Trimethylsilanolate sodium

Because trimethylsilanol 4 is more acidic than methanol or tert-butanol, tri-methylsilanol 4 and hexamethyldisiloxane 7 react rapidly with 12 M NaOH, KOH, or LiOH to give colorless crystalline precipitates of sodium trimethylsilanolate 96... 

Treatment of methyl p-chlorobenzoate with an equivalent amount of commercial potassium silanolate 97 in abs. diethyl ether affords, after 4h, pure, anhydrous potassium p-chlorobenzoate in 84% yield and methoxytrimethylsilane 13 a. Trimethylsilyl trifluoroacetate reacts hkewise with sodium trimethylsilanolate 96 in THF to give sodium trifluoroacetate, in 98% yield, and hexamethyldisiloxane 7 [119] (Scheme 4.45). 

N-Trimethylsilylamides or lactams 344 react with sodium trimethylsilanolate 96 to generate the anhydrous N-sodium salts 345 and hexamethyldisiloxane 7 in practically quantitative yield [125]. Likewise, silylated succinimide 201 is converted by sodium trimethylsilanolate 96 into hexamethyldisiloxane 7 and the anhydrous sodium salt 346, which reacts with aldehydes RCHO (R=C2H5, n-C Hy), in the presence of catalytic amounts of 96 to give, via 346, the silylated adducts 347 in 43-62% yield [125]. The imide chloride 348 gives, analogously, sodium chloride and 7 and the N-sodium salt 349, which condenses in situ with unreacted imide chloride 348 to give 91% of the amidine 350 [126] (Scheme 4.46). 

A Parr reactor charged with the step 1 product and 20 ml V, V-d i mcth Iformam i de was treated with 20 ml of 1.0 M sodium trimethylsilanolate (20 mmol) dissolved in tetra-hydrofuran (THF). The vessel was then degassed and charged with 54 psi nitric oxide. When the reaction was completed, the product was washed, dried, and the product isolated. 

Moreover, the formation of enoxy-silanes via silylation of ketones127 by means of N-methyl-N-TMS-acetamide (1 72) in presence of sodium trimethylsilanolate (173) was reported in 1969 and since then, the use of silylating reagents in presence of a catalyst has found wide appreciation and growing utilization as shown in recent papers128-132 (Scheme 27). Diacetyl (181) can be converted by trifluoromethylsul-fonic acid-TMS-ester (182) into 2,3-bis(trimethylsiloxy)-l, 3-butadiene (7treatment with ethyl TMS acetate (7 5)/tetrakis(n-butyl)amine fluoride l-trimethylsiloxy-2-methyl-styrene (i<56)130. Cyclohexanone reacts with the combination dimethyl-TMS-amine (18 7)/p-toluenesulfonic acid to 1-trimethylsiloxy-l-cyclohexene (iSS)131. Similarly, acetylacetone plus phenyl-triethylsilyl-sulfide (189) afford 2-triethylsiloxy-2-pentene-4-one (790)132. ... 

Materials. Diphenyl chlorophosphate, acetic anhydride, trimethylsilylisothiocyanate, anhydrous dimethylformamide (DMF), anhydrous acetonitrile, and anhydrous pyridine were from Aldrich. Water was purified on a Millipore Milli-Q system. Sodium trimethylsilanolate was obtained from Fluka. Diphenyl phosphoroisothiocyanatidate was synthesized as described (14). All of the peptides used in this study were either obtained from Bachem or Sigma. N-Acetyl proline was from Sigma. 

Sodium trimethylsilanolate has been reported as a convenient synthon for a hydroxy group in the ipso substitutions of fluoride in aromatic compounds. The S vAr displacement of the fluoride by the nucleophilic trimethylsilanolate leads to the silyl ether, which is immediately desilylated by the liberated fluoride ion yielding the sodium aryloxide salts. Acidification of these salts affords the hydroxylated product. For instance, 1,4-difluoroanthracene gives 1-hydroxy-4-fiuoroanthracene in 90% yield by treatment with sodium trimethylsilanolate. 

No reaction between trimethy](trifluoroniethyl)silane and sulfur dioxide occurs in the absence of an anionic initiator when one molar equivalent of tetrabutylammonium fluoride is used, clean formation of tetrabutylammonium trifluoromethanesulfinate is observed.112 Although oxidation to the corresponding sulfonate occurred readily upon treatment with 30% hydrogen peroxide, attempts to liberate the free acid from the salt proved unsuccessful. When sodium trimethylsilanolate was used as the initiator, however, the reaction sequence was successful. The overall yield of trifluoromethanesulfonic acid (31) was about 30%. 

Scheme 1. Reaction of the siloxysilane 4 with sodium trimethylsilanolate.

Hexaorganosiloxanes are very stable, both chemically and thermally. Hexa-phenyldisiloxane (m.p. 221 °C) can be distilled at 494°C without decomposition. It cannot be cracked at 300 °C, under 80 atm. hydrogen, or under any other conditions. Hexamethyldisiloxane (b.p. 100.5 C) is not attacked at 20 °C by either concentrated sulphuric acid or aqueous bases, but it can be decomposed to methane in a sealed tube at 100 °C [216]. It decomposes to sodium trimethylsilanolate in the presence of sodium amide in liquid ammonia, disodium oxide in pyridine or sodium hydroxide in methanol [217]. Hexaorganodisiloxanes also react with inorganic halides. Hexaethyl-disiloxane, on heating with the flourides of zinc, mercury(II) or antimony(III), yields triethylfluorosilane [218]. Heating it with boron tribromide produces bromotrieth-ylsilane [219]. 

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