Silica and zirconia supported olefin metathesis pre-catalysts: Synthesis, catalytic activity and multiple-use in dimethyl carbonate

Article abstract of DOI:10.1016/j.molcata.2012.01.022

This study is aimed at designing and synthesising new olefin metathesis catalysts grafted onto porous solid supports and using them in dimethyl carbonate (DMC) an eco-friendly solvent. Two hybrid organic-inorganic Hoveyda-type catalysts were prepared in a

Full text of DOI:10.1016/j.molcata.2012.01.022

Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
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Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Silica and zirconia supported olefin metathesis pre-catalysts: Synthesis, catalytic
activity and multiple-use in dimethyl carbonate
Adel Keraania,d, Cédric Fischmeisterb,d,∗, Thierry Renouarda,d, Marie Le Flochc,d
,
Amandine Baudrya,b,d, Christian Bruneaub,d, Murielle Rabiller-Baudrya,d,∗∗
a Université de Rennes 1 – UMR « Sciences Chimiques de Rennes » – CNRS – Chimie et Ingénierie des Procédés – 263 avenue du général Leclerc, CS 74205, case 1011,
35042 Rennes Cedex, France
b CNRS – UMR « Sciences Chimiques de Rennes » – Université de Rennes 1 – Catalyse et Organométalliques – 263 avenue du général Leclerc, 35042 Rennes Cedex, France
c CNRS – UMR « Sciences Chimiques de Rennes » – Université de Rennes 1 – Verres et Céramiques – 263 avenue du général Leclerc, 35042 Rennes Cedex, France
d Université Européenne de Bretagne, France
a r t i c l e i n f o
a b s t r a c t
Article history:
This study is aimed at designing and synthesising new olefin metathesis catalysts grafted onto porous
solid supports and using them in dimethyl carbonate (DMC) an eco-friendly solvent. Two hybrid
organic–inorganic Hoveyda-type catalysts were prepared in a few steps by initial grafting of a tailor-made
ligand by sol–gel process onto porous silica and zirconia. The new hybrid organic–inorganic catalysts were
then engaged in a series of model ring closing metathesis reactions (RCM) in the eco-friendly solvent DMC
and their multiple-use was studied.
Received 22 October 2011
Received in revised form 3 January 2012
Accepted 23 January 2012
Available online 31 January 2012
Keywords:
© 2012 Elsevier B.V. All rights reserved.
Catalyst multiple-use
Supported Hoveyda catalyst
Olefin metathesis
Ruthenium
Greener solvent
1. Introduction
recycling. To overcome these serious drawbacks that still ham-
per their industrial scale development, several solutions have
The development of clean catalytic processes has known an
increasing importance in the context of sustainable production
and in green chemistry [1]. In particular, olefin metathesis [2]
is a very powerful tool for the efficient catalytic formation of
carbon–carbon double bonds allowing the synthesis of various use-
ful intermediates and compounds for fine chemistry [3] and for
the synthesis of polymers [4]. Amongst ruthenium-based catalysts,
Hoveyda-type catalysts have received much attention as homoge-
neous recyclable catalysts used at laboratory scale as they combine
high stability and activity with an excellent tolerance towards
polar functional groups [5]. Nevertheless, rather few industrial pro-
cesses use metathesis reactions owing to the cost of homogeneous
catalysts together with difficulties of final separation of the molec-
ular catalysts from the reaction medium and their subsequent
been explored. Amongst those are the immobilizations of Hov-
eyda catalysts in non-conventional solvents such as ionic liquids
[6], supercritical (Sc) fluids [7] or perfluoroalkanes [8]. Recently,
an innovative green process named organic solvent nanofiltration
(OSN) has been used for the efficient separation and recovery of
homogeneous catalysts at room temperature and without phase
change [9]. Previous works from our research group [10] and oth-
ers [11] implemented OSN for the recovery of tailor-made Hoveyda
catalysts. Recently, we also reported an innovative approach for
metathesis reactions in a catalytic membrane reactor by immobi-
lization of an ionically tagged Hoveyda catalyst supported in an
ionic liquid already impregnated onto a polyimide membrane [12].
The heterogenisation of homogeneous Hoveyda catalyst by immo-
bilization on a porous solid support is the most widely used strategy
for recovery and recycling of this type of catalysts [13]. Due to
the solid nature of the immobilized catalyst, classical filtration or
centrifugation at the end of the metathesis reaction allows for an
easy separation of the product and recovery of the catalyst. This
immobilization can either be achieved by a covalent bond [14] or
by adsorption [15]. More recently, the integration of metathesis
reaction using Hoveyda catalyst grafted on porous solid support
or on SILP (Supported Ionic Liquid Phase) for continuous flow
∗
Corresponding author at: CNRS – UMR « Sciences Chimiques de Rennes » – Uni-
versité de Rennes 1 – Catalyse et Organométalliques and Chimie et Ingénierie des
Procédés – 263 avenue du général Leclerc, 35042 Rennes Cedex, France.
