Supporting Information
Wiley-VCH 2012
69451 Weinheim, Germany
Microfluidic Synthesis of Palladium Nanocrystals Assisted by
Supercritical CO2 : Tailored Surface Properties for Applications in
Boron Chemistry**
Thomas Gendrineau, Samuel Marre, Michel Vaultier, Mathieu Pucheault,* and Cyril Aymonier*
anie_201203083_sm_miscellaneous_information.pdf
Table of contents
1. Techniques and machines
8
2. Chemicals
8
3. Experimental procedures
8
4. Characterizations
10
5. Spectras
12
1. Techniques and machines
High Resolution Transmission Electron Microscopy (HR-TEM) pictures were performed with a JEOL 2200FS
microscope operating at 120 kV. Samples were prepared by deposing a drop of nanocrystals in dichloromethane
on a copper grid covered by a Formvar film coated with a carbon layer. Size distributions were determined by
manual counting of 59 crystals. The authors acknowledge S. Gomez for HR-TEM pictures achieved at the
CREMEM Center – Université Bordeaux 1. The XPS measurements were performed on powder samples inlayed
into an indium foil with an ESCALAB 220i-XL apparatus. The electron analyzer was operating at a constant pass
energy of 20 eV. The sample was exposed to non-monochromatized Mg Kα X-ray excitation (1253.6 eV with a
collected area of 250 µm). The operating pressure in the analytical chamber was less than 10-7 Pa. The binding
energies are referenced to the C1s signal due to ambient hydrocarbons (C-H and C-C) at 284.6 eV. The authors
acknowledge C. Labrugère for XPS measurements achieved at the ICMCB – Université de Bordeaux. GC-MS
analysis were performed with a HP 6890 series GC-system equipped with a J&W Scientific DB-1701 capillary
column, a HP 5973 mass selective detector (EI) using the following method : 70°C for 1 min then 20°C.min-1 until
230 °C then 6 min at 230 °C. 1H, 11B, 13C, 19F and 31P NMR were recorded on 300 MHz Avance I and 400 MHz
Avance II spectrometers. The chemical shifts (d) and coupling constants (J) are expressed in ppm and hertz
respectively. The following abbreviations were used to explain the multiplicities: s = singlet, d = doublet, m =
multiplet. The authors acknowledge CESAMO for NMR spectras achieved at the ISM – Université de Bordeaux 1.
2. Chemicals
Palladium bis(hexafluoroacetylacetonate) (Pd(hfa)2, 99%), 1,1’-bis(diphenylphosphino)ferrocene, 2,2’bis(diphenylphosphino)-1,1’-binaphtyl, cesium carbonate were purchased from Strem Chemicals and used without
further purification. 1,2-Bis(diphenylphosphino)propane, tri(3-furyl)phosphane, tri(cyclohexyl)phosphane, (2biphenyl)dicyclohexylphosphane, 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphino2',6'-dimethoxybiphenyl, bis(pinacolato)diboron, triethylamine, 1,3,5-mesitylene, potassium acetate and potassium
carbonate were purchased from Sigma-Aldrich and used without further purification. 1,3-Bis(2,3,5trimethylphenyl)imidazolium tetrafluoroborate was prepared as described in litterature.[a] Pinacol was purchased
from Sigma-Aldrich and distilled before use. 4-Bromoanisole, 4-iodotoluene and potassium iodide were purchased
from Fischer Scientific and used without further purification. Di(isopropyl)aminoborane were prepared as described
[b]
in litterature. Pressurized bottle of a mixture of CO2 and H2 (1:1 molar) was used as received from Air Liquid. All
catalytic reactions were carried out under argon atmosphere unless specified. All chemicals and nanoparticles
solutions were stored under argon. Toluene and methanol were distilled over CaH2. Isolated yields refer to
chromatographically and spectroscopically (NMR and GC-MS) homogeneous materials. Silica gel (230-400 mesh)
purchased from Merck was used for flash chromatography. Analytical TLC silica gel 60 F254 were used.
