Phosphonium and ammonium ionic liquids with aromatic anions: Synthesis, properties, and platinum extraction

Article abstract of DOI:10.1071/CH09340

Several hydrophobic long-chain quaternary ammonium and phosphonium ionic liquids (ILs) with functionalized aromatic anions were prepared following a metathesis route using tricaprylmethylammonium chloride (Aliquat 336) and trihexyl(tetradecyl)phosphonium

Full text of DOI:10.1071/CH09340

Full Paper
CSIRO PUBLISHING
www.publish.csiro.au/journals/ajc
Aust. J. Chem. 2010, 63, 511–524
Phosphonium and Ammonium Ionic Liquids with Aromatic
Anions: Synthesis, Properties, and Platinum Extraction∗
Anja Stojanovic,A,D,E Daniel Kogelnig,A,D Lisa Fischer,B Stephan Hann,B
Markus Galanski,A Michael Groessl,C Regina Krachler,A
and Bernhard K. KepplerA
AUniversity of Vienna, Department of Inorganic Chemistry, Waehringer Strasse 42,
1090, Vienna, Austria.
BDepartment of Chemistry, Division of Analytical Chemistry, University of Natural Resources
and Applied Life Sciences, Muthgasse 18, 1190, Vienna, Austria.
CInstitut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL),
1015 Lausanne, Switzerland.
DBoth authors contributed equally to this work.
ECorresponding author. Email: anja.stojanovic@univie.ac.at
Several hydrophobic long-chain quaternary ammonium and phosphonium ionic liquids (ILs) with functionalized aro-
matic anions were prepared following a metathesis route using tricaprylmethylammonium chloride (Aliquat 336) and
trihexyl(tetradecyl)phosphonium chloride (Cyphos IL101) as precursors. The incorporation of aromatic anions bearing
hydroxy-, methoxy-, thiol-, and thioether functionalities as well as tetraphenylborate anions resulted in an increased chem-
ical stability of the ILs and an alteration of their physico-chemical properties. Furthermore, aromatic anions significantly
decreased the water solubility and water uptake of both ammonium and phosphonium-based ILs. Thiol- and thioether
ILs were applied for the extraction of platinum from aqueous phase using liquid phase micro-extraction. Time dependent
studies showed a rapid elimination of up to 95% platinum after 30 min. With a leaching of the anion <0.01 wt-% into the
aqueous media, the evaluated ILs were found to be suitable as extracting agents for platinum from aqueous solutions.
Manuscript received: 17 June 2009.
Manuscript accepted: 26 August 2009.
Introduction
applied as phase-transfer catalysts, solvents, lubricants, gas
capture agents, coating materials, or chemical sensors.[2–4]
Because of the possibility to vary one or more of the phos-
phonium or ammonium cation’s substituents and to incorporate
various inorganic or organic anions, the amount of existing
quaternary ammonium and phosphonium ILs is continuously
growing.[3–6]
More recently, simple anion-metathesis reactions of ILs
based on tricaprylmethylammonium chloride (Aliquat 336,
Henkel Corp.), a cheap industrial product, or the readily
available trihexyl(tetradecyl)phosphonium chloride (Cyphos
IL101, Cytec), led to various amounts of new favourable
hydrophobic ILs.[3–8] The hydrophobicity of the well inves-
tigated imidazolium or pyridinium-based ILs is mostly given
by the fluorine-containing anion (e.g., hexafluorophosphate
or bis(trifluoromethylsulfonyl)imide). However, several studies
have shown that fluorine-containing anions, such as hexafluoro-
phosphate, are highly sensitive towards hydrolysis, forming
hydrofluoric acid and, therefore, pose some severe environmen-
tal risks.[9,10] In contrast, the hydrophobicity of Aliquat 336
and Cyphos IL101-based ILs is given by the long chain qua-
ternary cation, which opens the field for new applications of
fluorine-free hydrophobic ILs.
Salts with melting points below the boiling point of water are
generally defined as ionic liquids (ILs). Moreover, the term room
temperature ionic liquids (RTILs) is frequently used for salts
that are liquid at or below room temperature. ILs have gained
increasing attention during the past decades because of their
unique properties such as a negligible vapour pressure, good
thermal stability, or controllable miscibility. Contrary to inor-
ganic salts with high melting points, ILs with low melting points
generally consist of bulky and non-symmetrical organic cations
such as imidazolium, pyrrolidinium, pyridinium, ammonium,
or phosphonium, whereas various inorganic or organic anions
are known. Coincident with this variation of ILs with tailored
qualities, their physico-chemical properties such as polarity, vis-
cosity, orhydrophobicitycanbetunedbymodifyingthechemical
structure of their constitutional ions.[1]
Regarding the synthesis and application of ILs, long-chain
quaternary ammonium and phosphonium ILs are gaining more
and more interest because of their improved thermal and chem-
ical stability, miscibility, and solvating properties for specific
applications.[1] Several ILs based on these classes of cations are
already commercially available (e.g., from Cytec Industries or
Merck Solvent Innovation GmbH) and have been successfully
∗This paper is based on the poster “Thioether-functionalized ionic liquids and their task specificity for platinum uptake using liquid phase micro-extraction”
presented at COIL3, 3rd Congress on Ionic Liquids, May 31–June 4 2009, Cairns, Australia.
© CSIRO 2010
10.1071/CH09340
0004-9425/10/030511

512
A. Stojanovic et al.
Precursors
C14H29
Pϩ
C8H17
Nϩ
ClϪ
ClϪ
C8H17
C6H13
C6H13
Trihexyltetradecylphosphonium chloride (Cyphos IL101),
[PR ][Cl]
C6H13
C8H17
Tricaprylmethylammonium chloride (Aliquat 336),
[A336][Cl]
4
Anions
OϪ
OϪ
OϪ
O
O
O
SH
S
Thiosalicylate, [TS]
Benzoate, [BA]
2-(Methylthio)benzoate, [MTBA]
COOϪ
OϪ
O
BϪ
O
S
OH
OϪ
HO
OCH3
(Phenylthio)acetate, [PTA]
Salicylate, [Sal]
Vanillate, [Van]
Tetraphenylborate, [BPh4]
Fig. 1. Ionic liquids studied in this work.
Several Aliquat 336-derived ILs have already been success-
fully applied in different extraction and absorption processes,
e.g., of heavy metals or organic vapours.[5,7,8,11,12] We have
recently shown that tricaprylmethylammonium thiosalicylate,
[A336][TS], a hydrophobic, Aliquat 336-based IL with thiol-
functionality appended to the anion, can be used for efficient
extraction of cadmium from neutral aqueous solutions.[8] Fur-
thermore, several trihexyl(tetradecyl)phosphonium based ILs,
such as Cyphos IL101, have already been evaluated, for example,
for the uptake of Pd and Zn from hydrochloric acid solutions by
anion exchange[13,14] or as solid phase extractants for an efficient
preconcentration of Pt and Pu from acidic solutions.[15]
Herein, we present the synthesis of several new hydropho-
bic ILs based on Aliquat 336 and Cyphos IL101 cations
with aromatic anions among others bearing functional thiol-,
thioether-, methoxy-, and hydroxy groups. In addition, Aliquat
336- or Cyphos IL101-based ILs with functional aromatic anions
already reported in the literature are prepared and a set of overall
14 quaternary ammonium and phosphonium ILs are extensively
investigated for their physico-chemical properties such as den-
sity, viscosity, refractive index, chloride content, water solubility
and uptake, as well as thermal stability. From experimental
data thermal expansion coefficients, molar volumes, and molar
refractions, which may act as indicators for the polarizability of
the IL, are calculated.
deprotonation-metathesis route using corresponding Bronsted
acids or sodium salts as precursors.[4,8] Methylthiobenzoic
acid was prepared according to a literature protocol.[16] The
synthesis of trihexyl(tetradecyl)phosphonium thiosalicylate,
[PR4][TS], trihexyl(tetradecyl)phosphonium 2-methylthio-
benzoate, [PR4][MTBA], tricaprylmethylammonium 2-methyl-
thiobenzoate, [A336][MTBA], trihexyl(tetradecyl)phosphonium
salicylate, [PR4][Sal], trihexyl(tetradecyl)phosphonium vanil-
late, [PR4][Van], tricaprylmethylammonium vanillate,
[A336][Van], trihexyl(tetradecyl)phosphonium tetraphenyl-
borate, [A336][BPh4], trihexyl(tetradecyl)phosphonium(phenyl-
thio) acetate, [PR4][PTA], and tricaprylmethylammonium
(phenylthio)acetate, [A336][PTA], are reported for the first
time, whereas ILs tricaprylmethylammonium thiosalicylate,
[A336][TS], tricaprylmethylammonium benzoate, [A336][BA],
tricaprylmethylammonium salicylate, [A336][Sal], trihexyl
(tetradecyl)phosphonium benzoate, [PR4][[BA], and tricapryl-
methylammonium tetraphenylborate, [A336][BPh4], have
already been reported,[8,11,12,17,18] but no extensive charac-
terization regarding their physical behaviour is available.
In order to improve the yield and purity of the produced
ILs, experimental protocols were slightly modified. Previ-
ous experiments have shown that the dispersion metathesis
reaction of highly hydrophobic tricaprylmethylammonium and
trihexyl(tetradecyl)phosphonium chloride in an aqueous salt
solution negatively influences the yield of the IL. The solva-
tion of hydrophobic precursors in a suitable, water miscible
organic solvent, avoiding a dispersion reaction, led to an almost
quantitative anion exchange. After complete reaction, highly
viscous ILs were dissolved in dry dichloromethane, minimiz-
ing further loss during washing steps. All synthesized ILs were
repeatedly washed with small amounts of ice-cold water until
no chloride could be detected in the aqueous washing phase
with ion chromatography (IC, detection limit 20 ppb). The use
of ice-cold water resulted in a clear phase separation during
the washing steps. Following this synthesis methodology all ILs
were obtained in yields >90%.
Based on these results, the task specificity of the prepared
hydrophobic RTILs bearing thioether and thiol-containing aro-
matic anions are evaluated for platinum uptake from aqueous
solution using liquid phase microextraction (LPME) combined
with inductively coupled plasma sector field mass spectrometry
(ICP-SFMS).
Results and Discussion
Synthesis of ILs
The structures of ILs prepared and studied in this work are
presented in Fig. 1. ILs were synthesized applying a simple