Tel.: +33 02 23235998.
∗∗
Corresponding author: Tel.: +33 02 23235762.
E-mail addresses: cedric.fischmeister@univ-rennes1.fr (C. Fischmeister),
murielle.rabiller-baudry@univ-rennes1.fr (M. Rabiller-Baudry).
1381-1169/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.molcata.2012.01.022

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A. Keraani et al. / Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
Scheme 1. Synthesis of ligand 6.
process have been reported [16]. The use of eco-friendly solvents
in olefin metathesis reactions is another very important parameter
to consider in order to decrease its environmental impact. Toluene
and dichloromethane are conventional solvents most often used
in metathesis reactions, but they have a significant environmental
impact owing to their toxicity [17]. In contrast, due to their low
toxicity [18,19] dialkyl carbonates are considered as eco-friendly
solvents and they have been used in various catalytic transforma-
tions [18] including C H bond functionalisation reactions [20]. In
2008, dimethyl carbonate (DMC) was introduced in olefin metathe-
sis as an alternative to toluene and dichloromethane [21]. Since
then it has been used in particular for the transformations of vari-
ous renewable materials such as methyl oleate or terpenoids [22].
The feasibility of the integration of catalytic olefin metathesis with
organic solvent nanofiltration (OSN) in DMC was also recently
demonstrated with retention of the organometallic complex simi-
lar to those obtained in toluene [10].
The main objective of the present study was to immobilize
Hoveyda-type catalysts onto porous silica and zirconia with the
aim of studying their catalytic activity and multiple-use capac-
ity in the eco-friendly DMC. As far as we know, this is the first
example of immobilization of a Hoveyda-type catalyst onto zirco-
nia that is a less acidic support than silica. Herein, the synthesis of a
tailor-made silylated ligand is shown as well as the preparation of
hybrid organic–inorganic supported ligand and complexes. Finally,
the catalytic activity and reuse of the hybrid catalysts have been
evaluated.
Blechert showed that para-substitution with electron donating
groups resulted in slower initiation rates [26]. Based on these prop-
erties, several catalysts bearing alkyl- or alkoxy-para-substituents
have been reported for utilisation in ionic liquids and ScCO2 [6,8].
Consequently, the synthesis of the new silylated styrene ligand 6
was envisioned for the covalent anchorage of catalytic species onto
a solid support (Scheme 1). Ligand 6 was readily synthesized in 5
steps from the commercially available 2,5-dihydroxybenzaldehyde
1. Initial protection of both hydroxyl groups followed by a selec-
tive deprotection furnished 2 in 91% yield [27]. Etherification of
the residual hydroxyl group led to 3 that was converted into a
styrenyl compound 4 by a Wittig olefination. Subsequent alco-
hol deprotection with sodium methoxide furnished the styrenyl
derivative 5 in good yield (85%). Finally, 5 was alkylated with (3-
iodopropyl)trimethoxysilane in order to introduce the alkoxysilyl
group required for anchorage of the ligand onto the solid supports.
The reaction performed in DMF afforded the silylated styrene lig-
and 6 in 95% purity according to 1H NMR. Due to its poor stability
towards silica gel purification, this product was used without any
further purification.
2.2. Preparations of hybrids materials and catalysts
2.2.1. Preparations of hybrids materials
The preparation of two different hybrid materials M1 and M2
was carried out via sol–gel grafting of ligand 6 onto silica (Merck,
Geduran Si60, 500 m2 g−1) and zirconia (Orelis, 64 m2 g−1) pow-
ders, respectively (Scheme 2). The solid supports were initially
dried for 24 h at 70 ◦C under vacuum. The dried solids were added
at room temperature to a solution of ligand 6 in dry toluene and
refluxed for 24 h. The resulting powders were then washed succes-
sively with dichloromethane, diethyl ether and pentane affording
M1 and M2 as white powders.
In order to evidence the grafting of ligand 6, M1 and M2 powders
were studied by 29Si and 13C CP-MAS NMR, DRIFT and SEM-EDX.
The analysis of the silica powder M1 by SEM-EDX indicated the
presence of the organic silylated ligand 6 on the silica powder by
the detection of carbon arising from the organic ligand. The same
analysis performed on the zirconia powder M2 indicated the pres-
ence of carbon and silicium arising from ligand 6. The comparison
2. Results and discussion
2.1. Ligand synthesis
Previous works from different groups showed the influence of
aryl substituents of the chelating o-isopropoxystyrene ligand on
the catalyst efficiency, in particular the initiation step, and on recy-
clability. For instance, an electron-withdrawing substituent para to
the isopropoxy group [23] or an ortho-substitution of the same iso-
propoxy group [24] resulted in improved release (initiation) of the
ligand thus hampering efficient return considering the boomerang
mechanism that was recently ruled out [25]. On the other hand,

A. Keraani et al. / Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
75
Scheme 2. Preparation of hybrid materials M1 and M2.
