Ammonium ionic liquids with anions of natural origin

Article abstract of DOI:10.1039/c5ra11710k

This study was focused on presenting a new class of ionic liquids (ILs) with anions of natural origin. The salts were obtained by hydrolysis of defined triglycerides or edible vegetable oils (coconut oil and canola oil) by quaternary ammonium hydroxides. The basic physicochemical properties of the obtained products were studied and their microbial and deterrent activity was determined. Additionally, their susceptibility to biodegradation was evaluated. The described synthesis pathway utilizes vegetable oils and quaternary ammonium hydroxides as reactants in order to obtain ILs with anions of natural origin, which are characterized by specific biological activity. The majority of the prepared ILs exhibited excellent feeding deterrent properties and could be classified as readily biodegradable compounds. The employed method is characterized by low cost of substrates, high yields and high purity of the obtained products. It might potentially find application as a tool to synthesize environmentally friendly ILs with attractive properties for a wide range of applications.

Full text of DOI:10.1039/c5ra11710k

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ARTICLE
Ammonium Ionic Liquids with Anions of Natural Origin
Juliusz Pernaka, Bartosz Łęgosza, Filip Walkiewicza, Tomasz Klejdyszb, Andrzej Borkowskic, Łukasz
Chrzanowskia
Received 00th January 20xx,
Accepted 00th January 20xx
This study was focused on presenting a new class of ionic liquids (ILs) with anions of natural origin. The salts were obtained
by hydrolysis of defined triglycerides or edible vegetable oils (coconut oil and canola oil) by quaternary ammonium
hydroxides. The basic physicochemical properties of the obtained products were studied and their microbial and deterrent
activity was determined. Additionally, their susceptibility to biodegradation was evaluated. The described synthesis
pathway utilizes vegetable oils and quaternary ammonium hydroxides as reactants in order to obtain ILs with anions of
natural origin, which are characterized by specific biological activity. The majority of the prepared ILs exhibited excellent
feeding deterrent properties and could be classified as readily biodegradable compounds. The employed method is
characterized by low cost of substrates, high yields and high purity of the obtained products. It might potentially find
application as a tool to synthesize environmentally-friendly ILs with attractive properties for a wide range of applications.
DOI: 10.1039/x0xx00000x
www.rsc.org/
processes. These substances, such as saponins, alkaloids,
phenolics and terpenoids,17 are common components of
Introduction
Ionic liquids (ILs) attract much scientific interest due to their
properties and the possibility to obtain products with desired
features .1-3 ILs are considered as less hazardous alternatives to
volatile organic solvents, which is justified by their negligible
vapour pressure. As a result, they are commonly described as
‘green solvents’, which adhere to the twelve principles of
green chemistry.
essential oils and exhibit unique properties, including
widespread deterrence. One of the most effective natural
antifeedant found in Azadirachta indica is azadirachtin.18 This
compound displays activity towards a broad spectrum of pest,
therefore it is considered as one of the most efficient natural
feeding deterrents. Unfortunately, the complicated chemical
structure of azadirachtin, prevents its effective synthesis under
laboratory conditions, therefore there is a strong need for
effective and cheap alternatives. Such compounds can be
obtained from substances commonly present in nature. This
allows for obtaining products with lower toxicity compared to
synthetic chemicals. Synthesis of terpenoid lactones from
perillyl alcohols19 or dialkoxybenzenes from benzenediols20 as
well as use of quinones,21 cinnamic aldehyde22 or even
Furthermore, ILs have been intensely examined as compounds
with unique and ‘designable’ properties, which can be
adjusted by selecting appropriate ions in order to obtain a
specific utility. These characteristics make ILs attractive for a
wide range of applications in numerous fields, such as
materials science, electrochemistry, catalysis, and medicinal
chemistry.4 Recognition of the ILs’ biological activity resulted in
the establishment of the third generation of ILs (with targeted
biological properties, combined with physical and chemical
properties).5 They can be prepared directly from
pharmaceutically-active ingredients6-10 and also from
commonly used pesticides.11-16
aminoacids23 may lead to non-toxic antifeedants. As
a
consequence, recent literature reports describe ILs as a new
class of antifeedants.24-28
Among natural substances, oils (triglycerides) are most the
important source of raw materials for industry. Global
production of vegetable oils in 2013/14 reached an average of
162 500 mln tons per annum and is estimated to reach 208
690 mln tons in 2023.29 A constant growth in this sector is
expected. Their main sources are plants, such as rapeseed,
soya, sunflower and olives. Despite the nutritional value of
oils, only a relatively small part of their production yield is
intended for the food industry. Oils undergo numerous
Another potential application is associated with the control of
crop pests, which are a worldwide cause of crop loss and an
overall decrease of crop quality. Chemical compounds called
antifeedants or feeding deterrents were introduced in order to
prevent such pest activity. It is a class of substances, which
temporarily or permanently limits the pests` ability to feed or
reduces amount of food taken. There are several substances
biosynthesized by plants, which do not take part in life
processes,
such
as
saponification,
methanolysis,
hydrogenation and hydrolysis, which result in a wide variety of
products, such as surfactants, biofuels, plasticizers, lubricants,
paints and coatings.30,31 Sodium or potassium carboxylates
(soaps) are the oldest and most common surfactants, which
are known for over 2000 years. The replacement of alkali ions
a.Department of Chemical Technology, Poznan University of Technology, Poznan
60-965, Poland; juliusz.pernak@put.poznan.pl tel: 0048 61 665 3682.
b.Institute of Plant Protection, National Research Institute, Poznan 60-318, Poland.
c. Faculty of Geology, University of Warsaw, Warsaw 02-089, Poland.
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ARTICLE
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in common soaps with tetraalkylammonium halides leads to at room temperature. Salts with only one long alkyl chain (9-
the formation of tetraalkylammonium carboxylates.32-35 12) were waxes. This may be caused by mutual arrangements
Recently, a highly water soluble surfactant based on choline between cation and anion as well as influences of alkyl chains
carboxylate was described.36
among separate particles.
