Thermodynamic data measurement and analysis of organoaluminum supported by β-diketimine ligand in several solvents

Abstract

Organoaluminum compounds are supported by β-diketimine ligands were widely used in organic synthesis, homogeneous catalysis and other fields due to their unique structure and properties. In this article, the static equilibrium method was used to determine the solubility of LAlMe2 (L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) in four pure solvents (n-hexane, toluene, tetrahydrofuran, dichloromethane) and two binary solvent systems (n-hexane + toluene, n-hexane + dichloromethane). All operations were performed under Schlenk technology or a glove box under nitrogen atmosphere, and measurement temperature was 263.15 K to 308.15 K. The experimental results showed that the solubility of LAlMe2 gradually increased with the elevated of temperature and presents an increasing trend with the increase of the mass fraction of co-solvent in the mixed solvent. Hansen solubility parameter explained the dissolution behavior of LAlMe2. Six thermodynamic models were used to correlate the solubility data. The results showed that the Apelblat model and the Yaws model have the most extensive applicability in both pure solvent and binary solvent systems. In addition, thermodynamic parameters, such as ΔsolHo, ΔsolSo and ΔsolGo were calculated by Gibbs function and Van’t Hoff equation and the enthalpy- entropy compensation in the dissolution process was analyzed. It was concluded that dissolution is an endothermic process driven by entropy and ΔsolHo is the main factor affecting ΔsolGo.