Quantitation of solvent polarity based on molecular structure

Area of Science:

• Chemistry
• Physical Chemistry
• Computational Chemistry

Background:

• Solvent polarity is a critical parameter in chemical reactions and physical processes.
• Existing polarity indices often rely on experimental measurements, which can be time-consuming and require the physical substance.
• A structure-based, predictive index for solvent polarity is needed.

Purpose of the Study:

• To propose a novel numerical index for ranking solvent polarity.
• To base this index on molecular structure, specifically the content of exterjacent electrons.
• To validate the index against experimental polarity measurements.

Main Methods:

• The first-order valence molecular connectivity index (1Xv) was calculated for various solvents.
• The 1Xv index was modified to account for the number of isolated functional groups.
• The calculated index was compared with established experimental solvent polarity scales.

Main Results:

• The proposed index, 1Xv, effectively ranks solvents based on their polarity.
• A good correlation was observed between the calculated 1Xv index and experimental polarity measurements.
• The index can be rapidly computed using only molecular structure information.

Conclusions:

• The first-order valence molecular connectivity index (1Xv) provides a reliable, structure-based method for determining solvent polarity.
• This computational approach eliminates the need for experimental measurements and physical solvent samples.
• The index facilitates quick prediction of polarity for individual solvents and solvent mixtures.