The aim of the presented study was to investigate the NMR spectra confirmed that the desired structures were
properties, biological activity and biodegradability of formed. Protons in alkyl chains present in both cations and
alkyltrimethylamonium or dialkyldimethyl ammonium ILs with anions generated peaks in ranges from 0.82 to 1.01 ppm for
oils acting as anions of natural origin. The design focused on methyl groups and between 1.23 and 1.38 ppm for methylene
tetraalkylammonium carboxylates with symmetric cations, groups. Signals from protons of groups bonded directly to
comprising either two or three methyl groups. This strategy quaternary nitrogen atoms generated strong signals in range
was successful during previous studies,7,8,37,38 and the 3.18 to 3.34 ppm. Signals from protons of alkyl chains in α
synthetized salts could be classified as ILs.
position to quaternary nitrogen were detected as peaks
occurring from 3.25 to 3.46 ppm. Methylene groups in position
β to nitrogen were observed as peaks in range from 1.59 to
1.78 ppm. Additionally, signals from anions were detected.
Protons in β position to carbonyl group generated signals
between 1.49 and 1.71 ppm, hydrogen atoms in position α to
carbonyl were visible as signals from 2.11 to 2.29 ppm.
Chemical shifts for protons in position α to double bond were
observed between 2.00 and 2.12 ppm. Signals characteristic
for double bonds in unsaturated anions were observed at
values from 5.32 to 5.46 ppm.
Results and discussion
The studied quaternary ammonium salts were synthesized as
shown in Scheme 1. Two defined triglycerides - glyceryl
tristearate (TST) and trioleate (TOL) and two natural vegetable
oils – canola (CAN) and coconut oil (COCO) were used as
sources of anions. The selection of oils was based on the
significant differences in their fatty acid profiles. Average
molecular masses were calculated based on literature reports
describing chromatographic analyses of oil compositions.39,40
The CHN analysis was not conducted for canolates
cocoates 12 due to the fact that these compounds
contained mixtures (the anion was a mixture of different fatty
3, 7, 11 and
4, 8,
CH3
CH3
1)
R1
R2
R1
R2
KOH
- KX
acids). The analysis was also not conducted for salts
5
and
6
3
as
N
N
OH
X
in this case the cation was a mixture. In the case of salts
-8,
CH3
CH3
11 and 12 their purity was determined based on the TLC
O
analysis in order to exclude the presence of glycerol.
CH3
N
CH3
N
2)
R1
R2
R1
R2
O
R
O
Table 1. Prepared quaternary ammonium salts
+
3
3
-glycerol
R
RCOO
OH
R
O
CH3
CH3
Salt
R1
R2
Anion
Yield
[%]
State
O
O
[RCOO]
Scheme 1. Synthesis of quaternary ammonium salts.
1
2
3
4
5
C10H21
C10H21
C10H21
C10H21
CH2Ph
C10H21
C10H21
C10H21
C10H21
60% C12H25
40% C14H29
60% C12H25
40% C14H29
60% C12H25
40% C14H29
60% C12H25
40% C14H29
C16H33
C16H33
C16H33
TST
TOL
CAN
COCO
TST
97
96
98
95
95
wax
liquid
liquid
wax
Reactions were conducted in 2-propanol as solvent and
mixtures were heated under reflux. No transesterification
reaction occurred under these conditions. Progress of the
reaction was monitored by the decrease of the pH value. The
termination of the reaction was determined by the
stabilization of the pH value and then the solvent was
evaporated under reduced pressure. This endothermic
reaction led to the formation of quaternary ammonium salts
and glycerol. The products were obtained with high yields
(exceeding 95%) and are presented in Table 1. They were dried
under vacuum (10 mbar) at 60 °C and stored over P4O10. The
water content (measured by Carl-Fischer method) was
determined to be less than 750 ppm. All of the obtained salts
were liquids of high viscosity or waxes at ambient temperature
and did not tend to crystallize, therefore they may be classified
as ILs. Generally, ILs with saturated anion (TST, COCO) were
waxes, whereas unsaturated anions caused products to act as
liquids with high viscosity at ambient temperature.
Additionally, the influence of the cation structure was
,
wax
6
7
8
CH2Ph
CH2Ph
CH2Ph
,
TOL
CAN
95
96
98
liquid
liquid
wax
,
,
COCO
9
CH3
CH3
CH3
CH3
TST
TOL
CAN
COCO
95
98
98
96
wax
wax
wax
wax
10
11
12
C16H33
The solubility test was conducted using popular solvents
according to the method described by Vogel.41 The results are
presented in Table 2. ILs were insoluble in water, acetone and
acetonitrile, soluble in methanol, chloroform and moderately
in toluene. Solubility of ILs strongly depends on their chemical
structure. Lack of solubility in water can be explained by the
presence of long alkyl chains in both the cation and anion. Two
observed. Some of the salts with two long alkyl chains (
1
-
4) or
large substituents, such as the phenyl group (5-8), were liquids
2 | RSC Adv., 2015, 00, 1-3
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alkyl chains in structures of didecyldimethylammonium ILs
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DOI: 10.1039/C5RA11710K
ARTICLE
1
-4
points at -34 next
3
and third at 28 °C. For
led to insolubility in acetone and DMSO and moderate hexadecyltrimethylammonium ILs
solubility in toluene, whereas ILs with only one alkyl observed between -27 °C for IL 10 and -16 °C for IL 11
substituent in the cation and a lower level of charge shielding Crystallization of IL was first exhibited at around 11 °C and
were characterized by increased solubility 12 with then at 40 °C, with melting points at 35 °C and 78 °C. In case of
hexadecyltrimethylammonium cation). Behaviour of ILs 10 and 12 only one crystallization temperature and melting
benzalkonium ILs with phenyl and alkyl substituents point were observed: 24 and 38 °C for IL 10 and 56 and 77 C
9-12 glass transition was
.
9
(9-
o
5-8
confirmed this statement. It was observed that the structure for IL 12, respectively. In case of IL 11 a broad crystallization
of the anion was also important. Saturated anions with long region was observed from 6 °C (on cooling run) and two
(TST) and short (COCO) alkyl chains caused a decrease of melting peaks were observed at 22 and 71 °C.
solubility. On the other hand, the presence of double bond in
Table 3. Phase transition temperature and thermal stability of
unsaturated anions (TOL and CAN) and their disposition
resulted in an increase of solubility. All of the obtained ILs
exhibited limited solubility in water (up to 500 ppm) except for
obtained ILs
a
Tg
c
Tm
d
e
Tcb
Tonset5
Tonset50
[°C]
[°C]
[°C]
[°C]
[°C]
ILs
9 and 12 what was proven during the anti-microbial activity
studies. ILs containing a natural unsaturated anion (CAN) were
unstable during storage. Their yellowish colour darkened and
became orange. ILs with unsaturated anion obtained from
defined triglyceride (TOL) were stable and they did not change
their colour.