3. Experimental procedures
The experiments for NCs synthesis were carried out in a coaxial flowing microsystem made of two capillaries (inner
diameters : øint = 250 µm, øext = 750 µm, length = 1.3 m). The two capillaries system is built from a T-piece (T-piece
2 on Figure 1); the inner capillary (250 µm) is fixed on the left side of T-piece 2 and the external capillary (750 µm)
is fixed from the left side of the T-piece 2. Heating was provided by an oil bath (T = 100 °C), whereas the pressure
was controlled with a back-pressure regulator downstream (p = 25 MPa) (Figure 1). The precursor solution
-2
-1
[Pd(hfa)2] (9.1 10 M, 33 µL.min ) in toluene and an equimolar mixture of carbon dioxide and hydrogen (66 µL.min
1
) were injected in the inner silica capillary via a T-shape mixing part (T-piece 1). A second solution containing
ligands (1.08 10-2M for monodentate ligands (5 eq) and 5.36 10-3M for bidentate ligands (2.5 eq), 1400 µL.min-1) in
toluene is injected externally, the overall residence time being fixed at 17 s. Nanocrystals solution in toluene is then
collected, centrifugated at 2000 rpm for 5 minutes. Then, supernatant (~ 2 10-3 M) was gently collected, subjected
to sonication for 15 minutes and then directly used for catalysis.
Figure 1
Dppf-complexed NCs in solution were concentrated under reduced pressure to remove toluene. Diethyl ether was
added to the crude material, the mixture was stirred at room temperature for 5 minutes, then, NCs in suspension
were allowed to clot for 15 minutes and the supernatant was gently removed. This procedure was repeated 4 times.
The obtained powder was dried under vacuum overnight and then characterized by HR-MET and NMR.
Borylation reaction procedure using di(isopropyl)aminoborane
A septum-capped vial, equipped with a magnetic stirring bar, was charged with dppf-complexed palladium
nanocrystals solution (5 mL, 1% mol Pd). The vial was closed and concentrated under reduced pressure (ca. 1mL)
with a vacuum pump. 4-Bromoanisole (187 mg, 126 µL, 1.0 mmol), di(isopropyl)aminoborane (331 µL, 1.5 mmol;
1.5 eq) and triethylamine (404 µL; 3.0 mmol; 3.0 eq) were added and the reaction mixture was evacuated under
vacuum, placed under an argon atmosphere and stirred at 100°C for 1h (preheated oil bath). The mixture was
cooled at 0°C and methanol (2 mL) was added. The mixture was then allowed to warm to room temperature and
stirred for 1h. Then, the mixture was concentrated under vacuum to remove all volatils, pinacol (130 mg, 1.1 mmol,
1.1 eq) in Et2O (2 mL) was added and the reaction mixture was stirred for 4h. Et2O (10mL) was added, the reaction
-1
mixture was filtered over a celita pad and washed with a solution of CuCl 2 (3 x 5 mL, 50 g.L ). The organic layer
was washed one more time with brine (10 mL), dried over Na2SO4 and concentrated under reduced pressure to
afford analytically pur 2-(4-methoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (215 mg, 92%) as a pale brown
solid.
Borylation reaction procedure using bis(pinacolato)diboron
A vial, equipped with a magnetic stirring bar, was charged with P(Cy)3-complexed palladium nanocrystals solution
(5mL, 1% mol Pd). The vial was closed and concentrated under reduced pressure (ca. 1mL) with a vacuum pump.
Then, 4-bromoanisole (187 mg, 126 µL, 1.0 mmol), bis(pinacolato)diboron (508 mg, 2.0 mmol; 2.0 eq) and
potassium acetate (294 mg, 3.0 mmol, 3.0 eq) were added, the vial was closed and the reaction mixture was
evacuated under vacuum, placed under an argon atmosphere and stirred at 100°C for 1h (preheated oil bath). The
mixture was cooled to RT, Et2O (10 mL) was added and the reaction mixture was filtered over a celita pad and
washed with brine (3 x 5 mL). The organic layer was dried over Na2SO4 and concentrated under reduced pressure
to afford 2-(4-methoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (97% by GC-MS) as a pale brown solid
along with excess bis(pinacolato)diboron as only impurity. 1,3,5-mesitylene (120 mg, 1.0 mmol) was added to
crude compound and yield was determined by GC-MS.
