Nitrogen-containing ionic liquids: Biodegradation studies and utility in base-mediated reactions

Article abstract of DOI:10.1071/CH14499

Several ionic liquids (ILs) were prepared in order to study the susceptibility of various cores and substituents to biodegradability using the 'CO₂ headspace' test (ISO 14593). Several of the ILs contained tertiary amine substituents and were tested as solvents and reagents for several base mediated processes including Suzuki-Miyaura, Sonogashira, Knoevenagel, and Morita-Baylis-Hilman reactions. It was found that although these ILs contain basic functionality, they do not promote base mediated reactions. Density functional theory molecular calculations confirmed that the protonation of these ILs is energetically unfavourable. Journal compilation

Full text of DOI:10.1071/CH14499

CSIRO PUBLISHING
Aust. J. Chem. 2015, 68, 849–857
Full Paper
http://dx.doi.org/10.1071/CH14499
Nitrogen-Containing Ionic Liquids: Biodegradation
Studies and Utility in Base-Mediated Reactions
A D
,
B
C
B
Leigh Ford,
Kai E. O. Ylijoki, M. Teresa Garcia, Robert D. Singer,
A D
,
and Peter J. Scammells
A
Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash
University, 381 Royal Parade, Parkville, Vic. 3052, Australia.
B
Atlantic Centre for Green Chemistry, Department of Chemistry, Saint Mary’s University,
Halifax, Nova Scotia B3H 3C3, Canada.
C
Department of Surfactant Technology, IQAC-CSIC, Jordi Girona 18-26, 08034, Spain.
D
Corresponding authors. Email: leigh.ford@monash.edu; peter.scammells@monash.edu
Several ionic liquids (ILs) were prepared in order to study the susceptibility of various cores and substituents to
biodegradability using the ‘CO2 headspace’ test (ISO 14593). Several of the ILs contained tertiary amine substituents
and were tested as solvents and reagents for several base mediated processes including Suzuki–Miyaura, Sonogashira,
Knoevenagel, and Morita–Baylis–Hilman reactions. It was found that although these ILs contain basic functionality, they
do not promote base mediated reactions. Density functional theory molecular calculations confirmed that the protonation
of these ILs is energetically unfavourable.
Manuscript received: 8 August 2014.
Manuscript accepted: 3 October 2014.
Published online: 8 December 2014.
Knoevenagel condensation,[17] condensation reactions to gen-
erate heterocycles,[18–20] transesterification,[21–23] and bromina-
tion of alkenes.[24]
Introduction
Ionic liquids (ILs) have become a ubiquitous tool in synthetic,[1]
industrial,[2] and materials chemistry.[3,4] The ability to easily
alter both the organic cation and (in)organic anion provide
the opportunity to tailor the solvent to a specific need. Our
interest,[5–8] in addition to others,[9–11] in the biodegradation of
ILs stems from concerns regarding the long-term impact of
the increasing utility of these species in both industrial and
academic settings.
Aerobic biodegradation of carbon-containing molecules by
activated sludge represents a key component of wastewater
treatment, and is responsible for removing the majority of organic
contaminants.[12] Depending on a variety of both physical and
chemical properties, including aqueous solubility, volatility, and
lipophilicity, many organic residues may be physically removed
in varying degrees from the bulk sewage during primary
treatment. However ILs, due to their extremely low volatility
and high stability, are likely to accumulate in the biosphere. It is
therefore of great interest to design ILs susceptible to complete
biodegradation.
Further to our recent studies probing the biodegradability of
pyridinium ILs,[13] we report herein the synthesis of several ILs
and a study of their susceptibility to biodegradation. In addition
to several pyridinium ILs, other cyclic and acyclic alkyl ammo-
nium ILs were prepared (Chart 1). Several of these ILs contain
tertiary amines, whose basicity we hoped to exploit for synthetic
purposes, by using the IL as both solvent and reagent/catalyst.
The synthesis and use of basic ILs is well known.[14,15] Basic
ILs have been utilised for several diverse reactions including
Heck coupling,[16] copper free Sonogashira coupling,[16]
Results and Discussion
IL Synthesis
The majority of ILs utilised in this study were synthesised using
a two-step procedure starting with alkylation at nitrogen using
the required alkyl halide followed by anion metathesis using
known methodology (Scheme 1).[1] The anion of choice for the
majority of the ILs reported herein was the bis(tri-
fluoromethane)sulfonimide (i.e. bistriflimide) anion, as ILs
containing this anion tend to have low viscosity, low melting
point, high thermal stability, and low water solubility/misci-
bility,[1] which are often useful features for organic reactions. A
dicyanamide IL was also prepared to probe the effect of
increased water miscibility. Although the synthetic sequences
were all somewhat straightforward, it was found that each
substrate required distinct conditions for optimal alkylation
outcomes as described in the experimental section.
The general method for anion metathesis, converting the
halide salt into the bistriflimide, was performed by treating the
alkyl halide with commercially available lithium bistriflimide in
distilled water, followed by extracting the organic soluble IL
into dichloromethane. The absence of halide impurities was
confirmed using the AgNO3 precipitate test. The dicyanimide IL
was prepared by treatment of the halide salt with silver(I)
dicyanamide, prepared from commercially available sodium
dicyanamide upon treatment with silver(I) nitrate in water.
Journal compilation Ó CSIRO 2015
www.publish.csiro.au/journals/ajc

850
L. Ford et al.
R
ꢃ
ꢂ
N
R
N
R
N
N
NTf2
ꢃ
ꢃ
ꢂ
NTf2
ꢂ
NTf2
nBu
1 R ꢁ allyl
2 R ꢁ benzyl
4 R ꢁ NEt2
5 R ꢁ H
7 R = n-C6H13
3 R ꢁ CH2CH2N(iPr)2
6 R ꢁ CO2H
R
R
ꢃ
N
N
ꢂ
NTf2
ꢃ
ꢂ
NTf2
ꢃ
HO
N
R
Rꢀ
HO
HO
N
ꢂ
NTf2
8 R = n-C6H13
9 R ꢁ n-C5H11
Rꢀ ꢁ n-C4H9
10 R ꢁ n-C6H13
11 R ꢁ n-C7H15
ꢃ
ꢃ
OH
R
N
N
ꢂ
NTf2
N
N
ꢂ
N(CN)2
12 R ꢁ n-C6H13
13 R ꢁ n-C7H15
14
Chart 1.
The pyridinium ILs 1 and 2 have been prepared previously,[25]
however nothing has been reported regarding their biodeg-
radation. We wished to determine the effect of an unsaturated
nitrogen substituent on biodegradation, by comparison with other
N-substituted ILs that have previously shown good biodegrada-
tion.[13] The alkylation of pyridine with both allyl bromide and
benzyl bromide was carried out by addition of the alkyl halide at
low temperature, as a strong exothermic reaction occurred at
room temperature leading to discoloration of the IL product.
Following metathesis to the desired bistriflimide salt, both ILs
were synthesised in good overall yields. ILs 4–6 were synthesised
to compare the effect of differing functional groups on a similar
core (i.e. basic, neutral, and acidic).
LiNTf2 or
AgN(CN)2
Rꢀ–X
ꢂ
N ꢃ
Rꢀ
solvent
ꢂ
solvent
Y
N ꢃ
Rꢀ
N
R
X
R
R
Y ꢁ NTf2 or N(CN)2
R, Rꢀ ꢁ alkyl
Scheme 1.
ꢃ
ꢂ
N
ꢂ
ꢃ
N
ꢃ
N
Cl
Cl
N
Scheme 2.
