New strategies in extractive distillation: use of aqueous solutions off hydrotropes and organic bases as solvent for organic acids

Aqueous solutions of hydrotrope (p-toluene sulfonic acid) and organic bases (methyl diethanolamine, diethanolamine, etc.) have been successfully used as solvents in the extractive distillation of close boiling phenolic substances. This new class of solvents provides sufficiently high values of relative volatility (α ≈ 3) for such close boiling mixtures as 2,6-xylenol/ p-cresol, o-chlorophenol/phenol, and 2,4-dichlorophenol/ p-chlorophenol. Batch distillation experiments proved the efficacy of these solvents