Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 7, pp. 1158−1164.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © O.E. Zhuravlev, N.V. Verolainen, L.I. Voronchikhina, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 7,
OF SYSTEMS AND PROCESSES
Thermal Stability of 1,3-Disubstituted Imidazolium
Tetrachloroferrates, Magnetic Ionic Liquids
O. E. Zhuravlev, N. V. Verolainen, and L. I. Voronchikhina
Tver State University, Tver, Russia
Received August 20, 2010
Abstract—Thermal stability of synthesized magnetic liquids, tetrachloroferrates of 1,3-disubstitued derivatives of
imidazolium, was examined. An effect of the cation structure on thermal stability of ionic liquids was considered
and a mechanism of thermal destruction was suggested.
In recent years a number of reviews, publications, and
patents on various aspects of production and application
of ionic liquids (IL)  grows. The ionic liquids are
substances that are ﬂ uids at temperatures below 100°C
and consist of bulk organic cations and various organic
or inorganic anions. Ionic liquids are used as catalyst
media and solvents.
An anion nature exerts a signiﬁ cant inﬂ uence on IL
properties: melting temperature, viscosity, density. If
halides of transition metals (Fe, Co, Ni, Mn, etc.) are
used in the ionic liquid as anion, then such ILs respond
to magnetic ﬁ eld (they possess magnetic susceptibility).
This new feature of IL  enabled isolation of similar
compounds into group “magnetic ionic liquids”
(MIL) and based on 1-butyl-3-methylimidazolium
tetrachloroferrate their magnetic susceptibility was
studied. Liquids under study are paramagnetic owing to
the presence of stable tetrahedral anion FeCl
Depending on the nature of the cation and anion ILs
have different thermal stability. ILs can be decomposed
under an action of other substances such as protic
solvents, e.g., water which readily decomposes ionic
liquids, and of high temperatures. In the latter case the
decomposition temperature is determined by the nature
of the organic cation. The alkylammonium salts are
least stable and can be subjected to transalkylation and
dealkylation by heating to 150°C, while imidazole and
pyridine salts is much more stable.
Knowledge of the thermal stability of MILs enables
determination of a temperature range, in which they can
be used without any special precautions.
In the paper we examined the thermal stability
of synthesized new magnetic ionic liquids: tetra-
chloroferrates, 1,3-disubstituted derivatives of imid-
The spectra in the visible region were recorded on
a spectrophotometer SF-56 in a solution of acetone,
and IR spectra, on a Fourier spectrometer “Bruker”
Equinox 55 between two plates. Data of a differential
thermogravimetry was obtained on a device Q-1500 of
MOM company (Hungary), the temperature range was
20–500°C, heating rate was 5°C min
. Weight loss
curves were recorded on an instrument “Perkin-Elmer”
Pyris TGA, heating rate was 5 deg min
, an air ﬂ ow
was 20 ml min
Firstly based on the imidazole we synthesized
1-(β-cyanoethyl) imidazole by a nucleophilic addition of
acrylonitrile to the imidazole according to the scheme.
In a three-necked ﬂ ask equipped with a stirrer, reﬂ ux
condenser and dropping funnel 0.5 mol of imidazole
dissolved in 50 ml of acetone were placed. Upon heating