Dicationic ionic liquids as new feeding deterrents

Article abstract of DOI:10.1007/s11696-018-0495-6

Abstract: In this study, new quaternary bis(ammonium) salts with alkyl-1,X-bis(dimethyldecylammonium) cation and saccharinate, acesulfamate, lactate and pyroglutamate anions were synthesized and characterized by ¹H and ¹³C NMR spectr

Full text of DOI:10.1007/s11696-018-0495-6

Chemical Papers
https://doi.org/10.1007/s11696-018-0495-6
ORIGINAL PAPER
Dicationic ionic liquids as new feeding deterrents
1
1
2
Damian K. Kaczmarek · Kamil Czerniak · Tomasz Klejdysz
Received: 31 October 2017 / Accepted: 4 May 2018
©
The Author(s) 2018
Abstract
In this study, new quaternary bis(ammonium) salts with alkyl-1,X-bis(dimethyldecylammonium) cation and saccharinate,
1
13
acesulfamate, lactate and pyroglutamate anions were synthesized and characterized by H and C NMR spectroscopy.
Thermal gravimetric and diꢀerential scanning calorimetry analyses conꢁrmed that all salts were thermally stable and the
majority of them exhibited melting points below 100 °C. The physicochemical properties (viscosity, density, refractive index
values, and solubility) of the obtained salts were determined for three compounds with lactate anions. All the tested salts
have suitable properties which, in practical application, will reduce the losses caused by the most important storage insects.
Most of the synthesized ionic liquids had comparable or better deterrent activity than azadirachtin—an alkaloid known as
the most active antifeedant.
Graphical abstract
Keywords Quaternary bis(ammonium) salts · Dicationic ionic liquids · Antifeedant · Feeding deterrents
Introduction
eꢀects on non-target organisms (Geng et al. 2011). It is
necessary to develop safe and cheap methods for ꢁghting
harmful insects and searching for new active compounds,
especially of a natural origin. Substances that deter or
inhibit insect feeding are called food deterrents or antifeed-
ants (Isman 2002). Due to their speciꢁc properties, insect
antifeedants are environmentally friendly crop protection
agents. Antifeedants are allomone substances that mainly
inhibit feeding on stored products, limit the potential of pest
development and do not kill them directly (Lozowicka and
Kaczyński 2013). A key characteristic of these compounds
is selective action. Antifeedants exhibit activity against para-
sites and do not cause any negative eꢀects for useful insects
such as pest predators or pollinators (Pavela 2010). In addi-
tion, the use of deterrents may limit the application of toxic
The use of synthetic insecticides for stored-product protec-
tion from pests has led to problems such as disturbances of
the environment, insect resistance to pesticides and lethal
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s11696-018-0495-6) contains
supplementary material, which is available to authorized users.
*
Damian K. Kaczmarek
damian.rom.kaczmarek@doctorate.put.poznan.pl
1
2
Department of Chemical Technology, Poznan University
of Technology, 60-965 Poznan, Poland
Institute of Plant Protection - National Research Institute,
6
0-318 Poznan, Poland
Vol.:(0
1
123456789)
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Chemical Papers
insecticides and reduces the risk of contamination of food
with dangerous compounds.
on artiꢁcial sweeteners also show good deterrent activity
(Pernak et al. 2012).
Dicationic ionic liquids (DILs) are a group of com-
pounds consisting only of ions, they have a melting point
of less than 100 °C. DILs are composed of two cations
linked with a rigid or ꢂexible linker and two anions. In the
case of dicationic ionic liquids, the modiꢁcation potential
is much greater than in the case of monocationic ionic
liquids. It is not only possible to select cations and anions,
but also the type and length of the spacer (Claros et al.,
The aim of this study was the synthesis of a new com-
pound with antifeedant activity and containing gemini sur-
factant as a cation. As per the literature data, compounds
having one long alkyl chain exhibited better biological prop-
erties than compounds with a short alkyl chain (Pernak et al.
2013). Compounds with a low toxicity (artiꢁcial sweeteners
and natural acids) were used as a counterion. This combina-
tion was created to obtain a salt with the desired physico-
chemical properties and an increased biological activity. The
reason for this research was the need to ꢁnd new, cheaper
and more active antifeedants.
2
010, 2012). Additionally, DILs may contain appropriate
functional groups, such as thiol, ether, hydroxyl and amino
groups in the structure of cations (Lohar et al. 2016).
Currently, beside DILs, containing two imidazolium
groups as cations, an examination of compounds with
phosphonium (Yonekura and Grinstaꢀ, 2014), cholinium
Experimental
(
Silva et al. 2014), piperidinium (Haddad et al. 2014),
pyridinium (Mahrova et al. 2015), cations as well as asym-
metric DILs consisting of two diꢀerent cations was also
performed (Wang et al. 2015).