Fig. 1. DRIFT spectra of virgin silica (black) and hybrid silica material M1 (grey)
Fig. 2. DRIFT spectra of virgin zirconia (black) and hybrid zirconia material M2 (grey)
wavenumber (cm−1).
wavenumber (cm−1).
of the DRIFT spectra of the starting solids with the solids obtained
after grafting also evidenced the presence of ligand 6, as new bands
located in the region 1350–1750 cm−1 and 2900–3100 cm−1 were
detected with the grafted material M1 (Fig. 1).
An enlargement of the region 1350–1750 cm−1 showed the
presence of four new absorption bands at 1652 cm−1, 1452 cm−1
,
1387 cm−1, 1312 cm−1 corresponding to ꢀ(C C) styrene, ꢀ(C C)
aromatic, ı(CH3) and ı(CH2), respectively. Similarly, the region
2900–3100 cm−1 showed two new absorption bands at 2937 cm−1
and 2974 cm−1 attributable to ꢀ(CH3, CH2) asymmetric et ꢀ(CH3,
CH2) symmetric. In the case of M2 new bands also located at
800–1700 cm−1 and 2900–3100 cm−1 appeared (Fig. 2).
In order to confirm the covalent grafting of ligand 6 onto silica
and zirconia, solid-state NMR analyses were carried out (Table 1
and Fig. 3).
Fig. 3. Solid-state 29Si CP-MAS NMR spectrum of hybrid material M1.
attributed to the formation of Si
O Zr linkage although this cannot
The 29Si CP-MAS NMR analysis of M1 confirmed the covalent
bonding between the silica support and ligand 6 as T2 and T3 sub-
units [28] were detected in addition to the characteristic Q2, Q3 and
Q4 silica subunits (Fig. 3) [29].
be unambiguously determined (Fig. 4).
Finally, the 13C CP-MAS NMR spectra of M1 and M2 exhib-
ited chemical shifts characteristic of the grafted organic ligand 6
The effect of zirconium second-nearest neighbour on the 29Si
chemical shift is much less documented than silicon or other ele-
ments such as aluminium or titanium [30]. The 29Si CP-MAS NMR
analysis of M2 revealed the appearance of a broad signal cen-
tred at −50 ppm. For the reasons mentioned above, this signal was
Table 1
29Si CP-MAS NMR analysis of M1.
Chemical shift (ppm)
SiOn units
−58
−66
−90
−101
−110
T2
T3
Q2
Q3
Q4
Fig. 4. Solid-state 29Si CP-MAS NMR spectrum of hybrid material M2.

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A. Keraani et al. / Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
Fig. 5. Solid-state 13C CP-MAS NMR spectrum of hybrid material M1.
(Figs. 5 and 6). Of note, residual methoxy groups were detected
at 50 ppm for M1 whereas they were not observed for M2. This
may be explained by a higher condensation in M2 or by a different
chemical shift of the methoxy group for M1 (MeOSiOSi) than for
M2 (MeOSiOZr).
2.2.2. Preparation of supported catalysts
The new supported Hoveyda-type catalysts C1 and C2 were pre-
pared by reaction of the second generation Grubbs catalyst with
M1 or M2 powders in refluxing CH2Cl2 for 12 h. After washing and
drying, the solids were obtained as pale green powders thus indi-
cating the formation of the desired supported catalysts (Scheme 3)
[31]. To the best of our knowledge, catalyst C2 is the first example
of an homogeneous Hoveyda-type catalyst grafted onto a zirconia
support.
Fig. 7. DRIFT spectra of hybrid material M1 (blue) and supported catalyst C1 (red)
wavenumber (cm−1). (For interpretation of the references to colour in this figure
legend, the reader is referred to the web version of the article.)
The new powders C1 and C2 were analysed by the same analyt-
ical techniques as for the hybrid materials M1 and M2 in order to
evidence the formation of the desired supported catalysts.
The analysis of C1 by SEM-EDX revealed the presence of ruthe-
nium and chlorine thus suggesting the formation of the expected
complex. The DRIFT analysis of C1 confirmed the formation of the
desired complex as the intensity of the styrene vibration ꢀ(C C) at
1652 cm−1 decreased due to coordination to the ruthenium (Fig. 7).
In the case of the hybrid catalyst C2, due to the small amount
of grafted ruthenium species (see below), no noticeable difference
could be detected between the virgin hybrid material M2 and the
targeted supported catalyst C2 by SEM-EDX (precision is close to
5 atom% for each element).
Fig. 8. Solid-state 13C CP-MAS NMR spectra of M1 (a) and C1 (b). *New signals.
