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Issue 2, 2001
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The enormous acidifying effect of the supersubstituent [double bond, length half m-dash]NSO2CF3 on the acidity of derivatives of benzenesulfonamide and toluene-p-sulfonamide in the gas phase and in dimethyl sulfoxide

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Abstract

The effect of stepwise replacement of [double bond, length half m-dash]O oxygen atoms by [double bond, length half m-dash]NSO2CF3 fragments in the sulfonyl group of toluene-p-sulfonamide and benzenesulfonamide on their acidity has been studied in the gas phase and dimethyl sulfoxide (DMSO). Incorporation of the first [double bond, length half m-dash]NSO2CF3 group into 4-MeC6H4SO2NH2 increases its gas-phase acidity by 23.6 kcal mol−1. Substituting the second [double bond, length half m-dash]O by the [double bond, length half m-dash]NSO2CF3 group leads to an additional acidity increase of 10.7 kcal mol−1; the total acidity increase is thus 34.3 kcal mol−1 (25 powers of ten!). In DMSO solution the total acidity increase is 13 pKa units (17.7 kcal mol−1). These findings are also supported by computational studies using DFT B3LYP at the 6-31+G* level and the semiempirical PM3 method. The results of this work have potentially important implications for the design of new strongly acidic catalytic materials.

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Publication details

The article was received on 18 Jul 2000, accepted on 15 Nov 2000 and first published on 18 Dec 2000


Article type: Paper
DOI: 10.1039/B005765G
Citation: J. Chem. Soc., Perkin Trans. 2, 2001,0, 229-232
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    The enormous acidifying effect of the supersubstituent [double bond, length half m-dash]NSO2CF3 on the acidity of derivatives of benzenesulfonamide and toluene-p-sulfonamide in the gas phase and in dimethyl sulfoxide

    I. A. Koppel, J. Koppel, I. Leito, I. Koppel, M. Mishima and L. M. Yagupolskii, J. Chem. Soc., Perkin Trans. 2, 2001, 0, 229
    DOI: 10.1039/B005765G

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