A method for calculation of the aqueous solubility of organic compounds by using new fragment solubility constants.

For the calculation of the aqueous solubility of organic compounds, we defined new fragment solubility constants (fs) which were empirically determined on the basis of compiled data from the literature. First, 6 fundamental fs values were determined from data on 46 liquid alliphatic hydrocarbons. THese fs values were fixed, and data on 249 liquid aliphatic compounds with diverse functional groups were employed to optimize another 19 fs values of the groups. Then, 15 fs values of aromatic compounds were calculated based on the solubility data on 58 aromatic liquids and the aliphatic fs values.It has been shown that there is a linear relationship between the logarithims of the aqueous solubilities of organic liquids and the octanol-water partition constants (log P), and that the water solubilities can be calculated by using the correlation equation and log P values. The present paper is concerned with a method to calculate the aqueous solubilities of organic liquids simply, directly and more accurately on the basis of fs values. Furthermore, the calculation of the water solubilities of organic solids was attempted with a correction based on the melting points, in addition to using the fs values.