The supported catalysts C1 and C2 were then analysed by 29Si
CP-MAS NMR and their respective spectra were identical to those of
M1 and M2 thus demonstrating the stability of the inorganic matrix
during the consecutive grafting reactions. The 13C CP-MAS NMR
spectra of the supported catalysts C1 and C2 showed the appear-
ance of new bands characteristic of the N-heterocyclic carbene in
the aromatic region around 140 ppm and to a lower extent in the
aliphatic region at 22 ppm (ArCH3) and at 50 ppm in C2 (NCH2CH2N)
(Figs. 8 and 9). The 13C CP-MAS NMR of C2 revealed the formation
of the desired complex but the weak intensity of the new signal
suggested a low amount of anchored catalyst. As expected, this
technique appeared much more powerful than micro-analysis by
SEM-EDX to evidence slight modifications. For both catalysts C1
and C2, the characteristic carbene carbons Ru C and Ru C(N∩N)
could not be observed but it must be mentioned that these signals
are sometimes difficult to observe even by NMR in solution.
Quantitative analyses were performed by ICP-OES in order
to determine the ruthenium loadings. As suspected from the
Fig. 6. Solid-state 13C CP-MAS NMR spectrum of hybrid material M2.
Fig. 9. Solid-state 13C CP-MAS NMR spectra of M2 (a) and C2 (b). *New signals.

A. Keraani et al. / Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
77
Scheme 3. Preparation of hybrid catalysts C1 and C2 (Mes = 2,4,6-trimethylphenyl, Cy = cyclohexyl).
Table 2
Ruthenium loadings determined by ICP-OES.
Material
wt% Ru
Ru (mmol g−1
)
Ru (mol m−2
)
C1
C2
0.409
0.209
0.041
0.021
8.24 × 10−8
3.23 × 10−7
qualitative analysis, the ruthenium content was higher in M1 than
in M2 (Table 2). This difference may arise from several parameters
in particular the specific surface area and porous volume of the
two inorganic supports. As depicted in Table 3, the specific surface
area and pore volumes determined by low temperature nitrogen
adsorption experiments revealed a large difference between the
two solids that certainly accounts for the results obtained. In addi-
tion, the number of accessible surface hydroxyl groups per unit area
is another parameter to consider but that is difficult to evaluate. It
would also be interesting to achieve an in-depth study on the role
of acidity of the hydroxyl groups of the inorganic support on its
ability to be more or less grafted.
In conclusion, both qualitative and quantitative analyses
demonstrated the synthesis of the two supported catalysts. These
two catalysts were then evaluated in catalytic metathesis reactions
and the possibility to reuse these supported catalysts over several
runs was also screened.
Scheme 4. Model RCM reaction of diallyltosyl amide.
The same protocol was used for the two supported catalysts,
except the supported catalyst initial mass (55 mg of supported
catalyst C1, and 106 mg of supported catalyst C2). A single load
of supported catalyst corresponding to a substrate to Ru ratio of
0.7 mol% was used as well as the corresponding m0 mass of DATA.
The DATA conversion at 30 ◦C was monitored by gas chromatog-
raphy until stable conversion was reached. The supported catalyst
was then separated by mean of classical filtration and the follow-
ing cycle was initiated by addition of a new load of DATA (m0) and
so on. The catalytic activity of the supported catalysts was moni-
tored according to two criteria: the final conversion and the time
to reach this conversion. As depicted in Table 4, the reaction time
necessary to reach high conversion in the first run depended on the
catalyst, and for a given one it was sometimes necessary to increase
the reaction time in order to maintain high conversions during the
following cycles.
Good conversions were obtained in short reaction times (1–5 h)
with a low catalyst loading of 0.7 mol% of ruthenium in anhydrous
DMC (0.05 M) at 30 ◦C (Table 4). The best results were obtained with
the hybrid catalyst C1 that allowed two runs with almost full con-
version in a reasonable amount of time and two extra runs with
good conversions. The supported catalyst C2 also performed well
in the first 2 runs but longer reaction times were required. The
better results obtained with C1 may be attributed to the better
2.3. Catalytic activity and reusing of the supported catalysts
The new hybrid Hoveyda catalysts C1 and C2 grafted on silica
and zirconia showed good stability upon storing at 4 ◦C under argon
over one month without any sign of decomposition. They were
engaged in a series of model ring closing metathesis reactions of
N,N-diallyltosyl amide (DATA) in DMC to evaluate their activity and
multiple-use (Scheme 4). For long, Hoveyda based catalysts were
thought to be recyclable owing to the possibility of recovering the
pre-catalyst via boomerang or return and release process. With the
recent results disclosed by Plenio [25] it is more likely that only
a little fraction of the pre-catalyst is initially activated leaving the
remaining stable pre-catalyst available for the next run. In fact the
initial pre-catalyst loading constitutes a reservoir of catalyst that is
partially used in each consecutive run. In that case catalyst immo-
bilization still presents the interest of more efficient utilisation of
expensive catalysts over multiple consecutive uses by increasing
Turn Over Numbers with the same initial loading.
Table 4
Catalytic activity and multiple-use of supported catalysts C1 and C2 at 30 ◦C.
Cycle
C1
C2
Conv. (%)
t (min)
Conv. (%)
t (min)
Table 3
Specific surface area and porosity of the virgin silica and zirconia.
