Environmental Science and Pollution Research International 2016-02-01

Prediction of Setschenow constants of N-heteroaromatics in NaCl solutions based on the partial charge on the heterocyclic nitrogen atom.

Bin Yang, Zhongjian Li, Lecheng Lei, Feifei Sun, Jingke Zhu

Index: Environ. Sci. Pollut. Res. Int. 23 , 3399-405, (2016)

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Abstract

The solubilities of 19 different kinds of N-heteroaromatic compounds in aqueous solutions with different concentrations of NaCl were determined at 298.15 K with a UV-vis spectrophotometry and titration method, respectively. Setschenow constants, Ks, were employed to describe the solubility behavior, and it is found that the higher ring numbers of N-heteroaromatics gave rise to the lower values of Ks. Moreover, Ks showed a good linear relationship with the partial charge on the nitrogen atom (QN) for either QN > 0 or QN < 0 N-heteroaromatics. It further revealed that QN was well-matched in the prediction of salting-out effect for N-heteroaromatics compared to the conventional descriptors such as molar volume (VH) and the octanol-water partition coefficient (Kow). The heterocyclic N in N-heteroaromatics may interact with Na(+) ions in NaCl solution for QN < 0 and with Cl(-) for QN > 0.