Biodegradable ionic liquids: Selected synthetic applications

Article abstract of DOI:10.1071/CH07257

3-Methyl-1-(propyloxycarbonylmethyl)imidazolium octylsulfate 1a and 3-methyl-1-(pentyloxycarbonylmethyl)imidazolium octylsulfate 2a are ionic liquids that have previously been shown to be readily biodegradable in the CO₂ headspace test (ISO 14593). In the present study, these ionic liquids were evaluated as reaction media for Diels?Alder and hydrogenation reactions. The comparison of the performance of these two designer solvents in these reactions with those conducted in other, non-biodegradable ionic liquids has demonstrated that they are comparable and viable solvents. CSIRO 2007.

Full text of DOI:10.1071/CH07257

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CSIRO PUBLISHING
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Aust. J. Chem. 2007, 60, 843–847
Biodegradable Ionic Liquids: Selected Synthetic Applications
Sandrine Bouquillon,A Thomas Courant,A Darrell Dean,B,C
Nicholas Gathergood,D,E Saibh Morrissey,D Bruce Pegot,D
Peter J. Scammells,C,E and Robert D. SingerB
AUniversité de Reims Champagne-Ardenne, UFR Sciences UMR 6519, BP1039,
51687 Reims Cedex 2, France.
BDepartment of Chemistry, Saint Mary’s University, Halifax, Nova Scotia, B3H 3C3 Canada.
CDepartment of Medicinal Chemistry, Victorian College of Pharmacy, Monash University,
Parkville VIC 3052, Australia.
DNational Institute for Cellular Biotechnology, School of Chemical Sciences,
Dublin City University, Glasnevin, Dublin 9, Ireland.
ECorresponding authors. Email: peter.scammells@vcp.monash.edu.au; nick.gathergood@dcu.ie
3-Methyl-1-(propyloxycarbonylmethyl)imidazolium octylsulfate 1a and 3-methyl-1-(pentyloxycarbonylmethyl)imida-
zolium octylsulfate 2a are ionic liquids that have previously been shown to be readily biodegradable in the CO2 headspace
test (ISO 14593). In the present study, these ionic liquids were evaluated as reaction media for Diels–Alder and hydrogena-
tion reactions. The comparison of the performance of these two designer solvents in these reactions with those conducted
in other, non-biodegradable ionic liquids has demonstrated that they are comparable and viable solvents.
Manuscript received: 24 July 2007.
Final version: 6 September 2007.
We have previously reported our efforts toward the design, syn-
thesis, and evaluation of biodegradable ionic liquids.[1–4] This
research identified two new ionic liquids that proved to be ‘read-
ily biodegradable’ in the CO2 headspace test (ISO 14593).[4]
These ionic liquids were constructed to contain moieties that are
metabolizable, namely an ester side chain attached to the cationic
core and an alkylsulfate anion as the counter ion. Although ionic
liquids 1a and 2a (Scheme 1) proved to be readily biodegradable
as determined by the CO2 headspace test, they fell just below the
mark using the closed bottle test (OECD 301D). This discrep-
ancy can be understood in terms of different concentrations of
microorganisms contained in the wastewater used in both tests.
Hence, compounds 1a and 2a can therefore be appropriately
regarded as readily biodegradable owing to the close agreement
between these two separate, internationally accepted biodegrad-
ability tests. More generally, higher levels of biodegradation
may have been limited by the resistance of the imidazole core to
microbial metabolism.[5] Ionic liquid biodegradability has been
addressed in three recent reviews.[5–7]
We next sought to investigate the utility of these ionic liquids
as solvents in reactions of general interest. The side chain ester
moiety proved to be a key feature in improving the biodegrad-
ability of the dialkylimidazolium class of ionic liquids. This
improvement in biodegradability clearly comes at a price in
terms of chemical stability and limits the type of reactions that
can be practically performed in these ionic liquids.As these ionic
liquids are only suitable for very specific applications, they can
be regarded as ‘designer solvents’. However, covalent solvents
containing an ester group, such as ethyl acetate, have proved to be
useful media for a range of chemical reactions and we envisage
that this will also be the case for ester-containing ionic liquids.To
test this hypothesis we chose to investigate two commonly used
reactions in these ionic liquids, namely Diels–Alder and hydro-
genation reactions.These reactions have been well characterized
in several other ionic liquids and a wide range of covalent sol-
vents, which provides a useful point of reference for the present
study.[8–13]
Herein we report the use of the biodegradable ionic liquids
3-methyl-1-(propyloxycarbonylmethyl)imidazoliumoctylsulfate
1a and 3-methyl-1-(pentyloxycarbonylmethyl)imidazolium
octylsulfate 2a as designer solvents in two pH-neutral reac-
tions: the Diels–Alder reaction between cyclopentadiene and
methyl acrylate and palladium-catalyzed hydrogenations of
1-phenoxyocta-2,7-diene.
