A Probable Hydrogen-Bonded Meisenheimer Complex: An Unusually High SNAr Reactivity of Nitroaniline Derivatives with Hydroxide Ion in Aqueous Media

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• 作者：Mitsutaka Imoto ; Yasunori Matsui ; Motonori Takeda ; Akihiro Tamaki ; Hisaji Taniguchi ; Kazuhiko Mizuno ; Hiroshi Ikeda
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：August 5, 2011
• 年：2011
• 卷：76
• 期：15
• 页码：6356-6361
• 全文大小：871K
• 年卷期：v.76,no.15(August 5, 2011)
• ISSN：1520-6904

文摘

Observations show that nitroanilines exhibit an unusually high S_NAr reactivity with OH^{鈥?/sup> in aqueous media in reactions that produce nitrophenols. S_NAr reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered 1a in 97%, suggesting that the leaving ability of the NH₂ group far surpasses that of Cl under these conditions. An essential feature of S_NAr reactions of nitroanilines is probably that the NH₂ leaving group participates in a hydrogen-bonding interaction with H₂O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH鈥?/sup>, and H₂O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional S_NAr reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents.}