Materials
N,N-Dimethyldecylamine (90%, Sigma-Aldrich), 1,4-dibro-
mobutene (99%, Sigma-Aldrich), 1,6-dibromohexane (96%,
Sigma-Aldrich), 1,8-dibromooctane (98%, Sigma-Aldrich),
1,10-dibromodecane (97%, Sigma-Aldrich), 1,12-dibro-
mododecane (98%, Sigma-Aldrich), acesulfame K (≥99%,
Sigma-Aldrich), l-lactic acid (85%, Sigma-Aldrich), l-pyro-
glutamic acid (≥99%, Sigma-Aldrich), saccharin sodium
hydrate (99%, Alfa Aesar), potassium hydroxide (85%,
POCH), methanol, dimethyl sulfoxide, acetonitrile, acetone,
2-propanol, ethyl acetate, chloroform, toluene and hexane
were purchased from Sigma-Aldrich and used without fur-
ther puriꢁcation. Water was deionized by demineralizer HLP
Smart 1000 (Hydrolab).
In contrast to monocationic ionic liquids with a single
cation, DILs are characterized by higher density, viscosity
and glass transition temperature. They also exhibit very
high thermal stability. (Shirota et al. 2011; Claros et al.
2
010). Low volatility and excellent thermal properties
allow for their use in processes carried out in high tem-
peratures. (Fan et al. 2013).
DILs can be applied as acidic (Azizi and Shirdel 2016)
or basic catalysts (Fan et al. 2013), anti-corrosive addi-
tives and lubricants (Gindri et al. 2016a, b), antimicrobial
agents (Cancemi et al. 2017) and coatings or antioxidants
(
Czerniak and Walkiewicz 2017).
The use of natural food deterrents would be the best
solution due to ecological reasons. However, the cost of
obtaining them is high and uneconomical. This cost limits
the commercial application of natural compounds such as
azadirachtin. Currently, research for new compounds with
similar or better eꢃcacy is being conducted.
Synthesis
Alkane-1,X-bis(decyldimethylammonium) dibromides
were obtained by quaternization reaction between appro-
priate dibromo-alkane (0.1 mol) and decyldimethylamine
(0.2 mol). The reactions were conducted in acetonitrile at
60 °C for 24 h. Next, the solvents were removed by vacuum
evaporator and the product of reaction was mixed with ethyl
acetate. After adding the solvent, dibromide bis(ammonium)
precipitated as white solid and was isolated by ꢁltration. The
end product was dried under a reduced pressure at 70 °C
for 24 h.
Ionic liquids are used as cheap and safe feeding deter-
rents. These are mainly compounds containing ammonium
cations such as didecyldimethylammonium. The presence
of long alkyl chains determines the high activity of ionic
liquids in relation to diꢀerent types of beetles and pest
larvae (Pernak et al. 2013).
The most favorable direction for the development of the
third generation of ionic liquids, which are compounds
exhibiting biological activity, applies to the synthesis of
salts from natural and low-toxicity materials. Antifeedants
in the form of ionic liquids may contain natural anions,
e.g., lactate (Cybulski et al. 2008), theophyllinate (Markie-
wicz et al. 2014), fatty acids (Pernak et al. 2015) or abi-
etate (Klejdysz et al. 2016). In addition, compounds based
The next step was the synthesis of dicationic ionic liquids.
The ꢁrst method was based on the bromide anion exchange
reaction (metathesis reaction) in methanol according to
the method described earlier (Aher and Bhagat 2016). The
reaction was carried out between bis(ammonium) dibromide
(0.01 mol) and two molar equivalents of potassium salts of
appropriate acids (l-lactic acid, l-pyroglutamic acid) or
commercially available saccharin sodium and acesulfame
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3

Chemical Papers
potassium salts. The precipitated inorganic salt was removed
from the mixture by ꢁltration and the solvent was evapo-
rated under a reduced pressure. To remove all by-product,
bis(ammonium) salts were dissolved in acetone. The white
solid bromide sodium or potassium precipitated and was
removed by vacuum ꢁltration. Finally, the product was dried
under a reduced pressure at 55 °C for 24 h.
solubility” refers to 0.1 g compounds that have dissolved
in 2 or 3 ml of solvent. The last group included 0.1 g ILs
that did not dissolve in 3 ml and identiꢁed the compounds
as “low solubility”. Tests were conducted at 25 °C under
ambient pressure.
1
13
H and C NMR spectroscopic analyses were carried out
on a Varian Mercury 300 spectrometer operating at 300 and
75 MHz. Elemental analyses were performed at the Adam
Mickiewicz University, Poznan (Poland). The internal
standard was used in the analysis of tetramethylsilane and
The second method was based on acid–base neutrali-
zation reaction according to the method described previ-
ously (Niemczak et al. 2015). Quaternary bis(ammonium)
dihydroxide was obtained by the anion exchange reaction
of dibromide bis(ammonium) with potassium hydroxide in
methanol at room temperature. After neutralization of the
obtained quaternary bis(ammonium) dihydroxide (0.01 mol)
with appropriate acids (0.02 mol), solvent was removed by
vacuum evaporator and the product was dissolved in acetone
to precipitate other pollutants. The solid was recovered by
the solvent deuterated chloroform (CDCl ). CHN elemen-
3
tal analyses were performed at A. Mickiewicz University,
Poznan (Poland).
