Solubility in binary solvent systems I: Specific versus nonspecific interactions

Area of Science:

• Physical Chemistry
• Thermodynamics
• Solution Chemistry

Background:

• Benzil solubility studies are crucial for understanding solute-solvent interactions.
• Existing models often assume specific interactions, which may not always apply.
• Evaluating models for nonspecific interactions is essential for broad applicability.

Purpose of the Study:

• To investigate benzil solubility in binary solvent mixtures.
• To compare the predictive power of specific interaction models versus nonspecific interaction models.
• To validate the Nearly Ideal Binary Solvent (NIBS) model for benzil solubility.

Main Methods:

• Solubility measurements of benzil in carbon tetrachloride-alkane and cyclohexane-alkane binary mixtures at 25°C.
• Comparison of experimental data with predictions from stoichiometric complexation models.
• Evaluation of the Nearly Ideal Binary Solvent (NIBS) model for nonspecific interactions.

Main Results:

• A stoichiometric complexation model required multiple equilibrium constants without direct evidence of complexation.
• The Nearly Ideal Binary Solvent (NIBS) model predicted experimental solubilities with a maximum deviation of 5% and an overall deviation of 1.0%.
• The NIBS model's success was notable as benzil mole fraction solubility varied by a factor of 14.

Conclusions:

• Nonspecific interaction models, like NIBS, are highly effective for predicting benzil solubility in these systems.
• Complexation models are not necessary when specific solute-solvent interactions are absent.
• The NIBS model provides a robust framework for understanding solubility behavior across wide concentration ranges.