Suzuki-Miyaura coupling reaction
A vial, equipped with a magnetic stirring bar, was charged with complexed palladium nanocrystals solution (5mL,
1% mol Pd). The vial was closed and concentrated under reduced pressure (ca. 1mL) with a vacuum pump. Then,
4-bromoanisole (187.0 mg, 126 µL, 1.0 mmol), phenylboronic acid (242 mg, 2.0 mmol; 2.0 eq) and potassium
carbonate (414 mg, 3.0 mmol, 3.0 eq) were added, the vial was closed and the reaction mixture was evacuated
under vacuum, placed under an argon atmosphere and stirred at 100°C for 30 min to 1h (preheated oil bath). The
mixture was cooled at RT, Et2O (10 mL) was added, the reaction mixture was filtered over a celita pad and washed
with brine (3 x 5 mL). The organic layer was dried over Na2SO4 and concentrated under reduced pressure to afford
analytically pur 4-methoxybiphenyl (178 mg, 97% yield) as a pale orange solid.
One-pot palladium-catalyzed borylation/suzuki-Miyaura sequence
A septum-capped vial, equipped with a magnetic stirring bar, was charged with complexed palladium nanocrystals
solution (5mL, 1% mol Pd). The vial was closed and concentrated under reduced pressure (ca. 1mL) with a
vacuum pump. 4-Bromoanisole (187 mg, 126 µL, 1.0 mmol), di(isopropyl)aminoborane (330 µL, 1.5 mmol; 1.5 eq)
and triethylamine (480 µL; 3.0 mmol; 3.0 eq) were added and the reaction mixture was evacuated under vacuum,
placed under an argon atmosphere and stirred at 100°C for 1h (preheated oil bath). The mixture was cooled at RT
and and were successively added 4-iodotoluene (230 mg, 1.05 mmol, 1.05 eq), cesium carbonate (652 mg, 2 mmol,
2 eq), potassium iodide (1.7 mg, 0.01 mmol, 0.01 eq), water (180 µL, 10 mmol, 10 eq) and distilled methanol (1
mL). The vial was closed and the solution was stirred at reflux for 12h. The reaction mixture was allowed to cool at
25°C, quenched with a HCl 1M solution (5 mL), filtered over a celita pad and extracted with Et2O (3 x 10 mL). The
combined organic phases were washed successively with a 10 % NaHCO3 solution (2 x 10 mL), brine (2 x 10 mL),
dried over Na2SO4 and concentrated under reduced pressure to afford analytically pur 4-methoxy-4'-methylbiphenyl
(178 mg, 97% yield) as a pale yellow oil.
4. Characterizations
NC9
dppf
dppf
dppf
Pd NCs
dppf
dppf
dppf
H NMR (300 MHz, CDCl 3, 20°C, TMS): δ 7.29-7.24 (m, 12H), 4.76 (br s, 2H), 4.30 (br s, 2H); 13C NMR (75 MHz,
CDCl3, 20°C, TMS): δ 134.6, 133.5, 131.8, 131.6, 131.5, 128.5, 128.4, 74.5, 74.2, 73.7, 73.6; 31P NMR (121.5 MHz,
CDCl3, 20°C, H3PO4): δ 28.1.
1
4
2-(4-Methoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
[171364-79-7]
O
MeO
B
O
C13H19BO3
234,1 g.mol-1
Rf (heptane/ethyl acetate 95:5): 0.48; H NMR (300 MHz, CDCl3, 20°C, TMS): δ 7.79 (d, J = 8.7 Hz, 2H), 6.91 (d,
2
13
J = 8.7 Hz, 2H), 3.82 (s, 3H), 1.35 (s, 12H); C NMR (75 MHz, CDCl3, 20°C, TMS): δ 162.2, 136.5, 113.3, 83.5,
11
+.
55.1, 24.9; B NMR (96.3 MHz, CDCl3, 20°C, BF3.Et2O): δ 29.9; GC-MS (EI, H2): m/z (%): 234.2 (65) [M] and tR=
[c]
9.1 min; compound shown identical data to those previously reported.
1
2
7
4-Methoxybiphenyl
[613-36-7]
OMe
C13H12O
184,2 g.mol-1
Rf (petroleum ether/diethyl ether 95:5): 0.46; 1H NMR (300 MHz, CDCl3, 20°C, TMS): δ 7.60-7.53 (m, 4H), 7.467.41 (m, 2H), 7.35-7.32 (m, 1H), 7.21-6.99 (m, 2H), 3.87 (s, 3H); 13C NMR (75 MHz, CDCl 3, 20°C, TMS): δ 159.0,
140.7, 135.5, 133.6, 133.3, 132.5, 128.6, 128.0, 127.8, 126.6, 126.5, 114.1, 55.3; GC-MS (EI, H2): m/z (%): 184.1
.
