Gallou, Fabrice (2025) Finding suitable solvents for the green transformation. RSC Sustainability.

Abstract

Solvent usage is one of the most critical factors for the carbon footprint of the chemical
and pharmaceutical industries. Therefore, finding suitable green solvents that can
be sourced from biomass plays a central role in designing more sustainable manufacturing
processes. One of the greenest solvents is water, and chemical transformations
in or on aqueous solution play an increasingly important role. However, some processes
still require the extraction of the reaction product from water with an organic phase,
and analogous purifications might be necessary for the cleaning of the resulting chemical
waste water. To guide the search for suitable green solvents for extractions from
aqueous solution, the extraction efficiency of a series of green solvents was evaluated
for twelve solutes with molecular simulations. In particular, partition coefficients from
water were evaluated for cyclopentanol, ethyl acetate, 1-butanol, 2-pentanol, 2-methyl
tetrahydrofuran, 1-pentanol, cyclopentyl methyl ether, butyl methyl ether, butyl acetate,
1-octanol, and methyl oleate. Because of the high correlation of the partition
coefficient results of the different solvents with the widely available partition coefficient
of 1-octanol (LogPocoh, also known as logKow), the suitabilty of the selected solvents
for the extraction of a particular solute can be predicted. Cyclopentanol or 1-butanol
are best suited for hydrophilic molecules (LogPocoh < 0.5), while cyclopentyl methyl
ether and butyl methyl ether are particularly efficient for hydrophobic solutes (LogPocoh
2
> 2.6). Ethyl acetate or 1-pentanol turned out to be the most efficient extraction solvents
in the mid-range (LogPocoh between 0.5 to 2.6). The findings are verified based on
experimental extraction efficiencies of an aqueous solution from a micelle-enabled crosscoupling
transformation. The experimental extraction yields confirm that 1-butanol is
a suitable solvent for extractions of hydrophilic molecules from aqueous micellar media.
The experiments also show that only the six most hydrophilic solvents give rise to
a clear phase separation in the presence of residual organic solvents and surfactants.
This indicates that aqueous micellar media might require different extraction solvents
than other chemical reactions. This highlights that both insight at the molecular level
and practical considerations of the application at hand are needed for the selection of
suitable green solvents.

Item Type:	Article
Date Deposited:	19 Feb 2025 00:45
Last Modified:	19 Feb 2025 00:45
URI:	https://oak.novartis.com/id/eprint/54363