Phosphonium and Ammonium Ionic Liquids with Aromatic Anions
513
3
6
5
(a)
5
3
4
6a
4a
4
6
3a
5a
6.6
O
OϪ
6.6
6.8
7.0
7.2
7.4
7.6
7.8
8.0
8.2
7
5
1
2
SH
6
6.8
7.0
5
3
4
5
4
3
4
5a
7.2
7.4
7.6
7.8
4a
3
OϪ
O
OϪ
7
O
OϪ
7a
O
3a
6
1
1a
S
8
S
S
2
2a
6a
5a
6
3a
5
3
4a
6a
4
6
8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7
[ppm]
8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7
[ppm]
(b)
350
250
150
300
200
100
0
3
1
1
2
2
50
0
2a
1a
5
10
15
20
25
15
20
5
25
10
[min]
[min]
Fig. 2. (a) 1H,1H-COSY NMR spectra of [PR4][TS] (left) and [PR4][MTBA] (right). (b) CAD and UV traces of the ion pairing (IP) RP-HPLC chromatogram
of the ILs [PR4][TS] (left) and [PR4][MTBA] (right) under step-gradient elution conditions. Experimental conditions are reported in the literature.[19]
Peak notation: left: (1) thiosalicylate, (2) 2,2-dicarboxyphenyldisulfide (thiosalicylate dimer) – UV signal, (2a) 2,2-dicarboxyphenyldisulfide (thiosalicylate
dimer) – CAD signal, (3) [PR4] cation (sample concentration 1 mg mL−1); right: (1) 2-(methylthio)benzoic acid, (2) [PR4] cation (sample concentration
1 mg mL−1).
of corresponding anions were clearly observable in the 1H and
13C NMR spectra and assignable to the corresponding atoms.
Regarding NMR spectra of the thiol-containing ILs [A336][TS]
and [PR4][TS], the presence of a second species was observed
and identified as 2,2-dicarboxyphenyldisulfide, the thiosalicylic
acid dimer. RP-HPLC studies have confirmed that thiosalicylate
occurs under oxidizing conditions in equilibrium with the disul-
fide form, whereas the dimer fraction averaged 12 mol-%.[19]
The disulfide species was absent in both the H NMR spectra
and HPLC chromatogramms of 2-(methylthio)benzoate-based
ILs (Fig. 2).
Electrospray ionization–mass spectrometry (ESI-MS) spec-
tra of the prepared ILs displayed expected mass/charge
Characterization of ILs
One-dimensional 1H and 13C NMR as well as homonuclear
1H,1H-COSY, heteronuclear 1H,13C-HSQC, and HMBC NMR
experiments were performed to identify the prepared ILs. The
presence of the phosphorus was confirmed using 31P NMR spec-
troscopy. Chemical shifts of the 1H NMR spectra of the Aliquat
336 and Cyphos IL101 cations were in accordance with shifts
mentioned in the literature.[4,5,8] As expected, the chemical shift
differencesof0.6ppmmax. forthe 1Handof30ppmmax. forthe
13C NMR spectra were observed between corresponding ammo-
nium and phosphonium-based ILs.Whereas the proton signals of
cations in the aliphatic region could not explicitly be assigned for
allatomsbecauseofstrongoverlap, theprotonandcarbonsignals
1

514
A. Stojanovic et al.
Table 1. Physico-chemical properties of the studied ionic liquids
For water content the mean values of three independent measurements are given (RSD max. 5%)
Ionic liquid
State at room temperature
Water content [wt-%]
Chloride content [wt-%]
mp [◦C]
Td [◦C]
Viscosity η [cP] (25◦C)
[A336][TS]
[A336][BA]
[A336][MTBA]
[A336][PTA]
[A336][Sal]
[A336][Van]
[A336][BPh4]
[A336][Cl]
[PR4][TS]
Liquid
Liquid
Liquid
Semi-solid
Semi-solid
Semi-solid
Solid
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Semi-solid
Solid
Liquid
1.54
0.59
0.23
1.24
0.18
0.47
0.14
2.31
0.40
0.36
0.22
0.29
0.80
0.24
0.24
0.20
0.11
0.21
0.39
0.90
0.16
0.86
0.15
7.94
0.56
0.84
0.26
0.79
0.66
0.89
0.45
6.48
270
240
260
250
240
240
360
3220
3860
5242
—
—
—
50–55
—
2088
3875
674
875
530
567
—
—
390
360
350
320
340
355
370
[PR4][BA]
[PR4][MTBA]
[PR4][PTA]
[PR4][Sal]
[PR4][Van]
[PR4][BPh4]
[PR4][Cl]
96–98
1759 (1824)[3]
signals of the anions with the exception of the 2,2-
dicarboxyphenyldisulfide-form of the [TS] anion. This species
was not detectable under applied instrumental conditions.
FT-IR spectra confirmed the successful deprotonation by the
disappearance of the characteristic absorption bands of the car-
boxylic acid precursors after complete reaction. New absorption
bands at 743, 1466, and 1562 cm−1 could be assigned to stretch-
ing and bending vibrations of aromatic C–H groups.Whereas the
SH group of thiosalicalyte-containing ILs could not be observed,
because of its, in general, low intensity, the C–S bands of thio-
ether functionalized ILs at approximately 1273–1380 cm−1 were
clearly assigned.
The quantitative anion metathesis reaction and purity of the
preparedILswasfurtherconfirmedbyelementanalysis. Itiswell
known that quaternary long-chain ammonium and phosphonium
ILs are highly hygroscopic, which results in an alteration of their
physico-chemicalproperties.[1] Forthisreason, thewatercontent
of the prepared ILs (Table 1) was measured directly after dry-
ing and values measured by elemental analysis were interpreted
under consideration of water content. No significant deviations
from calculated values were obtained.
As the presence of impurities in ILs, especially residual
chloride ions, can significantly change the physico-chemical
properties of ILs, the chloride content of all prepared ILs was
measured.[20–22] The chloride content of the presented ILs was
significantly lower than 1 wt-%. Mikkola et al. have synthesized
several Aliquat 336-based ILs, applying an anion-metathesis
route under normal atmosphere, to gain ILs with a chloride con-
tent of up to 6 wt-%.[5] The authors stated that the presence of
moist air during synthesis may contribute to a higher chloride
amount.
As it can be seen fromTable 1 Cyphos IL101-based ILs are in
most cases RTILs, whereas the correspondingAliquat 336-based
ILs are semi-solid or solid at room temperature. This is in agree-
ment with observations of several other authors investigating
these two kinds of ILs.[6,22] Trihexyl(tetradecyl)phosphonium
vanillate, [PR4][Van], is an exception, being semi-solid at room-
temperature. This is probably because of the presence of several
functional groups appended to the aromatic anion, which makes
the packing of the crystal lattice more efficient by Coulomb
and dispersion interactions. As expected, tetraphenylborate-
containing ILs are solid at room temperature, which is governed
by strong π–π interactions of the phenyl rings, and hence
pronounced rigidness of the structure.[1]
Water Content and Solubility
The water content of all prepared ILs lies significantly below
2 wt-%, which is comparable with literature data regarding phos-
phonium and ammonium-based ILs.[6,23,24] However, there are
no significant differences in the water content between corre-
sponding ammonium and phosphonium ILs. Furthermore, no
distinct trend is observable regarding the anion. The water con-
tent is known to influence the physical state of ILs at room
temperature, which is clearly observable in the case of tri-
caprylmethylammonium salicylate, [A336][Sal]. Whereas the
corresponding IL was described in the literature as a ‘viscous
liquid’ at room temperature, because of its considerable water
content (up to 7 wt-%[11]), the obtained IL [A336][Sal] in our
work is semi-solid at room temperature, and exhibits a water
content of 0.18 wt-%.
In general, all the synthesized ILs are stable in air, immis-
cible with water, and soluble in common organic solvents as
shown in Table 2. The solubility of ILs in the solvents water,
ethyl acetate, ether, hexane, ethanol, methanol, acetone, toluene,
dichloromethane, chloroform, and acetonitrile was determined
visually by adding each solvent to small amounts of ILs.
All ILs showed remarkable solubility in acetone, toluene,
dichloromethane, chloroform, and acetonitrile and there are no
differences in solubility regarding ammonium and phosphonium
cations. However, whereas ILs containing [MTBA], [PTA], and
Our results indicate that conducting the synthesis under an
inert atmosphere with an optimized workup of products leads to
ILs with high yields and sufficient purity.
Physico-Chemical Properties
The physical state of the prepared ILs at room temperature varies
between liquid, semi-solid, and solid, depending on the type of
cation and anion chosen.

