Solubility determination, modeling, and intermolecular interactions of 2,2′-dihydroxybiphenyl in 13 mono-solvents

Abstract

The dissolution behavior of 2,2′-dihydroxybiphenyl in thirteen mono-solvents–including methyl acetate, ethyl acetate, 2-propanol, methyl propionate, ethanol, 1-propanol, isopropyl acetate, acetonitrile, methanol, n-propyl acetate, 1-butanol, 2-butanol, and isobutanol—was investigated using the static equilibrium method at temperatures ranging from 278.15 K to 313.15 K under 100 kPa. The results showed that solubility increased with rising temperature across all solvents, with methyl acetate exhibiting the highest solubility and isobutanol the lowest. Experimental data were successfully correlated using the van’t Hoff, λh, Wilson, and NRTL models, with the NRTL model providing the most accurate predictions. Mixing thermodynamic analysis revealed that although the dissolution process is exothermic (ΔmixH<0), it is predominantly entropy-driven. This behavior is attributed to the significant increase in system disorder upon solvation, which outweighs the energetic favorability at elevated temperatures. Furthermore, a discrepancy between intermolecular interaction energies and experimental trends was observed: despite stronger hydrogen-bonding capabilities in alcohols, solubility was lower than in esters. This is quantitatively rationalized by considering the energy penalty of disrupting extensive solvent self-association networks in alcohols, which offsets the gains from solute-solvent interactions. These findings provide essential data and theoretical insights for the industrial purification and solvent selection for 2,2′-dihydroxybiphenyl.