Thermal gravimetric analysis (TGA) was performed
e
using a Mettler Toledo Star TGA/DSC1 unit (Leicester,
UK) under nitrogen. Samples (2–10 mg) were placed in
aluminum pans and heated from 30 to 450 °C at a heating
−
1
ꢁ
ltration and the solvent in the mixture was evaporated by
rate of 10 °C min .
vacuum evaporator. The last step was drying under a reduced
pressure at 55 °C for 24 h.
Thermal transition temperature was determined by dif-
ferential scanning calorimetry (DSC), with a Mettler Toledo
Stare DSC1 (Leicester, UK) unit under nitrogen. Samples
(5–15 mg) were placed in aluminum pans and heated from
Characterization methods
−
1
2
5 to 100 °C at a heating rate of 10 °C min and cooled
−
1
The melting point was examined on METTLER TOLEDO
MP 90 melting point system. The solubility had been stud-
ied accordance to Vogel’s method. The solubility had been
determined in ten selected solvents, such as water, methanol,
DMSO, acetonitrile, acetone, 2-isopropanol, ethyl acetate,
chloroform, toluene and hexane.
with an intracooler at a cooling rate of 10 °C min to
-100 °C and then heated again to 100 °C.
Methods of the deterrent activity experiments
Tests on feeding activity of ionic liquids were done on three
species of most important pests of storage grain: granary
weevil (Sitophilus granarius (Linnaeus, 1758)), confused
ꢂour beetle (Tribolium confusum Jacquelin du Val, 1868)
and khapra beetle (Trogoderma granarium Everts, 1898).
The above-mentioned insects were reared in the labora-
tory in an incubator at 26 (±) 10 °C and 60 (± 5) % relative
humidity on uncrushed wheat grain (granary weevil) and
shredded products from wheat grain: ꢂour, bran and others
(confused ꢂour beetle and khapra beetle).
Refraction index was measured for obtained salts which
were liquid at room temperature. This test was made on
Abbe Rudolph Research Analytical J357 Automatic Refrac-
tometer and it was set in a range from 20 to 80 °C.
Viscosity has been examined by rotational viscometer
Rheotec RC30-CPS. The measurement consisted of exam-
ining the change in viscosity with temperature (20–80 °C).
Density was determined using an automatic density meter
DDM2911 with a mechanical oscillator method. The density
3
of the samples (approx. 2.0 cm ) was measured with respect
The experiment was conducted under identical condi-
tions in which insects were reared (temperature and rela-
tive humidity). The choice and no-choice tests were done.
The wafer discs were done from wheat ꢂour. Discs were
1 cm diameter, 1 mm thick and its average weight was about
15 mg. Prepared wafers were saturated by dipping in either
methanol only (control) or 1% solution of compounds in
methanol and then left to air dry for 30 min. After this,
wafers were weighed and oꢀered to insects on Petri dish:
to temperature-controlled conditions with Peltier, from 20
to 80 °C. The apparatus used was calibrated using deionized
water as the reference substance.
The solubility of the prepared salts was determined
according to Vogel’s Textbook of Practical Organic Chem-
istry (A. I. Vogel and B. S. Furniss, Vogel’s Textbook of
Practical Organic Chemistry, Longman, 4th edn, 1984).
Diꢀerent solvents were selected for the solubility test, such
as water, methanol, DMSO, acetonitrile, acetone, ethyl ace-
tate, chloroform, toluene, and hexane. The solubility test
was developed to classify the ionic liquid into one of three
groups for each solvent. The ꢁrst group included ILs, which
dissolved (0.1 g of IL) in 1 ml of solvent; these compounds
were described as “high solubility”. The term “moderate
– two discs previously only dipped in a solvent (control for
experiment in the variant no-choice test);
– two discs, one previously dipped in a solvent and second
in 1% solution of tested compound (choice test);
1
3

Chemical Papers
–
two discs previously dipped in a 1% solution of tested
compound (no-choice test).
room temperature and eleven were greasy with high viscos-
ity and density. Fifteen of the obtained salts can be included
as ionic liquids.
Both variants of experience and control were repeated
ve times. Experiments were performed on three species
The impact of the anion on the chemical shifts of the
alkyl chain was not signiꢁcant in the analysis of the proton
nuclear magnetic resonance. The shifts for hydrogen atoms
at the last and penultimate carbon atom in the alkyl chain
(–C H ) are, respectively, 0.88 and 1.26 ppm, The CH
ꢁ
of insect: 3 adults of S. granarius, 20 adults and 10 larvae
of T. confusum and 10 larvae of T. granarium. The number
of insects used to experiment depended on the intensity of
their food consumption. Adults used for experiments were
unsexed, 7–10 days old, and the larvae were 5–30 days old.
Insects were left in Petri dishes for 5 days, after this time,
wafers were reweighed. Weight loss of the wafers was the
basis to calculate three deterrency coeꢃcients: R relative, A
absolute and T total:
1
0
21
2
groups had the lowest chemical shift for saccharinate anion,
but the highest one for pyroglutamate anion. Chemical shifts
of the atoms next to the quaternary nitrogen atom strongly
depend on the anions. Compounds with lactate and pyro-
glutamate anions had the lowest values of chemical shifts,
and the saccharinate anions and acesulfamate anions caused
a shift towards a higher value. The viscosity, density and
refractive index were examined for DILs which were liq-
uid at 20 °C (RTILs). Figure 1 shows refractive index of
obtained RTILs.