H3C
Aꢀ
OR
N
N
ꢂ
O
1a R ꢁ n-Pr, A ꢁ OctOSO3
1b R ꢁ n-Pr, A ꢁ N(CN)2
2a R ꢁ n-Pent, A ꢁ OctOSO3
2b R ꢁ n-Pent, A ꢁ NTf2
2c R ꢁ n-Pent, A ꢁ BF4
Diels–Alder Reactions
The Diels–Alder reaction is one of the most studied reactions
and is a very important carbon–carbon bond forming reaction
for the formation of cyclic structures. It frequently results in
Scheme 1.
© CSIRO 2007
10.1071/CH07257
0004-9425/07/110843

844
S. Bouquillon et al.
Table 1. Reactions of cyclopentadiene and methyl acrylate in
1,3-dialkylimidazolium salts
reactions in haloaluminate ionic liquids will not be discussed
any further here.
The cycloaddition reaction between cyclopentadiene and
methyl acrylate proceeded in moderate isolated yield when con-
ducted in biodegradable ionic liquids 1a, 1b, and 2a (Table 1,
entries 8–10). All of these reactions appeared to have proceeded
quantitatively when examined by NMR spectroscopy alone
although some product was lost during workup and purification.
The selectivity for the endo isomer in these biodegradable ionic
liquid solvents was enhanced compared with those conducted in
molecularsolventsandevenbetterthanwhenconductedinwater.
The reaction between cyclopentadiene and 1,4-naphthoquinone
was also shown to proceed quite well in solvent 1a affording a
77% isolated yield of the adduct resulting from this reaction.The
decreased selectivity obtained when the reaction was conducted
between cyclopentadiene and methyl acrylate in solvents 1b and
2a may be explained by the fact that these reactions had to be
conducted at 40◦C. Ionic liquids 1b and 2a are extremely viscous
at room temperature and therefore required heating in order for
the reactions to proceed in solution. Such elevated temperatures
resulted in less of a preference for the kinetically favoured endo
product while increasing the preference for the thermodynami-
callyfavouredexoproduct.Theselectivityobservedinsolvent1a
(Table 1, entry 8) is comparable with the results obtained when
the reaction was conducted in 1-butyl-3-methylimidezolium
tetrafluoroborate ([bmim][BF4]) (Table 1, entry 3).
Attempts to recycle these biodegradable ionic liquid solvents
have met with limited success. In an attempt to recycle the sol-
vent used for the reaction described in Table 1, entry 10, only
65% w/w of solvent 2a was recovered after a single reaction.
This is undoubtedly due to unoptimized workup procedures in
whichdiethyletherisusedtoextractadductsfromtheionicliquid
phase. Some ionic liquid leaches into the ethereal layer, resulting
in loss. However, any residual ionic liquid in the extract is easily
removed during purification of the adduct. It should be recog-
nized that the use of diethyl ether to extract Diels–Alder adducts
from these reactions detracts from the overall ‘greenness’ of
these reaction systems; however, the modification of the workup
procedures should decrease or eliminate the need to use diethyl
ether. For example, the use of less polar solvents or solvents that
are less miscible with the ionic liquids being investigated may
enhance isolation of Diels–Alder adducts. Conversely, if adducts
are sufficiently volatile, they may be distilled directly from the
crude reaction mixture.
OCH3
IL
OCH3
O
C
O
3
4
5
Entry
Ionic liquid
Time [h]
Yield [%]
Endo-to-exo
ratio
1
2
3
4
5
6
7
8
9
10
[hmim][BF4]13
[emim][BF4]8
[bmim][BF4]12
[bmim][PF6]12
[bmim][SbF6]12
[bmim][Tf2N]12
1
72
24
24
24
24
24
72
72
72
16A
91
3.8
4.3
3.5
3.8
4.2
4.2
4.4
3.4
2.8
2.1
97B
97B
94B
99B
96B
72C
88C
82C
[bmim][CF3COO]12
1a
1b
2a
ANot isolated, estimated by 1H NMR spectroscopy.
BYield calculated from gas chromatography.