Phosphonium and Ammonium Ionic Liquids with Aromatic Anions
515
Table 2. Solubility of ionic liquids in selected solvents
Ionic liquid
Water
Ethyl acetate
Ether
–
Hexane
–
EtOH
√
MeOH
√
Acetone
√
Toluene
√
CH2Cl2
√
CHCl3
√
ACN
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
[A336][TS]
[A336][BA]
[A336][MTBA]
[A336][PTA]
[A336][Sal]
[A336][Van]
[A336][BPh4]
[PR4][TS]
–
–
–
–
–
–
–
–
–
–
–
–
–
–
√
√
√
√
√
√
–
–
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
–
–
–
–
–
–
√
√
√
√
–
–
–
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
[PR4][BA]
–
–
√
√
√
√
√
√
[PR4][MTBA]
[PR4][PTA]
[PR4][Sal]
[PR4][Van]
[PR4][BPh4]
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
–
–
–
–
√
√
√
√
–
–
–
give Tds in the range of 360–370◦C (Table 1). It is obvious
that in this case the highly symmetrical, voluminous, and rigid
anion exhibits a dominant impact on their decomposition, com-
parable with boron cluster-containing ILs.[30] Unexpectedly, the
[PR4][BA] showed a significantly higher Td as reported in the
literature (360◦C instead of 217.5◦C reported by Murugesan
et al.[18]), which reflects the different purity of the samples
(namely their water and chloride content) and the distinct
experimental setups used.
100
80
60
40
20
0
[A336][TS]
[PR4][TS]
[A336][MTBA]
[PR4][MTBA]
Density and Refractive Index
Densities of studied ILs as a function of temperature (293.15
to 333.15 K) are given in Table 3. For comparison purposes,
densities of the precursors trihexyl(tetradecyl)phosphonium and
tricaprylmethylammonium chloride are also cited.The influence
of cation and anion on the density has already been investigated
by several authors.[6,24] In contrast to imidazolium ILs (which
generally have densities >1 g cm−3), tetraalkylammonium and
100
200
300
T [°C]
400
500
600
Fig. 3. Thermogravimetric analysis curves of selected ammonium and
phosphonium ionic liquids.
phosphonium salts tend to have densities <1 g cm−3 [3,4,6]
cor-
,
[Sal] anions exhibit good solubility both in common polar sol-
vents ethanol, ethyl acetate, and methanol, in less polar solvents
such as ether as well as in the apolar solvent hexane, ILs contain-
ing [TS] and [BA] anions were not soluble in ether and hexane.
responding to our results. Comparing the values of the two
commercially available precursors, it is obvious that the dis-
placement of the chloride anion with aromatic anions leads to
an increase in density. This is consistent with observations made
by other working groups by the implementation of an aromatic
group into different imidazolium-based ILs.[6,26,27] This result
may be attributed to the increasing packing ability afforded both
by the phenyl ring and the bulkiness of the aromatic anion. In
general, all measured ILs show a linear dependence of density
with temperature, whereas the density decreases with increas-
ing temperature (max. 7 × 10−4 g cm−3 per ◦C, see Fig. 4). This
linearity is common for ILs and a consequence of the large tem-
perature difference between their working temperature and their
hypothetical critical temperatures.[23] Measured data were fitted
to equations of the type ln ρ = aT + b, and parameters are given
in Table 4. The slopes of the resulting lines correspond to the
thermal expansion coefficients (a = −αp) and as expected, they
Thermal Stability
Decomposition temperatures of the investigated phosphonium-
based ILs (340–390◦C) are ∼100◦C higher compared with their
ammonium analogues (Fig. 3). This is consistent with the lit-
erature, because quaternary phosphonium salts are known to
have higher decomposition temperatures than their nitrogen
analogues.[4,25] The measured values for ammonium-based ILs
(240–270◦C) are comparable with values reported for other
Aliquat 336-based ILs.[5,6]
It is well documented that the anion influences the thermal
stability of ILs.[26–28] Although the incorporation of aromatic
anions results in an increase in thermal stability,[8,29] no distinct
impact of the functional groups appended to the aromatic anion
on the decomposition temperature is observable in our study.
Whereas among the ammonium ILs [A336][Sal], [A336][BA],
and [A336][Van] exhibited the lowest decomposition temper-
ature (Td) of 240◦C, [PR4][PTA] showed the lowest thermal
stability among the phosphonium ILs with a Td of 320◦C. The
only exceptions are the tetraphenylborate-containing ILs, which
fall for all studied ILs in a range of 0.59–0.89 K−1 [23]
.
In addition, from the ratio of the molecular weight and den-
sity of selected ILs at a given temperature, molar volumes
were calculated (Table 3). The molar volumes of ammonium
and phosphonium cations with the same anion (either [BA]
or [TS]), approximately yield the value of 104 cm3 mol−1
,
which suggests a distinct molar volume contribution of the

516
A. Stojanovic et al.

Phosphonium and Ammonium Ionic Liquids with Aromatic Anions
517
0.950
0.945
1.52
1.52
1.51
1.51
1.50
1.50
1.49
1.49
1.48
1.48
1.47
0.940
0.935
0.930
0.925
0.920
0.915
0.910
0.905
0.900
0.895
292
302
312
322
332
295
305
315
325
335
T [K]
T [K]
[A336][TS]
[A336][BA]
[A336][MTBA]
[PR4][TS]
[PR4][BA]
[PR4][MTBA]
[PR4][PTA]
[PR4][Sal]
[PR4][Van]
[A336][TS]
[A336][BA]
[A336][MTBA]
[PR4][TS]
[PR4][BA]
[PR4][MTBA]
[PR4][PTA]
[PR4][Sal]
Fig. 4. Density, ρ, and refractive index, nD, of the studied ILs as a function of temperature.
Table 4. Maximum water content in water saturated ionic liquids (IL) and anion leaching in aqueous phase
ILs
Water saturation [wt-%]
MilliQ-H2O 10 mM CaCl2
21.2 20.8
Leaching of IL anion [ppm]
c (Cl−) [ppm]A
MilliQ-H2O
10 mM CaCl2
[A336][Cl]
414
2.0
5992
2.7
—
50
55.7
—
13.3
1
[A336][TS]
[A336][MTBA]
[PR4][Cl]
[PR4][TS]
[PR4][MTBA]
4.1
15.1
12.9
11.2
10.6
4.0
14.8
13.4
10.8
10.5
0.2
0.2
7980
5.2
8372
5.1
0.2
0.2
ADecrease of chloride concentration in aqueous phase (10 mM CaCl2) after extraction with ILs.
cations [PR4] and [A336], respectively. However, [MTBA]-
containing ILs show a significant variation. The molar vol-
ume of [A336][MTBA] is significantly higher compared with
[PR4][MTBA]. The difference between these two ILs yields a
molar volume of 72 cm3 mol−1. Furthermore, each anion shows
an individual contribution to the molar volume following the
trend: [BA] < [Sal] < [TS] < [PTA] < [Van]. We assume that an
additive nature of ILs and its components regarding density[31]
should not be neglected, however, as our results are based on just
a few data points, a more detailed investigation is of interest.
Measured refractive indices of several prepared ILs as well as
from [A336][Tf2N] and [PR4][Tf2N] as reference samples with
corresponding literature data are presented in Table 3. Refrac-
tive indices obtained for reference substances correspond with
published results,[23] with deviations of less than 1%.
Asforthedensity, therefractiveindicesdecreasewithincreas-
ing temperature. However, whereas the order of the ammonium-
based IL’s densities is the same as for the refractive indices,
no significant relation in order or spacing between density and
refractive index data is observed for phosphonium ILs.The influ-
ence of the anion on the refractive indices is clearly observable
when comparing the [Tf2N]-containing ILs with prepared aro-
matic ones. The incorporation of a phenyl ring significantly
increases the refractive indices. Furthermore, because ammo-
nium as well as phosphonium benzoate-containing ILs show the
lowest nD values, we can assume that added functionality also
increases the refractive index of the ILs.As the refractive index is
related to the electronic polarizability of a molecule, the nD value
may also be useful as an indicator of the behaviour of ILs in solu-
tion and for intermolecular forces.[32] Several authors[23,32,33]
have used molar refraction, Rm, as a measure for the relation
between density and refractive index and hence as an indicator
for polarizability of the substance.
In general, substances with a large index of refraction, and
hence large polarizability, should exhibit pronounced dispersion
forces and, therefore, might be suitable, for example, for the
solvating of species with similar polarizability.[33] The molar
refractions, Rm, were calculated according to the equation:
(n2 − 1)
(n2 + 2)
(n2 − 1)
(n2 + 2)
M
Rm
=
Vm
=
·
,
(1)
ρ
where n is the refractive index, Vm the molar volume, M the
molar mass, and ρ the density. Results are listed inTable 3.[34–37]
The molar refractions of phosphonium ILs are ∼30 cm3 mol−1
higher than those of ammonium ILs, which indicates their
higher polarizability. Interestingly, the change of the anion from
[Tf2N] to aromatic ones does not significantly influence the Rm
values.[23] Regarding the statement of Deetlefs et al.[38] that the
refractive index is higher when the compound is denser (and