(
C − E)
C + E)
R =
× 100 (choice test)
(1)
(
(
(
CC − EE)
A =
× 100 (no − choice test)
(2)
When analyzing the impact of temperature on the refrac-
tion index for three ionic liquids with a lactate anion (1c,
CC + EE)
4
c and 5c), a linear relationship was observed. The highest
C, CC is the amount of food from the control discs
consumed.
E, EE is the amount of food treated with tested compound
refraction index was observed for 4c in the entire tempera-
ture range. In addition, a linear relationship between density
and temperature was also noted (Fig. 2).
consumed.
Compound 1c had the highest density. The density of
liquids 4c and 5c was almost the same as water. In the lit-
erature, data for single ionic liquids, the correlation between
refractive index and the density were described. From these
data, it follows that ionic liquids with the highest refrac-
tive index also had the highest values of density. In the case
of the examined ionic liquids, an inverse relationship was
observed. The lowest measured density values were recorded
for the highest refractive index values.
Total coeꢃcient of deterrence (T) was the sum of relative
and absolute coeꢃcient.
The total coeꢃcient of deterrence, which ranged from
–
200 to 200, served as the index activity. The compounds
with T values ranging from 151 to 200, are very good deter-
rents, those with coeꢃcients values 101–150 are good deter-
rents and for the medium active T ranged from 51 to 100.
Compounds with T values lower than 50 are weak deterrents.
The coeꢃcients of deterrence of group of compounds were
analyzed by means of one-way ANOVA followed by the post
hoc Tukey test with homogenous subset. Calculations were
performed using Statistica 6.0.
Figure 3 shows the temperature dependence of the vis-
cosity for dilactate alkyl-1,X-bis(decyldimethylammonium).
Viscosity was measured for compounds 1c, 4c and 5c. ILs
1
c had the highest viscosity; on the other hand, liquid 5c
had the lowest viscosity. Two intervals were observed. In
the ꢁrst interval, for a temperature of 20–40 °C, there is a
sharp decrease in viscosity with a rise of temperature. In
contrast, in the second interval (40-80 °C), a decrease in the
measured viscosity value is much lower with an increase in
temperature. Such a dependence is also observed for single
ionic liquids with long alkyl chains.
Results and discussion
In our work, ꢁve new bis(ammonium) dibromides were syn-
thesized (Scheme 1, Step I) with a yield of about 90%. The
purity of compounds was measured and conꢁrmed by NMR.
The melting points of salts are presented in Table 1.
The next step was the synthesis of a compound with deter-
rent activity. This compound was obtained in an exchange
reaction (Scheme 1, Step II). As a result of this reaction, 20
new salts were created (Table 2).
Table 3 presents solubility of synthesized salts. All of
them were insoluble in nonpolar solvents such as ethyl ace-
tate, toluene and hexane, but soluble in chloroform.
Salts with saccharin anions (1a–5a) were soluble in polar
solvents, except for water. Synthesized salts with acesul-
fame anions (1b–5b) were characterized by weaker solubil-
ity in DMSO and isopropanol in comparison to 1a–5a salts.
Compounds 1b–5b were insoluble in DMSO and dissolved
poorly in isopropanol.
The synthesis of ILs was conducted with two methods
with a yield between 70 and 99%. All salts with cation
hexamethylene-1,6-bis(dimethyldecylammonium) (2a, 2b,
2
c, 2d) had the lowest eꢃciency. Three salts were liquid at
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Chemical Papers
Scheme 1 Synthesis of dicationic ionic liquids
Table 1 Bis(ammonium) dibromide salts
Thermal stability and diꢀerential scanning calorimetry
tests were conducted for all synthesized salts. The results of
the studies are presented in Table 4.
Salt
R
Yield (%)
Melting point (°C)
1
2
3
4
5
–C H –
95
92
93
90
91
218–221
235–236
174–178
124–127
103–105
4
8
It was observed that salts with acesulfamate and saccha-
rinate anions have lower values of glass transition tempera-
– H –
6
12
–C H –
8
16
ture (T ) than pyroglutamate or lactate anions. The lowest
g
–C H –
10
20
glass transition temperature for 1c–5c was recorded for an
eight-carbon alkyl linker and the highest for ILs with four
carbon atoms in the linker. In the case of the series with a
pyroglutamate anion, compounds with the shortest linker
had a very low T , while the 3d–5d DILs had a similar T
–C H –
12
24
The salts with lactate and pyroglutamate anions were
insoluble in solvents such as isopropanol and acetonitrile,
but exhibited solubility in methanol and water. However,
compounds 2d–5d dissolve better than salts 1c–5c and 1d.
DILs 1c–5c and 1d–5d dissolved poorly in acetone and ace-
tonitrile, except for 3d–5d.
g
g
and ranged from −11.1 °C (5d) to −15.3 °C (3d). Salts with
saccharin anions had the highest glass transition temperature
in the range from − 5.5 °C (5a) to 5.6 °C (1a). Only two
compounds (3a and 2b) exhibited a temperature of crystal-
lization (T ) and a melting point (T ) in the tested tempera-
c
m
ture range.
