Solubility of mono-alkyl magnesium complex in pure and binary solvents: Measurement, correlation, thermodynamics from 268.15 K to 318.15 K

Abstract

The mono-alkyl magnesium complex LMgBu (L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) played a significant role in organic synthesis and homogeneous catalysis. However, there were few reports on the solubility of this system. The solubility of the compound between 268.15 K and 318.15 K was determined by gravimetric analysis. Four pure solvents and two binary solvents were selected as experimental solvents. All the operations were carried out by Schlenk line techniques or in a glove box to ensure that the processes were under purified nitrogen atmosphere. The results have shown that the solubility increased with the rising of temperature within the measured temperature range. The difference in solubility can be attributed to the molecular structure, coordination bond, and molecular polarity. Besides, six thermodynamic models were used to correlate experimental solubility data, and Hansen solubility parameters (HSPs) were applied to explain the dissolution behavior. Those results showed that the polynomial model had the most extensive applicability for the pure solvents system. At different temperature, the calculated values of the Apelblat model were in good arrangement with the experimental values, as well as the MRS model was in the best arrangement for different molar ratio of solvent. And all the values of the relative average deviation (RAD and RMSD) of improved Jouyban-Acree models were less than 3%. The apparent thermodynamic properties (ΔsolHo, ΔsolSo, ΔsolGo, %ξH and %ξTS) were also calculated through the Van't Hoff model and Gibbs equation to analyze the heat of the dissolution process and enthalpy-entropy compensation of the compound. In short, the solubility and thermodynamic data of LMgBu obtained from this study will provide theoretical reference and supporting information on synthesis, crystallization, recrystallization, and other processes of the compound.