518
A. Stojanovic et al.
5500
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
[A336][CI]
[A336][TS]
[A336][BA]
[A336][MTBA]
[PR4][TS]
[PR4][BA]
[PR4][MTBA]
[PR4][PTA]
[PR4][Sal]
0
0.00295 0.00300 0.00305 0.00310 0.00315 0.00320 0.00325 0.00330 0.00335 0.00340
1/T [K]
Fig. 5. Viscosity, η, of the studied ionic liquids as a function of temperature.
hence more tightly packed), no such dependence was observed
in our study.
is well described in the literature,[1,10] a 10 mM CaCl2 solu-
tion with a distinct pH of 7.5 as model matrix was chosen.
Time-dependent extraction experiments were conducted using
a liquid-phase micro-extraction setup.[39] The total platinum
concentration was measured using an inductive coupled plasma
sector field mass spectrometry (ICP-SFMS).
Viscosity
Viscosity values of investigated ILs at 25◦C are presented in
Table 1. The incorporation of bulky, aromatic anions resulted
in a remarkable increase of viscosity regarding Aliquat 336-
based ILs. For example, [A336][MTBA] exhibited the highest
viscosity with 5242 cP, which indicates an increase of ∼150%
compared with the chloride-containing Aliquat 336 precursor
with 2088 cP.To the contrary, the prepared phosphonium-type IL
[PR4][MTBA] showed a significantly lower viscosity of 875 cP
compared with the Cyphos IL101 precursor with a measured
viscosity of 1759 cP. These results clearly indicate that the influ-
ence of cation or anion on the viscosity of the evaluated ILs
cannot be considered separately, and confirms the fact that for
the prediction of physico-chemical properties, ILs should always
be regarded as a whole.
As it can been seen in Fig. 6, selected functionalized ILs
exhibited different affinities towards platinum. Whereas tri-
hexyl(tetradecyl)phosphonium 2-(methylthio)benzoate, [PR4]
[MTBA], showed a high and fast uptake of platinum (almost
100% in 30 min), both thiosalicylate-containing ILs revealed
a significantly decreased efficiency ([A336][TS] 85% and
[PR4][TS] 76%, respectively). Furthermore, only 40% of the
platinum was extracted with [A336][MTBA] after 120 min from
the aqueous phase. Interestingly, the extraction efficiency cor-
relates with the order of descending viscosity: [PR4][MTBA] >
[A336][TS] > [PR4][TS] > [A336][MTBA]. Hence, our results
evidently indicate that not only the functionality appended
to the anion, but also the physico-chemical properties of the
evaluated ILs seem to exhibit a remarkable impact on the
extraction efficiency. This is in accordance with observations
of Papaiconomou et al.[40] who investigated the extraction effi-
ciency of thioether-functionalized ILs for PdII.Although the soft
acid PdII certainly exhibits a high affinity towards thio-ether
groups, the change of the cation – and hence the alternation
of the IL’s physico-chemical properties – resulted in a different
extracting behaviour.
As expected, the viscosity decreased with increasing temper-
ature (Fig. 5), whereas the rate of decrease was much higher for
more viscous ILs. This is in accordance with results reported in
the literature for several other quaternary ammonium ILs.[6] In
general, all ILs exhibited Newtonian behaviour.
Evaluation of Selected Thioether-Functionalized ILs as
Extracting Agents for Platinum from the Aqueous Phase
Selected thiol and thio-ether functionalized RTILs, [A336][TS],
[A336][MTBA], [PR4][TS], and [PR4][MTBA] were evalu-
ated for their platinum uptake from an aqueous model matrix.
Because the extraction efficiency as well as water solubility of
ILs is dependent on the ionic strength of the aqueous phase and
Water Saturation and Anion Leaching of Evaluated ILs
Since the water inclusion of ILs as well as their leaching into
an aqueous phase play a significant role both for their possible
application as extracting agent as well as for the elucidation of

Phosphonium and Ammonium Ionic Liquids with Aromatic Anions
519
Reference sample
[A336][MTBA]
[PR4][MTBA]
[A336][TS]
[PR4][TS]
measured for [A336][Cl] and [PR4][Cl] in the pure water phase,
respectively. The leached anion concentrations were signifi-
cantly higher in 10 mM CaCl2, averaging 5992 and 8372 ppm,
respectively, which corresponds to a maximum chloride loss
into the aqueous phase of 12 wt-%. In contrast, functionalized
ILs (both ammonium and phosphonium) showed a maximum
anion leaching of 5.2 ppm for [PR4][TS], which corresponds to
a maximum leaching of 0.01 wt-%. In addition, there were no
significant differences in the leaching of anions regarding the
composition of the aqueous phase. Although no clear correla-
tion between the platinum extraction and the physical behaviour
of evaluated ILs can be given with the investigated data so far,
it seems obvious that S-functionalized ILs are suitable for the
elimination of platinum from the aqueous phase.
120
100
80
60
40
20
0
0
20
40
60
80
100
120
Time [min]
Conclusions
Fig. 6. Extraction efficiency of [A336][TS], [A336][MTBA], [PR4][TS],
and [PR4][MTBA] for platinum.Aqueous phase: 0.01 M CaCl2 (pH 7.5); ini-
tial Pt concentration: 7.5 µg L−1; reference sample: time dependent studies
without ionic liquids. The measurement uncertainty of the entire procedure
is in the range of 15% (coverage factor 2).
In this report we presented several hydrophobic phosphonium
and ammonium-based ILs that contained functionalized aro-
matic anions. ILs were obtained with high yield (>90%) and
sufficient purity. Physico-chemical properties of the prepared
ILs were determined and the impact of the different constituents
on the bulk properties of the ILs was discussed. In general, our
results have shown that the incorporation of aromatic anions
into ILs leads to a remarkable increase in density and ther-
mal stability.The alteration of different functionalities appended
to the anion did not result in significant differences of mea-
sured physico-chemical properties. Studied phosphonium ILs
exhibited significantly higher thermal stability and presumed
polarizability compared with their ammonium counterparts.The
anion exchange resulted in a significant alternation of viscosity
for the investigated ILs. It is clear from the obtained experimen-
tal data that the anion alone cannot serve as an explanation for the
viscosity, which indicates the combined influence of the cation
and anion of the respective IL.
Furthermore, selected ILs bearing thiol- and thioether func-
tionalities were evaluated as potential extracting agents for plat-
inum from aqueous solutions. The IL [PR4][MTBA] has shown
an extraordinary affinity towards platinum (with an extraction
efficiency of almost 100%). However, because of the remarkable
differences in extracting behaviour between [A336][MTBA] and
[PR4][MTBA], the presence of the thioether functionality cannot
be the sole explanation for the strong affinity of [PR4][MTBA]
towards platinum.The physico-chemical parameters such as vis-
cosity as well as hydrophobicity of the ILs as an entity seem to
have an influence on the extracting processes and have to be
further investigated. Although the studied ILs exhibit a different
water uptake capacity, the facilitated metal ion transport into ILs
because of the predominant absorption of solvated ions, does not
seem to play a dominant role. Despite the relatively high water
saturation of ILs, no significant leaching of IL anions into the
aqueous phase was observed. Hence, the simple exchange of
the chloride anion of Aliquat 336 and Cyphos IL101 with func-
tionalized aromatic anions leads to hydrophopic ILs, usable as
extracting agents for platinum from aqueous solutions.
possiblereactionmechanism, theseparametersweredetermined.
For these experiments ∼2 g of the ILs were vigorously shaken
with 2 mL of aqueous phase. Because of the dependence of both
water uptake and leaching on the ionic strength of the aqueous
phase, experiments with high purity water (MilliQ, Millipore)
and 10 mM CaCl2 solution (pH 7.5) were conducted. For com-
parison, theexperimentswerealsoconductedwiththeprecursors
Aliquat 336 and Cyphos IL101. However, whereas a clear phase
separation was achieved after centrifugation for Cyphos IL101,
the presence of a white emulsion phase was observed forAliquat
336. The anion content was measured by ion chromatography in
the clear upper aqueous phase. Simultaneously, the water content
of saturated ILs was measured.All obtained data are presented in
Table 4. The maximum measured water uptake of Cyphos IL101
of 13.4 wt-% is in accordance with data from Cytec Ind.[37]
In contrast, Aliquat 336 exhibited a significantly higher water
uptake of up to 21.2 wt-%.As expected, the exchange of the chlo-
ride anion with the aromatic anions led to a decreasing affinity
for water of the prepared ILs (decrease of up to 17 wt-%). Inter-
estingly, evaluated ILs displayed severe differences in their water
saturation concentrations. Whereas [A336][MTBA] exhibited a
water uptake of up to 15 wt-%, the water content of [A336][TS]
did not exceed 4.5 wt-%. In contrast, the water concentrations
of the corresponding phosphonium ILs were comparable and
averaged in both cases ∼11 wt-%.
Hence, there is no correlation between water and metal ion
uptake of tested RTILs and the assumption of a facilitated metal
ion transport into ILs because of predominant absorption of
solvated ions cannot serve as an explanation for different extrac-
tion efficiencies. However, the negligible influence of chloride
ion concentration on the water uptake of ILs, as already men-
tioned in the literature,[10] is confirmed with the obtained data.
Whereas a slightly ‘salting-in’ effect was observed for ammo-
nium ILs, no significant variations of the chloride concentrations
were detected in the case of phosphonium ILs.
Experimental
General Experimental
The precursors Aliquat 336 and Cyphos IL101 showed a
significant leaching into the aqueous phase under neutral con-
ditions. The chloride concentrations of 414 and 7980 ppm were
1H, 13C, 31P, and two-dimensional COSY, HSQC, and HMBC
NMR spectra were recorded with a Bruker Avance III 500 MHz
NMR spectrometer at 500.32 (1H), 125.81 (13C), and 202.53