1
2
3
4
5
98
98
81
70
43
105
181
239
300
300
97
88
54
211
240
392
Material
Specific surface area (m2 g−1
)
Porous volume (cm3 g−1
)
Silica
Zirconia
496
64
0.71
0.21

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A. Keraani et al. / Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
diffusion of reagents through the pore channels to the catalytic
sites. The decrease in activity of the hybrid catalysts C1 and C2
during consecutive runs may have different origins such as the
intrinsic stability of the catalyst (interactions with hydroxide OH),
and the leaching of catalyst over time. To enhance the stability
and the reuse of the hybrid catalyst, capping of free Si OH or
Zr OH on solid supports may be envisaged as already reported
[13d]. Catalyst leaching is also an important issue due to the
release of the ligand on the pre-catalyst and consecutive natu-
ral deactivation. In such a case, catalyst immobilization via the
NHC ligand would be a better solution to prevent ruthenium
leaching [13e,g].
4.1. Ligand synthesis
4.1.1. 3-Formyl-4-hydroxyphenyl benzoate (2)
2,5-Dihydroxybenzaldehyde (2 g, 14.5 mmol, 1.0 equiv.) was
dissolved in 15 mL of dry CH2Cl2 in a Schlenk tube. Dry Et3N (4.4 mL,
31.9 mmol, 2.2 equiv.) was then added followed by benzoic anhy-
dride (6.9 g, 31.9 mmol, 2.1 equiv.) and 4-dimethylaminopyridine
(0.18 g, 1.4 mmol, 0.1 equiv.). The reaction mixture was stirred
at room temperature for 5 h and then diluted with 40 mL of
diethyl ether and washed, sequentially, with a saturated solution of
NaHCO3 and brine. The organic phase was dried over Na2SO4 and
then concentrated under reduced pressure. The light brown residue
was dissolved in a mixture of MeOH:THF (32 mL/8 mL) before addi-
tion of anhydrous K2CO3 (2 g, 1 equiv.). The resulting mixture was
stirred for 1 h and then diluted with 40 mL of diethyl ether and
acidified by a dropwise addition of 20 mL of 2 N aqueous HCl. The
organic phase was washed several times with a saturated solution
of Na2HPO4 until full removal of benzoic acid (monitored by TLC). 2
was obtained as a white solid (3.3 g, 91%) of good enough purity and
used without any further purification. NMR data were consistent
with reported data [27]. 1H NMR (400.16 MHz, CDCl3, 25 ◦C, TMS, ı
(ppm)): 7.05 (d, 2.9 Hz, 1H, CH), 7.35 (dd, 9.1 Hz, 2.9 Hz, 1H, CH), 7.42
(d, 3.0 Hz, 1H, CH), 7.55 (m, 2H), 7.69 (m, 1H), 8.25 (d, 7.9 Hz, 2H, CH),
8.89 (s, 1H, OH), 10.98 (s, 1H, CHO); 13C NMR (50.33 MHz, CDCl3, ı
(ppm)): 114.6, 120.2, 128.2, 128.4, 132.3, 132.1, 135.1, 145.1, 159.5,
167.1, 188.2.
3. Conclusion
This study has shown the feasibility of the immobilization
and multiple-use of new hybrid organic–inorganic Hoveyda cat-
alysts in dimethyl carbonate (DMC) an eco-friendly solvent. The
design, the preparation and the characterization of Hoveyda-
type catalysts supported onto silica (C1) and an original catalyst
supported onto zirconia (C2) have been realised. The hybrid
Hoveyda catalysts exhibited stability, activity, selectivity in a
model RCM reaction and it was possible to use the catalyst
over several consecutive runs. The activities of the hybrid cat-
alysts were highly dependent on the intrinsic properties of the
solid supports. To enhance the stability and reuse of the hybrid
catalyst, protection of the free hydroxy groups on the solid
supports may be a valuable alternative. This grafting on zir-
conia powder was then successfully transposed to the grafting
of the zirconia active layer of a tubular inorganic ultrafiltration
membrane to prepare a catalytic membrane allowing both the
catalytic reaction and the separation in a single step process
[32].
4.1.2. 3-Formyl-4-(propan-2-yloxy)phenyl benzoate (3)
In a Schlenk tube maintained under an argon atmosphere,
2
(1.0 g, 4.12 mmol, 1 equiv.) and K2CO3 (0.85 g, 6.20 mmol,
1.5 equiv.) were dissolved in dry DMF (15 mL), and were stirred for
1 h at 40 ◦C. 2-Bromopropane (0.58 mL, 6.20 mmol, 1.5 equiv.) dis-
solved in DMF (5 mL) was then added to the stirring solution. The
reaction mixture was stirred overnight at 40 ◦C. The organic prod-
ucts were extracted with diethyl ether, and the resulting organic
phase was washed with water. Purification by column chromatog-
raphy on silica gel using petroleum ether/diethyl ether (95/5, v/v)
as the eluent afforded 3 as a white solid (0.92 g, 79%). 1H NMR
(400.16 MHz, CDCl3, 25 ◦C, TMS, ı (ppm)): 1.45 (d, 6.0 Hz, 6H, CH3);
4.68 (sept, 6.0 Hz, 1H, CH), 7.05 (d, 8.8 Hz, 1H, CH), 7.21 (d, 2.3 Hz,
1H, CH), 7.40 (dd, 9.2 Hz, 2.8 Hz, 1H, CH), 7.50–7.53 (m, 2H, CH),
7.62–7.66 (m, 2H, CH), 8.18 (d, 8.0 Hz, 2H, CH), 10.51 (s, 1H, CHO).
