Silanes reaction with alcohols

Intermolecular Insertions. Singlet carbenes undergo insertion reactions with X H bonds such as O—H (alcohols), N—H (amines), Si H (silanes), and so on. The reactions with alcohols can be extremely fast. Here, however, we focus on the C H insertion reactions of singlet carbenes, in which carbon-carbon bonds are created. ... 

Although silicon nanocrystals are now more commonly prepared by a variety of means which are easier to scale up, e.g., pyrolysis of silanes (Xuegeng et al. 2004), thermal treatment of silsesquioxanes (Hessel et al. 2006, 2010), and from reactions of molecular silicon compounds (Wilcoxon et al. 1999 Bley and Kauzlarich 1996), this review will concentrate on routes which proceed via the formation of porous silicon. More general reviews of silicon nanocrystals Irom physics and chemistry perspectives are available (Shirahata 2011 Kang et al. 2011 Heitmann et al. 2005). Derivatization of porous silicon and SiNCs usually relies on the chemistry of the hydrogen-terminated silicon surface, which shares some of the organic reactivity of hydrosilanes (Buriak 2002). Reaction with alcohols results in Si-O-C bonded monolayers (Sweryda-Krawiec et al. 1999), but these are suseeptible to hydrolysis under ambient conditions. Alternately, addition of surface Si-H aeross a C = C double bond produces Si-C bonded monolayers, which are very stable. 

Silane reacts with methanol at room temperature to produce methoxymonosilanes such as Si(OCH2)4 [78-10-4] HSi(OCH2)3, and H2Si(OCH3)2 [5314-52-3] but not H SiOCH [2171 -96-2] (23). The reaction is catalyzed by copper metal. In the presence of alkoxide ions, SiH reacts with various alcohols, except CH OH, to produce tetraalkoxysHanes and hydrogen (24). 

The reaction of halosilanes with alcohols proceeds analogously. Dihinctional amines react with tetrahalosilanes to yield tetrakis(dialkylamino)silanes. 

Many other reactions of ethylene oxide are only of laboratory significance. These iaclude nucleophilic additions of amides, alkaU metal organic compounds, and pyridinyl alcohols (93), and electrophilic reactions with orthoformates, acetals, titanium tetrachloride, sulfenyl chlorides, halo-silanes, and dinitrogen tetroxide (94). 

Allyl silanes react with epoxides, in the presence of Bp3-OEt2 to give 2-allyl alcohols. The reaction of a-bromo lactones and CH2=CHCH2Si SiMe3)3 and AIBN leads to the a-allyl lactone. " Benzyl silanes coupled with allyl silanes to give ArCH2—R derivatives in the presence of VO(OEt)Cl2 " and allyltin compounds couple with allyl silanes in the presence of SnCU. " Allyl silanes couple to the a-carbon of amines under photolysis conditions. ... 

Allylic silanes react with aldehydes, in the presence of Lewis acids, to give an allyl-substituted alcohol. In the case of benzylic silanes, this addition reaction has been induced with Mg(C104)2 under photochemical conditions. The addition of chiral additives leads to the alcohol with good asymmetric induction. In a related reaction, allylic silanes react with acyl halides to produce the corresponding carbonyl derivative. The reaction of phenyl chloroformate, trimethylallylsilane, and AICI3, for example, gave phenyl but-3-enoate. ... 

Homoallylic alcohols.1 In the presence of fluoride ion these silanes react with aldehydes to form homoallylic alcohols in high yield (equation I). Crotyltrifluo-rosilanes undergo a similar reaction with aldehydes, but in this case the stereose-... 

Trimethylsilyl ethers and esters.i The reaction of alcohols and allyltrimethyl-silane in acetonitrile with TsOH as catalyst (70 80°, 1 3 hours) results in trimethyl-silyl ethers in 85-95% yield with elimination of propene. The same reaction with carboxylic acids results in trimclhylsilyl esters. Phenols do not undergo this reaction. 

Transsilylation. Several reagents have been recommended for preparation of /-butyldimethylsilyl ethers by transsilylation. These include allyl-r-butyldimethyl-silane and /-butyldimethylsilyl enol ethers of pentane-2,4-dione and methyl aceto-ucelate,2 both prepared with r-butyldimethylchlorosilane and imidazole. Unlike the reaction of r-butyldimethylchlorosilane with alcohols, which requires a base catalyst, these new reagents convert alcohols to silyl ethers under slightly acidic conditions (TsOH) in good yield. The trimethylsilyl ethers of pentane-2,4-dione and methyl acetoacetate convert alcohols to trimethylsilyl ethers at room temperature even with no catalyst. The former reagent is also useful for silylation of nucleotides.3... 