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Chemical Papers
Table 2 Dicationic ionic liquids
Salt Anion Yield (%) State at 25 (°C) Melting point (°C)
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
a
a
a
a
a
b
b
b
b
b
c
Saccharinate 89
Grease
Solid
Solid
Solid
Solid
Grease
Solid
Solid
Grease
Grease
Liquid
Grease
Grease
Liquid
Liquid
Grease
Grease
Grease
Grease
Grease
–
70
96
92
91
116.2–166.8
75.2–75.6
106.6–106.3
121.1–121.9
Acesulfamate 81
–
83
85
89
82
90
86
99
90
90
102.6–102.8
141.0–141.4
–
–
–
–
–
–
–
–
–
–
–
–
Lactate
c
c
Fig. 2 Density of synthesized salts 1c, 4c and 5c
c
c
d
d
d
d
d
Pyroglutamate 75
70
90
95
99
Fig. 3 Viscosity of synthesized ionic liquids 1c, 4c and 5c
except for 5b, where a decrease in the T
parameter
onset50%
was noted. The other two series (1a–5a and 1d–5d) were
characterized by an almost linear increase in stability with
growth in the alkyl linker, except for DIL 5a.
Compounds with a lactate anion and the didecyldimethyl-
ammonium (DDA) cation described in the literature showed
higher thermal stability, but the ones with benzyldimethy-
lalkyl ammonium (BA) cation exhibited a lower value than
in the case of all the obtained salts. In addition, compounds
with DDA and BA cations had a glass transition tempera-
ture, which was not observed in bis(ammonium) compounds.
ILs with cationic species such as chlormequat (CC), dial-
lyldimethylammonium (DADMA), didecyldimethylammo-
nium (DDA), hexadecylpyridinium (HEXA) or benzylalky-
ldimethylammonium (BA), acesulfame and saccharinate
anions have already been reported. Compounds with CC
and DADMA cations exhibited higher thermal stability than
Fig. 1 Refractive index of obtained RTILs (1c, 4c, 5c)
The thermal stability of the tested salts was also deter-
mined. It can be seen that compounds with saccharinate
anions (1a–5a) and acesulfamate (1b–5b) have a slightly
higher stability than the other synthesized salts. DILs 1d–5d
were characterized by a decrease in the T
value for ILs
onset
onset5%
with eight carbon atoms in the alkyl linker (3d). T
values
ranged from 237 to 320 °C. The lowest values were recorded
for the 1c–5c series, where the minimum value was observed
in the case of 3c DIL. On the other hand, the highest values
were observed for compounds with the acesulfamate anion,
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Chemical Papers
Table 3 Solubility of prepared
Salt
Anion
Solvents
A
salts at 25 °C
B
C
D
E
F
G
H
I
J
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
a
a
a
a
a
b
b
b
b
b
c
Saccharinate
±b
−
−
−
−
±
−
−
−
−
±
+a
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
±
±
±
±
±
−
−
−
−
−
±
±
±
±
±
±
±
+
+
+
+
+
+
+
±
+
+
+
+
+
+
+
+
+
+
+
±
±
±
±
±
±
±
±
±
+
+
+
+
±
+
±
±
±
±
−
−
−
−
−
−
−
−
−
−
−c
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
−
Acesulfamate
Lactate
+
+
+
+
+
−
−
−
−
−
−
−
−
−
−
c
±
±
±
±
c
c
c
d
d
d
d
d
Pyroglutamate
±
+
+
+
+
A water, B methanol, C DMSO, D acetonitrile, E acetone, F isopropanol, G ethyl acetate, H chloroform, I
toluene, J hexane
a
b
c
High solubility, moderate solubility, low solubility
the synthesized compounds, but in the case of DDA, HEXA
and BA, the stability was lower or comparable with the
tested substances. Antifeedants containing anion deriving
from natural acids have also been reported in the literature.
These compounds exhibited thermal stability at a similar
level as bis(ammonium) compounds or slightly higher (Per-
nak et al. 2013; Cybulski et al. 2008; Hough-Troutman et al.
linear increase with an extension linker between quaternary
nitrogen. A similar relationship was observed for salts with
saccharinate anions (1a–5a). The rest of the compounds
exhibited the lowest activity for the shortest linker. Synthe-
sized ILs can be included in three groups with medium, good
and very good activity. Activity towards an adult confused
ꢂour beetle increased with the number of carbon atoms with
the exception of salts with a pyroglutamate anions (1d–5d).
The graph of larvae confused ꢂour beetle (Tribolium confu-
sum) showed similar activity for all salts obtained, at a very
good activity level (Fig. 6).
2
009). DILs with lactate, pyroglutamate, saccharinate and
acesulfamate anions were stated by very good or good deter-
rent properties (Fig. 4).
In the case of granary weevil (Sitophilus granaries), the
synthesized series of quaternary ammonium compounds
with acesulfamate, saccharinate and pyroglutamate anions
had minimum activity for a compound with six carbon atoms
in the linker alkyl.