IL
1
2
3
1
2
3
1
2
3
4
5
6
7
8
9
-
-
-
-
-
-
-4
-14
-5
74
-
-
-
-
-
-
-1
-7
-1
79
-
-
-
-
-
198
210
200
195
180
190
183
180
210
205
212
198
290
288
258
270
265
282
260
250
280
275
270
268
Table 2. Solubility of prepared ILs at 20 oC
-11 29
-21 11 36
1
16
0
33 78
-19 49
35 81
52
3
56
78
-
71
-
-
-
28
-
-
-
Solvent
-47 -38
1
51
40
-
-
-
34 -34
-
-
11
11
24
6
-
-
-
-
-
26
35
38
22
77
IL
A
B
C
D
E
F
G
H
I
10 -27
11 -16
12
-
-
1
2
3
4
5
6
7
8
9
-
-
-
-
-
-
-
-
-
-
-
-
±
+
+
+
+
+
+
+
+
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
±
-
-
-
±
±
-
-
-
±
+
+
±
+
+
+
+
+
+
+
+
±
±
+
±
±
+
+
±
±
+
+
±
-
-
±
±
-
-
56
a – glass transition, b – crystallization temperature, c – melting point, d
– temperature Tonset to 5% mass loss, – temperature from Tonset to
e
50% mass loss.
-
-
±
±
±
+
+
±
±
±
-
-
-
Generally, all of the prepared ILs were stable in the
temperature range 180-210 oC (Table 3). Two-step thermal
10
11
12
±
±
-
degradation
processes
were
observed
for
all
didecyldimethylammonium ILs. In case of IL
1
the first step
-
-
ended at 369 °C and the second ranged from 369 to 440 °C
with a mass loss 82 % and 8 %, respectively. First degradation
A – water, B – methanol, C – DMSO, D – acetonitrile, E – acetone, F –
ethyl acetate, G – chloroform, H – toluene, I – hexane; `+` - complete
solubility, `±` - limited solubility, `-` - insoluble.
of IL
range of 367-484 °C. For IL
314 °C for the first steep and the second between 314-497 °C.
Decomposition of IL occurred in two steps with the first one
at 357 °C and the second ranging from 357 to 498 °C. ILs with
benzalkonium cation exhibited multistep thermal
decompositions. For IL the first one ended at 260 °C, the
2
occurred at 367 °C followed by a second step in the
3
decompositions were observed to
Phase transition temperatures and thermal stability of ILs were
presented in Table 3. Each of the prepared salts melted below
4
100 °C. In case of didecyldimethylammonium ILs
transition were observed. Crystallization temperatures for
these ILs ranged from around -14 ( ) up to 74 °C ( ). Two liquid
fractions were observed for IL : low with melting point at -1°C
and high with a melting point at 79 °C. Only one liquid fraction
was observed for ILs and with a melting point of -7 and -1
1-4 no glass
5
2
1
second exhibited between 260-340 °C and the third ranged
from 360 to 410 °C with mass losses of 38, 42 and 4%
1
respectively. IL
exhibited between 190 and 367 °C with 82% mass loss and
second ranging from 377 up to 440 °C. For ILs and only one
step was observed in the range of 180-320 and 180-340 °C,
respectively. In case of hexadecyltrimethylammonium ILs 12
multistep thermal decompositions were also observed. First
decomposition step of IL ended at 310 °C, the next step
6 showed two steps of decomposition – first
2
3
°C, respectively. Three melting temperatures were observed
o
for IL 4: -21, 11 and 36 C. Among benzalkonium ILs only one
7
8
salt was characterized by glass transition (
7), which was
9-
observed at -47 °C. Three fractions were determined for IL
5:
first with crystallization at 0, second at 33, and the last at 78
°C. The melting temperatures were at 1, 35 and 81 °C
9
ranged from 320 to 420 °C with mass losses of 75 and 12 %, for
the first and second step respectively. Two steps were
observed for IL 10: first at 310 °C with 78% mass loss and
respectively. Three fractions were observed For IL
7 with
crystallization temperatures at -38, 1 and 34 °C, and melting
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second in the range of 310 to 430 °C with 12% mass loss. Three Didecyldimethylammonium ILs
RSC Advances
1-
4
were as efficient as
steps were characterized for IL 11: the first step ranged from azadirachtin (±10%) or even better towards Sitophilus
210 to 310 °C, the second from 320 to 370 °C and the third granarius beetles. In case of Tribolium confusum, both beetles
from 370 to 440 °C, with mass losses of 73, 4 and 5 % and larvae, benzalkonium ILs
5-8 exhibited the highest
respectively. The first step of thermal decomposition for IL 12 efficiency. Feeding deterrent activity towards Trogoderma
ended at 309 °C (78%) and the next occurred between 320 and granarium was comparable for these two groups of ILs.
400 °C (10%).
Hexadecyltrimethylammonium ILs 9-10 were most efficient
In the next step the feeding deterrent activity of the prepared towards Tribolium confusum larvae, in other cases their results
ILs was examined. The obtained results were comparable to significantly differed from other tested compounds, yet they
azadirachtin. The synthesized ILs were tested against beetles still remained good deterrents. Tribolium confusum beetle was
of Sitophilus granarius, Tribolium confusum (both beetles and the most resistant species to the tested ILs – differences
larvae) and larvae of Trogoderma granarium. Feeding between tested ILs and azadirachtin were highest.
deterrent activity was estimated based on the amount of food
Table 5. Feeding deterrent activity of synthesized ILs towards
consumed. Values of coefficients A (absolute coefficient of
deterrence) and R (relative coefficient of deterrence) were
Tribolium confusum larvae and Trogoderma granarium beetle
calculated as follows:
Trogoderma granarium
Tribolium confusum (larvae)
ꢁꢁ − ꢂꢂ
(beetle)
ꢀ =
× 100
IL
ꢁꢁ + ꢂꢂ
ꢁ − ꢂ
A
R
Det.act.b
good
A
R
Det.act.b
good
ꢃ =
× 100
ꢁ + ꢂ
31.5
95.3
53.3
96.2
1
2
Where CC was the average weight of the food consumed in the
control, TT was the average weight of the food consumed in
the no-choice test and C and T expressed the average weights
of the food consumed in the choice test. The sum of these two
coefficients was used to evaluate the deterrent activity based
on the following criteria: 200 – 151 very good, 150 – 101 good,
100 – 50 medium, < 50 weak. Values of coefficients A and R
were presented in Tables 4 and 5.
very good
very good
very good
very good
very good
very good
64.6
57.1
78.7
93.4
98.8
66.4
80.3
92.5
94.0
98.3
97.0
3
4
100.0
100.