13C NMR (50.33 MHz, CDCl3, ı (ppm)): 22.4, 72.2, 115.5, 121.3,
129.1, 129.5, 130.6, 131.3, 134.2, 144.6, 158.7, 165.7, 189.6, 196.3;
HRMS (EI): m/z: 284.1069 [M+.]; elemental analysis (%) calculated
for C17H16O4: C 71.82, H 5.67; found: C 70.93, H 5.62.
4. Experimental
General: All reactions were carried out under an inert atmo-
sphere of dry argon, with standard Schlenk tube techniques. DMF
was freshly distilled over CaH2 before use. Dimethyl carbonate was
˚
distilled and stored over 4 A molecular sieves prior to use. The sec-
ond generation Grubbs catalyst was purchased from Sigma–Aldrich
and stored under argon. Silica gel (Geduran Si60) was purchased
from Merck. Zirconia powder was kindly provided by Orelis in
1995. Liquid NMR data were recorded on Bruker DPX 200 and
Bruker Ascend 400 MHz spectrometers. The 29Si and 31C solid state
CP-MAS NMR spectra were recorded on a Bruker Avance 300 spec-
trometer. The recycle time were respectively 3.5 and 2 s. The rotor
spinning rate was 8 kHz for 29Si and 10 kHz for 13C. The content
of ruthenium was determined at the UMR-CNRS “Sciences Chim-
iques de Rennes” of the University of Rennes 1 by Inductively
Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysis.
Surface areas were determined by Brunauer–Emmett–Teller (BET)
method on Micromeritics ASAP 2010 analyser at the UMR-CNRS
“Sciences Chimiques de Rennes” of the University of Rennes 1, and
the average pore volume was calculated by the BJH method. DRIFT
spectra were registered on Perkin Elmer spectrometer (Paragon
1000) using the Spectrum for windows software. Background was
registered on KBr (IR grade) powder carefully grinded in an agate
mortar. Supported catalysts were dispersed in KBr and carefully
grinded before spectrum recording. Conditions were: average of 20
4.1.3. 3-Ethenyl-4-(propan-2-yloxy)phenyl benzoate (4)
Ph3P+CH3I− (2.13 g, 5.27 mmol, 1.5 equiv.) was slowly added at
room temperature to a suspension of NaH (126.6 mg, 5.27 mmol,
1.5 equiv.) in THF (15 mL), and the reaction mixture was heated at
60 ◦C for 2 h. After cooling to room temperature, the resulting solu-
tion was added to 3 (1.0 g, 3.51 mmol, 1 equiv.) dissolved in diethyl
ether (15 mL). After stirring overnight at 30 ◦C, the reaction was
quenched by the addition of 9 mL of water and the organic products
were extracted with 20 mL of diethyl ether. Purification by column
chromatography on silica gel using petroleum ether/diethyl ether
(95/5, v/v) as the eluent afforded 4 as a colourless solid (0.70 g,
71%). 1H NMR (400.16 MHz, CDCl3, 25 ◦C, TMS, ı (ppm)): 1.36 (d,
6.0 Hz, 6H, CH3); 4.52 (sept, 6.0 Hz, 1H, CH); 5.27 (d, 11.2 Hz, 1H,
CH), 5.72 (d, 17.7 Hz, 1H, CH), 6.91 (d, 8.8 Hz, 1H), 7.01–7.09 (m, 2H,
CH); 7.31 (d, 2.5 Hz, 1H, CH); 7.49–7.51 (m, 2H, CH), 7.61–7.65 (m,
1H, CH), 8.21 (d, 7.90 Hz, 2H, CH). 13C NMR (50.33 MHz, CDCl3, ı
(ppm)): 22.6, 72.0, 115.3, 115.5, 119.7, 121.9, 129.0, 129.5, 130.1,
scans, resolution: 2 cm−1, recording between 4000 and 600 cm−1
.
No corrections were achieved on raw spectra that are given as
registered.

A. Keraani et al. / Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
79
(ppm): large signal (−55 to −45); 31C CP-MAS NMR: ı (ppm): 7
(CH2), 20 (2CH3), 49 (O CH3), 73 (CH, CH2), 110–119 (3CH3 aro-
matic, CH2 styrene), 126 (C aromatic, CH styrene), 135 (C aromatic),
137 (C aromatic).