520
A. Stojanovic et al.
(31P), or 500.10 (1H), 125.75 (13C), and 202.44 (31P) MHz (stan-
dard Bruker pulse programs) in (D6)DMSO at 298 K, using the
Leaching and Water Uptake Experiments
DistinctamountsofILs(2 g)weretransferredintopolypropylene
(PP) tubes and 2 mL of the corresponding aqueous phase (pure
water or 10 mM CaCl2 (pH 7.5)) was added. The mixture was
vigorously shaken for 5 min on a Vortex, until a fine emulsion
was formed. The sample-containing tubes were centrifuged for
30 min at 1029g until a clear phase separation was achieved.
The water phase was removed using a syringe with a needle and
adequately diluted for ion chromatographic measurements. Ion
chromatographywascarriedoutusingaICS1000(DionexCorp.,
CA, USA) instrument with a RFC-30 Reagent-free controller,
KOH as eluent and a conductivity detector (Ion Pac AS20 4 mm
analytical anion column; KOH gradient: from 10 to 50 mM KOH
in 40 min, 1.0 mL min−1 flow rate, column temperature 30◦C;
detection limits: Cl: 20 ppb, TS: 50 ppb, MTBA: 50 ppb). The
water content in the IL phase was determined using a volumetric
Mettler-Toledo DL38 Karl-Fischer titrator.
solvent residual peak for 1H and 13C as an internal reference. 31
P
chemical shifts were measured relative to 85% H3PO4. Elemen-
talanalysis(C, H, N, S, Cl)wascarriedoutbytheMicroanalytical
Laboratory, University of Vienna[20] (the chloride content of
mineralized ILs was measured by potentiometric titration using
AgNO3 as titrant). ESI-MS measurements were performed with
an Esquire3000 ion trap mass spectrometer (Bruker Daltonics,
Bremen, Germany) equipped with an orthogonal (ESI+) source.
ILs were diluted with methanol to ensure good spraying condi-
tions. The samples were introduced by flow injection at a rate
of 4 µL min−1 using a Cole-Parmer 74900 single-syringe infu-
sion pump. Infrared spectra were measured with a BrukerVertex
70 FTIR spectrometer (4000–400 cm−1) using sodium chloride
windows. Thermogravimetric measurements were conducted
on a Mettler-Toledo TGA/SDTA 851e analyzer at a scan rate
of 5◦C min−1 over a temperature window of 25 to 600◦C.
Nitrogen was used as the purge gas. Melting points were deter-
mined with a Melting Point B-540 instrument from Büchi,
Switzerland. Viscosity measurements were conducted using
a Bohlin CVO Rheometer System, Malvern Instruments Ltd,
UK (cone method; shear rate of 100 s−1; temperature range
25–60◦C; gradient 5◦C min−1). The validity of the applied
method was determined by measuring the viscosity of Cyphos
IL101. Obtained values at 25◦C were consistent with val-
ues reported in the literature.[3] Density measurements were
conducted using a calibrated glass pycnometer (Heislinger,
Germany). Refraction indices were measured with an Abee-
refractometer AR4D (Kruess, Germany). The water content of
the ILs was measured using a Mettler-Toledo DL39 Karl-Fischer
(KF) coloumeter. The chloride content in the aqueous wash-
ing phase during synthetic procedures was measured by ion
chromatography, using a ICS1000 (Dionex Corp., CA, USA)
instrument with a RFC-30 Reagent-free controller, KOH as elu-
ent, and a conductivity detector (Ion Pac AS20 4 mm analytical
anion column; KOH gradient: from 10 to 50 mM KOH in 40 min,
1.0 mL min−1 flow rate, column temperature 30◦C; detection
limits: Cl: 20 ppb).
Synthesis of ILs
Chemicals
Aliquat 336 ([A336][Cl], Aldrich, Austria, purum >97%),
trihexyl(tetradecyl)phosphonium chloride, Cyphos IL101,
([PR4][Cl], Fluka, Switzerland, purum >95%), thiosalicylicacid
(Fluka, purum >97%), benzoic acid (Riedel-de Haen, Germany,
purum >99%), (phenylthio)acetic acid (Aldrich, purum 96%),
sodium salicylate (Acros, Austria, purum 99%), vanillic acid
(Acros, purum 98.5%), tetraphenylboron sodium (Acros, purum
99.5%), and sodium hydroxide (Bakker, 50%) were used as
received without further purification. Dichloromethane for syn-
thesis was distilled over P2O5 before use. 2-(Methylthio)benzoic
acid was synthesized according to the method reported in the
literature.[16] Ultra pure water was obtained from a Millipore
SynergyUV Ultrapure Water system (Molsheim, France) and
was used throughout all syntheses.
Tricaprylmethylammonium Thiosalicylate, [A336][TS]
Aliquat 336 was transferred to a round-bottom flask and
purged with argon. An eqimolar amount of thiosalicylic acid
was dispersed in water and deprotonated with a two-fold excess
of sodium hydroxide. Thiosalicylate solution was added to Ali-
quat 336 and the dispersion was vigorously stirred under an inert
atmosphere for 4 h at 40◦C.The IL phase was separated from the
aqueous phase in a separation funnel. Because of its high vis-
cosity the IL was also dissolved in dry dichloromethane in order
to minimize loss during washing steps. The organic phase was
washed several times with small amounts of ice-cold water. The
water phases were collected and evaporated for 2 h at 1 kPa and
40◦C. The resulting white precipitate was washed three times
with ethanol and dried in a drying chamber for 48 h at 40◦C. The
precipitate was identified as sodium chloride by ion chromato-
graphy. The main water content of the IL was evaporated for 2 h
at 40◦C and 1 kPa on a rotary evaporator. The IL was finally
dried under vacuum at 0.1 Pa for 24 h at 40◦C. [A336][TS]:
greenish-yellow viscous liquid. Yield: 98%. δH 0.85–0.88 (m,
12H, CH2–CH3), 1.26–1.29 (m, 44H, –CH2–), 1.54–1.62 (m,
6H, N–CH2–CH2–), 2.96 (s, 3H, N–CH3), 3.19–3.22 (m, 6H,
N–CH2–), 6.68 (t, 3J 7.9, Harom (5)), 6.93 (t, 3J 7.9, Harom
Extraction Experiments
Batch experiments were performed by LPME based on the setup
of Liu et al.[39] For platinum determination a certified sin-
gle element ICP standard was used (Merck KGaA, Darmstadt,
Germany).Amodelsolution(20 mL)containing7.5 µg L−1 Ptin
10 mM CaCl2, which had been adjusted to pH 7.5 by using supra-
pur o-phosphoric acid and sodium hydroxide, was prepared in a
50 mL polyethylene (PE) flask. The investigated IL was drawn
into a 1 mL syringe (Terumo Europe, Leuven, Belgium), which
was connected with a 5 cm long polyetheretherketone (PEEK)
capillary (1/16ꢀ OD PEEKTM PolymerTubing, BESTA-Technik
GmbH, Wilhelmsfeld, Germany) and the plunger was depressed
to expose a 10 µL drop of IL. Aliquots were taken after 30, 60,
90, and 120 min. In order to exclude the possibility of Pt precip-
itation under experimental conditions, reference measurements
were conducted using the same setup, without IL. The extraction
experiments were performed three times for each IL. ICP-SFMS
determination of Pt was carried out by a high resolution ICP-
SFMS (Element 2, Thermo Fisher, Bremen, Germany). To avoid
contamination, all sample preparation steps and measurements
were carried out under clean room conditions (class 100000 and
class 10000 with clean benches class 100, respectively) with
temperature control (20◦C) and overpressure (+5 Pa).
3
3
(4)), 7.02 (t, J 7.4, Harom (5a)), 7.12 (t, J 7.4, Harom (4a)),
3
3
7.26 (d, J 7.9, Harom (3)), 7.46 (d, J 7.4, Harom (3a)), 7.82
(d, 3J 7.4, Harom (6a)), 7.88 (d, 3J 7.9, Harom (6)). δC 14.5
(–CH2–CH3), 21.8 (–CH2–CH3), 22.5, 22.6, 26.2, 28.9, 29.1,

