title: Absolute pKas of Sulfonamides in Ionic Liquids: Comparisons to Molecular Solvents.
abstract: Absolute pKas of 25 sulfonamides in four ionic liquids (ILs) were measured spectroscopically with high precision and subsequently compared with those in conventional molecular solvents. It is found that the acidity order of these sulfonamides is as follows: in water > in DMSO > in ILs > in acetonitrile (ACN). The well-known solvent polarity index ε fails to explain the observed stronger bond-weakening effect of ILs in comparison to that of ACN, whose ε value is much greater. In addition, the regression analyses show that the pKas of sulfonamides determined in ILs linearly correlate with these in molecular solvents of distinct properties, but with various slopes. A rationale and related discussion on the effect of solvation in ILs are presented.
authors.affiliation: State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin 300071, People's Republic of China.
authors.forename: Zedong
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin 300071, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University , Beijing 100084, People's Republic of China.
authors.forename: Pengju
authors.initials: P
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin 300071, People's Republic of China.|Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University , Beijing 100084, People's Republic of China.
authors.forename: Jin-Pei
authors.initials: JP
authors.lastname: Cheng