- Acetyldi-t-butylsilane and acetyldi-t-butylfluorosilane: Synthesis of functionalized acylsilanes
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The preparation of acetyldi-t-butylsilane and acetyldi-t-butylfluorosilane, the first stable acylsilanes containing functional groups on silicon, is described. The new preparative procedure involves treatment of α-ethoxyvinyllithium with a halosilane to give an α-silyl enol ether, which is hydrolyzed under mild conditions to give the corresponding acetylsilane. Bulky t-butyl groups on silicon can be used to protect a reactive fluorine substituent during the hydrolysis step.
- Dexheimer, Edward M.,Spialter, Leonard
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- Acetyltrimethylsilane Keto-Enol System. Determination of the Keto-Enol Equilibrium Constant and Acid Dissociation Constants of the Keto and Enol Forms in Aqueous Solution
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The enol isomer of the prototype α-silyl-substituted ketone, acetyltrimethylsilane, was generated by flash photolytic photooxidation of α-(trimethylsilyl)ethanol in aqueous solution and its rates of acid- and base-catalyzed ketonization in that medium were determined.These, in combination with rates of enolization of the ketone determined by iodine scavenging, provided the keto-enol equilibrium constant pK(E)=4.89, the dissociation constant of the enol ionizing as an oxygen acid pK(a)E=11.54, and the dissociation constant of the ketone ionizing as a carbon acid pK(a)K=16.44.Comparison of these results with corresponding values for simple alkyl-substituted carbonyl compounds shows that α-silyl substitution raised KE markedly, lowers K(a)E modestly, and raised K(a)K somewhat more strongly.Possible causes of these effects are discussed.
- Kresge, A. J.,Tobin, J. B.
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- Reactions of Acyl Silanes with Fluoride Ion
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Acyl silanes react with fluoride ion to give products arising either from intermediates equivalent to acyl anions or from rearrangement involving alkyl group migration from the silicon atom to the carbonyl carbon atom, depending upon acyl silane structure and reaction conditions.
- Page, Philip C. Bulman,Rosenthal, Stephen
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p. 2351 - 2363
(2007/10/02)
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- ALPHA CARBOCATION STABILIZATION BY SILICON, GERMANIUM AND TIN
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The hydrolyses of a number of α-metalloidal vinyl ethers were found to undergo a ratel-imiting protonation to produce α- silil, germyl or stannyl carbocations.Comparative rate data leads to the ordering: C>Sn>Ge>Si>H, for the stabilization of such intermediates.
- Soderquist, John A.,Hassner, Alfred
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p. 1899 - 1902
(2007/10/02)
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