Evidence for the Intracomplex Reaction in Gattermann-Koch Formylation in Superacids: Kinetic and Regioselectivity Studies

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• 作者：Mutsuo Tanaka ; Masahiro Fujiwara ; Qiang Xu ; Yoshie Souma ; Hisanori Ando ; and Kenneth K. Laali
• 刊名：Journal of the American Chemical Society
• 出版年：1997
• 出版时间：June 4, 1997
• 年：1997
• 卷：119
• 期：22
• 页码：5100 - 5105
• 全文大小：289K
• 年卷期：v.119,no.22(June 4, 1997)
• ISSN：1520-5126

文摘

Kinetic and regioselectivity data are reported for theGattermann-Koch formylation of m-xylene,1-methylnaphthalene, and toluene in HF-SbF₅ andCF₃SO₃H-SbF₅ as a functionof SbF₅/substrate molar ratio.The kinetic study for m-xylene formylation inHF-SbF₅ provided crucial evidence in favor ofintracomplex reactionvia a third-order rate equation,[ArH][ArH₂⁺SbF₆^-][CO],where the formylation electrophile HCO⁺ is generatedbyCO protonation by the arenium ion. Dependence of regioselectivityon substrate, superacid, and SbF₅/substratemolar ratio showed that high para regioselectivity stemsfrom intracomplex reaction and the observedregioselectivityreflects the ratio between the intracomplex and the conventionalreactions. Comparison in regioselectivity betweenGattermann-Koch formylation and Friedel-Crafts formylation with useof HCOF suggested that regioselectivitytrends do not reflect the nature of the electrophile but the reactionpathway; the Friedel-Crafts formylation alsoappears to have intracomplex reaction character.