IL 3, containing a N,N-diisopropyl substituent on the pendant
nitrogen, was also prepared as the moiety containing a N,N-
dimethylamino side chain was prone to nucleophilic displace-
ment of the tertiary amino group on the b-carbon releasing
pyridine and led to isolation of dimethylaziridinium chloride
after concentration under vacuum (Scheme 2). Presence of the
N,N-dimethylaziridinium chloride by-product was confirmed
by H NMR spectroscopy (d 3.44, s, 6H and d 4.02, s, 4H in
D2O). No decomposition was observed in the case of ILs bearing
the more sterically hindered N,N-diisopropyl groups.
to biodegradability based on previous studies;[26] however, it
was anticipated that they may be useful in base promoted
reactions. Furthermore, alkyl ammonium ILs are becoming
widely used in industry particularly as lubricants.[27] Despite
many alkyl ammonium bistriflimide ILs having desirable phys-
ical properties, they have been shown to be poorly biodegrad-
able.[28,29] Hence, we hypothesised that the more water miscible
alkyl ammonium bistriflimides may be more susceptible to
biodegradability in an aqueous environment and therefore
prepared ILs 7, 8, and 9 having increasingly polar substituents
for enhanced water solubility.
Mono-alkylation of DABCO proceeded in good yield using
either an alkyl chloride at reflux, or by addition of an alkyl
bromide at low temperature and stirring at room temperature
overnight. Mono-alkylation of the N,N-dimethylpiperazine core
required use of the less reactive chloroalkane under microwave
irradiation conditions, while use of the more reactive iodo- and
bromo-alkyl halide resulted in dialkylation of the piperazine
ring.[30] In both cases, the hexyl derivative was found to be
extremely viscous at room temperature; indeed the IL 12 was
solid at room temperature. Surprisingly, homologation by one
carbon had a dramatic effect, lowering both the melting point
and viscosity (both being liquids at ambient temperature).
1
IL4 was synthesisedfrom picolyl chloride hydrochloride upon
treatment with diethylamine in anhydrous acetonitrile at ꢀ108C.
This reaction afforded a cleaner product when acetonitrile was
employed as the reaction solvent (rather than dichloromethane or
diethyl ether), with isolation of pure 3-(aminomethyl)pyridine
after a simple aqueous workup. Alkylation at the nitrogen in the
pyridine ring occurred smoothly using 1-bromobutane. Reaction
in this position, rather than the tertiary amine, was confirmed
1
by the characteristic H NMR spectrum shift of the pyridinium
ring protons in addition to lack of shift of the benzylic-type
methylene signal.
ILs based on other non-aromatic amine-based cores, specifi-
cally 1,4-dimethylpiperazine and 1,4-diazabicyclo[2.2.2]octane
(DABCO), in addition to simple alkyl ammonium ILs were also
synthesised. We did not expect these cores to be very susceptible

Nitrogen-Containing Ionic Liquids
851
60
NEt2
ꢂ
NTf2
N
N
ꢃ
ꢂ
ꢃ
NTf2
Percentage
biodegradation
nBu
N(iPr)2
3
4
6
8
4
7
3
4
3
9
3
5
1
1
1
2
1
3
1
1
0
0
0
6
10 11 12 13 14
ꢃ
ꢃ
C7H15
N
Compound number
N
ꢂ
NTf2
N
N
ꢂ
C6H13
NTf2
Fig. 1. Biodegradation data (CO2 Headspace test) associated with the ionic
liquids 1–14.
7
13
Chart 2.
Table 1. Ionic liquid biodegradation results
from the ‘CO2 headspace’ test (ISO 14593)
low susceptibility to biodegradation by Sphingomonas pauci-
mobilis.[32] It is clear that pyridinium ILs 1 and 2, containing
unsaturated substituents (allyl and benzyl respectively), are not
susceptible to mineralisation. Interestingly the polarity of alkyl
ammonium ILs had little effect on biodegradability, we had
hoped that the alcohol-containing side chains would provide a
site susceptible to degradation, in line with previous results.[13]
It is unlikely that low water solubility is a major factor in the
lack of biodegradation as dicyanamide IL 14, being completely
miscible with water, was not observed to mineralise.
Due to the poor mineralisation, inhibition tests were
performed in order to evaluate inhibition as a possible cause
or contributory factor to the negligible biodegradation observed
for most of the ILs. To evaluate the toxicity of these ILs to the
microorganisms responsible for aerobic biodegradation, solu-
tions containing a mixture of the compound and a reference
substance (SDS) were tested. Biodegradation percentages for
the mixtures of ILs and SDS were calculated based on the
theoretical IC yields anticipated from only the reference sub-
stance. For all ILs tested, a certain degree of inhibition of the
inoculum activity was found (see Table S5 in the Supplementary
Material). However, the inhibition percentages were lower than
the limit commonly accepted to consider inhibitory effects
(25 %). Although these compounds are slightly inhibitory at
the concentration applied in the test, toxicity seems to play a
minor role and the lack of degradation is attributable to non-
amenability of the organic cations to microbial attack under the
conditions of the test.
Compound number
BiodegradationA [%]
1
0 ꢁ 1.7
1 ꢁ 0.3
0 ꢁ 0.4
3 ꢁ 0.5
3 ꢁ 1.6
60 ꢁ 5.0
4 ꢁ 0.3
6 ꢁ 0.6
3 ꢁ 0.7
1 ꢁ 1.2
1 ꢁ 1.7
0 ꢁ 3.7
0 ꢁ 3.2
0 ꢁ 3.8
2
3
4
5
6
7
8
9
10
11
12
13
14
AIL initial concentration ¼ 20 mg C Lꢀ1; 95 % con-
fidence limits calculated from four replicates.
Biodegradation Studies
To evaluate the biodegradability of the test ILs, the ‘CO2 head-
space’ test (ISO 14593) was utilised. This method allows the
evaluation of the ultimate aerobic biodegradability of an organic
compound in an aqueous medium at a given concentration of
microorganisms by analysis of inorganic carbon (IC). The test IL,
the sole source of carbon (and energy), was added at a concen-
tration of 20 mgC Lꢀ1 to a mineral salt buffer medium. These
solutions were inoculated with activated sludge collectedfrom an
activated sludge treatment plant, washed, and aerated before use
and incubated in sealed vessels with a headspace of air.
ILs as Reagents
Biodegradation (mineralisation to carbon dioxide) was deter-
mined by measuring the IC producedinthe test bottlesinexcess of
that produced in blank vessels containinginoculatedmediumonly.
The carbon dioxide generated during the biodegradation process
was determined by using a total organic carbon (TOC) analyser
equipped with a non-dispersive infrared (NDIR) detector. Sodium
n-dodecyl sulfate (SDS) was used as the reference substance; the
test ran for 28 days and four replicates were performed for each IL.
The extent of biodegradation was expressed as a percentage of the
theoretical amount of inorganic carbon (ThIC) based on the
amount of test compound added initially.
Unfortunately, almost all ILs tested showed no significant
mineralisation under the conditions used in ready biodegrada-
tion assessments (Fig. 1, Table 1), the only exception being IL 6.
This result is consistent with previous studies showing ILs with
an ester in the 3-position of the pyridine ring show good
mineralisation.[31] IL 5 has been reported previously to have
Given the numerous literature reports describing the use of
tertiary amine bases in the Suzuki–Miyaura reaction[33–36] we
envisaged utilising ILs 3, 4, 7 and 13 (Chart 2) as both solvents
and reagents for the reaction.
Attempts to perform Suzuki–Miyaura couplings in the
basic ILs under standard conditions (1 equiv. Ar–I, 1.1 equiv.
