Modeling of the Solubility of 2-Ethyl or 2-tert-pentyl Anthraquinone in Organic Solvents

Abstract

Hydrogen peroxide production via the Reidl-Pfleiderer process critically depends on the solubility of alkylated anthraquinones in the working solvents. Existing solubility prediction models suffer from limitations such as complex parametrization and poor interpretability. To address this, this study develops a boiling point correlation model (BPCM) that predicts 2-ethylanthraquinone (EAQ) solubility using solvent boiling points (T_B) and temperature (T) between 303.15 and 343.15 K. Experimental solubility data for EAQ and 2-tert-pentylanthraquinone (TPAQ, an isomer mixture of 2-tert-pentylanthraquinone and 2-s-pentylanthraquinone with a mass ratio of 3:1) in aromatic solvents (toluene, xylenes, and trimethylbenzene) and tris(2-ethylhexyl) phosphate (TOP) were measured systematically via dynamic equilibrium methods. The BPCM achieved average relative deviations (ARD) of <5% for pure solvents and mixing solvents, surpassing Wilson/NRTL models in simplicity. Furthermore, a universal correlation bridged TPAQ to EAQ solubility (ARD < 1%), enabling direct TPAQ estimation from EAQ data. This work reduces experimental workloads by >90% while maintaining industrial-grade accuracy for EAQ and TPAQ solubility in aromatic and phosphate-based systems.