130.6, 131.7, 133.9, 144.9, 153.3, 165.8; HRMS (EI): m/z: 282.1232
[M+•].
4.1.4. 3-Ethenyl-4-(propan-2-yloxy)phenol (5)
DRIFT: (KBr): ꢀ (cm−1): 2974: ꢀ(CH3, CH2) symmetric, 2937:
ꢀ(CH3, CH2) asymmetric, 1652: ꢀ(C C) styrene, 1452: ꢀ(C C) aro-
matic, 1387: ı (CH3), 1312: ı (CH2).
In a Schlenk tube maintained under an argon atmosphere, 4
(1.0 g, 3.39 mmol, 1 equiv.) was dissolved in anhydrous THF (8 mL),
and the reaction mixture was cooled at −45 ◦C. Sodium methox-
ide (26% in MeOH, 0.71 mL, 3.39 mmol, 1 equiv.) was then added
to the stirring solution, and the reaction mixture was stirred for
30 min at −45 ◦C. The reaction was quenched by addition of 3 mL
of a 1 N HCl solution and extracted with diethyl ether. The com-
bined organic extracts were dried with MgSO4, concentrated under
vacuum. Purification by flash column chromatography on silica gel
using PE/Et2O (90:10, v/v) as the eluent afforded 5 as a thick oil
(0.53 g, 88%). NMR data were consistent with reported data [6c].
1H NMR (400.16 MHz, CDCl3, 25 ◦C, TMS, ı (ppm)): 1.31 (d, 6.1 Hz,
6H, CH3); 4.35 (sept, 6.1 Hz, 1H, CH); 4.56 (bs, 1H, OH), 5.23 (d,
11.2 Hz, 1H, CH); 5.67(d, 17.6 Hz, 1H, CH); 6.68 (dd, 8.7 Hz, 2.9 Hz,
1H, CH); 6.78 (d, 8.8 Hz, 1H, CH); 6.95 (d, 2.8 Hz, 1H, CH); 7.01 (dd,
17.6 Hz, 11.2 Hz, 1H, CH).
4.1.8. Synthesis of the hybrid silica catalyst (C1)
In a Schlenk tube maintained under an argon atmosphere,
Grubbs second generation catalyst (9.2 mg, 0.011 mmol) was added
to a solution of hybrid material M1 (202 mg) in anhydrous and
degassed CH2Cl2 (15 mL). The reaction mixture was refluxed at
40 ◦C for 12 h. After cooling the reaction mixture at room tem-
perature, the silica gel was washed successively with CH2Cl2 until
the filtrate had no colour, and dried under vacuum overnight to
obtain as a green powder. 29Si CP-MAS NMR: ı (ppm): −58 (T2),
−66 (T3), −90 (Q2), −101 (Q3), −110 (Q4). 31C CP-MAS NMR: ı
(ppm): 6 (CH2), 20 (CH3), 22 (CH3), 49 (O CH3), 73 (CH, CH2),
110–119 (CH3 aromatic, CH2 styrene), 126 (C aromatic, CH styrene),
129 (CH aromatic) 135 (C aromatic), 137 (C aromatic). ICP-OES:
Ru: 0.041 mmol Ru/g of silica, 4.0 × 10−3 mole of catalyst/100 mg
4.1.5. 2-Ethenyl-1-(propan-2-yloxy)-4-((3-
trimethoxysilyl)propyl)benzene
(6)
of silica SiO2 grafted → 8.24 × 10−8 mol m−2
.
In a Schlenk tube maintained under an argon atmosphere,
product 5 (0.2 g, 1.77 mmol, 1.5 equiv.) was slowly added at 0 ◦C
to a suspension of NaH (42.5 mg, 1.77 mmol, 0.9 equiv.) in DMF
(4 mL), and the reaction mixture was stirred at room temperature
for 1 h. After cooling the reaction mixture to 0 ◦C, (3-iodopropyl)
trimethoxysilane was added and the reaction mixture was stirred
at room temperature for 1 h. After dilution with saturated aqueous
K2CO3, the organic products were extracted with diethyl ether. The
organic phase was dried with MgSO4, filtered over a pad as silica
gel and concentrated under vacuum. 1H NMR (200.12 MHz, CDCl3,
25 ◦C, TMS, ı (ppm)): 0.85 (t, 8.1 Hz, 2H, CH2); 1.31 (d, 6.0 Hz, 6H,
CH3); 1.92 (m, 2H, CH2); 3.65 (s, 9H, CH3); 3.90 (m, 2H, CH2); 4.40
(sept, 6.05 Hz, 1H, CH); 5.20 (d, 10.1 Hz, 1H, CH); 5.71 (d, 17.3 Hz,
1H, CH); 6.71–6.85 (m, 2H, CH); 6.90–7.15 (m, 2H, CH); HRMS (ESI):
m/z: 363.1605 [M+Na]+ calculated for C17H28O5NaSi: 363.16037.