0
good
good
5
43.0
100.0
48.3
good
very good
very good
good
very good
very good
very good
medium
very good
good
6
7
40.2
64.9
82.4
54.6
66.6
92.7
72.8
92.6
100.0
100.0
69.3
63.5
82.4
85.1
61.2
78.1
53.6
50.9
87.6
98.4
98.0
34.5
87.6
58.9
64.6
8
Table 4. Feeding deterrent activity of synthesized ILs towards
Sitophilus granarius (beetle) and Tribolium confusum (beetle)
9
good
10
11
12
84.1
very good
very good
95.0
Sitophilus granarius (beetle) Tribolium confusum (beetle)
good
97.9
IL
100.
0
stand.a
88.4
100.0
94.2
very good
very good
A
R
Det.act.b
A
R
Det.act.b
aazadirachtin, bfeeding deterrent activity,
very good
very good
medium
medium
1
2
62.3
80.3
100.0
100.0
9.1
69.1
71.8
20.2
very good
very good
good
medium
good
3
4
5
88.8
100.0
35.1
100.0
98.1
9.5
38.5
6.0
84.3
91.3
72.2
Influence of ions on feeding deterrent activity of obtained ILs is
presented in Schemes 2 and 3. The role of either cation and
anion was clearly visible. Proper selection of cation and anion
may potentially increase the efficiency of ILs compared to the
reference standard - azadirachtin.
medium
100.0
100.
0
100.
0
good
good
good
6
7
9.1
100.0
100.0
47.9
32.4
very good
67.9
Comparison of the structures of synthetized ILs (Scheme 1)
with the azadirachtin structure (Scheme 4) led to the
conclusion that the employed strategy of searching for new
feeding deterrents is justified.
good
good
good
good
good
good
good
8
45.3
8.5
100.0
94.6
96.8
96.7
96.6
25.9
40.1
11.6
40.9
41.8
92.3
61.3
70.6
78.0
55.9
9
medium
good
10
11
12
5.7
High activity of quaternary ammonium halides against
microorganisms was the basis for testing the synthesized ILs in
this field. The influence of introducing an organic anion to the
structure was determined. Anti-microbial activity was
investigated against cocci, rods and fungi by specifying
MIC/MBC and MIC/MFC values, which were presented in
16.7
13.7
medium
100.
0
stand.a
74.3
100.0
85.0
very good
very good
aazadirachtin, bfeeding deterrent activity.
Tables 6 and 7. ILs
9 and 12 were eliminated from further
studies due to limited solubility in water (approx. 500 ppm).
Most of the synthesized ILs can be described as good or very
good feeding deterrents. Moreover, the results were strongly
influenced
by
the
tested
organisms.
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corresponding halides. Introduction of an organic cation into
the structures of ILs with all three kinds of cation did not result
lower their activity. Among didecyldimethylammonium ILs the
MIC/MBC values calculated for IL
towards M. luteus, S. aureus and S. epidermidis was higher
than the corresponding halide. ILs and were the most
efficient against E. faecium. In case of rods tested for ILs
1 indicated that activity
2
4
1-8,
10 and 11, S. marcescens, P. vulgaris and P. aeruginosa
presented highest tolerance to tested ILs with high MIC/MBC
values.
Table 6. Anti-microbial activitya of didecyldimethylammonium ILs 1-4
Strain
1
2
3
4
[DDA]
[Cl]
Scheme 2. Influence of anion on feeding deterrent activity of
didecyldimethylammonium ILs 1-4.
M. luteus
S. aureus
MIC
<0.1
<0.1
0.1
0.1
1.0
2.0
0.1
2.0
0.1
0.1
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MFC
MIC
MFC
<0.1
0.2
1.0
1.0
2.0
2.0
1.0
4.0
8.0
8.0
2.0
4.0
1.0
2.0
2.0
4.0
1.0
4.0
31.0
0.5
1.0
0.1
0.2
0.1
0.2
0.1
0.2
0.1
0.2
0.1
0.2
1.0
2.0
0.1
0.5
4.0
8.0
16.0
31.0
4.0
4.0
4.0
4.0
S. epidermidis
E. faecium
M. catarrhalis
E. coli
<0.1
1.0
0.1
0.2
1.0
4.0
2.0
1.0
1.0
4.0
4.0
4.0
0.1
1.0
0.2
0.2
1.0
1.0
8.0
0.5
8.0
62.0
0.1
0.5
62.0
0.5
B. subtilis
0.5
0.2
2.0
1.0
S. marcescens
P. vulgaris
P. aeruginosa
C. albicans
R. rubra
>500
>500
62.0
62.0
31.0
>500
125.0
>500
>500
31.0
62.0
Scheme 3. Role of cation in feeding deterrence activity for ILs with anion of
natural origin (COCO), cation: didecyldimethylammonium 4, benzalkonium 8
and hexadecyltrimethylammonium 12.
500.0 125.0
125.0 250.0 125.0 250.0
>500
31.0
62.0
62.0
62.0
500.0 125.0 500.0
31.0
31.0
8.0
4.0
4.0
4.0
8.0
8.0
16.0
31.0
31.0
31.0
a in ppm.
It should be assumed that ILs
against those microbial species. The exceptions were two ILs
with CAN anion ( and ), which proved to be highly effective
against S. marcescens.