Obtained ILs showed very good activity towards larvae
khapra beetle (Trogoderma granarium). From each series of
compounds, the lowest activity was noted for the salts with
a linker with six carbon atoms (2c, 3d). Taking into account
the data describing the biological activity for all the obtained
compounds towards tested insects, the slight advantage of
the salt with the cation long alkyl linkers (in particular for
the linker with 12 carbon atoms) was noticeable, but there
was no such dependence for all tested insects. ILs with 8,
10 or 12 carbon atoms in the bis(ammonium) cation were
characterized by the highest activity than the reference com-
pound (Azadirachtin) to insects such as the confused ꢂour
beetle or larvae of both tested species.
Statistical analysis of the deterrent’s activity conꢁrmed
very good antifeedant properties for all synthesized com-
pounds with eight, ten and twelve carbon atoms in the linker
alkyl, beyond the series with lactate anions (1c–5c). The
same activity was presented by salts with an acesulfamate
and pyroglutamate anion and four carbon atoms in the linker
(
Fig. 5).
In the case of an adult confused ꢂour beetle (Tribolium
confusum), all salts with acesulfamate anions (1b–5b)
showed activity at a very good level. This series noted a
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Chemical Papers
Table 4 Thermal analysis (DCS and TG) of synthesis salts
Salt Tg (°C) Tc (°C) Tm (°C) Tonset5% (°C) Tonset50% (°C)
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
a
a
a
a
a
b
b
b
b
b
c
5.6
2.7
−4.5
4.8
−5.5
6.0
−5.0
14.5
–
–
54.7
–
–
–
62.7
–
–
–
–
–
–
–
–
–
–
–
–
–
83.4
–
–
–
83.1
–
–
–
–
–
–
–
–
–
–
–
215
222
224
222
236
222
230
226
230
225
200
207
210
210
211
198
214
193
213
214
251
256
265
268
320
273
284
270
288
271
237
249
243
257
262
253
257
265
272
284
−21.3
–
−26.7
−29.2
−34.9
−30.1
−32.9
−25.1
−39.0
−15.3
−12.5
−11.1
c
c
c
c
d
d
d
d
d
–
–
–
–
T glass transition temperature, T temperature of crystallization, T
g
c
m
melting point, T
decomposition temperature of 5% sample,
onset5%
T
decomposition temperature of 50% sample
onset50%
Fig. 5 Deterrent activity towards adult and larvae confused ꢂour bee-
tle (Tribolium confusum)
Fig. 4 Deterrent activity towards granary weevil (Sitophilus grana-
ries)
On the basis of previous data regarding ILs with acesulfa-
mate, saccharinate and lactate anions, it can be concluded
that synthesized DILs have high feeding deterrence activity.
Efficacy of salts with acesulfamate and saccharinate
anion depends most likely on the amphiphilicity of the
cation. Hence, acesulfamates and saccharinates com-
prising [2-(acryloyloxy)ethyl]trimethylammonium,
Fig. 6 Biological activity of synthesized ionic liquids towards khapra
beetle (Trogoderma granarium)
[2-(methacryloyloxy)ethyl]trimethylammonium, 2-chlo-
roethyltrimethylammonium, trimethylvinylammonium or
(2-acetoxyethyl)alkoxymethyl-dimethylammonium cations
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Chemical Papers
were characterized by medium or weak biological activity (T
coeꢃcient did not exceed 114). However, antifeedant activ-
ity for ILs with more hydrophobic cations was signiꢁcantly
higher, and in several cases (i.e., alkoxymethyl(2-hydrox-
yethyl)dimethylammonium, didecyldimethylammonium
salts) exhibited very good eꢃcacy similar to the reference
substance (azadirachtin—the compound of natural origin
with the highest feeding deterrence activity). The feeding
deterrence activity was determined also for precursor of ILs
with didecyldimethylammonium cation—didecyldimeth-
ylammonium chloride. The obtained results allowed us to
evaluate the impact of anion exchange on antifeedant activ-
ity—saccharinates or acesulfamates were characterized by
increased biological activity in comparison to precursor
with chloride anion. Therefore, we can conclude that used
bis(ammonium) dibromides also have a deterrent activity.
Furthermore, in terms of general eꢃcacy against all of the
tested insects, the obtained DILs exhibit the best eꢃciency
azadirachtin. The highest eꢃcacy towards all examined stor-
age insects was observed for compounds with twelve carbon
atoms in the alkyl linker.
Acknowledgements This work was supported by 03/52/DSPB/0708,
Poznan University of Technology, Department of Chemical
Technology.
Open Access This article is distributed under the terms of the Crea-
tive Commons Attribution 4.0 International License (http://creativeco
mmons.org/licenses/by/4.0/), which permits unrestricted use, distribu-
tion, and reproduction in any medium, provided you give appropriate
credit to the original author(s) and the source, provide a link to the
Creative Commons license, and indicate if changes were made.
