Manifestation of Polar Reaction Pathways of 2,3-Dichloro-5,6-dicyano-p-benzoquinone

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• 作者：Xingwei Guo ; Herbert Mayr
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：August 21, 2013
• 年：2013
• 卷：135
• 期：33
• 页码：12377-12387
• 全文大小：796K
• 年卷期：v.135,no.33(August 21, 2013)
• ISSN：1520-5126

文摘

Reactions of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) with silyl enol ethers, silyl ketene acetals, allylsilanes, enamino esters, and diazomethanes have been studied in CH₃CN and CH₂Cl₂ solutions. The second-order rate constants for C attack at DDQ (log k_C) correlate linearly with the nucleophile-specific parameters N and s_N and are 2鈥? orders of magnitude larger than expected for SET processes, which strongly supports the polar mechanism for C鈥揅 bond formation. The second-order rate constants for O attack agree well with the calculated rate constants for rate-determining single electron transfer (SET). As a radical clock experiment ruled out outer sphere electron transfer, an inner sphere electron transfer mechanism is suggested for O attack.