# Experimental and Modeling Assessment of Polyphenol Solubility in Alcohol + Ethyl Acetate Mixtures for Extraction Applications

## TL;DR

This study measures and models how well certain polyphenols dissolve in alcohol and ethyl acetate mixtures, helping optimize their extraction for industrial use.

## Contribution

The work provides new solubility data and modeling for four polyphenols in alcohol and ethyl acetate mixtures, revealing solubility maxima due to solvent synergy.

## Key findings

- Ethanol showed higher solubility than methanol for most polyphenols, except trans-polydatin.
- Ethyl acetate had the lowest solubility but enhanced it synergistically in binary mixtures.
- Trans-resveratrol showed a 129% solubility increase in methanol + ethyl acetate mixtures.

## Abstract

Polyphenols are valuable bioactive compounds widely used
in the
pharmaceutical and cosmetic industries, yet their extraction is often
limited by low solubility in conventional solvents. This work extends
the solubility database of four polyphenols (trans-polydatin, p-coumaric acid, quercetin, and trans-resveratrol) by determining and modeling their equilibrium
solubility in methanol, ethanol, and ethyl acetate at 298.2 K and
0.1 MPa. Additionally, solubility in two binary mixtures (methanol
+ ethyl acetate and ethanol + ethyl acetate) was measured to assess
the ester cosolvent effect. Excess solubility was calculated to evaluate
nonideality, and experimental data were correlated using the Abraham
solvation model, the CNIBS/R–K equation, and solvatochromic
(KAT) parameters. Higher solubility was observed in ethanol than methanol
for all compounds except for trans-polydatin, while
ethyl acetate showed the lowest values. All ternary systems exhibited
solubility maxima due to synergistic effect of ethyl acetate, being
the greatest solubility enhancement observed for trans-resveratrol, with a 129% increase at 0.4 mole fraction of the ester
solvent in the methanol + ethyl acetate binary solvent mixture. Eventually,
all systems were accurately described by the Abraham model, CNIBS/R-K
equation, and KAT parameters.