Solubilities of Amino and Nitro Substituted Stilbene Sulfonic Acids: Investigations and Applications

Abstract

The recovery of 4,4 0 -dinitrostilbene-2,2 0 -disulfonic acid (DNS) and 4,4 0 -diaminostilbene-2,2 0 -disulfonic acid (DSD) and the purification of 4-amino-4 0 -nitrostilbene-2,2 0 -disulfonic acid (ANSD) are important processes during their individual production. To increase the yields of DNS, DSD, and the purity of ANSD, detailed studies on the solubilities of these three stilbene sulfonic acids (SSA) are necessary. Herein, the static analytical method was used to investigate the effects of pH, temperature, and ionic strength on the solubilities of these three SSA. On the basis of the results, new processes were proposed to recover more DNS and DSD during their production. In addition, a new purification method was developed to obtain ANSD with a purity of > 99 %.

Experimental Determination and Thermodynamic Models for Solid–Liquid Equilibrium of 4-(4-Aminophenoxy)-N-methylpyridine-2-carboxamide in Pure and Binary Solvent Mixtures for T = (278.15–328.15) K

“…The Jouyban–Acree model is widely used to describe the solubility of a solute with the variation of both temperature and the initial composition of binary solvent mixtures. − This equation is expressed as eq where J i is the model constant, T is the absolute temperature, and the other symbols have the same meaning as in eq . In these works, we expressed the variation in ln X A and ln X B values in eq as or ( N = 2) where the A 1 , B 1 , A 2 , B 2 , and J i terms are the model constants, which are listed in Table .…”