However, as can be seen from Table 6 for M. catarrhalis, E. coli
and B. Subtilis, the highest efficiency was observed for ILs
and , which remained at a similar level to reference
compound. Additionally, the tested fungi exhibited higher
tolerance to the synthesized ILs than the original halide. IL
1-8, 10 and 11 were not active
Scheme 4. Chemical structure of azadirachtin A.18
3
7
Quaternary ammonium salts – didecyldimethylammonium
chloride [DDA][Cl], benzalkonium chloride [BA][Cl] and
hexadecyltrimethylammonium bromide [CET][Br] – were used
as reference compounds. Values presented in Tables 6 and 7
indicate that the effect of introducing an organic anion into the
IL structure strongly depended on the tested species. The
synthesized ILs were active against cocci as compared to
1
2
3
was most efficient against C. albicans and R. rubra. Similar
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observations were made for benzalkonium ILs (Table 7). first effect is associated with the influence of the cation. All
Introduction of the natural anion allowed to retain the activity four hexadecyltrimethylammonium ILs reached the highest
against all cocci species. IL
lowest MIC/MBC values for S. aureus and S. epidermidis. IL
with the CAN anion was characterized as most active towards biodegradability
cocci as well as fungi. Only two hexadecyltrimethylammonium benzalkonium ILs was diversified. The second effect may be
ILs 10 and 11 were tested. Activity of ILs with unsaturated attributed to the effect of the anion. Among ILs the highest
anions remained similar to the reference halides for cocci. biodegradation efficiency was observed when oleate or canola
Slight decrease in efficiency of 10 and 11 was observed oil were used as anions (87% and 84% for and with the
didecyldimethylammonium cation, 100% for both and with
6
was the most efficient, presenting biodegradation efficiency (100% for
and could be classified as readily biodegradable, whereas the
of didecyldimethylammonium and
9, 10, 11 and 90% for 12)
7
1-8
2
3
towards fungi.
6
7
the benzalkonium cation, accordingly). Considerably lower
biodegradability was observed in case of ILs comprising
Table 7. Anti-microbial activitya of ILs 5-8, 10, and 11
coconut oil as anions (36% for
4
with the
with the
didecyldimethylammonium cation, 12% for
8
[BA]
[Cl]
[CET]
[Br]
5
6
7
8
10 11
benzalkonium cation, accordingly), whereas the mineralization
Strain
of ILs with stearate anions was lowest (5% for
didecyldimethylammonium cation, 8% for
1
with the
2.0
2.0
2.0
4.0
2.0
4.0
4.0
0.5
1.0
0.5
4.0
0.5
2.0
4.0
0.1
0.1
1.0
4.0
4.0
4.0
4.0
2.0
4.0
2.0
4.0
2.0
4.0
2.0
8.0
2.0
2.0
2.0
4.0
2.0
2.0
62.0
0.1
0.1
0.2
2.0
2.0
2.0
1.0
1.0
1.0
2.0
1.0
2.0
1.0
1.0
2.0
4.0
8.0
16.0
31.0
0.1
4.0
2.0
2.0
2.0
4.0
4.0
31.0
0.5
1.0
1.0
1.0
2.0
4.0
2.0
16.0
2.0
0.5
1.0
M. luteus
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MFC
MIC
MFC
5
with the
benzalkonium cation, accordingly). On the basis of the
obtained results, it can be established that the use of
alkyltrimethylammonium cation results in increased
biodegradability compared to dialkyldimethylammonium-
based cation. Additionally, the analysis of biodegradability of
dialkyldimethylammonium ILs leads to the conclusion that the
use of unsaturated oil components as anions (oleate or canola
oil) results in improved biodegradability as opposed to ILs with
saturated anions (stearate or coconut oil).
S. aureus
1.0
8.0
1.0
S. epidermidis
E. faecium
M. catarrhalis
E. coli
8.0
0.5
31.0
8.0
2.0
1.0
16.0 16.0 16.0
8.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
0.5
4.0
1.0
2.0
1.0
2.0
2.0
2.0
2.0
2.0
4.0
4.0
1.0
4.0
1.0
4.0
0.5
16.0
31.0
31.0
4.0
B. subtilis
1.0
Table 8. Biodegradability of ILs 1-12
2.0
Time window
Biodegradation
S. marcescens
P. vulgaris
P. aeruginosa
C. albicans
R. rubra
62.0 >500
500.0 >500
>500 >500
>500 >500
>500 >500
>500 >500
>500 >500
>500 >500
31.0
62.0
31.0
62.0
125.0
>500
1.0
between 10
and 60%
[days]
IL
after 28 days
[%]
Classification
8.0 500.0
500.0 >500 125.0 500.0
500.0 >500 250.0 >500
250.0 >500 500.0 250.0
1
2
5 ± 1
87 ± 7
-
8
9
-
not readily biodegradable
readily biodegradable
readily biodegradable
not readily biodegradable
not readily biodegradable
readily biodegradable
readily biodegradable
not readily biodegradable
readily biodegradable
readily biodegradable
readily biodegradable
readily biodegradable
500.0 >500 >500 250.0 125.0
3
84 ± 8
16.0 16.0
500.0 62.0 16.0 31.0
31.0 8.0 4.0 31.0
125.0 31.0 4.0 125.0
8.0
8.0
2.0
4.0
4.0
4.0
16.0
31.0
1.0
4
36 ± 4
2.0
2.0
4.0
2.0
0.5
0.5
5
8 ± 2
-
31.0
16.0
6
100 ± 9
100 ± 12
12 ± 3
2
2
-
a in ppm.
7
Every tested species presented different tolerance to the
examined ILs. In general, it was observed that ILs with
didecyldimethylammonium cation were most efficient. Highest
activity among obtained ILs was observed for IL . The tested
8
1-4
9
100 ± 8
100 ± 10
100 ± 11
90 ± 10
2
2
3
7
1
10
11
12
ILs were not effective against S. marcescens, P. vulgaris and P.
aeruginosa. The loss of activity compared to the reference
compounds might be explained by the large ILs anion
The results obtained during biodegradation tests revealed that
the studied ILs exhibited different susceptibility to
mineralization processes (Table 8). The majority of the ILs (8
out of 12) were readily biodegradable (biodegradation
efficiency > 80%), one was dissipated to a lesser extent
(biodegradation efficiency < 40%), whereas the remaining ILs
(3 out of 12) were resistant to biodegradation (biodegradation
Based on studies focused on the biodegradability of ILs, it can
be established that their susceptibility to biodegradation
processes depends on three fundamental structural factors:
the core of the cation, the type of cation substituents and the
type of the anion.41 The core of the cation was the same for all
ILs
tested
in
the
framework
of
this
study
(tetraalkylammonium), therefore it can be concluded that the
latter two factors influenced the biodegradability. The
fundamental effect of the type and number of cation
substituents on the biodegradation of ILs was confirmed in
efficiency
< 10%). The differences in biodegradability
correspond well with the structural differences among the
studied ILs and allow for distinction of two major effects. The
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numerous studies.42,43 Overall, the increased number of long- 1H NMR spectra were recorded on a Mercury Gemini 300
chain alkyl substituents results in decrease of the spectrometer operating at 300 MHz with TMS as the internal
a
biodegradability. This observation correspond well with the standard. 13C NMR spectra were obtained with the same
results of this study, since higher biodegradability was instrument at 75 MHz. Water content was determined using
observed for ILs comprising the alkyltrimethylammonium an Aquastar volumetric Karl Fischer titration with Composite 5
cation (9-12) compared to dialkyldimethylammonium-based solution as the titrant and anhydrous methanol as a solvent.
