acetone-d6 (99.8%), methanol-d4 (100%) and DMSO-d6
(99.8%) were available from Euriso-top. 18O2 (98.5 atom.%)
was also purchased from Euriso-top.
1H NMR spectra were obtained using an AM 250 Bruker
spectrometer. Nitrogen sorption isotherm analysis was per-
formed using a Catasorb apparatus. Diffuse reflectance
Preparation of supported catalyst
A solution of triphenylphosphine oxide (620 mg, 2.25 mmol)
in 10 mL CH2Cl2 was de-gassed and triflate anhydride (176.5
mL, 1 mmol) added under argon. The solution thus obtained
was stirred at room temperature for 15 min and a solution of
iron tetrasulfophthalocyanine (tetrabutylammonium salt, 486
mg, 0.25 mmol) in 20 mL CH2Cl2 was added. The resulting
solution was stirred at 20 1C for 30 min. This solution was
added dropwise to a suspension of the silica modified with
3-aminopropyltriethoxysilane (4.85 g) containing triethyla-
mine (190 ml, 1.38 mmol) at 0 1C. The resulting mixture was
allowed to warm to 20 1C and stirred at this temperature for 1 h.
The blue solid was isolated by filtration, washed with ethanol
and water, and dried at 50 1C for 24 h.
UV-vis spectra of solid catalysts were recorded on
a
Perkin-Elmer Lambda 9 spectrophotometer. The complex
loading of the supported catalyst was determined by iron
analysis using the inductively coupled plasma mass spectro-
metry method.
The oxidation products were identified by NMR and
GC-MS methods. The quantitative GC analyses were not
reproducible because of the instability of the substrates and/
or reaction products under GC conditions. Therefore, conver-
sions and product yields were determined by 1H NMR
using biphenyl as the internal standard, as indicated in
Figure S1 (ESIw) for the case of the oxidation of 2-hydro-
xybenzyl alcohol. Similar procedures were used for the other
substrates.
Typical procedure for the oxidation of phenols
To a 0.02 M solution of substrate (20 mmol) and a 0.0096 M
solution of biphenyl (internal standard) in 1 mL deuterated
solvent was added FePcS–SiO2, containing 0.2 mmol of the
complex (1 mol%). The reaction was started by the addition of
The reaction products were identified by GC-MS (Hewlett-
Packard 5973/6890 system; electron impact ionization at
70 eV, He carrier gas, 30 m  0.25 mm cross-linked 5% PHME
siloxane (0.25 mm coating) capillary column, HP-5MS).
The degradation products of the aromatic rings were ana-
lyzed by GC-MS (capillary column VF5-MS, 100% dimethyl-
polysiloxane, 30 m  0.25 mm, 0.25 mm coating) using
trimethylsulfonium hydroxide as the derivatization agent.8 A
trimethylsulfonium hydroxide solution (MeOH, 0.1 M) was
prepared from trimethylsulfonium iodide and Ag2O according
to ref. 8. The reaction mixture (100 mL) was mixed with 40 mL
of a 0.1 M Me3SOH solution at room temperature and
immediately injected. Volatile methylated derivatives of com-
pounds with phenolic and carboxylic groups were formed
under the analysis conditions (the injector temperature was
220 1C), and were analyzed by GC-MS. A control injection of
the initial reaction mixture exhibited only the signals of
methylated 2-HBA. Analysis of the reaction mixture after
30 min and 2 h showed the presence of methylated derivatives
of catechol, salicylic acid, maleic acid, succinic acid, hydro-
xysuccinic acid and acetic acid. Identification of the products
was performed using authentic samples and the library of
mass-spectra, NIST 02.
t
a 70% aqueous BuOOH solution (20 ml, 140 mmol) and was
run, under stirring, for 2 h at 30 1C. The catalyst–substrate–
oxidant ratio was 1 : 100 : 700. After the reaction, the catalyst
was separated by filtration and the reaction mixture analyzed
by 1H NMR. Product yields and conversions were determined
by the integration of the corresponding proton signals relative
to the internal standard signals (ESIw).
18O2 experiments
Labelling experiments were performed under an atmosphere
containing 20.4% 18O2 (99.6% 18O enrichment) and 79.2%
Ar. The reaction flask contained 0.02 mmol substrate and 0.47
mmol 18O2 (23.5-fold excess of substrate). The isotopic com-
positions of the products and gas phase were determined by
GC-MS. Each sample was analyzed three times and the m/z
peak intensities of each peak were obtained by integrating all
scans of that peak.11
The 18O content in 2-hydroxymethyl-1,4-benzoquinone
could not be directly measured by the relative intensities of
138 [M+] and 140 [M + 2]+ peaks since the authentic 2-HQ
sample exhibited a significant and varying m/z = 140 signal
(15–25% with respect to peak m/z = 138). We propose that
2-HQ could be partially reduced to 2-hydroxymethyl-1,4-
hydrobenzoquinone under the conditions of MS analysis
(electron impact ionization at 70 eV). Indeed, the relative
intensity of peak m/z = 140 increased along with the decreas-
ing amount of sample injected. Taking into account that the
18O content in quinone should be the same as that in hydro-
quinone, we determined the 18O content in hydroquinone after
treating the reaction mixture with triphenylphosphine. This
procedure was highly reproducible, and the 18O content in
hydroquinone obtained from the labelling experiments in the
presence of 18O2 was found to be 6.2 Æ 0.3%.
Materials
Amino-modified silica was prepared using Degussa Aerosil
200 amorphous silica according to a published procedure,9
and had a BET surface area of 185 m2 gÀ1 with 0.5 mmol NH2
group gÀ1 (chemical analysis). The sodium salt of iron tetra-
sulfophthalocyanine was prepared using a modified procedure
of Weber and Busch.10 The replacement of the sodium ion
with tetrabutylammonium cation was performed as follows.
Four equivalents of (Bu4N)OH (3.4 mL of a 40% aqueous
solution) were added to a solution of FePcS (1.5 g, 1.3 mmol)
in 50 mL water. The tetrabutylammonium salt of FePcS was
extracted with CH2Cl2 (5 Â 100 mL). The organic fraction was
dried, the solvent removed and the product dried overnight in
a vacuum at 50 1C.
Results and discussion
In the course of developing accessible and economically viable
supported catalysts, we have recently shown that iron
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This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006
New J. Chem., 2006, 30, 1768–1773 | 1769