Measurement and thermodynamic analysis of the solubility of iodine-containing organoaluminum supported by nitrogenous ligands in pure solvents

Abstract

In this work, the solubility of L1H (1) (L1 = HC(CMeNAr)2, Ar = 2,4,6-Me3C6H2, molecular weight 334.5) in five pure solvents and the solubility of L1AlI2(2) (molecular weight 614.29) and L2AlI2(3) (L2 = HC(CMeNAr)2, Ar = 2,6-Et2C6H3, molecular weight 642.34) in four pure solvents ranging from 268.15 K to 303.15 K were determined by static analysis method.The experimental results showed that the solubility of the three compounds increased with the increase of temperature. At 303.15 K, the order of solubility (102x) of L1H (1) was toluene (37.160) > tetrahydrofuran (34.590) > n-hexane (25.527) > ethanol (0.849) > methanol (0.275). The order of solubility (102x) of L1AlI2(2) is dichloromethane (10.475) > toluene (2.383) > tetrahydrofuran (2.200) > n-hexane (0.352). The order of solubility (102x) of L2AlI2(3) is dichloromethane (5.836) > toluene (3.607) > tetrahydrofuran (0.829) > n-hexane (0.289). Seven common thermodynamic models are used to correlate experimental solubility data: Apelblat model, Yaws model, polynomial empirical equation, λh model, Wilson model, NRTL model, and UNIQUAC model. Most models fit well, with an average absolute relative deviation (ARD) less than 5 % and an average root mean square deviation (RMSD) less than 0.2 %. Among them, the Apelblat model has a wide range of applicability in terms of empirical models with an average ARD less than 3.5 %. The Wilson model has the best fitting effect in terms of activity coefficient models with an average ARD of 0.538 %. Hirshfeld surface analysis of L1AlI2(2) and L2AlI2(3) showed that H···H contact had the highest contact rate between the two compounds. accounting for 65.0 % and 66.0 %, respectively. In addition, Hansen solubility parameters were calculated to account for differences in solubility of L1H (1) in different solvents. Finally, the calculation results of the apparent thermodynamic function show that the dissolution process of the three compounds is an entropy-enhancing and endothermic process. The solubility data determined in this paper, the activity coefficient calculated by fitting, and the melting enthalpy can be used as basic chemical data for the synthesis and recrystallization of organoaluminum compounds.