Phosphonium and Ammonium Ionic Liquids with Aromatic Anions
521
29.2, 29.4, 31.6, 31.8 (–CH2–), 48.1 (N–CH3), 61.0 (N–CH2–),
124.3 (Carom (5a)), Carom (4a)), 128.9 (Carom (2)), 130.0 (Carom
(6a)), 131.5 (Carom (6)), 136.4 (Carom (3)), 138.6 (Carom (2a)),
158.6 (Carom (1)), 168.8 ((COO−)a), 170.7 (COO−). m/z (ESI+)
340.6, 368.6, 396.6, 424.6, 452.6. m/z (ESI−) Found: 153.2.
Calc. 153.2. νmax/cm−1 3045 (CH3, νas), 2954 (CH2, νas), 2855
(CH2, νs), 1647 (C=O, ν), 1469–1370 (CH3 + CH2, δ), 1269–
629 (CHarom + C–O, δ) (Found: C 72.65, H 11.24, N 2.65, S 6.10.
Calc. for C32H59NO2S·0.45H2O (529.96): C 72.52, H 11.38, N
2.64, S 6.05%.)
Tricaprylmethylammonium (Phenylthio)acetate,
[A336][PTA]
The IL was synthesized following the same procedure as
described above for [A336][BA]. However, the phenylthioacetic
acid was dissolved in a water/acetonitrile mixture (1/1) and Ali-
quat 336 was dissolved in acetonitrile. The reaction mixture was
stirred at 60◦C for 24 h. [A336][PTA]: yellowish semi-solid, gel.
Yield: 95%. δH 0.85–0.88 (m, 12H, –CH2–CH3), 1.26–1.29 (m,
44H, –CH2–), 1.59–1.62 (m, 6H, N–CH2–CH2–), 2.94 (s, 3H,
N–CH3), 3.18–3.21 (m, 6H, N–CH2–), 3.37 (s, 2H, –S–CH2–),
7.04 (d, Harom (6)), 7.21 (m, Harom (4,5)), 7.65 (d, 3J 7.4, Harom
(3)). δC 14.4 (–CH2–CH3), 21.8 (–CH2–CH3), 22.5, 22.6, 26.2,
26.3, 28.9, 29.1, 29.2, 29.4, 31.6, 31.8(–CH2–), 32.9(–S–CH2–),
47.9 (N–CH3), 60.9 (N–CH2–), 124.4 (Carom (6)), 126.8 (Carom
(5)), 128.9 (Carom (4)), 140.3 (Carom (1)), 168.8 (COO−). m/z
(ESI+) 340.6, 368.7, 396.6, 424.7, 452.7. m/z (ESI−) Found:
167.1. Calc. 167.2. νmax/cm−1 3050 (CH3, νas), 2925 (CH2, νas),
2855 (CH2, νs), 1609 (C=O, ν), 1466 (CH3 + CH2, δ), 1352 (C–
S, ν), 1206–474 (CHarom + C–O, δ) (Found: C 70.12, H 11.81,
N 2.49, S 5.67. Calc. for C33H61NO2S·0.09H2O (565.37): C
70.11, H 10.83, N 2.48, S 5.67%.)
Tricaprylmethylammonium Benzoate, [A336][BA]
Benzoicacidwasdissolvedinawater/ethanolmixture(1/1)in
a round-bottom flask, purged with argon and deprotonated with
a two-fold amount of sodium hydroxide. An equimolar amount
of Aliquat 336 was dissolved in ethanol and added. The reaction
mixture was vigorously stirred under inert atmosphere for 5 h
at 60◦C. After removal of solvents on the rotary evaporator, the
IL was dissolved in dry dichloromethane and washed several
times with small amounts of ice-cold water. The water phases
were collected and evaporated for 2 h at 1 kPa and 40◦C. The
resulting white precipitate was washed three times with ethanol
and dried in a drying chamber for 48 h at 40◦C. The precipitate
was identified as sodium chloride by ion chromatography. The
solvent was evaporated for 2 h at 40◦C and 1 kPa on a rotary
evaporator and the IL dried under vacuum at 0.1 Pa for 24 h at
40◦C. [A336][BA]: clear yellowish viscous liquid. Yield: 97%.
δH 0.85–0.88 (m, 12H, CH2–CH3), 1.26–1.29 (m, 44H, –CH2–),
1.59–1.63 (m, 6H, N–CH2–CH2–), 2.95 (s, 3H, N–CH3), 3.18–
3.22 (m, 6H, N–CH2–), 7.21 (m, 3J 7.9, Harom (5,4)), 7.18 (m,
3J 7.9, Harom (3,6)). δC 14.5 (–CH2–CH3), 21.8 (–CH2–CH3),
22.5, 22.6, 26.2, 26.3, 28.9, 29.1, 29.2, 29.4, 31.6, 31.8 (–CH2–),
48.0 (N–CH3), 60.9 (N–CH2–), 127.2 (Carom (6)), 128.2 (Carom
(4)), 139.3 (Carom (5)), 142.5 (Carom (1)), 168.4 (COO−). m/z
(ESI+) 340.6, 368.7, 396.7, 424.7, 452.8. m/z (ESI−) Found:
121.1. Calc. 121.1. νmax/cm−1 3059 (CH3, νas), 2925 (CH2, νas),
2855 (CH2, νs), 1605 (C=O, ν), 1564 (C=C, δ), 1469–1370
(CH3 + CH2, δ), 1060–670 (CHarom + C–O, δ) (Found: C 74.84,
H 11.45, N 2.70. Calc. for C32H59NO2·0.10H2O (519.54): C
73.98, H 11.40, N 2.70%.)
Tricaprylmethylammonium Salicylate, [A336][Sal]
Sodium salicylate was dissolved in water in a round-bottom
flask and purged with argon. An equimolar amount of Aliquat
336 was dissolved in acetone and added drop wise to the sodium
salicylate solution. The reaction mixture was vigorously stirred
under an inert atmosphere for 24 h at room temperature. Despite
the water/acetone miscibility a second IL phase was formed and
separated in a separation funnel. The IL was dissolved in dry
dichloromethane and washed several times with small amounts
of ice-cold water. The water phases were collected and evapo-
rated for 2 h at 10 mbar and 40◦C.The resulting white precipitate
was washed three times with ethanol and dried in a drying cham-
ber for 48 h at 40◦C. The precipitate was identified as sodium
chloride with ion chromatography. The solvent was evaporated
for 2 h at 40◦C and 1 kPa on a rotary evaporator and the IL was
dried under vacuum at 0.1 Pa for 24 h at 40◦C. [A336][Sal]:
white-yellowish solid. Yield: 91%. δH 0.85–0.88 (m, 12H,
–CH2–CH3), 1.26–1.29 (m, 44H, –CH2–), 1.59–1.61 (m, 6H,
N–CH2–CH2–), 2.95 (s, 3H, N–CH3), 3.19–3.22 (m, 6H, N–
Tricaprylmethylammonium 2-(Methylthio)benzoate,
[A336][MTBA]
3
CH2–), 6.55 (m, Harom (3,5)), 7.09 (t, J 7.5, Harom (4)), 7.64
(d, 3J 7.5, Harom (6)). δC 14.4 (–CH2–CH3), 21.8 (–CH2–CH3),
22.5, 22.6, 26.2, 28.9, 29.1, 29.2, 29.4, 31.6, 31.8 (–CH2–), 48.0
(N–CH3), 61.0 (N–CH2–), 116.1 (Carom (3)), 116.4 (Carom (5)),
121.3 (Carom (2)), 130.3 (Carom (6)), 131.7 (Carom (4)), 163.7
(Carom (1)), 171.5 (COO−). m/z (ESI+) 340.6, 368.5, 396.8,
424.7, 452.7. m/z (ESI−) Found: 137.1. Calc. 137.1. νmax/cm−1
3053 (CH3, νas), 2924 (CH2, νas), 2855 (CH2, νs), 1588 (C=O,
ν), 1544 (C=C, δ), 1486, (CH3 + CH2, δ), 1378 (O–H, ν), 1288–
536 (CHarom + C–O, δ) (Found: C 76.15, H 11.71, N 2.76. Calc.
for C32H59NO3·0.05H2O (506.72): C 75.85, H 11.67, N 2.76%.)
The IL was synthesized following the same procedure as
described above for [A336][BA]. However, both previously
synthesized 2-(methylthio)benzoic acid and Aliquat 336 were
dissolved in acetone and stirred at room temperature for 48 h.
[A336][MTBA]: orange viscous liquid. Yield: 96%. δH 0.85–
0.88 (m, 12H, CH2–CH3), 1.26–1.29 (m, 44H, –CH2–), 1.54–
1.60 (m, 6H, N–CH2–CH2–), 2.2 (3, 3H, –S–CH33), 2.95 (s, 3H,
N–CH3), 3.18–3.22 (m, 6H, N–CH2–), 6.94 (t, J 7.4, Harom
(5)), 7.05 (d, 3J 7.4, Harom (3)), 7.15 (t, 3J 7.4, Harom (4)), 7.65
3
(d, J 7.4, Harom (6)). δC 14.5 (–CH2–CH3), 15.7 (–S–CH3),
21.8 (–CH2–CH3), 22.5, 22.6, 26.2, 28.9, 29.1, 29.2, 29.4, 31.6,
31.8 (–CH2–), 47.9 (N–CH3), 60.9 (N–CH2–), 122.7 (Carom
(5)), 123.3 (Carom (3)), 128.0 (Carom (4)), 128.7 (Carom (6)),
139.3 (Carom (2)), 140.7 (Carom (1)), 162.2 (COO−). m/z (ESI+)
340.8, 368.9, 396.6, 424.6, 452.6. m/z (ESI−) Found: 167.2.
Calc. 167.2. νmax/cm−1 3053 (CH3, νas), 2925 (CH2, νas), 2855
(CH2, νs), 1598 (C=O, ν), 1544 (C=C, δ) 1464 (CH3 + CH2, δ),
1364 (C–S, v), 1063–652 (CHarom + C–O, δ) (Found: C 70.16, H
11.81, N 2.48, S 5.66. Calc. for C33H61NO2S·0.07H2O (565.08):
C 70.14, H 10.83, N 2.48, S 5.67%.)
Tricaprylmethylammonium Vanillate, [A336][Van]
The IL was synthesized following the same procedure as
described above for [A336][BA]. Aliquat 336 was dissolved in
acetone, whereas vanillic acid was dispersed in water before
deprotonation. The solution was vigorously stirred under an
inert atmosphere for 24 h at 40◦C. [A336][Van]: dark brown
highly viscous liquid. Yield: 98%. δH 0.85–0.88 (m, 12H, –
CH2–CH3), 1.25–1.27 (m, 44H, –CH2–), 1.59–1.60 (m, 6H,
CH2–CH2–), 2.94 (s, 3H, N–CH3), 3.18–3.35 (m, 6H, N–CH2–),

