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M. Papp, R. Skoda-Földes / Journal of Molecular Catalysis A: Chemical 378 (2013) 193–199
knowledge, there is no example for double carbonylation reactions
carried out under such conditions.
In the present paper we report on our results concerning selec-
tive double carbonylation of aryl iodides with phosphine-free
silica-palladium catalysts. The silica supports were obtained by the
modification of silica gel with ILs.
added and the resulting mixture was stirred for 24 h at room tem-
perature. After evaporation of the solvents, the catalyst was dried
at 35 ◦C in vacuo for 3 h. Palladium content of the catalyst: 0.29%
(determined by ICP).
2.1.5. Preparation of Pd/silica
0.02 mmol (20.7 mg) Pd2(dba)3·CHCl3 was dissolved in a mix-
ture of 2 ml acetonitrile and 2 ml THF. The mixture was stirred
for 15 min at room temperature. Then 550 mg silica (Kieselgel 60
(0.040–0.063 mm), Merck, pre-treated by heating for 5 h at 250 ◦C)
was added and the resulting mixture was stirred for 24 h. The sol-
vents were removed in vacuo and the catalyst was dried at 35 ◦C
in vacuo for 3 h and was stored under argon until use. Palladium
content of the catalyst: 0.55% (determined by ICP).
2. Experimental
2.1. Preparation of supported catalysts
2.1.1. Preparation of SILP-Pd-1
200 mg [BMIM][BF4] and 0.02 mmol (20.7 mg) Pd2(dba)3·CHCl3
was dissolved in a mixture of 2 ml acetonitrile and 2 ml THF. The
mixture was stirred for 15 min at room temperature. Then 550 mg
silica (Kieselgel 60 (0.040–0.063 mm), Merck, pre-treated by heat-
ing for 5 h at 250 ◦C) was added under stirring and the resulting
mixture was stirred for 24 h. The solvents were removed in vacuo
and the catalyst was dried at 35 ◦C in vacuo for 3 h and was stored
under argon until use. Palladium content of the catalyst: 0.40%
(determined by ICP).
2.2. Catalytic reactions
2.2.1. Catalytic reactions at atmospheric pressure
In a typical experiment a solution containing the palladium cat-
alyst (with 3.6 mol Pd-content) was placed in a Schlenk-tube.
Under argon, 0.2 mmol (22.5 l) iodobenzene (4), 0.5 mmol (44 l)
morpholine (5a), 0.25 mmol (35 l) triethylamine and 1 ml DMF
was added and the atmosphere was changed to carbon monoxide.
The reaction was conducted for 3 h at 100 ◦C. The reaction mixture
was analysed by gas chromatography.
2.1.2. Preparation of SILP-Pd-2
200 mg [BMIM][BF4] and 0.04 mmol (8.7 mg) Pd(OAc)2 was dis-
solved in a mixture of 2 ml acetonitrile and 2 ml THF. The mixture
was stirred for 15 min at room temperature. Then 550 mg silica
(Kieselgel 60 (0.040–0.063 mm), Merck, pre-treated by heating for
5 h at 250 ◦C) was added under stirring and the resulting mixture
was stirred for 24 h. The solvents were removed in vacuo and the
catalyst was dried at 35 ◦C in vacuo for 3 h and was stored under
argon until use. Palladium content of the catalyst: 0.49% (deter-
mined by ICP).
2.2.2. Catalytic reactions at elevated pressure
In a typical experiment the catalyst (containing 3.6 mol
Pd) was placed in a stainless steel autoclave. Iodobenzene (4)
(0.2 mmol, 22.4 l), the amine (5a–g) (0.5 mmol), base (0.25 mmol)
and solvent (1 ml) were transferred into it under an inert atmo-
sphere. It was charged with carbon monoxide (30 bar) and heated
with stirring in an oil bath at 100 ◦C for 3, 8 or 12 h. After cooling to
room temperature, the liquid phase was removed with a syringe.
The reaction mixture was analysed by gas chromatography and the
catalyst was reused.