ILs (1-8). The biodegradation rate of ILs comprising Purity of the synthesized salts was determined by TLC method
tetrabutylammonium cation and different natural organic and analysis of NMR spectra. Elemental analyses were
acids was studied by Ferlin et al. 2013.44 The authors reported performed at the Adam Mickiewicz University, Poznan
that the overall biodegradability of the obtained ILs was below (Poland).
25% therefore none could be classified as readily
Solubility
biodegradable. This contrasts with the results presented in this
study, however the differences may be a result of structural
differences between the cations as well as anions. On the
other hand, the results obtained by Ferlin et al. suggest that
differences in the biodegradability of ILs may also be caused by
the use of different anions. This is in accordance with the
results presented in this study, as notable differences between
ILs comprising the same cation and different anions could be
observed for dialkyldimethylammonium-based salts (high
biodegradability in case of oleate or canola oil and low
biodegradability in case of stearate or coconut oil. This
confirms that the influence of the anion is also an important
factor when considering the biodegradability of ILs.
The solubility of prepared ILs was determined according to
Vogel`s Textbook of Practical Organic Chemistry.45 Popular
representative solvents were chosen and ranked in descending
order of Snyder polarity index value (water – 9.0, methanol –
6.6, DMSO – 6.5, acetonitrile – 6.2, acetone – 5.1, ethyl acetate
– 4.3, chloroform – 4.1, toluene – 2.3, hexane – 0.0). The term
`complete solubility` refers to ILs, which were dissolved (0.1g
of IL) in 1 mL of solvent, while the term `limited solubility`
means that the IL was dissolved in 3 mL of solvent. The term
`insoluble` was used to describe no solubility of 0.1 g of IL in 3
mL of solvent. Tests were conducted at 20oC under ambient
pressure.
Experimental
Thermal stability
Materials
Thermal transition temperatures were determined by DSC,
with a Mettler Toledo Stare DSC1 (Leicester, UK) unit, under
nitrogen. Samples (between 5 and 15 mg) were placed in
aluminum pans and heated from 25 to 120 oC at a heating rate
of 10 oC/min, cooled with an intracooler at a cooling rate of 10
ºC/min to -100 oC, then heated again to 120 oC.
Thermogravimetric analysis was performed using a Mettler
Toledo Stare TGA/DSC1 unit (Leicester, UK), under nitrogen. ILs
(between 2 and 10 mg) were placed in aluminum pans and
Glyceryl tristearate (97%) and oleate (98%), vegetable oils
(rapeseed, coconut) and quaternary ammonium halides:
didecyldimethylammonium
chloride
[DDA][Cl]
(98%),
benzalkonium chloride [BA][Cl] (60% C12, 40% C14; 95%),
hexadecyltrimethylammonium bromide [CET][Br] (98%),
potassium hydroxide and all solvents were supplied by Sigma-
Aldrich and POCh, and used as obtained.
o
o
heated from 30 to 450 C at a heating rate of 10 C/min. Two
cycles at different heating/cooling rates (10 and 2oC/min)
were conducted.
Synthesis
Quaternary ammonium halides (0.03 mol) were placed in
round-bottomed flasks with 50 mL of 2-propanol. Next, a
stoichiometric amount of potassium hydroxide dissolved in 2-
propanol was added. The mixture was stirred at ambient
temperature for 10 minutes. In the next step, the precipitated
inorganic salt was filtered off and 0.01 mol of triglyceride was
added. Reaction was monitored by pH electrode placed in
flask. Reagents were heated under reflux until the pH reached
constant value. The solvent was evaporated under vacuum at
60 oC and then the flask content was dissolved in 50 mL of
chloroform and placed in a separator. The organic layer was
then washed three times with 20 mL of distilled water. After
separation of phases the organic layer was poured to a flask
and the solvent was evaporated under reduced pressure. The
Feeding deterrent activity
The bioassay experiments were conducted with Tribolium
confusum Duv. (larvae and adults), Sitophilus granaries L.
(adults), and Trogoderma granarium Ev. (larvae). The insects
were grown on a wheat grain or whole-wheat meal diet in
laboratory colonies, which were maintained at 26 ± 1oC and 60
± 5 % relative humidity. Choice and no-choice tests for insect-
feeding were conducted following a previously described
procedure.46 Wheat wafers discs (1 cm in diameter, 1 mm
thick) were saturated by dipping either in ethanol only
(control) or in a solution of the studied ILs (1%) in ethanol to
be tested. After evaporation of the solvent (30 min of air-
drying) the wafers were weighted and offered to the insects in
plastic boxes as the sole food source for 5 days. The feeding of
insects was recorded under three sets of conditions: (1) on two
control discs (CC), (2) on a choice between one treated disc (T)
and one control disc (C; choice test), and (3) on two treated
o
product was then dried under vacuum (10 mbar) at 60 C for
24 h.
Analysis
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discs (TT; no-choice test). Each of the three experiments was containing mineral medium, inoculum (cell density at approx.
repeated five times with 3 adults of Sitophilus granaries, 20 106 cells/mL determined with plastic Paddle Tester for aerobic
adults and 10 larvae of Trogoderma granarium. The number of bacteria, Hach, USA) and tested ILs at a concentration of
individual insects depended on the intensity of their food approx. 10-30 mg/L, which was equal to 100 mg/L of
consumption. The adults used for experiments were unsexed, Theoretical Oxygen Demand (ThOD, calculated based on
7-10 days old, and the larvae were 5-30 days old. After 5 days equation CcHhNnOoPp).
ꢏꢐ
ꢇ ꢉ
16[2ꢆ + ꢈ ℎ − 3ꢊ + ꢌꢈ ꢍ − ꢎ]
ꢋ
the discs were weighted and the average weight of eaten food
ꢏꢐ
ꢂℎꢄꢅ =
was calculated.