522
A. Stojanovic et al.
6.68 (d, 3J 8, Harom (5)), 7.25 (d, 3J 8, Harom (6)), 7.40 (s, Harom
(2)). δC 14.4 (–CH2–CH3), 21.8 (–CH2–CH3), 22.5, 22.6, 26.2,
28.9, 29.1, 29.2, 29.4, 31.6, 31.8 (–CH2–), 48.0 (N–CH3), 55.19
(–O–CH3), 61.0 (N–CH2–), 113.8 (Carom (2)), 114.4 (Carom (5)),
122.5 (Carom (6)), 133.8 (Carom (1)), 146.5 (Carom (3)), 147.7
(Carom (4)), 168.8 (COO−). m/z (ESI+) 340.5, 368.5, 396.7,
424.7, 452.7. m/z (ESI−) Found: 167.0. Calc. 167.2. νmax/cm−1
3053 (CH3, νas), 2925 (CH2, νas), 2855 (CH2, νs), 1557 (C=O,
ν), 1464 (C=C, δ), 1351 (CH3 + CH2, δ), 1277 (O–H, ν), 1179–
636 (CHarom + C–O, δ) (Found: C 74.86, H 11.41, N 2.59. Calc.
for C33H61NO4·0.14H2O (538.31): C 73.63, H 11.37, N 2.60%.)
136.3 (Carom (3)), 139.1 (Carom (2a)), 158.6 (Carom (1)), 168.6
((COO−)a), 170.7 (COO−). δP 33.7. m/z (ESI+) Found: 483.9.
Calc. 483.9. m/z (ESI−) Found: 152.9. Calc. 153.2. νmax/cm−1
3045 (CH3, νas), 2925 (CH2, νas), 2855 (CH2, νs), 2545 (S–
H, ν), 1688 (C=O, ν), 1462–1378 (CH3 + CH2, δ), 1221–645
(CHarom + C–O, δ) (Found: C 73.23, H 11.50, S 5.00. Calc. for
C39H73PO2S·0.14H2O (639.54): C 73.24, H 11.44, S 5.01%.)
Trihexyl(tetradecyl)phosphonium Benzoate, [PR4][BA]
The IL was synthesized following the same procedure
described above for [A336][BA]. [PR4][BA]: clear yellowish
viscous liquid. Yield: 98%. δH 0.86–0.89 (m, 12H, –CH2–
CH3), 1.25–1.30 (m, 24H, –CH2–), 1.36–1.39 (m, 6H, –CH2–
CH3), 1.4 (m, 6H, P–CH2–CH2–CH2–), 1.47–1.49 (m, 6H,
P–CH2–CH2–), 2.16–2.22 (m, 6H, P–CH2–), 7.21 (m, Harom
(5,3)), 7.80 (m, Harom (6,2,4)). δC 14.4 (–CH2–CH3), 18.2 (P–
CH2–), 21.0 (P–CH2–CH2–), 22.1 (–CH2–CH3), 22.5 (–CH2–
CH3), 22.6, 28.6, 29.1, 29.2, 29.4, 29.5, 30.1, 30.3, 31.6, 30.9,
31.8 (remaining CH2), 127.1 (Carom (3)), 128.1 (Carom (4)),
129.3 (Carom (6)), 142.9 (Carom (1)), 168.4 (COO−). δP 33.7.
m/z (ESI+) Found: 483.9. Calc. 483.9. m/z (ESI−) Found: 121.2.
Calc. 121.1. νmax/cm−1 3049 (CH3, νas), 2925 (CH2, νs), 1606
(C=O, ν), 1564 (CH3 + CH2, δ), 1462 (CH3 + CH2, δ), 1355–
669 (CHarom + C–O, δ) (Found: C 77.14, H 12.12. Calc. for
C39H73PO2·0.12H2O (607.13): C 77.16, H 12.05%.)
Tricaprylmethylammonium Tetraphenylborate,
[A336][BPh4]
The IL was synthesized following the same procedure
as described above for [A336][Sal]. Both Aliquat 336 and
tetraphenylboron sodium were dissolved in acetone and stirred at
room temperature for 12 h. [A336][BPh4]: yellowish semi-solid,
gel.Yield: 90%. δH 0.86–0.89 (m, 12H, –CH2–CH3), 1.27–1.29
(m, 44H, –CH2–), 1.59–1.60 (m, 6H, N–CH2–CH2–), 2.90 (s,
3H, N–CH3), 3.15–3.25 (m, 6H, N–CH2–), 6.80 (t, 3J 7.4, Harom
3
(3)), 6.94 (t, J 8, Harom (2,4)), 7.18 (m, Harom (1,5)). δC 14.4
(–CH2–CH3), 21.8 (–CH2–CH3), 22.3, 22.6, 26.2, 28.9, 29.1,
29.2, 29.4, 31.6, 31.8 (–CH2–), 47.9 (N–CH3), 61.0 (N–CH2–),
121.9 (Carom (3)), 125.7 (Carom (2,4)), 136.0 (Carom (1,5)), 163.3
(Carom (6)), 163.7 (Carom (6)), 164.0 (Carom (6)), 164.4 (Carom
(6)). m/z (ESI+) 340.6, 368.7, 396.8, 424.7, 452.7. m/z (ESI−)
Found: 319.0. Calc. 319.2. νmax/cm−1 3051 (CH3, νas), 2925
(CH2, νas), 2854 (CH2, νs), 1472–1377 (CH3 + CH2, δ), 1266–
475 (CHarom) (Found: C 85.87, H 11.02, N 1.95. Calc. for
C49H74NB·0.05H2O (688.29): C 85.51, H 10.77, N 2.04%.)
Trihexyl(tetradecyl)phosphonium
2-(Methylthio)benzoate, [PR4][MTBA]
The IL was synthesized following the same procedure as
described above for [A336][MTBA]. [PR4][MTBA]: yellow vis-
cous liquid. Yield: 90%. δH 0.84–0.89 (m, 12H, –CH2–CH3),
1.24–1.29 (m, 24H, –CH2–), 1.36–1.38 (m, 6H, –CH2–CH3),
1.4 (m, 6H, P–CH2–CH2–CH2–), 1.47–1.49 (m, 6H, P–CH2–
CH2–), 2.17–2.20 (m, 6H, P–CH2–), 2.22 (s, 3H, –S–CH2),
6.96 (t, 3J 7.5, Harom (5)), 7.08 (d, 3J 7.5, Harom (3)), 7.18
(t, 3J 7.5, Harom (4)), 7.68 (d, 3J 7.5, Harom (6)). δC 14.3
(–CH2–CH3), 15.7 (–S–CH3), 18.2 (P–CH2–), 21.0 (P–CH2–
CH2–), 22.3 (–CH2–CH3), 22.6 (–CH2–CH3), 28.6, 29.1, 29.2,
29.4, 29.5, 30.1, 30.3, 31.6, 30.9, 31.8 (remaining CH2), 122.7
(Carom (5)), 123.5 (Carom (3)), 128.6 (Carom (4)), 129.9 (Carom
(6)), 139.6 (Carom (2)), 169.1 (COO−). δP 33.7. m/z (ESI+)
Found: 483.8. Calc. 483.9. m/z (ESI−) Found: 167.2. Calc.
167.2. νmax/cm−1 3045 (CH3, νas), 2925 (CH2, νas), 2855 (CH2,
νs), 1601 (C=O, ν), 1462 (CH3 + CH2, δ), 1355 (C–S, ν), 1109–
651 (CHarom + C–O, δ) (Found: C 73.62, H 11.60, S 4.92. Calc.
forC40H75PO2S·0.08H2O(652.46):C73.64, H11.53, S4.91%.)
Trihexyl(tetradecyl)phosphonium Thiosalicylate,
[PR4][TS]
Cyphos IL101 ([PR4][Cl]) was transferred to a round-bottom
flask, dissolved in acetone and purged with argon. An eqimolar
amount of thiosalicylic acid was dispersed in water and deproto-
nated with a two-fold excess of sodium hydroxide.Thiosalicylate
solution was added dropwise to the [PR4][Cl] solution and the
reaction mixture was vigorously stirred under inert atmosphere
for 48 h at room temperature.The formed IL phase was separated
from the solution in a separation funnel. Because of its high vis-
cosity the IL was also dissolved in dry dichloromethane in order
to minimize the loss during washing step.The organic phase was
washed several times with small amounts of ice-cold water. The
water phases were collected and evaporated for 2 h at 1 kPa and
40◦C. The resulting white precipitate was washed three times
with ethanol and dried in a drying chamber for 48 h at 40◦C. The
precipitate was identified as sodium chloride by ion chromato-
graphy. The main water content of the IL was evaporated for 2 h
at 40◦C and 1 kPa on a rotary evaporator. The IL was dried under
vacuum at 0.1 Pa for 24 h at 40◦C. [PR4][TS]: slightly yellowish
viscous liquid.Yield: 93%. δH 0.84–0.89 (m, 12H, –CH2–CH3),
1.24–1.29 (m, 24H, –CH2–), 1.36–1.38 (m, 6H, –CH2–CH3),
1.4 (m, 6H, P–CH2–CH2–CH2–), 1.46–1.48 (m, 6H, P–CH2–
CH2–), 2.17–2.20 (m, 6H, P–CH2–), 6.68 (t, 3J 7.9, Harom (5)),
6.63 (t, 3J 7.9, Harom (4)), 7.12 (t, 3J 7.5, Harom (5a)), 7.26 (m,
Harom (3,4a)), 7.53 (d, 3J 7.5, Harom (3a)), 7.88 (m, Harom (6,6a).
δC 14.4 (–CH2–CH3), 18.2 (P–CH2–), 21.0 (P–CH2–CH2–),
22.3 (–CH2–CH3), 22.5 (–CH2–CH3), 22.6, 28.6, 29.1, 29.2,
29.4, 29.5, 30.1, 30.3, 31.6, 30.9, 31.8 (remaining CH2), 118.8
(Carom (4)), 124.5 (Carom (3a)), 124.7 (Carom (5a)), 128.9 (Carom
(2)), 129.4 (Carom (5)), 131.1 (Carom (4a,6a)), 131.8 (Carom (6)),
Trihexyl(tetradecyl)phosphonium 2-(Phenylthio)acetate,
[PR4][PTA]
The IL was synthesized following the same procedure as
described above for [A336][PTA]. Phenylthioacetic acid was
dissolved in a water/acetonitrile mixture (1.5:1) and the solu-
tion was vigorously stirred under an inert atmosphere for 12 h
at 60◦C. [PR4][PTA]: yellowish semi-solid, gel. Yield: 98%. δH
0.86–0.89 (m, 12H, –CH2–CH3), 1.24–1.30 (m, 24H, –CH2–),
1.38–1.39 (m, 6H, –CH2–CH3), 1.44 (m, 6H, P–CH2–CH2–
CH2–), 1.47–1.49 (m, 6H, P–CH2–CH2–), 2.18–2.22 (m, 6H,
P–CH2–), 3.35 (s, 2H, –S–CH2–), 7.04 (m, Harom (4)), 7.21
(m, Harom (6,5)). δC 14.3 (–CH2–CH3), 18.2 (P–CH2–), 21.0
(P–CH2–CH2–), 22.3 (–CH2–CH3), 22.6 (–CH2–CH3), 28.6,
29.1, 29.2, 29.4, 29.5, 30.1, 30.3, 31.6, 30.9, 31.8 (remain-
ing CH2), 124.2 (Carom (4)), 126.6 (Carom (5)), 128.9 (Carom
(6)), 140.7 (Carom (1)), 168.5 (COO−). δP 33.7. m/z (ESI+)

