Homologous Series and Aqueous Solubility

A linear decrease of the aqueous solubility within several homologous series of hydrocarbons has been found. Coates et al. [8] reported the following correlations with Cw at 23°C  

Similar straight-line correlations between aqueous solubility and Nc or M have been found for certain homologous series of mono- and multifunctional compounds such as 1-alkanols, 2-alkanols [6], 2-alkanones [9], n-alkyl acetates [10], n-alkyl /3-ethoxypropionates [11], n-alkyl a-acetoxypropionates, and n-alkyl lactates [12]. In contrast, Sobotka and Kahn [13] have found significant deviations from simple linear correlations with Nc for the series of ethyl esters of monocarbonic acids. They report a zig zag curve caused by the relatively higher solubility of the members with odd values for Nq- The odd-even effect is discussed in detail by Burrows [14], with further examples provided. 

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