References
Aher SB, Bhagat PR (2016) Convenient synthesis of imidazolium
based dicationic ionic liquids. Res Chem Intermed 42:5587–5596.
https://doi.org/10.1007/s11164-015-2388-4
(
Czerniak et al. 2014; Pernak et al. 2013; Hough-Troutman
Azizi N, Shirdel F (2016) Task speciꢁc dicationic acidic ionic liq-
uids catalyzed eꢃcient and rapid synthesis of benzoxanthenones
derivatives. J Mol Liq 222:783–787. https://doi.org/10.1016/j.
molliq.2016.07.128
et al. 2009; Pernak et al. 2007).
According to the previous papers, the highest deterrent
activity (T parameter equal to 190) was reached for the IL
with lactate anion. The obtained DILs with the same anion
exhibited the highest possible eꢃcacy according to the
methodology (T equal to 200)—a noticeably better result in
comparison to azadirachtin (Cybulski et al. 2008; Czerniak
et al. 2014). So far, no studies on the feeding deterrence of
the ILs with pyroglutamate anion have been reported.
Cancemi P, Buttacavoli M, D’Anna F, Feo S, Fontana RM, Noto
R, Sutera A, Vitale P, Gallo G (2017) The eꢀects of structural
changes on the anti-microbial and anti-proliferative activities
of diimidazolium salts. New J Chem 41:3574–3585. https://doi.
org/10.1039/C6NJ03904A
Claros M, Graber TA, Brito I, Albanez J, Gavin JA (2010) Synthesis
and thermal properties of two new dicationic ionic liquids. J Chil
Chem Soc 55:396–398. https://doi.org/10.4067/S0717-97072
0
10000300027
Claros M, Galleguillos HR, Brito I, Graber TA (2012) Thermophysi-
cal properties of a new dicationic ionic liquid. J Chem Eng Data
5
7:2147–2152. https://doi.org/10.1021/je3000876
Conclusions
Cybulski J, Wiśniewska A, Kulig-Adamiak A, Lewicka L, Cieniecka-
Rosłonkowicz A, Kita K, Fojutowski A, Nawrot J, Materna K,
Pernak J (2008) Long-Alkyl-Chain Quaternary Ammonium Lac-
tate Based Ionic Liquids. Chem Eur J 14:9305–9311. https://doi.
org/10.1002/chem.200800973
Two methods of synthesis of bis(ammonium) salt and ionic
liquids with sweet anions (acesulfamate, saccharinate), as
well as anions occurring naturally (lactate and pyrogluta-
mate) and gemini surfactant cations were described. The
selection of cation and anion allowed to design the desired
properties of the obtained compounds.
Czerniak K, Walkiewicz F (2017) Synthesis and antioxidant properties
of dicationic ionic liquids. New J Chem 41:530–539. https://doi.
org/10.1039/C6NJ02428A
Czerniak K, Giszter R, Niemczak M, Walkiewicz F, Klejdysz T (2014)
Ammonium ionic liquids containing an ester group as stored prod-
uct insect antifeedants. Przem Chem 93:1632–1636. https://doi.
org/10.12916/przemchem.2014.1632
The eꢀect of the anion and length of the alkyl linker on
solubility was determined. The compounds with sweet ani-
ons had medium or weak solubility in water, in comparison
to compounds with natural anions. An inverse correlation in
solubility for solvents such as acetonitrile and isopropanol
was observed. In addition, the inꢂuence of an alkyl linker
on physicochemical properties such as density, viscosity and
refractive index was determined for bis(ammonium) lactates.
An important advantage of the synthesized compounds was
high thermal stability (values ranging from 237 to 320 °C),
which also allowed them to be exposed to high-temperature
conditions.
Fan M, Yang J, Jiang P, Zhang P, Li S (2013) Synthesis of novel dica-
tionic basic ionic liquids and its catalytic activities for biodiesel
production. RSC Adv 3:752–756. https://doi.org/10.1039/C2RA2
2
233G
Geng ZF, Liu ZL, Wang CF, Liu QZ, Shen SM, Liu ZM, Du SS, Deng
ZW (2011) Feeding deterrents against two grain storage insects
from Euphorbia ꢀscheriana. Molecules 16:466–476. https://doi.
org/10.3390/molecules16010466
Gindri IM, Palmer KL, Siddiqui DA, Aghyarian S, Frizzo CP, Mar-
tins MAP, Rodrigues DC (2016a) Evaluation of mammalian and
bacterial cell activity on titanium surface coated with dicationic
imidazolium-based ionic liquids. RSC Adv 6:36475–36483. https
:
//doi.org/10.1039/C6RA01003B
Furthermore, it was noted that most of the salts obtained
had a comparable or better antifeedant activity than
Gindri IM, Siddiqui DA, Frizzo CP, Martins MAP, Rodrigues
DC (2016b) Improvement of tribological and anti-corrosive
1
3

Chemical Papers
performance of titanium surfaces coated with dicationic imida-
zolium-based ionic liquids. RSC Adv 6:78795–78802. https://doi.
org/10.1039/C6RA13961B
Pavela R (2010) Antifeedant activity of plant extracts on Leptino-
tarsa decemlineata Say. and Spodoptera littoralis Bois. larvae.