4.1.9. Synthesis of the hybrid zirconia catalyst (C2)
In a Schlenk tube maintained under an argon atmosphere,
Grubbs second generation catalysts (20.9 mg, 0.025 mmol) was
added to a solution of hybrid material M2 (293 mg) in anhydrous
and degassed CH2Cl2 (15 mL). The reaction mixture was refluxed
for 12 h. After cooling the reaction mixture at room temperature,
the silica gel was washed successively with CH2Cl2 until the fil-
trate had no colour, and dried under vacuum overnight to obtain
as a green powder. 29Si CP-MAS NMR: ı (ppm): large signal (−55
to −45). 31C CP-MAS NMR: ı (ppm): 6 (CH2), 20 (CH3), 22 (CH3), 49
(O CH3), 73 (CH, CH2), 110–119 (CH3 aromatic, CH2 styrene), 126
(C aromatic, CH styrene), 129 (CH aromatic) 135 (C aromatic), 137
(C aromatic). ICP-OES: Ru: 2.07 × 10−3 mole of catalyst/100 mg of
zirconia grafted → 3.23 × 10−7 mol m−2
.
4.1.6. Synthesis of the hybrid silica material (M1)
In a Schlenk tube maintained under an argon atmosphere, silica
gel (Merck) (1.1 g, 18 mmol) dried for 24 h at 70 ◦C under vac-
uum was added at room temperature to a solution of ligand 6
(0.3 g, 0.88 mmol) in dry toluene (15 mL). The reaction mixture was
refluxed for 24 h. After cooling the reaction mixture at room tem-
perature, the silica gel was washed successively four times with
CH2Cl2, diethyl ether and then with pentane. The solid was dried
under vacuum overnight affording M1 as a white powder. 29Si CP-
MAS NMR: ı (ppm): −58 (T2), −66 (T3), −90 (Q2), −101 (Q3), −110
(Q4); 31C CP-MAS NMR: ı (ppm): 6 (CH2), 20 (CH3), 49 (O CH3), 73
(CH, CH2), 110–119 (CH3 aromatic, CH2 styrene), 126 (C aromatic,
CH styrene), 135 (C aromatic), 137 (C aromatic). DRIFT: (KBr): ꢀ
(cm−1): 2974: ꢀ(CH3, CH2) symmetric, 2937: ꢀ(CH3, CH2) asym-
metric, 1652: ꢀ(C C) styrene, 1452: ꢀ(C C) aromatic, 1387: ı (CH3),
1312: ı (CH2).
4.1.10. Typical procedure for RCM reactions of DATA and
multiple-use
A solution of diallytosylamide DATA (80 mg, 0.32 mmol) in
anhydrous DMC (4 mL) was added under nitrogen to catalyst C1 or
C2 (0.7 mol% Ru) and the mixture was stirred under argon at 30 ◦C.
Reaction samples were analysed by gas chromatography at regular
intervals. The reaction mixture was cannula filtered under nitro-
gen atmosphere and the solid was washed four times with 4 mL
of anhydrous DMC. A new run was started by addition of 4 mL of
anhydrous DMC and DATA (80 mg, 0.32 mmol) to the solid catalyst
C1 or C2.
4.1.11. Conversion of DATA by metathesis monitored by GC
analysis
Conversion of diallytosylamide (DATA) was determined by
gas chromatography quantification using a mainly apolar station-
ary phase made of PDMS-PDPS (95-5) in a semicapillary column
(EquityTM-5, 30 m × 0.53 mm × 1.5 ␮m film thickness, provided by
Supelco). Injection at 250 ◦C was followed by analysis at a con-
stant temperature of 230 ◦C, and the detection was obtained by a
FID detector at 250 ◦C. The carrier gas was nitrogen at 18 kPa. The
RSD value on the concentration of DATA was less than 1%, thus the
accuracy on conversion was better than 2%.
4.1.7. Synthesis of the hybrid zirconia material (M2)
In a Schlenk tube maintained under an argon atmosphere, zirco-
nia (351 mg, 2.85 mmol) pre-treated at 70 ◦C for 24 h was added at
room temperature to a solution of ligand 6 (0.26 g, 0.75 mmol) dis-
solved in dry toluene (15 mL). The reaction mixture was refluxed for
24 h. After cooling the reaction mixture at room temperature, the
zirconia was washed successively four times with CH2Cl2, diethyl
ether and then with pentane. The solid was dried under vacuum
overnight affording M2 as a white powder. 29Si CP-MAS NMR: ı

80
A. Keraani et al. / Journal of Molecular Catalysis A: Chemical 357 (2012) 73–80
Acknowledgements
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The authors acknowledge the French Ministry of Research
(MENRT) for a PhD grant to AK, Rennes Metropole for financial
support, O. Merdrignac for BET analysis, Y. Le Gall for ICP-OES
measurements and Orelis (now Applexion-Novasep) company for
zirconia powder supply.
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