Ar–B(OH)2, 0.1 equiv. Pd(PPh3)2Cl2, 5 equiv. IL, 908C, 1.5 h),
resulted in only trace formation of the desired coupled product
(Table 2). This result was consistent across the ILs tested and led
to concerns regarding the ability of the pendant amine group to
participate in the palladium catalytic cycle. Furthermore, addi-
tion of an aqueous base to the reaction mixture (2 M aqueous
Na2CO3) resulted in good conversion into the biaryl product
(Table 2, entries 2, 4, and 6). Given the complex nature of the
Suzuki–Miyaura reaction it was hard to determine why the
reaction in the IL failed. The possibility of the IL inhibiting
the reaction, perhaps via deactivation of an intermediate

852
L. Ford et al.
Table 2. Suzuki–Miyaura coupling reactions in ionic liquids (ILs) 3, 4, and 13
cat. 10 mol-%
Ar—I
ꢃ
Arꢀ—B(OH)2
Ar—Arꢀ
IL
Entry
1
IL
Ar
Ar0
Ph
Cat.C
Base
–
Yield [%]
0
MeO
3
A
A
2
3
Ph
Na2COA3
74
MeO
B
3
4
4
4
Ph
Ph
Ph
Ph
A
A
–
,5
87
Na2CO3
Ph
5
6
13
13
A
A
–
0
Ph
Na2CO3
80
MeO
MeO
MeO2C
7
8
4
4
B
B
–
0
MeO2C
Na2CO3
24
A2 M Na2CO3 (aq.) for all reactions indicated.
BWater added to reaction.
CMethod A – Pd(Ph3P)2Cl2, method B – Pd(Ph3P)4.
palladium species by the triflimide anion, seemed unlikely due
to it’s non-coordinating nature and the fact that the reaction
proceeds in the presence of aqueous base. It is more likely that
the problem lies in the failure of the pendant amine to participate
in the catalytic cycle. This could be due to either electronic or
steric factors, the pendant amines on the ILs are likely poor
surrogates for triethylamine or N,N-diisopropylethylamine
(DIPEA) on both counts. Repeating the reaction in the presence
of water (Table 2, entry 3) reinforced that it was the addition of
aqueous base that was required for the reaction to occur.
These results indicate that pendant amino groups on the
prepared IL were unsuccessful in promoting the Suzuki–
Miyaura reaction in the absence of aqueous base and, in this
respect, offer no real advantage over conventional solvents.
Similar results were also observed when performing Sono-
gashira couplings (Scheme 3).[37] When the reaction was
performed in the presence of triethylamine the coupled product
was isolated in excellent yield (method A), however no product
was observed in its absence (method B).
Modifying the reaction conditions, utilising sonication and
also using an alternate catalyst, in an attempt to improve the
yield, had little effect (Table 3). Moderate conversion was
obtained by addition of copper(I) iodide, however several
homo-coupled bis-alkyne and biphenyl by-products were also
observed by 1H NMR spectroscopy and could not be separated
from the desired product using standard flash chromatography.
Once again the basic ILs showed no advantage over using
conventional solvents.
Table 3. Sonogashira coupling reactions in ionic liquids (ILs) 3 and 4
I
ꢃ
Entry
IL
Catalyst
Time [h]
Temp [8C]
Yield [%]
1
2
3
4
5
6
3
4
4
4
4
4
Pd(PPh3)2Cl2
Pd(PPh3)2Cl2
Pd(PPh3)2Cl2
PdCl2
6
6
25
25
40
60
70
55
0A
17A
19
18
10
12
20
0
Pd(PPh3)2Cl2
Pd(PPh3)2Cl2
27
70B,C
AMixture was sonicated at ambient temperature.
BCuI (5 mol-%) added.
CCrude product.
The use of basic ILs to mediate Knoevenagel condensations
is known.[38] Screening of several of our basic ILs showed that
they were indeed able to facilitate condensation between benz-
aldehyde and ethyl cyanonitrile to give methyl-2-cyano-3-
phenylacrylate. Stirring both the aldehyde and cyanoester in
the IL at ambient temperature overnight, followed by extraction
of the product with a mixture of hexane/Et2O (4 : 1) gave the
desired product. The results are summarised in Table 4.
ILs 4 and 7 gave the best yields; it is possible that these
species act as organocatalysts (reacting with benzaldehyde due

Nitrogen-Containing Ionic Liquids
853
I
Table 4. Morita–Baylis–Hillman (MBH) reaction results
O
PdCl2 5 mol-%
O
ꢃ
O
OH
O
ꢂ
solvent
rt, 24 h
NTf2
ꢃ
H
method A – 95 %
method B – 0 %
O
Ph
O
O
N
ꢃ
N(iPr)2
method A – (1.5 equiv. Et3N)
method B – no Et3N
Solvent
Co-solvent
Yield [%]
47C
DBUA
n/a
not observedD
not observedD
,5D
not observedD
not observedD
not observedD
Scheme 3.
7
n/a
TMEDAB
n/a
13
MeOH
MeOH
n/a
H
N
TMEDA
N
ꢃ
BF4ꢂ
N
4
4
MeOH
N
ADBU: 1,8-Diazabicyclo[5.4.0]undec-7-ene.
BTMEDA: tetramethylethylenediamine.
CIsolated yield.
Chart 3.
DYield determined by liquid chromatography–mass spectrometry.
ꢃ
N
NEt2
Me
N
N
N
to their lower steric hindrance when compared with 3 and 13)
during the condensation, a mechanism that has been reported
previously.[39] In addition, 7 is very similar to ILs reported by
Hardacre[38] used to catalyse the Knoevenagel condensation.
In light of the results of the Knoevenagel condensation we
turned to the Morita–Baylis–Hillman (MBH) reaction, predict-
ing that similar results would be observed. Disappointingly,
none of the ILs tested were able to catalyse the MBH reaction
between benzaldehyde and methyl acrylate (Table 4). Methanol
(added as a co-solvent) has been reported to aid other ILs in the
MBH reaction, but unfortunately had no effect.[40] This suggests
that the pendant amines have significantly reduced nucleophi-
licity, most likely due to steric bulk. However, the lack of
reactivity of DABCO-based IL 13 is surprising, given the known
utility of DABCO in the MBH reaction.
Interestingly Cheng and co-workers[40] have reported an IL
that does catalyse the MBH reaction (Chart 3). When the
reaction is carried out in common imidazolium IL solvents, a
dramatic decrease in yield is observed. This could be due to the
reaction with the imidazolium core via removal of the acidic
C2-proton under basic conditions.
ꢃ
ꢃ
Me
(iPr)2
15
16
17
Chart 4.
O
O
O
IL, 25ꢄC, 24 h
NC
ꢃ
OMe
H
NC
OMe
Ph
∗
yield
IL
3
4
7
49 %
89 %
87 %
13 26 %
∗
isolated
Scheme 4.
likely not representative of the actual protonation equilibrium,
the qualitative agreement with experiment is very good; calcula-
tions indicate that formation of a doubly cationic species through
simple protonation is a significantly endergonic process and
unlikely to occur to a significant extent. The high energy barrier
tothe formation ofdicationswithDABCO and DABCO-based IL
13 is likely dueto electrostatic repulsion between the two positive
nitrogens held close in proximity bythe constraintsofthe bicyclic
ring system. Such a rationale also partially explains why
DABCO-based IL 13 is not reactive as a nucleophile in MBH
reactions, despite the lack of steric bulk. The constraints of a
bicyclic system reducing both basicity and nucleophilicity are
supported by DFT calculations for the protonation of model ILs
16 and 17, where such constraints are not present. The Gibbs
energy changes for model ILs 16 and 17 are 5.1 and 2.7 kcal
molꢀ1 respectively. While these barriers are significantly lower
than those calculated for DABCO and DABCO-based IL model
15, protonation is still thermodynamically uphill, which is in
good agreement with the good to moderate levels of reactivity
observed in the Knoevenagel condensation (Scheme 4).
Modelling Studies
Density functional theory (DFT) calculations were undertaken
to rationalise the low basicity observed for DABCO-based ILs.
We hypothesised that the positive charge on one nitrogen atom
of the bicyclic diamine reduces the basicity of the second amine
functionality, as protonation would result in a high-energy
dicationic species. The protonation energetics of DABCO and
simplified model ILs (Chart 4) by hydronium were calculated at
the B3LYP/6–311þþG** level.