ꢏꢏꢛꢜ
ꢏꢐ
ꢑꢎꢒꢓꢆꢔꢒꢕꢖ ꢑꢕꢗꢗ ꢎꢘ ꢙℎꢓ ꢙꢓꢗꢙ ꢗꢔꢚꢗꢙꢕꢊꢆꢓ
Anti-microbial activity
Allylthiourea (1.16 mg/L) was added to inhibit nitrification. All
samples were analyzed in triplicates together with controls
(sodium benzoate without inoclum, tested substances without
inoculum) and blanks (medium and inoculum without tested
substances). Gas tight flasks were connected with the
respirometric system and incubated in the dark at 22 °C for 28
days. The CO2 sensor range spanned the volume of 0–15%.
Sensitivity of the respirometer was at 0.2 µL/h. The
biodegradation efficiency was calculated based on the oxygen
uptake in each bottle (measured automatically by the Micro-
Oxymax) and corrected for the oxygen demand of the blank,
with the respect to the Theoretical Oxygen Demand and the
amount of ILs tested.
Anti-microbial activity was determined by the tube dilution
method. A series of ammonium salts dilutions was prepared
on Müller–Hinton broth medium (bacteria) or Sabouraud
broth medium (fungi). A suspension of the microorganisms,
prepared from 24 h cultures of bacteria in the Müller–Hinton
broth medium and from 48 h cultures in the Sabouraud agar
medium for fungi, at a concentration of 106 cfu mL-1, were
added to each dilution in a 1+1 ratio. Growth (or lack of
growth) of the microorganisms was determined visually after
incubation for 24 h at 37 °C (bacteria) or 48 h at 28–30 °C
(fungi). The lowest concentration at which there was no visible
growth (turbidity) was taken as the MIC. Then, one loopful
from each tube was cultured on an agar medium with
inactivates (0.3% lecithin, 3% polysorbate 80 and 0.1% cysteine
L) and incubated for 48 h at 37 °C (bacteria) or for 5 days at
28–30 °C (fungi). The lowest concentration of the salt
supporting no colony formation was defined as the MBC and
MFC. The following microorganisms were used during the
tests: standard strains representative of cocci: Micrococcus
luteus ATCC 9341, Staphylococcus aureus ATCC 6538,
Staphylococcus epidermidis ATCC 12228, Enterococcus faecium
ATCC 49474; rods: Moraxella catarrhalis ATCC 25238,
Escherichia coli NCTC 8196, Bacillus subtilis ATCC 6633,
Serratia marcescens ATCC 8100, Proteus vulgaris NCTC 4635,
Pseudomonas aeruginosa ATCC 15442 and fungi: Candida
albicans ATCC 10231, Rhodotorula rubra (Demml 1889, Lodder
1934). Standard strains were supplied by the National
Collection of Type Cultures (NCTC) London and American Type
Culture Collection (ATCC). Rhodotorula rubra was obtained
from the Department of Pharmaceutical Bacteriology, K.
Marcinkowski University of Medical Sciences, Poznan.
Didecyldimethylammonium stearate (1)
1H NMR (DMSO-d6) (ppm): 0,82 (t, 9H); 1,19 (m, 56H); 1,50 (m,
2H); 1,59 (m, 4H); 2,05 (m, 2H); 3,21 (s, 6H); 3,23 (m, 4H).
13C NMR (DMSO-d6) δ (ppm): 13,9; 22,5; 25,2; 26,2; 27,0; 29,1;
31,7; 39,0; 51,2; 63,4; 179,9.
Elemental analysis calc. (%) for C40H83NO2 (610,09 g/mol):
C 78.75, H 13.71, N 2.30. Found: C 79.12, H 14.00, N 2.40.
Didecyldimethylammonium oleate (2)
1H NMR (DMSO-d6) (ppm): 0,88 (t, 9H); 1,27 (m, 48H); 1,63 (m,
2H); 1,65 (m, 4H); 2,00 (m, 4H); 2,12 (m, 2H); 3,25 (s, 6H); 3,29
(m, 4H); 5,33(m, 2H).
13C NMR (DMSO-d6) δ (ppm): 13,8; 21,5; 22,3; 25,0; 26,9; 29,0;
31,5; 38,7; 51,0; 63,4; 129,6; 179,9.
Elemental analysis calc. (%) for C40H81NO2 (608,08 g/mol):
C 79.01, H 13.43, N 2,30. Found: C 79.16, H 13.63, N 2.41.
Didecyldimethylammonium canolate (3)
1H NMR (CDCl3) (ppm): 0,86 (t, 9H); 1,26 (m, 45H); 1,51 (m,
2H); 1,63 (m, 4H); 2,00 (m, 4H); 2,11 (m, 2H); 3,31 (s, 6H); 3,36
(m, 4H); 5,32 (m, 2H).
Ready biodegradability according to OECD 301 F test –
manometric respirometry
13C NMR (CDCl3) δ (ppm): 14,0; 22,1; 25,8; 26,6; 26,8; 28,7;
31,3; 39,0; 51,2; 62,7; 129,7; 175,4.
The test was performed according to OECD guideline for 301 F
test. The oxygen uptake and CO2 production was determined
every 5 h for 28 days using the Micro-Oxymax Respirometer
(Columbus Instruments, USA). The activated sludge was
collected from a local municipal wastewater treatment plant
(Czajka, Warsaw, Poland). Prior to use, the activated sludge
was aerated for 7 days in mineral medium which was also used
for subsequent tests. The mineral medium consisted of KH2PO4
- 85 mg/L, K2HPO4 – 220 mg/L, Na2HPO4·2H2O – 220 mg/L,
NH4CL – 17 mg/L, CaCl2·2H2O – 37 mg/L, MgSO4·2H2O – 23
mg/L, FeCl3– 0.25 mg/L. The measured pH was at 7.2. The test
was performed in brown glass bottles (100 mL Simax)
Didecyldimethylammonium cocoate (4)
1H NMR (CDCl3) (ppm): 0,88 (t, 9H); 1,26 (m, 44H); 1,53 (m,
2H); 1,66 (m, 4H); 2,11 (m, 2H); 3,30 (s, 6H); 3,37 (m, 4H).
13C NMR (CDCl3) δ (ppm): 13,9; 22,5; 25,2; 26,2; 28,9; 29,1;
31,7; 39,1; 51,1; 63,3; 179,8.
Benzalkonium stearate (5)
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1H NMR (DMSO-d6) (ppm): 0,88 (t, 6H); 1,26 (m, 48H); 1,54 (m,
2H); 1,74 (m, 2H); 2,11 (m, 2H); 3,18 (s, 6H); 3,23 (m, 2H); 4,73
(m, 2H); 7,43 (m, 3H); 7,56 (m, 2H).
