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Pregled bibliografske jedinice broj: 234229

Časopis

Autori: Gabelica, Vesna; Kresge, Alexander Jerry
Naslov: Protonation of Trimethylsilyl-Substituted Carbon-Carbon Multiple Bonds in Aliphatic Systems. Conformational Dependence of the beta-Silyl Stabilization of Carbocations
( Protonation of Trimethylsilyl-Substituted Carbon-Carbon Multiple Bonds in Aliphatic Systems. Conformational Dependence of the beta-Silyl Stabilization of Carbocations )
Izvornik: Journal of the American Chemical Society (0002-7863) 118 (1996), 16; 3838-3841
Vrsta rada: članak
Ključne riječi: carbocation stabilization; β -silyl effect; conformational dependence
( carbocation stabilization; β -silyl effect; conformational dependence )
Sažetak:
Rates of carbocation protonation to give carbocation products were measured in concentrated perchloric acid solutions for cyclohexene, propyne, 1-hexyne, and their trimethyl-silyl-substituted analogs. The trimethylsilyl substituent accelerated the reaction markedly and provided the following β -silyl carbocation stabilizing effects: δ Δ G≠ = 5.7 kcal/mol-1 for the cyclohexyl systems and δ Δ G≠ = 6.5 kcal/mol-1 for both acetylenic systems. These effects are substantially greater than δ Δ G≠ = 2.9 and 3.4 kcal/mol-1 found previously for the protonation of ethyl vinyl ether and phenylacetylene, which suggests that the silyl effects in these previously systems were attenuated by additional carbocation stabilization provided through their ethoxy and pheny groups. The present effects, on the other hand, fall far short of δ Δ G≠ = 16-17 kcal/mol-1 found for conformationally optimum systems. The influence of conformation on the magnitude of β -silyl effects and how this impinges on the presently studied systems is discussed.
Izvorni jezik: eng
Rad je indeksiran u
bazama podataka:
Current Contents Connect (CCC)
SCI-EXP, SSCI i/ili A&HCI
Kategorija: Znanstveni
Znanstvena područja:
Kemija
URL cjelovitog teksta:
Google Scholar: Protonation of Trimethylsilyl-Substituted Carbon-Carbon Multiple Bonds in Aliphatic Systems. Conformational Dependence of the beta-Silyl Stabilization of Carbocations



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