The experimentally determined pKa values of doubly proton-
ated DABCO (DABCOH22þ) are pKa1 ¼ 2.97 (H2O and DMSO),
and pKa2 ¼ 8.82(H2O),[41] 8.93(DMSO).[42] Thisdatashows that
the first protonation of DABCO is quite favourable while the
second is much less so and are in agreement with our experimen-
tal determination of the reduced basicity of DABCO-based ILs.
B3LYP/6–311þþG** DFT calculations for DABCO proton-
ation qualitatively agree with the experimental pKa values:
DG1 ¼ ꢀ65.0kcal molꢀ1, and DG2 ¼ 37.4 kcal molꢀ1, suggest-
ing that theoretical results will qualitatively mirror experiment.
The calculated protonation Gibbs energy change for bicyclic
model IL 15 is 34.6kcal molꢀ1. While this DG value is large and
Conclusion
A series of ILs with cores including pyridine, 1,4-dimethyl-
piperazine, 1,4-diazabicyclo[2.2.2]octane (DABCO), and several

854
L. Ford et al.
simple alkyl ammonium ILs were synthesised and their biode-
gradability determined using the ‘CO2 headspace’ test (ISO
14593). All ILs showed poor biodegradability apart from IL 6,
which showed a high extent of ultimate biodegradation, consis-
tent with previous studies. ILs 3, 4, 7, and 13 were utilised for
several base mediated reactions and were found to have sur-
prisingly low basicity/nucleophilicity; it is very likely that the
formation of the requisite organic dication is thermodynamically
uphill and unfavourable. This proposal was supported by DFT
calculations and comparison to previously reported pKa data.
warm slowly to room temperature and stirred overnight.
The resulting solid residue was dissolved in anhydrous MeCN
and the desired product was isolated by precipitation through
addition of Et2O followed by rapid filtration under a stream of
nitrogen. The resulting product (0.9 g, 4.50 mmol, 41 %) was
treated under general conditions to give the triflimide as a clear
oil (1.72 g, 96 %). dH (400 MHz, DMSO-d6) 9.03 (dd, J 6.8, 1.3,
2H), 8.64 (tt, J 7.6, 1.3, 1H), 8.19 (dd, J 7.6, 6.8, 2H), 6.17 (ddt,
J 17.0, 10.3, 6.3, 1H), 5.45 (dq, J 10.3, 1.2, 1H), 5.39 (dq, J 17.0,
1.2, 1H), 5.27 (d, J 6.3, 2H). dH (100 MHz, DMSO-d6) 145.89,
144.81, 131.68, 128.25, 121.83, 119.47 (q, JC–F 319.9), 62.44.
m/z 120.0803. HRMS Anal. Calc. for C8H10Nþ 120.0808. m/z
279.9165. HRMS Anal. Calc. for C2F6NO4Sꢀ2 279.9178.
Experimental
General
1-Benzylpyridinium Triflimide (2)[25]
Commercially available reagents and solvents were used
without further purification, apart from benzaldehyde, which
was freshly distilled before use. The 1H and 13C NMR spectra
were recorded on a Bruker Avance DPX 300 spectrometer at
400 and 100 MHz, respectively. High resolution mass spectra
were obtained using a Waters LCT Premier XE time-of-flight
mass spectrometer fitted with an electrospray (ESI) ion source
and controlled with MassLynx software version 4.5. Low reso-
lution mass spectra using electrospray ionisation (ES-MS)
were obtained using a Micromass PlatformII instrument.
Unless otherwise stated, the cone voltage was 20 eV. Liquid
chromatography–mass spectrometry (LC-MS) was performed
on an Agilent 6100 Series Single Quadrupole LC/MS/Agilent
1200 Series Reverse Phase HPLC, column: Luna C8(2) 5u 50X
4.6 mm 100A. All products were obtained in greater than 95 %
To 0.5 mL anhydrous pyridine (6.2 mmol) in anhydrous toluene
(1 mL) in an ice bath was added benzyl bromide (0.95 mL,
11.0 mmol) dropwise with stirring. The solution was allowed to
warm slowly to room temperature and stirred overnight. The
solid residue, which formed, was dissolved in anhydrous MeCN
and the desired product was isolated by precipitation through
addition of Et2O followed by rapid filtration under a stream of
nitrogen. The resulting orange solid (281 mg, 1.1 mmol) was
treated under general conditions to give the triflimide as a clear
oil (0.5 g, 98 %). dH (400 MHz, DMSO-d6) 9.21 – 9.18 (m, 2H),
8.63 (tt, J 7.8, 1.3, 1H), 8.20 – 8.16 (m, 2H), 7.53 – 7.51 (m, 2H)
7.48 – 7.43 (m, 3H), 5.85 (s, 2H). dC (100 MHz, DMSO-d6)
146.00, 144.82, 134.25, 129.39, 129.25, 128.74, 128.49, 119.47
(q, JC–F 319.8), 63.35. m/z 170.0969. HRMS Anal. Calc. for
C12H12Nþ 170.0964. m/z 279.9177. HRMS Anal. Calc. for
C2F6NO4Sꢀ2 279.9178.
1
purity as determined by LC, unless otherwise indicated. H
NMR data for all known compounds matched literature data and
can be found in the Supplementary Material. All computations
were conducted with the Spartan’10 and Gaussian 09 (Revision
C.01) computational software packages.[43] Initial stationary
point searches were carried out with the semiempirical AM1
method.[44] The lowest energy conformers of 16, 16-H1, 17, and
17-H1 were located via an AM1 conformational search. These
AM1 optimised structures were then used as starting points for
geometry optimisation at the B3LYP/6–31G* level.[45–47] These
DFT optimised structures were then used as starting points for
further geometry optimisation at the B3LYP/6–311G* level,
followed by the B3LYP/6–311þþG** level. Vibrational anal-
yses were carried out to confirm the nature of all stationary
points and to calculate the thermal corrections (enthalpy and
entropy) for 298 K, 1 atm, gas phase. The low basicity coun-
terions were omitted. An archive of atomic coordinates in the .
pdb file format and tables of thermodynamic parameters are
provided as Supplementary Material.
1-(2-(Diisopropylamino)ethyl)pyridinium Triflimide (3)
To 2-diisopropylaminoethyl chloride hydrochloride (3.17 g,
1.6 mmol) in 8 mL of distilled water at 0–58C was added conc.
NH4OH (aq.) dropwise until pH 8–9 was reached. The aqueous
solution was extracted with Et2O (3 ꢂ 20 mL), dried (Na2SO4),
filtered, and concentrated under vacuum (at room temperature)
to give 2.63 g of a yellow oil. The oil was transferred to a sealed
tube, dissolved in 2 mL of anhydrous toluene (2 mL) and pyri-
dine (1.1 equiv.) was added at 08C. The resulting solution was
stirred at room temperature for 5 min, allowed to reach room
temperature, and then heated at 1008C for 3 days. The crude salt
was treated under general conditions to give the triflimide as a
bright yellow liquid. dH (400 MHz, DMSO-d6) 8.90–8.92
(m, 2H), 8.57 (tt, J 7.8, 1.3, 1H), 8.12–8.17 (m, 2H), 4.55 (t, J
5.4, 2H), 2.97 (sept, J 6.6, 2H), 2.89 (t, J 5.4, 2H), 0.74 (d, J 6.6,
12H). dC (100 MHz, DMSO-d6) 145.25, 127.20, 119.49 (q, JC–F
320.1), 59.78, 46.50, 45.30, 20.23. m/z 207.1857. HRMS Anal.
Calc. for C13H23Nþ2 207.1856. m/z 279.9180. HRMS Anal. Calc.
for C2F6NO4Sꢀ2 279.9178.