Ind Crops Prod 32:213–219. https://doi.org/10.1016/j.indcr
op.2010.04.010
Haddad B, Villemin D, Belarbi E-H, Bar N, Rahmouni M (2014) New
dicationic piperidinium hexafluorophosphate ILs, synthesis,
characterization and dielectric measurements. Arabian J Chem
Pernak J, Syguda A, Mirska I, Pernak A, Nawrot J, Prądzyńska A, Grif-
ꢁn ST, Rogers RD (2007) Choline-derivative-based ionic liquids.
Chem Eur J 13:6817–6827. https://doi.org/10.1002/chem.20070
0285
7
:781–787. https://doi.org/10.1016/j.arabjc.2011.01.002
Hough-Troutman WL, Smiglak M, Griꢃn S, Reichert WM, Mirska I,
Jodynis-Liebert J, Adamska T, Nawrot J, Stasiewicz M, Rogers
RD, Pernak J (2009) Ionic liquids with dual biological function:
sweet and anti-microbial, hydrophobic quaternary ammonium-
based salts. New J Chem 33:26–33. https://doi.org/10.1039/B8132
Pernak J, Wasiński K, Praczyk T, Nawrot J, Cieniecka-Rosłonkowicz
A, Walkiewicz F, Materna K (2012) Sweet ionic liquids-cycla-
mates: synthesis, properties, and application as feeding deterrents.
Sci China Chem 55:1532–1541. https://doi.org/10.1007/s1142
6-012-4631-9
1
3P
Isman M (2002) Insect antifeedants. Pestic Outlook 13:152–157. https
Pernak J, Nawrot J, Kot M, Markiewicz B, Niemczak M (2013)
Ionic liquids based stored product insect antifeedants. RSC Adv
3:25019–25029. https://doi.org/10.1039/C3RA41716F
Pernak J, Łęgosz B, Walkiewicz F, Klejdysz T, Borkowski A, Chr-
zanowski Ł (2015) Ammonium ionic liquids with anions of natu-
ral origin. RSC Adv 5:65471–65480. https://doi.org/10.1039/
C5RA11710K
:
//doi.org/10.1039/B206507J
Klejdysz T, Łęgosz B, Czuryszkiewicz D, Czerniak K, Pernak J (2016)
Biobased ionic liquids with abietate anion. ACS Sustain Chem
Eng 4:6543–6550. https://doi.org/10.1021/acssuschemeng.6b013
8
1
Lohar T, Kumbhar A, Barge M, Salunkhe R (2016) DABCO function-
alized dicationic ionic liquid (DDIL): a novel green benchmark in
multicomponent synthesis of heterocyclic scaꢀolds under sustain-
able reaction conditions. J Mol Liq 224:1102–1108. https://doi.
org/10.1016/j.molliq.2016.10.039
Shirota H, Mandai T, Fukazawa H, Kato T (2011) Comparison between
dicationic and monocationic ionic liquids: liquid density, ther-
mal properties, surface tension, and shear viscosity. J Chem Eng
56:2453–2459. https://doi.org/10.1021/je2000183
Lozowicka B, Kaczyński P (2013) Synthesis and antifeedant activity of
novel alpha-asarone derivatives against stored-product pests. Pest
Manag Sci 69:964–974. https://doi.org/10.1002/ps.3461
Mahrova M, Pagano F, Pejakovic V, Valea A, Kalin M, Igartua A,
Tojo E (2015) Pyridinium based dicationic ionic liquids as base
lubricants or lubricant additives. Tribol Int 82:245–254. https://
doi.org/10.1016/j.triboint.2014.10.018
Silva EFA, Siopa F, Figueiredo BFHT, Gonçalves AMM, Pereira JL,
Gonçalves F, Coutinho JAP, Afonso CAM, Ventura SPM (2014)
Sustainable design for environment-friendly mono and dicationic
cholinium-based ionic liquids. Ecotoxicol Environ Saf 108:302–
310. https://doi.org/10.1016/j.ecoenv.2014.07.003
Wang J, Wang M, Yang X, Zou W, Chen X (2015) Crystal structure and
thermal decomposition kinetics of 1-(pyridinium-1-yl)propane-
(1-methylpiperidinium) bi[bis(triꢂuoromethanesulfonyl)imide],
[PyC Pi][NTf ] . Chin J Chem Eng 23:816–821. https://doi.
Markiewicz B, Sznajdrowska A, Chrzanowski Ł, Ławniczak Ł, Zgoła-
Grześkowiak A, Kubiak K, Nawrot J, Pernak J (2014) Ionic liq-
uids with a theophyllinate anion. New J Chem 38:3146–3153.
https://doi.org/10.1039/C4NJ00463A
3
2 2
org/10.1016/j.cjche.2014.07.005
Yonekura R, Grinstaꢀ MW (2014) The eꢀects of counterion composi-
tion on the rheological and conductive properties of mono- and
diphosphonium ionic liquids. Phys Chem Chem Phys 16:20608–
20617. https://doi.org/10.1039/C4CP02594F
Niemczak M, Giszter R, Czerniak K, Marcinkowska K, Walkiewicz F
(
2015) Bis(ammonium) ionic liquids with herbicidal anions. New
J Chem 5:15487–15493. https://doi.org/10.1039/C4RA16151C
1
3