The surface of silica is highly reactive and hydroxyl groups exchange hydrogen for deuterium with D20 [14—16] but not with D2. They can be replaced by Cl from Cl2 or CC14 [16] and they react with silanes and aluminium chloride [15,19], Surface alcoholates are formed when silica is contacted with primary or secondary alcohols [20] either by the reaction with hydroxyl groups... 

We have previously reported on the synthesis of a series of mono- and bifunctional poly(DMS) having a variety of reactive end groups, such as silan (Si-H), vinyl, hydroxyalkyl, dimethylamino and carboxyllic acid groups.7 We have also described already on telechelic poly(DMS) having tosylate end group, lb and l b, where the hydrosilation reaction of poly(DMS) having silan end group was performed with allyl alcohol in the presence of Pt/C catalyst, followed by the tosylation reaction with tosyl chloride in the presence of dimethylaminopyridine.9... 

Doyle and co-workers have employed Rh2(pfb)4 as a highly selective catalyst for the room temperature synthesis of silyl ethers from alcohols and triethylsilane.159 The selectivity of the catalyst is demonstrated by reactions of olefinic alcohols, in which hydrosilylation is not competitive with silane alcoholysis when equimolar amounts of silane and alcohol are employed. High yields (>85%) of triethylsilyl ethers are obtained from reactions of alcohols such as benzyl alcohol, 1-octanol, 3-buten-l-ol, cholesterol, and phenol. Tertiary alcohols are not active in this system. 

Acohols - [ALCOHOL FUELS] (Vol 1) - [FEEDSTOCKS-COALCHEMICALS] (Vol 10) - [DISTILLATION, AZEOTROPIC AND EXTRACTIVE] (Vol 8) - [COALCONVERSIONPROCESSES - LIQUEFACTION] (Vol 6) - [FLAME RETARD ANTS - PHOSPHORUS FLAME RETARD ANTS] (Vol 10) - [EXPLOSIVES AND PROPELLANTS - PROPELLANTS] (Vol 10) -as antifreeze [ANTIFREEZES AND DEICING FLUIDES] (Vol 3) -for automotive motor fuel [FUELS, SYNTHETIC - LIQUID FUELS] (Vol 12) -from castor oil [CASTOR OIL] (Vol 5) -in ceramic processing [CERAMICS - CERAMIC PROCESSING] (Vol 5) -from hydrocarbon oxidation [HYDROCARBON OXIDATION] (Vol 13) -as hypnotic and sedative [HYPNOTICS, SEDATIVES, ANTICONVULSANTS, AND ANXIOLYTICS] (Vol 13) -m metal polishes [POLISHES] (Vol 19) -from oxo process [OXO PROCESS] (Vol 17) -permanganate oxidation [MANGANESE COMPOUNDS] (Vol 15) -reactions with silanes [SILICON COMPOUNDS - SILANES] (Vol 22) -role m mineral processing [MINERALS RECOVERY AND PROCESSING] (Vol 16)... 

Protection of hydroxyl groups.l The reagent is obtained from styrene-divi-nylbenzene copolymer by lithiation (n-BuLi, TMEDA) and reaction with dichlo-rodiphenylsilane. Silylation of an alcohol is effected by reaction with 1 and diiso-propylethylamine. The silane is useful for preferential silylation of primary alcohols in the presence of secondary alcohols. 

The fact that silanol persistence can be favored by equilibrium conditions rather than control of condensation kinetics by steric or electronic factors is usually not considered. The phase separation which results from highly condensed systems continuously removes material from deposition solutions, depleting soluble silane species. While condensed silanols or siloxanes are typically not regarded as participating in a reversible reaction with water or alcohol, they do indeed participate in an equilibrium reaction. Iler [16] has shown that even hydrated amorphous silicon dioxide has an equilibrium solubility in methanol, which implies the formation of soluble low molecular... 

Analogous results were obtained for the enantioselective enzymatic esterifications of the related t-butyl-substituted alcohols 101 and 103 (carbon analogues of the silanes 95 and 97, respectively). Reaction with racemic 2-(4-chlorophenoxy)propanoic acid in water-saturated benzene yielded the corresponding t-butylalkyl (+)-2-(4-chlorophenoxy)propanoates 102 and 104, respectively76,77. The enantiomeric purity of the remaining (—)-2-(4-chlorophenoxy)propanoic acid was somewhat lower than that observed for the esterification of the analogous silicon compounds [91.1% ee (101), 71.6% ee (103)]. No esterification was observed for the Si/C analogues trimethylsilanol (MesSiOH) and t-butanol (MesCOH). 

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