General Method for Anion Metathesis (NTf2)
The quaternary salt (1.0equiv.) was dissolved in distilled water to
which LiNTf2 (1.1equiv.) in minimal distilled water was added.
The resulting solution was stirred at room temperature for 30 min.
CH2Cl2 was added and the separated aqueous layer washed twice
more with CH2Cl2. The combined organic layers were washed
with cold distilled water until negative to a AgNO3 precipitate
test, dried (Na2SO4), filtered, and concentrated under vacuum
before drying overnight under high vacuum (0.1mmHg at 608C).
1-Butyl-3-((diethylamino)methyl)pyridinium Triflimide (4)
Picolyl chloride HCl salt (10.0 g, 61.0 mmol) was suspended in
anhydrous acetonitrile, the suspension was cooled in an ice/
brine bath (ꢀ10 to 08C) and Et2NH (40 mL, 387 mmol) was
added in 2 ꢂ 20 mL portions slowly. The mixture was allowed to
reach room temperature and stirred for 4 days. The resulting
mixture was filtered, and the precipitate was washed with small
portions of anhydrous MeCN (3 mL). The filtrate was concen-
trated under vacuum to give a residue, which was dissolved in
100 mL of 2 M NaOH and extracted with 3 ꢂ 100 mL diethyl
ether, the combined organics were dried (Na2SO4), filtered, and
1-Allylpyridinium Triflimide (1)[25]
To 1 mL of anhydrous pyridine (12.4 mmol) in anhydrous tol-
uene (2 mL) in an ice bath was added allyl bromide (0.95 mL,
11.0 mmol) dropwise with stirring. The solution was allowed to

Nitrogen-Containing Ionic Liquids
855
concentrated under vacuum to give 9.7 g (97 %) of an orange oil.
dH (CDCl3, 400 MHz) 8.54 (dd, J 2.4, 0.4, 1H), 8.49 (dd, J 4.8,
1.2, 1H), 7.74 (br, 1H), 7.25 (dd, J 7.6, 4.6, 1H), 3.61 (s, 2H),
2.55 (q, J 6.8, 4H), 1.07 (t, J 6.8, 6H).
1H), 4.54 (t, J 7.4, 2H), 2.50 (s, 3H), 1.90 (quin, J 7.4, 2H), 1.29
(sex, J 7.4, 2H), 0.92 (t, J 7.4, 3H). dC (100 MHz, DMSO-d6)
163.20, 147.39, 146.11, 145.24, 131.86, 128.29, 119.59 (q, JC–F
319.9), 61.09, 32.91, 18.87, 13.26. m/z 180.1022. HRMS Anal.
Calc. for C10H14NOþ2 180.1019. m/z 279.9182. HRMS Anal.
Calc. for C2F6NO4Sꢀ2 279.9178.
To the crude material from above (1.22 g, 7.4 mmol) in 3 mL
of anhydrous toluene was added 1-bromobutane (0.79 mL,
7.3 mmol), the resulting solution was stirred at room tempera-
ture for 1 h before being heated to 808C overnight. The resulting
solution was cooled to room temperature, 25 mL of distilled
water was added, and the aqueous solution was extracted with
3 ꢂ 20 mL of Et2O. The crude salt was treated under general
conditions to give the triflimide (3.55 g, 97 %) as a red oil. dH
(400 MHz, DMSO-d6) 8.96–8.99 (m, 2H), 8.50–8.52 (m, 1H),
8.08–8.11 (m, 1H), 4.60 (t, J 7.3, 2H), 3.74 (s, 2H), 2.51 (q, J 7.3,
4H), 1.89 (q, J 7.5, 2H), 1.29 (sex, J 7.5, 3H), 0.99 (t, J 7.1, 6H),
0.91 (t, J 7.4, 3H). dC (100 MHz, CDCl3) 144.83, 143.85,
142.99, 142.38, 127.81, 119.60 (q, JC–F 319.4), 61.92, 53.73,
33.12, 18.98, 12.94, 11.60. m/z 221.2018. HRMS Anal. Calc. for
C14H25Nþ2 221.2012. m/z 279.9180. HRMS Anal. Calc. for
C2F6NO4Sꢀ2 279.9178.
N-(2-(Dimethylamino)ethyl)-N,N-
dimethylhexylammonium Triflimide (7)
N,N0-Tetramethylethylene diamine (1.5mL, 10.0mmol) was
dissolved in anhydrous toluene (2mL), 1-chlorohexane
(1.35 mL, 10.0mmol) was added, and the resulting solution was
microwaved at 1008C for 1 h, and then concentrated under vac-
uum to give a white solid. The crude salt was treated under
general conditions to give the triflimide as a light yellow oil
(4.24 g, 89% over two steps). dH (400MHz, DMSO-d6) 3.36 (t, J
6.2, 2H), 3.25–3.29 (m, 2H), 3.04 (s, 6H), 2.61 (t, J 6.2, 2H), 2.19
(s, 6H), 1.61–1.69 (m, 2H), 1.25–1.32 (m, 6H), 0.88 (t, J 6.9, 3H).
dC (100MHz, DMSO-d6) 119.46 (q, JC–F 320.0), 63.67, 59.82,
52.30, 50.35, 44.98, 30.60, 25.39, 21.80, 21.67, 13.75. m/z
201.2321. HRMS Anal. Calc. for C12H29Nþ2 201.2325. m/z
279.9169. HRMS Anal. Calc. for C2F6NO4Sꢀ2 279.9178.
1-Butyl-3-methylpyridinium Triflimide (5)[48]
3-Picoline (1mL, 10.3mmol) was dissolved in 10 mL of anhy-
drous toluene, 1-bromobutane (1.2mL, 11.3mmol) was added,
and the resulting mixture stirred at room temperature for 3 h,
before being refluxed for 14 h. The top layer of the biphasic
mixture was decanted carefully and the bottom (IL) layer was
shaken with 3 ꢂ 10mL of Et2O decanting the organic layer each
time. The resulting material was carefully placed under vacuum.
The resulting residue was treated under general conditions to give
the triflimide as a clear oil (4.03 g, 91 % over two steps). dH
(400 MHz, DMSO-d6) 8.99 (s, 1H), 8.90–8.91 (m, 1H), 8.44 (d,
J 7.9, 1H), 8.05 (dd, J 7.9, 6.2, 1H), 4.54 (t, J 7.4, 2H), 2.50 (s, 3H),
1.90 (quin, J 7.4, 2H), 1.29 (sex, J 7.4, 2H), 0.92 (t, J 7.4, 3H). dC
(100 MHz, DMSO-d6) 145.69, 144.18, 141.93, 141.92, 138.82,
127.30, 119.47 (q, JC–F 319.9), 60.46, 32.55, 18.74, 17.78, 13.20.
m/z 150.1280. HRMS Anal. Calc. for C10H16Nþ 150.1277. m/z
279.9178. HRMS Anal. Calc. for C2F6NO4Sꢀ2 279.9178.
N,N-Diethyl-N-(2-hydroxyethyl)hexylammonium
Triflimide (8)
2-(Diethylamino)ethanol (1.17 g, 10.0mmol) was dissolved in
2 mL of anhydrous toluene, 1-bromohexane (1.4mL, 10.0mmol)
was added at room temperature, and the resultant solution was
stirred at room temperature for 1 h and then heated to 808C for
48h, the resulting solution was concentrated under vacuum. The
resulting residue was treated under general conditions to give the
triflimide (4.53 g, 94% over two steps) as a pale yellow oil. dH
(400MHz, DMSO-d6) 5.24 (t, J 5.0, 1H), 3.76–3.77 (m, 2H), 3.29
(dd, J 9.0 and 3.9, 4H), 3.17–3.22 (m, 2H), 1.55–1.63 (m, 2H),
1.29 (m, 6H), 1.18 (t, J 7.1, 6H), 0.87 (t, J 6.9, 3H). dC (100MHz,
DMSO-d6) 119.46 (q, JC–F 320.0), 58.26, 57.33, 54.50, 53.23,
30.62, 25.40, 21.87, 20.94, 13.77, 7.25. m/z 202.2166. HRMS
Anal. Calc. for C12H28NOþ 202.2165. m/z 279.9173. HRMS
Anal. Calc. for C2F6NO4Sꢀ2 279.9178.