2.1.3. Preparation of SILP-Pd-3
200 mg [BMIM][PF6] and 0.02 mmol (20.7 mg) Pd2(dba)3·CHCl3
was dissolved in a mixture of 2 ml acetonitrile and 2 ml THF. The
mixture was stirred for 15 min at room temperature. Then 550 mg
silica (Kieselgel 60 (0.040–0.063 mm), Merck, pre-treated by heat-
ing for 5 h at 250 ◦C) was added under stirring and the resulting
mixture was stirred for 24 h. The solvents were removed in vacuo
and the catalyst was dried at 35 ◦C in vacuo for 3 h and was stored
under argon until use. Palladium content of the catalyst: 0.33%
(determined by ICP).
2.3. Analytical measurements
Reaction mixtures were analysed by gas chromatography
(Hewlett Packard 5890) and GC-MS (Hewlett Packard 5971A GC-
MSD, HP-1 column). Conversions and selectivities of the reactions
were determined by GC.
2.1.4. Preparation of SILP-Pd-4
The palladium-content of the catalysts and palladium leaching
were determined by ICP.
The products 6a–c, 6e–g and 7a–g were identified on the basis of
their MS spectra.
Ionic liquid 1 was prepared according to a known method [26].
A mixture of 10 mmol (3.23 g) of 1 and 10 mmol (1.05 g)
ammonium-tetrafluoroborate and 50 ml acetonitrile was stirred at
room temperature for 5 days. The precipitated solid was removed
by filtration through alumina and the solvent was evaporated. The
residue was dissolved in dichloromethane (50 ml) and the solu-
tion was filtered through activated charcoal and alumina. After
removal of the solvent in vacuo, 2 was obtained in 65% yield. (Ele-
mental analysis: Calc. for C13H27N2O3SiBF4: C, 41.72; H, 7.27; N,
7.49; Found: C, 41.95; H, 7.35; N, 7.63.)
4.8 mmol (1.8 g) of 2 was dissolved in 50 ml chloroform and
3.0 g silica (pre-treated by heating for 5 h at 250 ◦C) was added.
The mixture was refluxed for 24 h. Then the SILP material was fil-
tered and washed with pentane (50 ml), acetonitrile (100 ml) and
diethylether (100 ml) and was dried in vacuo to produce the sup-
ported ionic liquid 3. The amount of ionic liquid supported on silica
was determined by measuring the weight increase after heating
the material to constant weight at 150 ◦C in vacuo (180 mg 2 on 1 g
silica).
6a: MS(m/z/rel.int.): 219(M+)/6; 105/100; 77/54; 51/22
6b: MS(m/z/rel.int.): 177(M+)/6; 105/100; 77/44; 51/17
6c: MS(m/z/rel.int.): 205(M+)/4; 105/100; 77/75; 51/30
6e: MS(m/z/rel.int.): 261(M+)/5; 218/5; 105/100; 77/65; 51/14
6f: MS(m/z/rel.int.): 245(M+)/3; 216/3; 188/4; 105/100; 77/90;
51/31
6g: MS(m/z/rel.int.): 203(M+)/1; 202/5; 175/3; 105/100; 77/73;
51/10
7a: MS(m/z/rel.int.): 191(M+)/11; 190/34; 176/9; 160/6; 105/100;
86/12; 77/68; 51/24
7b: MS(m/z/rel.int.): 149(M+)/20; 148/44; 105/100; 77/71; 51/22;
50/8
7c: MS(m/z/rel.int.): 177(M+)/13; 176/42; 148/3; 134/3; 105/100;
77/49; 51/10
7d: MS(m/z/rel.int.): 205(M+)/10; 162/27; 105/100; 77/51; 51/12
7e: MS(m/z/rel.int.): 233(M+)/10; 232/12; 190/14; 148/6; 134/4;
105/100; 77/28; 51/3
A solution of 8.95 mol (9.3 mg) Pd2(dba)3·CHCl3 in 2 ml ace-
tonitrile and 2 ml THF was stirred for 15 min. Then 500 mg of 3 was