13C NMR (DMSO-d6) δ (ppm): 14,0; 21,7; 22,6;26,2; 27,0; 29,2;
31,8; 38,9; 50,0; 63,7; 67,5; 126,8; 127,6; 129,0; 130,4; 132,9;
173,3.
Hexadecyltrimethylammonium cocoate (12)
1H NMR (CDCl3) (ppm): 0,88 (t, 6H); 1,26 (m, 42H); 1,56 (m, 2H); 1,71 (m,
2H); 2,11 (m, 2H); 3,34 (s, 9H); 3,45 (t, 2H).
13C NMR (CDCl3) δ (ppm): 13,9; 22,5; 25,2; 26,1; 27,0; 29,5; 31,7; 39,0;
52,9; 66,6; 179,8.
Benzalkonium oleate (6)
1H NMR (DMSO-d6) (ppm): 1,01 (t, 6H); 1,38 (m, 30H); 1,72 (m,
2H); 1,89 (m, 2H); 2,12 (m, 4H); 2,29 (m, 2H); 3,34 (s, 6H); 3,46
(m, 2H); 4,94 (m, 2H); 5,46 (m, 2H); 7,58 (m, 3H); 7,69 (m, 2H).
13C NMR (DMSO-d6) δ (ppm):14,0; 21,7; 22,6; 26,2; 27,1; 29,5;
31,8; 34,6; 39,1; 49,7; 63,8; 67,6; 127,5; 129,1; 130,5; 133,0;
173,3.
Conclusions
This study presents a new method of obtaining ILs from
natural sources. It is focused on the use of natural vegetable
oils as anionic moieties for synthesis of biologically active ILs.
The salts were synthesized with high yield and purity. It was
established that both the physicochemical properties
(solubility, phase transition temperatures and thermal
stability) and activity of the studied ILs depend on their
chemical structures. The feeding deterrent activity was very
good to good in the case of Sitophilus granarius (beetle),
Tribolium confusum (larvae), Trogoderma granarium (beetle)
and medium to good in case of Tribolium confusum (beetle).
Comparison of anti-microbial properties of the obtained ILs
and precursor compounds revealed that the studied ILs were
characterized by similar activity. A species-specific diversity in
the efficiency of the ILs could be observed during both the
feeding deterrent activity and anti-microbial activity assays,
which is most likely associated with their structural
differences. Furthermore, the biodegradation tests confirmed
that most of the ILs exhibited high biodegradation efficiency (
> 80%) and may be classified as readily biodegradable. The
tests revealed a notable influence of the cations (ILs with
alkyltrimethylammonium cation were more biodegradable
compared to ILs with dialkyldimethylammonium cation),
followed by the effect of anions (ILs with unsaturated oleate
and canola oil anions were more biodegradable compared to
ILs with saturates stearate and coconut oil anions). These
findings confirm that the described method may be
successfully used for synthesis of ILs from natural products and
elucidates valuable guidelines for the design of efficient
products with attractive properties for a wide range of
applications.
Benzalkonium canolate (7)
1H NMR (CDCl3) (ppm): 0,88 (t, 6H); 1,26 (m, 38H); 1,61 (m,
2H); 1,76 (m, 2H); 2,01 (m, 4H); 2,18 (m, 2H); 3,23 (s, 6H); 3,34
(m, 2H); 4,86 (m, 2H); 5,33 (m, 2H); 7,45 (m, 3H); 7,58 (m, 2H).
13C NMR (CDCl3) δ (ppm): 14,0; 22,6; 25,3; 26,2; 27,2; 29,5;
31,8; 34,6; 39,2; 49,6; 63,1; 67,4; 127,6; 129,0; 129,8; 130,4;
133,0; 179,9.
Benzalkonium cocoate (8)
1H NMR (CDCl3) (ppm): 0,88 (t, 6H); 1,26 (m, 36H); 1,60(m, 2H);
1,76 (m, 2H); 2,18 (m, 2H); 3,23 (s, 6H); 3,36 (m, 2H0; 4,86 (m,
2H); 7,45 (m, 3H); 7,60 (m, 2H).
13C NMR (CDCl3) δ (ppm): 14,0; 22,5; 25,2; 26,2; 27,1; 29,4;
29,4; 31,7; 34,6; 39,2; 49,5; 63,1; 67,5; 127,5; 129,0; 133,0;
179,9.
Hexadecyltrimethylammonium stearate (9)
1H NMR (DMSO-d6) (ppm): 0,88 (t, 6H); 1,25 (m, 52H); 1,54 (m,
2H); 1,72 (m, 2H); 2,11 (m, 2H); 3,34 (s, 9H); 3,43 (m, 2H).
13C NMR (DMSO-d6) δ (ppm):14,0; 22,6; 24,9; 26,1; 29,6; 31,8;
38,9; 53,2; 66,8; 173,8.
Elemental analysis calc. (%) for C37H77NO2 (568,01 g/mol):
C 78.24, H 13.66, N 2.47. Found C 78.03, H 13.29, N=2.79.
Hexadecyltrimethylammonium oleate (10)
1H NMR (DMSO-d6) (ppm): 0,88 (t, 6H); 1,26 (m, 46H); 1,54 (m,
2H); 1,72 (m, 2H); 2,00 (m, 4H); 2,11 (m, 2H); 3,33 (s, 9H); 3,43
(m, 2H); 5,35 (m, 2H).
13C NMR (DMSO-d6) δ (ppm): 14,0; 22,6; 23,1; 24,8; 26,9; 29,6;
31,8; 38,7; 53,1; 72,7; 129,7; 180,4.
Acknowledgements
This work was supported by National Science Center, Poland,
(grant No. DEC-2012/07/B/ST5/00806)
Elemental analysis calc. (%) for C37H75NO2 (566,00 g/mol):
C 78.52, H 13.36, N 2.47. Found C 78.71, H 13.71, N 2.72.
Notes and references
1
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1H NMR (CDCl3) (ppm): 0,88 (t, 6H); 1,26 (m, 44H); 1,56 (m,
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2
3
4
13C NMR (CDCl3) δ (ppm): 13,9; 22,5; 25,2; 26,1; 27,0; 29,5;
31,8; 39,0; 53,0; 66,6; 129,7; 179,9,
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Ammonium ionic liquids with anions of natural origin are biodegradable agents with antifeedant and anti-microbial activity.