1-Butyl-3-carboxypyridinium Triflimide (6)
N-Butyl-N,N-bis(2-hydroxyethyl)pentylammonium
Triflimide (9)
Nicotinic acid (1.23 g, 10.0 mmol) was suspended in 10 mL of
anhydrous MeCN in a sealed tube, 1-iodobutane (1.2 mL,
10.5 mmol) was added and the resulting mixture was stirred at
room temperature for 1 h. The mixture was heated at 1008C
overnight and concentrated under vacuum. The resulting residue
was taken up in 20 mL of distilled water washed with CH2Cl2
(3 ꢂ 15 mL), the aqueous solution was concentrated under
vacuum to give 1.14 g of a 10 : 1 mixture of the alkylated product
and nicotinic acid. The residue was dissolved in 15 mL of dis-
tilled water and treated with LiNTf2 (1.09 g, 3.8 mmol) in
minimal distilled water. The resulting cloudy mixture (which
cleared) was stirred for 30 min at room temperature. The mixture
was diluted with 25 mL of 4 : 1 CH2Cl2/EtOAc and the aqueous
solution was washed with a further 2 ꢂ 25 mL of 4 : 1 CH2Cl2/
EtOAc, and the combined organic layers were washed with ice-
cold 5 mL portions of distilled water until negative to a AgNO3
precipitate test. The organic layer was dried (Na2SO4), filtered,
and concentrated under vacuum and placed under high vacuum,
and then dried overnight under high vacuum (0.1 mmHg at
608C) to give to the desired triflimide (2.58 g, 56 %) as a light
orange oil. dH (400 MHz, DMSO-d6) 11.10 (br, 1H), 8.99 (s,
1H), 8.90–8.91 (m, 1H), 8.44 (d, J 7.9, 1H), 8.05 (dd, J 7.9, 6.2,
To a suspension of diethanolamine (924 mg, 8.8 mmol) and
potassium carbonate (1.27 g, 9.2 mmol) in anhydrous MeCN
(11 mL), was added 1-bromobutane (1.0 mL, 9.2 mmol) drop-
wise, with stirring, at 08C. After 5 min the ice bath was removed
and the solution was allowed to reach room temperature and
stirred for 24 h. The solution was filtered, concentrated under
vacuum, and the resulting residue was purified by silica plug
(dichloromethane) to yield 1.15 g of clear oil (81 %). dH
(400 MHz, CDCl3) 3.62 (t, J 5.4, 4H), 2.86 (s, 2H), 2.66 (t, J 5.4,
4H), 2.55–2.52 (m, 2H), 1.45 (pent, J 7.5, 2H), 1.30 (sex, J 7.5,
2H), 0.91 (t, J 7.3, 3H). To a portion of the clear oil (553 mg,
3.4 mmol) in anhydrous toluene (2 mL) was added 1-iodobutane
(0.45 mL, 3.9 mmol). The resulting mixture was heated in a
sealed tube at 1208C for 6 h, and then cooled to room tempera-
ture. The solution was diluted with 25 mL of distilled water, and
the aqueous layer was washed consecutively with 3 ꢂ 10 mL
portions of Et2O. The aqueous solution was then treated under
general conditions to give the triflimide as a colourless oil (1.3 g,
75 %). dH (400 MHz, DMSO-d6) 5.22 (t, J 5.1, 2H), 3.78–3.79
(m, 4H), 3.40 (t, J 5.1, 4H), 3.29 (t, J 4.2, 4H), 1.57–1.68 (m,

856
L. Ford et al.
4H), 1.22–1.36 (m, 6H), 0.92 (t, J 7.2, 3H), 0.87 (t, J 7.2, 3H).
dC (100 MHz, DMSO-d6) 119.46 (q, JC–F 319.9), 59.98, 59.24,
59.01, 56.63, 54.57, 27.86, 23.17, 21.60, 20.86, 19.11, 13.72,
13.46. m/z 232.2281. HRMS Anal. Calc. for C13H30NO2þ
232.2271. m/z 279.9177. HRMS Anal. Calc. for C2F6NO4S2ꢀ
279.9178.
3 ꢂ 15 mL of Et2O. The crude salt was treated under general
conditions to give the triflimide as a clear oil (5.23 g, 86 % over
two steps). dH (400 MHz, DMSO-d6) 3.24 (t, J 7.5, 6H), 3.13–
3.17 (m, 2H), 3.01 (t, J 7.5, 6H), 1.60–1.68 (m, 2H), 1.23–1.35
(m, 8H), 0.87 (t, J 6.9, 3H). dC (100 MHz, DMSO-d6) 119.51
(q, JC–F 319.9), 63.30, 51.56, 44.70, 30.99, 28.19, 25.82, 21.99,
21.02, 13.89. m/z 211.2175. HRMS Anal. Calc. for C13H27N2þ
211.2169. m/z 279.9184. HRMS Anal. Calc. for C2F6NO4S2ꢀ
279.9178.
1-Hexyl-1,4-dimethylpiperazinium Triflimide (10)
1,4-Dimethylpiperazine (500 mL, 3.7 mmol) and 1-chlorohex-
ane (462 mL, 3.4 mmol) were microwaved at 1108C in 2 mL of
anhydrous MeCN for 1.5 h. The resulting mixture was concen-
trated under vacuum to give 242 mg (1.0 mmol) of crude prod-
uct. The crude salt was treated under general conditions to give
the triflimide as a clear oil (483 mg, 30 % over two steps). dH
(400 MHz, DMSO-d6) 3.36 (dd, J 8.0, 3.7, 4H), 3.30 (s, 2H),
3.00 (s, 3H), 2.56–2.73 (m, 4H), 2.27 (s, 3H), 1.62–1.70 (m, 2H),
1.28–1.30 (m, 6H), 0.86–0.90 (t, J 6.8, 3H). dC (100 MHz,
DMSO-d6) 119.51 (q, JC–F 319.9) 59.23, 47.52, 44.45, 30.71,
25.47, 21.90, 20.86, 13.82. m/z 199.2167. HRMS Anal. Calc. for
C12H27Nþ2 199.2169. m/z 279.9170. HRMS Anal. Calc. for
C2F6NO4S–2 279.9178.
1-(2-Hydroxyethyl)-1,4-diazabicyclo[2.2.2]octanium
Dicyanimide (14)
To DABCO (224 mg, 2.0 mmol) in 2.5 mL of anhydrous MeCN
was added 2-chloroethanol (134 mL, 2.0 mmol) and the mixture
was microwaved at 808C for 40 min. The resulting solution was
concentrated under vacuum, the remaining residue was dis-
solved in 10 mL of distilled water and washed with 3 ꢂ 5 mL of
Et2O. The aqueous solution was treated with AgN(CN)2
(348 mg, 2 mmol) and stirred overnight at room temperature.
The heterogenous mixture was filtered, the filtrate concentrated
under vacuum and then taken up in MeOH and placed in the
freezer overnight, filtered and then concentrated under vacuum
and placed under high vacuum, and then dried under high vac-
uum (0.1 mmHg at 608C) to give a clear brown oil (402 mg, 90 %
over two steps). dH (400 MHz, DMSO-d6) 5.29 (s, 1H), 3.85
(s, 2H), 3.36 (t, J 7.5, 6H), 3.30 (t, J 5.2, 2H), 3.02 (t, J 7.5, 6H).
dC (100 MHz, DMSO-d6) 119.10, 65.37, 54.15, 52.48, 44.71.
m/z (LRMS) 66 [Mꢀ], 157 [Mþ].