(100) [M]+ and tR= 9.4 min; compound shown identical data to those previously reported.[d]
8
4-Methoxy-4'-methyl-1,1'-biphenyl
[53040-92-9]
OMe
C14H14O
198,2 g.mol-1
Rf (heptane/ethyl acetate 95:5): 0.54; 1H NMR (200 MHz, CDCl3, 20°C, TMS): δ 7.41 (d, 2J = 8.8 Hz, 2H), 7.35 (d,
2
J = 8.0 Hz, 2H), 7.12 (d, 2J = 8.0 Hz, 2H), 6.86 (d, 2J = 8.6 Hz, 2H), 3.73 (s, 3H), 2.28 (s, 3H); 13C NMR (75 MHz,
CDCl3, 20°C, TMS): δ 159.0, 138.0, 136.4, 133.8, 129.5, 128.0, 126.6, 114.2, 55.3, 21.1; GC-MS (EI, H2): m/z (%):
199 (80) [M+H]+ and tR= 10.1 min; compound shown identical data to those previously reported.[e]
[a] A. J. Arduengo, R. Krafczyk, R. Schmutzler, H. A. Craig, J. R. Goerlich, W. J. Marshall, M. Unverzagt, Tetrahedron 1999,
55, 14523-14534.
[b] L. Marcianisi, N. Richy, M. Vaultier, M. Pucheault, Chem. Commun. 2012, 48, 1553-1555.
[c] S. Claudel, C. Gosmini, J. M. Paris, J. Périchon, Chem. Commun. 2007, 3667-3669.
[d] B. Lipshultz, K. Siegmann, E. Garcia, F. Kayser, J. Am. Chem. Soc. 1993, 115, 9276-9282.
[e] L. G. Xie, Z. X. Wang, Angew. Chem. Int. Ed. 2011, 50, 4901-4904; Angew. Chem. 2011, 123, 5003-5006.
8
Thdppf
1
1
6
Y:\data\Student\nmr\data\Student\nmr
4.30#
4.27#
4.01#
4
NC9
dppf
Pd NCs
dppf!
dppf
dppf
dppf
dppf
dppf
2
x# acetone#
0
[ppm]
1H#
TG23.3B 1 1 Y:\data\Student\nmr\data\Student\nmr
Scale : 1.2516 Shift : -0.0293 ppm = -8.789 Hz
Thdppf 1 1 Y:\data\Student\nmr\data\Student\nmr
[rel]
25
20
15
10
5
0
4.76#
TG-23-2B-400MHz
140
2
1
Y:\data\JML\nmr
133.6#
133.2#
134.6#
133.5#
131.8#
131.6#
131.5#
128.5#
128.2#
128.5#
128.4#
120
dppf
dppf
dppf
Pd NCs
dppf
dppf!
100
dppf
dppf
TG-23-2B-400MHz
2
80
1
TG-23-2B-400MHz 5 1 Y:\data\JML\nmr
Scale : 8.3103 Shift : 0.0781 ppm = 3.9306 Hz
13C#
[ppm]
Y:\data\JML\nmr
Scale : 1.5066
72.5#
74.5#
74.2#
73.7#
73.6#
[ *1e6]
10
8
6
4
2
0
TG23-3B-400MHz
1
1
- 70
Y:\data\JML\nmr
- 75
dppf
dppf
dppf
dppf
- 80
dppf
dppf
dppf
dppf
dppf
Pd NCs
dppf
dppf
Pd NCs
dppf
- 85
after 3 washings of NCs with Et2O
without Et2O washing
[ppm]
19F#
[rel]
10
5
0
-5
6#75.9#
O
O
4
from Vaultier borylation
4-MeOC6H4B
1H
O
O
4
from Vaultier borylation
4-MeOC6H4B
11B
O
O
4
from Vaultier borylation
4-MeOC6H4B
13C
O
O
4
from Vaultier borylation
4-MeOC6H4B
GC-MS
O
4
from Miyaura borylation
4-MeOC6H4B
O
x B2pin2 excess
1H
O
4
from Miyaura borylation
4-MeOC6H4B
O
B2pin2
excess
13C
O
4
from Miyaura borylation
4-MeOC6H4B
O
B2pin 2 excess
x
GC-MS
MeO
7
toluene
x
« PhB(OH)2 »
excess
x
1H
MeO
7
13C
MeO
7
GC-MS
MeO
8
1H
MeO
8
13C
MeO
8
GC-MS