Determination and analysis of solubility of 5-bromo-7-azaindole in pure and mixed solvent systems at different temperatures (T = 278.15–323.15 K)

Abstract

This research adopted the static balance method to study the solubility of 5-bromo-7-azaindole impurity indole in ten kinds of pure solvents (methanol, ethyl acetate, n-butyl alcohol, n-propanol, isopropanol, dichloromethane(DCM), acetonitrile, methyl acetate, ethanol and n-hexane) and four mixed solvents (n-hexane + methyl acetate, n-hexane ＋ethyl acetate, n-hexane + ethanol and n-hexane + dichloromethane) at atmospheric pressure. The research experimental temperatures ranged from 278.15 to 323.15 K. The aim of this paper is to study the solubility of 5-bromo-7-azaindole in different solvent systems, and to provide reference for selecting suitable solvents in crystallization process. The modified Apelblatand and λh models were used to fit the solubility data of pure solvents. RMSDmax were 0.080 % and 0.29 %, respectively. Meanwhile, the CNIBS/R-K model and Jouyban–Acree model were in good agreement with the solubility data of binary solvent mixtures. RMSDmax were 0.043 % and 0.031 %, respectively. The KAT-SER model was used to investigate the interaction of 5-bromo-7-azaindole in pure solvent and the effect of polarity on the solubility of hydrogen bond in solute solvent system. The results showed that the hydrogen bond donor capacity accounted for 33.26 % of the total solvent effect.