1-Heptyl-1,4-dimethylpiperazinium Triflimide (11)
1,4-Dimethylpiperazine (410 mL, 3.0 mmol) and 1-chloro-
heptane (385 mL, 2.5 mmol) were microwaved at 1508C in 2 mL
of anhydrous MeCN for 1 h. The resulting mixture was con-
centrated under vacuum to give 397 mg (1.6 mmol) of crude
product which was diluted in 15 mL of distilled water and
washed with Et2O (3 ꢂ 5 mL). The crude salt was treated under
general conditions to give the triflimide as clear oil (681 mg,
55 % over two steps). dH (400 MHz, DMSO-d6) 3.36 (dd, J 8.4,
4.2, 4H), 3.31 (d, J 4.6, 2H), 3.00 (s, 3H), 2.70 (d, J 13.7, 2H),
2.58–2.63 (m, 2H), 2.27 (s, 3H), 1.62–1.70 (m, 2H), 1.24–1.34
(m, 8H), 0.87 (t, J 6.8, 3H). dC (100 MHz, DMSO-d6) 119.50
(q, JC–F 319.9), 59.20, 47.49, 44.40, 39.52, 31.01, 28.18, 25.75,
21.98, 20.89, 13.85. m/z 213.2327. HRMS Anal. Calc. for
C13H29Nþ2 213.2325. m/z 279.9169. HRMS Anal. Calc. for
C2F6NO4Sꢀ2 279.9178.
ISO 14593: CO2 Headspace Test
To evaluate the biodegradability of the test ILs, the ‘CO2
headspace’ test (ISO 14593) was applied. This method allows
the evaluation of the ultimate aerobic biodegradability of an
organic compound in an aqueous medium at a given concen-
tration of microorganisms by analysis of inorganic carbon (IC).
The test IL, as the sole source of carbon and energy, was added at
a concentration of 20 mgC Lꢀ1 to a buffer-mineral salt medium.
These solutions were inoculated with activated sludge collected
from an activated sludge treatment plant, washed, and aerated
before use and incubated in sealed vessels with a headspace of
air. Biodegradation (mineralisation to carbon dioxide) was
determined by measuring the IC produced in the test bottles in
excess of that produced in blank vessels containing inoculated
medium only. SDS was used as a reference substance. The test
ran for 28 days. The extent of biodegradation was expressed
as a percentage of the theoretical amount of inorganic carbon
(ThIC) based on the amount of test compound added initially.
The reference substance, SDS, underwent 89 ꢁ 2 % biodegra-
dation in this assay.
1-Hexyl-1,4-diazabicyclo[2.2.2]octanium
Triflimide (12)[49]
To DABCO (2.28 g, 20.3 mmol) in 25 mL of anhydrous MeCN
at 08C, was added 1-bromoheptane (2.8 mL, 19.9 mmol) drop-
wise with stirring. The resulting solution was allowed to reach
room temperature and stirred overnight. The resulting solution
was concentrated under vacuum. The residue (915 mg) was
treated under general conditions to give the triflimide as a clear
oil (1.5 g, 96 %) which crystallised on standing (mp ꢀ28–318C).
dH (400 MHz, DMSO-d6) 3.24 (t, J 7.5, 6H), 3.13–3.18 (m, 2H),
3.01 (t, J 7.5, 6H), 1.60–1.68 (m, 2H), 1.25–1.33 (m, 6H), 0.88 (t,
J 7.0, 3H). dC (100 MHz, DMSO-d6) 119.48 (q, JC–F 320.0),
63.26, 51.53, 44.68, 30.67, 25.50, 21.82, 20.94, 13.76. m/z
197.2022. HRMS Anal. Calc. for C12H25Nþ2 197.2012. m/z
279.9173. HRMS Anal. Calc. for C2F6NO4Sꢀ2 279.9178.
Supplementary Material
1H and 13C NMR and computational data are available on the
Journal’s website.
Acknowledgements
The authors thank the ARC Centre of Excellence for Free Radical Chemistry
and Biotechnology, the Natural Science and Engineering Research Council
of Canada (NSERC-DG to RDS), and the Spanish Ministerio de Economia y
Competitividad (CTQ2013-41514-P to MTG) for financial support.
Computational facilities were provided by ACEnet, the regional high per-
formance computing consortium for universities in Atlantic Canada. ACE-
net is funded by the Canada Foundation for Innovation (CFI), the Atlantic
Canada Opportunities Agency (ACOA), and the provinces of Newfoundland
1-Heptyl-1,4-diazabicyclo[2.2.2]octanium
Triflimide (13)[49]
To DABCO (1.41 g, 12.5 mmol) in 25 mL of anhydrous MeCN,
was added 1-chloroheptane (1.9 mL, 12.4 mmol) dropwise
with stirring. The resulting solution was gently refluxed
overnight then concentrated under vacuum. The resulting
residue was dissolved in 30 mL of distilled water, washed with

Nitrogen-Containing Ionic Liquids
857
and Labrador, Nova Scotia, and New Brunswick. The authors also thank Dr
Jason Dang for obtaining all HRMS data.
[30] For alternate conditions to selectively monoalkylate dimethylpiper-
azine see: T. Ru¨ther, K. R. Harris, M. D. Horne, M. Kanakubo,
T. Rodopoulos, J.-P. Veder, L. A. Woolf, Chem. – Eur. J. 2013, 19,
17733. doi:10.1002/CHEM.201302258
References
[31] J. R. Harjani, R. D. Singer, M. T. Garcia, P. J. Scammells, Green Chem.
2008, 10, 436. doi:10.1039/B800534F
[1] P. Wasserscheid, T. Welton, Ionic Liquids in Synthesis 2008 (Wiley-
VCH Verlag GmbH & Co. KGaA: Weinheim).
[32] C. Abrusci, J. Palomar, J. L. Pablos, F. Rodriguez, F. Catalina, Green
Chem. 2011, 13, 709. doi:10.1039/C0GC00766H
[2] N. V. Plechkova, K. R. Seddon, Chem. Soc. Rev. 2008, 37, 123.
doi:10.1039/B006677J
[33] I. Greiner, E. Hohmann, L. Vida, G. Keglevich, Open Org. Chem. J.
2008, 2, 65.
[34] B. H. Lipshutz, T. B. Petersen, A. R. Abela, Org. Lett. 2008, 10, 1333.
doi:10.1021/OL702714Y
[35] F. Chanthavong, N. E. Leadbeater, Tetrahedron Lett. 2006, 47, 1909.
doi:10.1016/J.TETLET.2006.01.092
[3] M. Antonietti, D. Kuang, B. Smarsly, Y. Zhou, Angew. Chem. Int. Ed.
Engl. 2004, 43, 4988. doi:10.1002/ANIE.200460091
[4] M. Galin´ski, A. Lewandowski, I. Ste˛pniak, Electrochim. Acta 2006,
51, 5567. doi:10.1016/J.ELECTACTA.2006.03.016
[5] N. Gathergood, P. J. Scammells, Aust. J. Chem. 2002, 55, 557.
doi:10.1071/CH02148
[36] N. Miyaura, K. Yamada, A. Suzuki, Tetrahedron Lett. 1979, 20, 3437.
doi:10.1016/S0040-4039(01)95429-2
[6] N. Gathergood, M. T. Garcia, P. J. Scammells, Green Chem. 2004, 6,
166. doi:10.1039/B315270G
[37] K. Sonogashira, J. Organomet. Chem. 2002, 653, 46. doi:10.1016/
S0022-328X(02)01158-0
[7] M. T. Garcia, N. Gathergood, P. J. Scammells, Green Chem. 2005, 7, 9.
doi:10.1039/B411922C
[38] C. Paun, J. Barklie, P. Goodrich, H. Gunaratne, A. McKeown, V. I.