CIsolated yield.
the formation of different isomers where the product ratios
are dependent on several factors, most notably solvent polar-
ity. The solvent dependency of the Diels–Alder reaction has led
to the investigation of this reaction in a wide array of solvents
including, quite recently, ionic liquids. The use of ionic liq-
uids as solvents for this reaction has, in many cases, resulted in
improved endo/exo product ratios and enhanced isolated yields
of adducts. Furthermore, the selectivity of the Diels–Alder reac-
tion in ionic liquids has been shown to be dependent on several
factors including hydrogen bond donor capacity of the ionic liq-
uid, size of the substituents attached to the ionic liquid core,
electrostatic attraction between the ions of the ionic liquid, high-
est occupied molecular orbital and lowest unoccupied molecular
orbital (HOMO–LUMO) interactions, overall polarity of the
ionic liquid, and salt impurities.
Owing to the plethora of comparative data available for the
Diels–Alder reaction conducted in ionic liquids[8–13] and other
molecular solvents, we opted to investigate the Diels–Alder reac-
tion in the biodegradable ionic liquids 1a and 2a. The overall
stability, and indeed the biodegradability, of these ionic liquids
hinges around the ester moiety in the side chain. As this moi-
ety is obviously sensitive to both acid and base hydrolysis, any
reaction conducted in them must necessarily be a pH-neutral
reaction. The Diels–Alder reaction is therefore ideally suited for
these designer solvents and vice versa. However, Diels–Alder
reactions involving the addition of Lewis acids or nucleophilic
moieties have been precluded from the present study.
The reaction between cyclopentadiene and methyl acrylate
is perhaps the most widely studied Diels–Alder reaction in
ionic liquids. As shown in Table 1, when this reaction is con-
ducted in 1,3-dialkylimidazolium salts, it affords high yields
of adduct with enhanced endo-to-exo ratios when compared
with molecular solvents.[9,13,14] When conducted in Lewis acidic
haloaluminate ionic liquids, the endo-to-exo ratio increases to a
remarkable 19:1.[10] However, haloaluminate ionic liquids are
not recyclable and are somewhat hazardous to use. They react
violently with moisture and generate HCl on hydrolysis, a com-
mon occurrence during workup of many reactions. This class of
ionic liquid are notoriously ‘non-green’ and hence, Diels–Alder
Hydrogenation Reactions
In 2000, Dupont and coworkers described the selective Pd-
catalyzed hydrogenation of butadiene to but-1-ene or but-2-ene
in [bmim][BF4] or [bmim][PF6] and showed the possibility
of recycling the catalytic system.[15] Other metal salts as
Co(acetylacetonate(acac))2, Co(acac)3, Fe(acac)3, andNi(acac)2
have also shown activities for this reaction.[15] Since this
study,[16] more selective conditions involving Pd(0) nanoparti-
cles induced from Pd(acac)2 in [bmim][BF4] have been found.A
72% yield of but-1-ene could be attained with a constant pressure
of 0.4 MPa of hydrogen at 40◦C.[16]
Bouquillon and coworkers have developed some catalytic
recyclable Pd-catalyzed processes in the molten salt (Bu4NBr),
i.e. Heck reactions with allylic alcohols, dehydrogenation
of benzylic alcohols, and isomerization of (homo-)allylic
alcohols.[17–19] A variety of conditions have been evaluated
for the selective hydrogenation of 1-phenoxyoctadiene in the

Biodegradable Ionic Liquids
845
Table 2. Screening of conditions for the hydrogenation of phenoxyocta-2,7-diene in [bmim][BF4]
O
7
8
O
H2, cat.
IL (1 g)
6
O
Entry
Catalyst (equiv.)
T
[◦C]
PH
[MPa]
t
Conversion
[%]
Products
2
[h]
7
8
1
2
3
4
5
6
7
Co(acac)3 (1)
Ni(acac)2 (1)
Pd(acac)2 (0.1)
Ni(acac)2 (1)
Co(acac)3 (1)
Pd(acac)2 (0.1)
Pd(acac)2 (0.1)
Pd(acac)2 (0.03)
Pd(acac)2 (0.03)
Pd(acac)2 (0.03)
Pd(acac)2 (0.03)
Pd(acac)2 (0.03)
Pd(acac)2 (0.03)
Pd(acac)2 (0.03)
Pd(acac)2 (0.03)
RT
RT
RT
100
100
100
100
RT
RT
RT
RT
RT
RT
RT
RT
0.1
0.1
0.1
1.0
1.0
1.0
1.5
1.2
1.2
1.2
1.2
1.2
1.2
0.1
0.1
24
24
24
24
24
24
24
20
20
20
20
7
–
–
–
–
–
–
–
61
92
93
98
100
69
70
63
46
64
68
76
48
37
14
36
22
25
40
40
36
35
43
41
57
36
67
43
31
70
28
22
17
9
14
15
13
5
8
9A
10A
11A
12
13
14
15 (R1)A
14
24
24
ARecycling: at each run, addition of hydrogen and one equivalent of PhOC8H13
.
