophiles. A significant feature of this lithiation-substitution reaction is the generally high Ar-diastereoselectivity only single diastereomers of products were isolated (Scheme 41) <2001JA315>. 

Butoxydiphenylsilyl chloride, (1) (C6H5)2Si This silyl chloride is... 

Isopropoxydimethylsilyl)methyl chloride. (i-PrO)Me2SiCH2Cl. This silyl chloride is obtained by reaction of /-PrOH and N(C2H5)3 with (ClMe2Si)CH2Cl in refluxing ether. It is available from Aldrich. 

Hydraxymethylation. The Grignard reagent (1) prepared from this silyl chloride adds to aldehydes or ketones to provide adducts (2), which undergo oxidative... 

A subsequent study from the same laboratory revealed greatly improved conditions for this reaction (141). Markedly increased enantioselectivities are observed when the reaction is conducted in the presence of 2 equiv of both hexamethylphos-phoric triamide (HMPA) and a silyl chloride. Optimal conditions require t-... 

During the deprotonation, the polystyrene resin takes on a deep red color, which disappears after addition of the silyl chloride. 

In an undivided cell, the sacrificial anode is used so that it is oxidized in preference to the silyl and chloride ions. There is thus a requirement for the reduction potential of the sacrificial anode to be more negative than the reduction potential of the silyl chlorides, Eesich that is, E°m < E°sici (Equation (3) and Equation (4)) ... 

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