Phosphonium and Ammonium Ionic Liquids with Aromatic Anions
523
Found: 483.6. Calc. 483.9. m/z (ESI−) Found: 167.0. Calc.
167.2. νmax/cm−1 3045 (CH3, νas), 2925 (CH2, νas), 2855 (CH2,
νs), 1611 (C=O, ν), 1462 (CH3 + CH2, δ), 1347 (C–S, ν), 1267–
475 (CHarom + C–O, δ) (Found: C 73.58, H 11.57, S 4.92. Calc.
forC40H75PO2S·0.10H2O(652.88):C73.59, H11.53, S4.91%.)
Trihexyl(tetradecyl)phosphonium
bis(trifluoromethyl-
sulfonyl)imide, [PR4][Tf2N] and tricaprylmethylammonium
bis(trifluoromethylsulfonyl)imide, [A336][Tf2N], were pre-
pared following the synthesis protocols reported in the
literature.[6]
The IL samples used for elemental analysis, viscosity, TGA,
and IR-measurements as well as for the determination of water
content were further dried at vacuum at 0.1 Pa for additional 48 h
at 40◦C.
Trihexyl(tetradecyl)phosphonium Salicylate, [PR4][Sal]
The IL was synthesized following the same procedure as
described above for [A336][Sal]. [PR4][Sal]: yellowish vis-
cous liquid. Yield: 95%. δH 0.86–0.89 (m, 12H, –CH2–CH3),
1.25–1.30 (m, 24H, –CH2–), 1.36–1.39 (m, 6H, –CH2–CH3),
1.42 (m, 6H, P–CH2–CH2–CH2–), 1.47–1.49 (m, 6H, P–CH2–
CH2–), 2.18–2.22 (m, 6H, P–CH2–), 6.62 (m, Harom (3, 5)),
7.15 (t, 3J 7.9, Harom (4)), 7.66 (d, 3J 8, Harom (6)). δC
14.3 (–CH2–CH3), 18.1 (P–CH2–), 20.9 (P–CH2–CH2–), 22.0
(–CH2–CH3), 22.6 (–CH2–CH3), 28.6, 29.1, 29.2, 29.4, 29.5,
30.1, 30.3, 31.6, 30.9, 31.8 (remaining CH2), 116.35 (Carom
(3,5)), 120.3 (Carom (2)), 130.4 (Carom (6)), 132.0 (Carom (4)),
163.4 (Carom (1)), 171.7 (COO−). δP 33.7. m/z (ESI+) Found:
483.8. Calc. 483.9. m/z (ESI−) Found: 137.1. Calc. 137.1.
νmax/cm−1 3045 (CH3, νas), 2925 (CH2, νas), 2856 (CH2, νs),
1589 (C=O, ν), 1485 (CH3 + CH2, δ), 1379 (O–H, ν), 1292–
537 (CHarom + C–O, δ) (Found: C 74.62, H 11.90. Calc. for
C39H73PO3·0.28H2O (625.91): C 74.84, H 12.23%.)
Acknowledgements
The authors are grateful to Professor Peter Unfried, Institute of Inorganic
Chemistry, University of Vienna, for conducting TGA measurements, Pro-
fessor Gerhard Schleining, Department of Food Sciences and Technology,
University of Natural Resources and Applied Life Sciences, Vienna, for his
assistance in viscosity measurements and the Austrian Federal Ministry of
Agriculture, Forestry, Environment and Water Management (Project number
A600702) for the financial support.
References
[1] (a) N.V. Plechkova, K. R. Seddon, in Methods and Reagents for Green
Chemistry (EdsA. Perosa, F. Zecchini) 2007, pp. 105–130 (JohnWiley
Sons: New York, NY).
(b) P. Wasserscheid, T. Welton (Eds), Ionic Liquids in Synthesis 2007
(Wiley-VCH: Weinheim).
Trihexyl(tetradecyl)phosphonium Vanillate, [PR4][Van]
(c) R. D. Rogers, K. R. Seddon, S. Volkov (Eds), Green Industrial
Applications of Ionic Liquids 2002, Vol. 92 (NATO Science Series, II:
Mathematics Physics and Chemistry; Kluwer Academic: Dordrecht).
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(e) S. Chowdhury, R. S. Mohan, J. L. Scott, Tetrahedron 2007, 63,
2363. doi:10.1016/J.TET.2006.11.001
The IL was synthesized following the same procedure
described above for [A336][Van]. [PR4][Van]: dark brown semi-
solid. Yield: 96%. δH 0.86–0.89 (m, 12H, –CH2–CH3), 1.25–
1.30 (m, 24H, –CH2–), 1.36–1.39 (m, 6H, –CH2–CH3), 1.42 (m,
6H, P–CH2–CH2–CH2–), 1.47–1.49 (m, 6H, P–CH2–CH2–),
2.16–2.21 (m, 6H, P–CH2–), 6.65 (d, 3J 8, Harom (5)), 7.19
(d, 3J 8, Harom (6)), 7.40 (s, Harom (2)). δC 14.3 (–CH2–CH3),
18.1 (P–CH2–), 20.9 (P–CH2–CH2–), 22.3 (–CH2–CH3), 22.9
(–CH2–CH3), 28.6, 29.1, 29.2, 29.4, 29.5, 30.1, 30.3, 31.6, 30.9,
31.8 (remaining CH2), 55.8 (–O–CH3), 113.5 (Carom (2)), 114.0
(Carom (5)), 122.3 (Carom (6)), 156.5 (Carom (4)), 168.6 (COO−).
δP 33.7. m/z (ESI+) Found: 483.9. Calc. 483.9. m/z (ESI−)
Found: 166.9. Calc. 167.2. νmax/cm−1 3045 (CH3, νas), 2925
(CH2, νas), 2855 (CH2, νs), 1555 (C=O, ν), 1462 (CH3 + CH2,
δ), 1337(C–S, ν), 1270–635(CHarom + C–O, δ)(Found:C73.88,
H 11.64. Calc. for C40H75PO4·0.08H2O (650.44): C 73.86, H
11.70%.)
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Trihexyl(tetradecyl)phosphonium Tetraphenylborate,
[PR4][BPh4]
The IL was synthesized following the same procedure as
described above for [A336][BPh4]. [PR4][BPh4]: white solid.
Yield: 98%. δH 0.86–0.89 (m, 12H, –CH2–CH3), 1.25–1.30 (m,
24H, –CH2–), 1.36–1.39 (m, 6H, –CH2–CH3), 1.42 (m, 6H,
P–CH2–CH2–CH2–), 1.47–1.49 (m, 6H, P–CH2–CH2–), 2.18–
3
3
2.22 (m, 6H, P–CH2–), 6.80 (t, J 7.4, Harom (3)), 6.92 (t, J
7.4, Harom (2,4)), 7.19 (m, Harom (1,5)). δC 14.3 (–CH2–CH3),
18.1 (P–CH2–), 20.9 (P–CH2–CH2–), 22.2 (–CH2–CH3), 22.6
(–CH2–CH3), 28.6, 29.1, 29.2, 29.4, 29.5, 30.1, 30.3, 31.6,
30.9, 31.8 (remaining CH2), 121.9 (Carom (4)), 125.8 (Carom
(2,4)), 136.0 (Carom (1,5)), 163.3 (Carom (6)), 163.7 (Carom (6)),
164.0 (Carom (6)), 164.4 (Carom (6)). δP 33.7. m/z (ESI+) Found:
483.8. Calc. 483.9. m/z (ESI−) Found: 319.0. Calc. 319.2.
νmax/cm−1 3048 (CH3, νas), 2925 (CH2, νas), 2855 (CH2, νs),
1465 (CH3 + CH2, δ), 1377–478 (CHarom + C–O, δ) (Found: C
82.79, H 11.60. Calc. for C56H88PB·0.11H2O (805.02): C 83.55,
H 10.97%.)
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