presence of a Pdii salt in [bmim][BF4] at room temperature (see
Table 2).
solvent, and in this case, 1-phenoxyoct-2-ene 7 was prepared in
70%yield, withonly12%of1-phenoxyoctane8formed.Theout-
come obtained using this ionic liquid was superior to the results
associated with the other ILs that were screened (Table 2, entries
1, 3, 4, 5). The octyl sulfate counterion is an important factor
in improving biodegradation in ionic liquids and in the study
shown in Table 2 appears to be a major factor for the improved
selectivities. The second beneficial parameter is the inclusion of
the ester group into the side chain, which could probably inter-
act with the metallic centre, and this modification can also be
attributed to the improved conversion of the hydrogenation of
phenoxyocta-2,7-diene (Table 2, compare entries 1 and 3).
Recycling of the IL solvents was also examined with
[bmim][BF4] (Table 2, entries 1 and 2) and 3-methyl-1-
(pentoxycarbonylmethyl)imidazolium octylsulfate 2a (Table 2,
entries 6 and 7). In both cases, the selectivity of the hydrogena-
tion was improved compared with the first runs; however, a drop
in conversion was observed, due to extraction by diethyl ether
involving partial solubilization of catalyst and IL.The repeat run
experiment again gave greater conversions and selectivities for
the 3-methyl-1-(pentoxycarbonylmethyl)imidazolium octylsul-
fate 2a over the [bmim][BF4] example. Here again, modification
of the workup procedures should decrease or eliminate the need
to use diethyl ether.
In summary, the biodegradable ionic liquids 3-methyl-
1-(propyloxycarbonylmethyl)imidazolium octylsulfate 1a and
3-methyl-1-(pentyloxycarbonylmethyl)imidazoliumoctylsulfate
2a have been evaluated as solvents for Diels–Alder and hydro-
genation reactions. In both cases, product yields were compa-
rable with those obtained with other, non-biodegradable ionic
liquids. For the selective hydrogenation of the diene 6 to the
alkene 7, a 13% increase in yield to 70% was observed when
changing from [bmim][BF4] to the biodegradable ionic liquid
2a. These results indicate that 1a and 2a are viable solvents for
reactions in which the side-chain ester is stable to the conditions
employed. A more detailed analysis of the chemical and thermal
At room temperature, Pd(acac)2 seems to be the best catalyst
(Table 2, entries 1–3) to induce the hydrogenation process. When
temperature and hydrogen pressure were increased, Ni(acac)2
and Co(acac)3 induced hydrogenation but the best catalyst
was still Pd(acac)2 (Table 2, entries 4–7). In the presence of
Pd(acac)2 as catalyst, 1-phenoxyocta-2,7-diene could be hydro-
genated at the terminal position at room temperature, with
low or high pressures of hydrogen; however, the selectivities
were poor.
Under 1.2 MPa of H2, selectivity was limited but recycling
was favoured, whereas under 0.1 MPa of H2, the best selectivity
was observed with a decrease in recycling efficiency (Table 2,
entries8–15). Underthesameconditionsusingeitheracetonitrile
or toluene as the solvent, no hydrogenation of phenoxyocta-2,7-
diene was observed using Pd(acac)2. Changing the catalyst to
Pd/C gave rapid and complete hydrogenation of phenoxyocta-
2,7-diene in either acetonitrile or toluene.
Table 3 shows the effect of ionic liquid structure on the
selectivity of the hydrogenation of 1-phenoxyocta-2,7-diene.
Good conversion of 1-phenoxyocta-2,7-diene was observed for
[bmim][BF4] (Table 3, entry 1) with 1-phenoxyoct-2-ene 7
prepared in 57% yield; however, the selectivity of the reac-
tion was only moderate with 13% of 1-phenoxyoctane 8 also
formed. The incorporation of an ester group into the side chain
led to higher conversion (Table 3, entry 3) while maintaining
the same ratio 7:8 as Table 3, entry 1. Changing the coun-
terion from BF4 to bis(trifluoromethene) sulfonimide (NTf2)
led to a decrease in conversion and selectivity (Table 3, com-
pare entries 3 and 4). The inclusion of an extra methyl group
on the imidazolium ring in the 2 position of the ionic liquid
(IL) had a negligible effect (Table 3, compare entries 4 and 5).