Paˆrvulescu, C. Hardacre, J. Mol. Catal. Chem. 2007, 269, 64.
doi:10.1016/J.MOLCATA.2007.01.002
[39] (a) Ł. Albrecht, B. Richter, C. Vila, H. Krawczyk, K. A. Jørgensen,
Chem. – Eur. J. 2009, 15, 3093. doi:10.1002/CHEM.200802285
(b) R. G. Gore, L. Myles, M. Spulak, I. Beadham, T. M. Garcia,
S. J. Connon, N. Gathergood, Green Chem. 2013, 15, 2747.
doi:10.1039/C3GC40992A
[8] N. Gathergood, P. J. Scammells, M. T. Garcia, Green Chem. 2006, 8,
156. doi:10.1039/B516206H
[9] E. Liwarska-Bizukojc, D. Gendaszewska, J. Biosci. Bioeng. 2013,
115, 71. doi:10.1016/J.JBIOSC.2012.08.002
[10] Y. Deng, P. Besse-Hoggan, M. Sancelme, A.-M. Delort, P. Husson, M.
F. C. Gomes, J. Hazard. Mater. 2011, 198, 165. doi:10.1016/J.JHAZ
MAT.2011.10.024
[11] D. Coleman, N. Gathergood, Chem. Soc. Rev. 2010, 39, 600.
doi:10.1039/B817717C
[12] S. J. Khan, J. E. Ongerth, Chemosphere 2004, 54, 355. doi:10.1016/
J.CHEMOSPHERE.2003.07.001
[13] L. Ford, J. R. Harjani, F. Atefi, M. T. Garcia, R. D. Singer, P. J.
Scammells, Green Chem. 2010, 12, 1783. doi:10.1039/C0GC00082E
[14] A. R. Hajipour, F. Rafiee, J. Iran. Chem. Soc. 2009, 6, 647.
doi:10.1007/BF03246155
(c) L. Myles, R. G. Gore, N. Gathergood, S. J. Connon, Green Chem.
2013, 15, 2740. doi:10.1039/C3GC40975A
(d) L. Myles, N. Gathergood, S. J. Connon, Chem. Commun. 2013, 49,
5316. doi:10.1039/C3CC41588K
(e) I. Beadham, M. Gurbisz, N. Gathergood, in Handbook of Green
Chemistry (Ed. P. T. Anastas) 2010, Vol. 9 – Designing Safer
Chemicals, pp. 137–158 (Wiley-VCH: Weinheim).
(f) I. Beadham, M. Gurbisz, N. Gathergood, in Handbook of Green
Chemistry (Ed. P. T. Anastas) 2010, Vol. 9 – Designing Safer
Chemicals, pp. 159–226 (Wiley-VCH: Weinheim).
[15] C. Chiappe, B. Melai, A. Sanzone, G. Valentini, Pure Appl. Chem.
2009, 81, 2035.
[16] (a) M. J. Earle, S. Forsyth, U. Frohlich, N. Gunaratne, S. Katdare, K. R.
Seddon, The Queen’s University of Belfast, Ionic Liquids with a
Cation Comprising a Basic Moiety 2006, WO2006072775A3.
(b) S. A. Forsyth, U. Fro¨hlich, P. Goodrich, H. Q. N. Gunaratne,
C. Hardacre, A. McKeown, K. R. Seddon, New J. Chem. 2010, 34, 723.
doi:10.1039/B9NJ00729F
[17] C. Ye, J. C. Xiao, B. Twamley, A. D. LaLonde, M. Grant Norton,
J. M. Shreeve, Eur. J. Org. Chem. 2007, 2007, 5095. doi:10.1002/
EJOC.200700502
[40] X. Mi, S. Luo, J.-P. Cheng, J. Org. Chem. 2005, 70, 2338. doi:10.1021/
JO048391D
[41] R. L. Benoit, D. Lefebvre, M. Fre´chette, Can. J. Chem. 1987, 65, 996.
doi:10.1139/V87-170
[42] P. Paoletti, J. H. Stern, A. Vacca, J. Phys. Chem. 1965, 69, 3759.
doi:10.1021/J100895A019
[43] (a) Spartan ’10 2011 (Wavefunction, Inc.: Irvine, CA). Available at
http://www.wavefun.com
(b) M.J. Frisch,G.W.Trucks, H.B.Schlegel,G.E.Scuseria,M. A.Robb,
J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson,
H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov,
J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota,
R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro,
M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov,
R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant,
S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E.
Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E.
Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W.
Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth,
[18] H. R. Shaterian, K. Azizi, J. Mol. Liq. 2013, 183, 8. doi:10.1016/
J.MOLLIQ.2013.04.005
[19] H. R. Shaterian, M. Mohammadnia, J. Mol. Liq. 2012, 173, 55.
doi:10.1016/J.MOLLIQ.2012.06.007
[20] I. Yavari, E. Kowsari, Mol. Divers. 2009, 13, 519. doi:10.1007/
S11030-009-9146-8
[21] Y. Zhang, Q. Jiao, B. Zhen, Q. Wu, H. Li, Appl. Catal., A 2013, 453,
327. doi:10.1016/J.APCATA.2012.12.029
[22] M. Fan, J. Yang, P. Jiang, P. Zhang, S. Li, RSC Adv. 2013, 3, 752.
[23] S. Zhou, L. Liu, B. Wang, F. Xu, R. C. Sun, Chin. Chem. Lett. 2012, 23,
379. doi:10.1016/J.CCLET.2012.01.034
[24] P. Primerano, M. Cordaro, A. Scala, Tetrahedron Lett. 2013, 54, 4061.
doi:10.1016/J.TETLET.2013.05.097
¨
P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B.
Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09 (Revision
C.01) 2010 (Gaussian, Inc.: Wallingford, CT).
[25] X. Wang, C. A. Ohlin, Q. Lu, Z. Fei, J. Hu, P. J. Dyson, Green Chem.
2007, 9, 1191. doi:10.1039/B704503D
[44] E. G. Zoebisch, E. F. Healy, J. Stewart, J. Am. Chem. Soc. 1985, 107,
3902.
[45] C. Lee, W. Yang, R. Parr, Phys. Rev. B: Condens. Matter Mater. Phys.
[26] C. C. Pretti, M. M. Renzi, S. E. S. Focardi, A. A. Giovani, G. G. Monni,
B. B. Melai, S. S. Rajamani, C. C. Chiappe, Ecotoxicol. Environ. Saf.
2011, 74, 748. doi:10.1016/J.ECOENV.2010.10.032
[27] J. Qu, J. J. Truhan, S. Dai, H. Luo, P. J. Blau, Tribol. Lett. 2006, 22,
207. doi:10.1007/S11249-006-9081-0
[28] S. Stolte, S. Steudte, O. Areitioaurtena, F. Pagano, J. Tho¨ming,
P. Stepnowski, A. Igartua, Chemosphere 2012, 89, 1135. doi:10.1016/
J.CHEMOSPHERE.2012.05.102
1988, 37, 785. doi:10.1103/PHYSREVB.37.785
[46] A. D. Becke, J. Chem. Phys. 1993, 98, 1372. doi:10.1063/1.464304
[47] A. D. Becke, J. Chem. Phys. 1993, 98, 5648. doi:10.1063/1.464913
[48] C. A. Ohlin, P. J. Dyson, G. Laurenczy, Chem. Commun. 2004, 1070.
doi:10.1039/B401537A
[49] A. Wykes, S. L. MacNeil, Synlett 2007, 2007, 107. doi:10.1055/
S-2006-956460
[29] A. S. Wells, V. T. Coombe, Org. Process Res. Dev. 2006, 10, 794.
doi:10.1021/OP060048I