Recent developments in biocatalysis in multiphasic ionic liquid
Jan von Langermann
Received: 3 April 2018 /Accepted: 8 April 2018 /Published online: 27 April 2018
International Union for Pure and Applied Biophysics (IUPAB) and Springer-Verlag GmbH Germany, part of Springer Nature 2018
Ionic liquids are well known and frequently used ‘designer solvents’ for biocatalytic reactions. This review highlights recent
achievements in the field of multiphasic ionic liquid-based reaction concepts. It covers classical biphasic systems including
supported ionic liquid phases, thermo-regulated multi-component solvent systems (TMS) and polymerized ionic liquids. These
powerful concepts combine unique reaction conditions with a high potential for future applications on a laboratory and industrial
scale. The presence of a multiphasic system simplifies downstream processing due to the distribution of the catalyst and reactants
in different phases.
Keywords Ionic liquids
Within the last decades, biocatalysts became a very powerful
alternative to classical chemical and chemical reaction sys-
tems (Nestl et al. 2011;Reetz2013). This includes their use
from laboratory up to large-scale applications for the synthesis
of bulk chemicals, fine chemicals and agrochemicals (Wenda
et al. 2011;Patel2011; Busacca et al. 2011). Major examples
comprise the synthesis of bio-based compounds such as
(bio)ethanol, acrylamide, antibiotics and various intermedi-
ates for active pharmaceutical ingredients (APIs) (Muñoz
Solano et al. 2012). Herein biocatalysts, applied either as iso-
lated enzymes or whole microbial cells, offer significant ad-
vantages, e.g. mild reaction conditions, high regio- and
enantio-selectivities and a general use of water as solvent.
The increasing demand for new bioactive molecules and
bio-based products continues to fuel the search for new
biocatalysts for the use in synthetic pathways (Renata et al.
2015; Bornscheuer et al. 2012).Alreadyexistingbiocatalysts
can be further improved by protein engineering techniques to
adjust certain features such as substrate range (Turner 2003),
selectivity (Luetz et al. 2008), solvent compatibility (Reetz
2003), and process stability (Singh et al. 2013).
Consequently, biocatalysts are frequently used to enable alter-
native and more eco-friendly synthetic pathways, which also
include an integrated use with classical chemical and catalytic
reaction systems (Wohlgemuth 2010).
However, enzymes usually operate best in aqueous media
because of their native origin in prokaryotic or eukaryotic
cells. Nevertheless, there are various successful examples of
biocatalysis in or with organic solvents (Stepankova et al.
2013). These reactions are frequently carried out in two-
phase systems consisting of organic solvents and water.
Here, the organic phase is often used as a substrate and product
reservoir (if the main reactants are only sparingly soluble in
water), whereas the aqueous phase contains and stabilizes the
enzyme by retaining its hydration shell (Hernández Fernández
et al. 2015). In addition, the product can be recovered from the
organic layer. The stability of biocatalysts in such classical
non-aqueous environments is unfortunately often limited,
which pathed the success of ionic liquids (ILs) as substitutes
for molecules solvents or volatile organic compounds (VOCs)
(Kragl et al. 2002; Sheldon et al. 2002; Oppermann et al. 2011;
Zhao and Baker 2013; Sheldon 2014, 2016; Stein and Kragl
2014; Sivapragasam et al. 2016;Itoh2017).
This article is part of a Special Issue on ‘Ionic Liquids and Biomolecules’
edited by Antonio Benedetto and Hans-Joachim Galla.
* Udo Kragl
Department of Chemistry, Industrial Chemistry, University of
Rostock, 18051 Rostock, Germany
Faculty for Interdisciplinary Research, Department Life, Light and
Matter, University of Rostock, 18051 Rostock, Germany
Biophysical Reviews (2018) 10:901–910