The highest conversion for the hydrogenation of 1-phenoxyocta-
2,7-diene was observed using the biodegradable 3-methyl-
1-(pentoxycarbonylmethyl)imidazolium octylsulfate 2a as the

846
S. Bouquillon et al.
Table 3. Hydrogenation of phenoxyocta-2,7-diene in ionic liquids
O
7
O
H2, Pd(acac)2
IL (1 g), 24 h
6
O
8
Entry
1
Ionic liquid
ConversionA [%]
Compound 7
yield [%]
Compound 8
yield [%]
ꢂ
N
N
N
76
57
13
BFꢀ4
ꢂ
N
2B
48
85
75
36
64
44
5
18
28
BFꢀ4
O
ꢂ
N
N
N
3
BFꢀ4
O
O
2c
ꢂ
N
O
O
4
NTfꢀ2
2b
ꢂ
N
N
N
N
5
75
85
55
40
70
48
30
12
5
NTfꢀ2
O
O
O
2b
ꢂ
N
O
6
Oct SOꢀ4
Oct SOꢀ4
2a
ꢂ
N
O
7B
2a
AConditions: Pd(acac)2 (0.03 equiv.), H2 (0.1 MPa), 24 h.
BRecycling experiment.
stability of these ionic liquids is in progress and will be reported
in due course.
5 mmol), which was then dried at 60◦C under high vacuum for
4 h.The flask was then released to a nitrogen atmosphere, cooled
to room temperature, and capped with a septum. Methyl acrylate
(0.45 mL, 0.430 g, 5 mmol) was injected and stirred for 15 min.
Cyclopentadiene (0.58 mL, 0.436 g, 7 mmol) was then injected
at once and the reaction mixture was stirred for 72 h at room
temperature (reactions conducted in solvent 1b and 2a were car-
ried out at 40◦C). All organics were removed from the ionic
liquid with ether extractions (8 × 10 mL). The ether extractions
were combined and the solvent removed by rotary evapora-
tion. Product was purified by column chromatography on silica
with hexane first to remove dicyclopentadiene and then 30:1
hexane/ethyl acetate to give a clear oil (0.546 g, 3.5 mmol, 72%).
δH (300 MHz, CDCl3), endo:exomixture2.9:1, endoisomer6.19
(dd, J 5.4, 3.0, 1H), 5.93 (dd, J 5.7, 2.7, 1H), 3.63 (s, 3H), 3.20
(br s, 1H), 2.98–2.91 (m, 2H), 1.95–1.87 (m, 1H), 1.55–1.26 (m,
3H); exo isomer 6.12 (m, 2H), 3.69 (s, 3H), 3.04 (br s, 1H), 2.98–
2.91 (m, 1H), 2.25–2.21 (m, 1H), 1.95–1.87 (m, 1H), 1.55–1.26
(m, 3H). δC (75 MHz, CDCl3) 175.20, 174.75, 137.86, 137.47,
135.59, 132.26, 51.38, 51.13, 49.45, 46.45, 46.20, 45.52, 43.02,
42.81, 42.41, 41.51, 30.20, 29.11.
The design of biodegradable chemicals generally involves
the incorporation of functionality that is susceptible to micro-
bial metabolism. In the case of biodegradable reaction media, it
is likely that the presence of such groups will limit the range of
reactionsthatcanbeaccommodated. Ideallyasuiteofbiodegrad-
able ionic liquids will be developed to cover the various
applications in which biodegradability is an important factor.
Experimental
The syntheses of all ionic liquids used in the present study
have been reported previously.[1–4] Co(acac)3, Ni(acac)2, and
Pd(acac)2 were purchased from Strem. [Bmim][BF4] (99+%)
1
was sourced from Solvionic. H and 13C NMR spectra of ILs
were recorded on a BrukerAvance DPX 300 spectrometer at 300
and 75.4 MHz respectively.The presence of HF was not detected
in the commercial [bmim][BF4] or 2c by 19F NMR spectroscopy.
pHmeasurementsforbothmaterialswereneutral. Meltingpoints
are uncorrected. Reactions were monitored by TLC on pre-
coated silica gel 60 F254 aluminium plates, whereas column
chromatography was carried out on silica gel 60 (63–200 µm;
Merck).
