the proper acid dissolved in water (water solution 1 M) at room
temperature. The mixture was stirred for an additional 24 h. The
solvent and gaseous by-products were then removed on a rotary
evaporator. All salts were checked for the presence of starting
materials by NMR.
Subsequently, the mixtures were cooled to room temperature
and the products extracted with diethyl ether (3 ¥ 5 mL). The
combined extracts were then washed with water, dried with
MgSO4, and analyzed by GC-MS and NMR spectroscopy.
Recycling experiments
N,N-Dimethylpyrrolidinium◦ nitrate. Hygroscopic white
solid, m.p. = 220 ◦C (lit.8 220 C). 1H NMR (250 MHz, D2O):
d = 2.18 (m, 4H, CH2), 3.07 (s, 6H, CH3N), 3.43 (m, 4H, CH2);
13C NMR (62.9 MHz, D2O): d = 22.50, 52.48, 66.72.
After product extraction, the resulting mixtures were dried
under vacuum before new reagents (styrene and H2O2) were
added. Reactions were stopped after 3 h and product extraction
performed as described above.
N,N-Dimethylpyrrolidinium hydrogen sulfate. Hygroscopic
white solid, m.p. = 204 ◦C. 1H NMR (250 MHz, D2O): d = 2.06
(m, 4H, CH2), 2.97 (s, 6H, CH3N), 3.35 (m, 4H, CH2); 13C NMR
(62.9 MHz, D2O): d = 22.45, 52.54, 66.61.
References
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N,N-Dimethylpyrrolidinium formate. Hygroscopic white
solid, m.p. = 209 ◦C. 1H NMR (250 MHz, D2O): d = 2.20
(m, 4H, CH2), 3.11 (s, 6H, CH3N), 3.49 (m, 4H, CH2), 8.40
(s, 1H HC); 13C NMR (62.9 MHz, D2O): d = 22.50, 52.54, 66.72,
171.37.
N,N-Dimethylpyrrolidinium◦perchlorate. Hygroscopic white
solid, m.p. = 280 ◦C (lit.8 280 C). 1H NMR (250 MHz, D2O):
d = 2.18 (m, 4H, CH2), 3.09 (s, 6H, CH3N), 3.47 (m, 4H, CH2);
13C NMR (62.9 MHz, D2O): d = 22.50, 52.54, 66.72.
N,N-Dimethylpyrrolidinium trifluoroacetate. Hygroscopic
◦
1
white solid, m.p. = 192 C. H NMR (250 MHz, D2O): d =
2.18 (m, 4H, CH2), 3.09 (s, 6H, CH3N), 3.47 (m, 4H, CH2); 13
C
NMR (62.9 MHz, D2O): d = 22.50, 52.54, 66.72, 117.25 (q, 291
Hz).
N,N-Dimethylpiperidinium nitrate. Hygroscopic white
solid, m.p. ca. 245 ◦C (melting point is very close to the
1
decomposition temperature). H NMR (250 MHz, D2O): d =
1.61 (q, J = 5.5 Hz, 2H, CH2), 1.84 (m, 4H, CH2), 3.05 (s, 6H,
CH3), 3.30 (t, 4H, J = 5.5 Hz, CH2).13C NMR (62.9 MHz,
D2O): d = 20.74, 21.28, 52.44, 63.76.
N,N-Dimethylpiperidinium acetate. Hygroscopic white
solid, m.p. 164 ◦C. 1H NMR (250 MHz, D2O): d = 1.59 (q, J =
5.5 Hz, 2H, CH2), 1.84 (m, 4H, CH2), 1.86 (s, 3H, CH3); 3.05
(s, 6H, CH3), 3.28 (t, J = 5.7, 4H, CH2); 13C NMR (62.9 MHz,
D2O): d = 20.72, 21.25, 24.00, 52.44, 63.76.
5 P. J. Dyson, T. J. Geldbach, Metal Catalysed Reactions in Ionic
Liquids, Springer, Berlin, 2005; J. Dupont, R. F. de Souza and
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1588.
N,N-Dimethylpiperidin◦ium trifluoroacetate. Hygroscopic
white solid, m.p. ca. 201 C (melting point is very close to the
1
decomposition temperature). H NMR (250 MHz, D2O): d =
1.61 (q, J = 5.5 Hz, 2H, CH2), 1.84 (m, 4H, CH2), 3.04 (s, 6H,
CH3), 3.28 (t, J = 5.7, 4H, CH2); 13C NMR (62.9 MHz, D2O):
d = 20.70, 21.23, 52.40, 63.76, 117.25 (q, 291 Hz).
General procedure for the Wacker oxidation
R
Reactions were carried out in glass vials equipped with Teflonꢀ
screw caps under magnetic stirring using a parallel synthesizer.
PdCl2 (0.1 mmol) was added to the selected IL (1.0 mL), followed
by H2O2 (35%, 11.5 mmol) and styrene (10 mmol). The reaction
mixtures were heated at 60 ◦C and stirred vigorously for 3 h.
14 D. Zhao, Z. Fei, R. Scopelliti and P. J. Dyson, Inorg. Chem., 2004,
43, 2197.
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