General Method for Hydrogenation Reactions
IL (1.00 g), 1-phenoxyocta-2,7-diene (100 mg, 0.5 mmol), and
palladium acetylacetonate (5 mg, 0.015 mmol, 0.03 equiv.) were
introduced in a 50 mL Schlenk tube. The tube was succes-
sively evacuated and refilled with hydrogen at atmospheric
General Method for Diels–Alder Reactions
An oven-dried round-bottom flask was charged with 3-methyl-1-
(propyloxycarbonylmethyl)imidazolium octylsulfate 1a (2.0 g,

Biodegradable Ionic Liquids
847
pressure three times and the mixture was stirred at room tem-
perature for 24 h. The reaction mixture was extracted with ether
(5 × 10 mL) and volatiles were removed under reduced pressure.
The resulting oil was purified by column chromatography (SiO2,
petroleum spirits/ethyl acetate, 95:5).
[5] R. S. Boethling, E. Sommer, D. DiFiore, Chem. Rev. 2007, 107, 2207.
doi:10.1021/CR050952T
[6] P. J. Scammells, J. L. Scott, R. D. Singer, Aust. J. Chem. 2005, 58, 155.
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[7] J. Ranke, S. Stolte, R. Störmann, J. Arning, B. Jastorff, Chem. Rev.
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[8] (a) T. Welton, Chem. Rev. 1999, 99, 2071. doi:10.1021/CR980032T
(b) P. Wasserscheid, W. Keim, Angew. Chem. Int. Ed. 2000, 39, 3772.
doi:10.1002/1521-3773(20001103)39:21<3772::AID-ANIE3772>3.
0.CO;2-5
1-Phenoxyocta-2,7-diene 6
δH 1.51 (2H, tt, J 7.7, 7.5), 2.07–2.18 (4H, m), 4.43 (2H,
d, J 5.6), 4.48 (2H, dd, J 7.2, 1.5), 5.59–5.92 (3H, m), 6.83–
6.98 (3H, m), 7.19–7.39 (2H, m). Gas chromatography–mass
spectrometry coupled technique (GCMS) t 8.18 min. m/z 202
(4) [M+]; 94 (52).
(c) J. S. Wilkes, M. J. Zaworotko, J. Chem. Soc. Chem. Commun. 1992,
965. doi:10.1039/C39920000965
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doi:10.1002/(SICI)1097-4660(199704)68:4<351::AID-JCTB613>3.
0.CO;2-4
1-Phenoxyoct-2-ene 7
(e) J. Dupont, R. F. de Souza, P. A. Z. Suarez, Chem. Rev. 2002, 102,
3667. doi:10.1021/CR010338R
δH 0.88 (3H, t, J 7.8), 1.17–1.30 (4H, m), 1.30–1.47 (2H, m),
2.07 (2H, dt, J 6.9, 7.0), 4.47 (2H, d, J 5.7), 5.65–5.92 (2H, m),
6.87–6.99 (3H, m), 7.21–7.39 (2H, m). GCMS t 8.89 min. m/z
204 (13) [M+]; 94 (72).
[9] T. Fischer, A. Sethi, T. Welton, J. Woolf, Tetrahedron Lett. 1999, 40,
793. doi:10.1016/S0040-4039(98)02415-0
[10] C. W. Lee, Tetrahedron Lett. 1999, 40, 2461. doi:10.1016/S0040-
4039(99)00249-X
1-Phenoxyoctane 8
[11] M. J. Earle, P. B. McCormac, K. R. Seddon, Green Chem. 1999, 1, 23.
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[12] I. Hemeon, C. DeAmicis, H. Jenkins, P. J. Scammells, R. D. Singer,
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P. J. Dyson, Adv. Synth. Catal. 2005, 347, 266. doi:10.1002/ADSC.
200404301
δH 0.82–1.00 (3H, m), 1.17–1.54 (10H, m), 1.78 (2H, tt, J
6.6, 7.3), 3.94 (2H, t, J 6.6), 6.87–6.99 (3H, m), 7.22–7.37 (2H,
m). GCMS t 9.42 min. m/z 206 (30) [M+]; 94 (100); 77 (24).
Acknowledgements
We gratefully acknowledge the Australian Research Council (ARC Linkage
International to P.J.S. and R.D.S.), the Natural Sciences and Engineering
Research Council of Canada (NSERC-Discovery to R.D.S. and NSERC–
Research Capacity and Development to S.M.U.), EGIDE for T.C., and
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