Organic Process Research & Development
Article
0
(
7) Hagio, H.; Sugiura, M.; Kobayashi, S. Org. Lett. 2006, 8, 375−
Table 6. Reusability of the SiliaCat Pd hydrogel in the
3
78.
selective catalytic hydrogenation of trans-cinnamic acid
(8) Pagliaro, M.; Pandarus, V.; Ciriminna, R; Bel
́
̀
and, F.; Cara, P. D.
under mild conditions
ChemCatChem 2012, 4, 432−445.
(9) Pandarus, V.; Ciriminna, R.; Bel
b
leaching (ppm)
́
and, F.; Pagliaro, M. Catal. Sci.
Technol. 2011, 1, 1616−1623.
time
(h)
conversion
a
selectivity
(%)
(10) Park, C. M.; Kwon, M. S.; Park, J. Synthesis 2006, 3790−3794.
run
(yield) (%)
Pd
Si
(
11) (a) Ikawa, T.; Sajiki, H.; Hirota, K. Tetrahedron 2005, 61, 2217−
231. (b) Mori, A.; Mizusaki, T.; Miyakawa, Y.; Ohashi, E.; Haga, T.;
Maegawa, T.; Monguchi, Y.; Sajiki, H. Tetrahedron 2006, 62, 11925−
1932.
12) Morrow, J.; Carson, J.; Arunajatesan, V. Catalyst Design for the
1
2
3
4
5
2
2
2
2
2
100 (99.4)
100 (99.8)
100 (99.3)
100
100
100
100
99
0.09 (1.8)
0.09 (1.8)
0.12 (2.3)
0.09 (1.6)
0.08 (1.5)
0.06 (1.2)
0.03 (0.6)
0.02 (0.4)
0.03 (0.5)
0.02 (0.3)
2
1
(
100
99
Hydrogenation of Cinnamic Acid to Hydrocinnamic Acid. In
Proceedings of the 21st North American Catalysis Society Meeting 2009;
Curran Associates, Inc.: Red Hook, NY, 2011; Vol. 1, p 897.
a
Conversion in final product determined by GC/MS analysis. Isolated
b
yield of the crude product. Leaching in Pd and Si determined by ICP-
OES analysis in solution (DMF solvent 50 mg/mL, with respect to the
crude product) and in the solid crude product.
(
13) Pandarus, V.; Bel
Pagliaro, M. Catal. Lett. 2012, 142, 213−217.
14) Fidalgo, A.; Ciriminna, R.; Ilharco, L. M.; Pagliaro, M. Chem.
Mater. 2005, 17, 6686−6694.
́ ̀
and, F.; Ciriminna, R.; Demma Cara, P.;
(
The performance of the new catalyst is often superior to
conventional solid Pd-based catalysts. For example, in the
hydrogenation of cinnamic acid, the SiliaCat Pd(0) catalyst
gave considerably higher yields in hydrocinnamic acid than a
Pd(5%)/C commercial catalyst. Leaching of entrapped Pd is
negligible. We ascribe the excellent performance of the SiliaCat
Pd(0) material to both the ultrasmall (2−4 nm) size of the
crystalline Pd nanoparticles as well as to their sol−gel
entrapment in the organosilica matrix. The former aspect is
crucial and has been discussed in detail by us in a recent
13
structural characterization study of the SiliaCat Pd(0) material.
Entrapment within the methylated silica cages, in its turn,
imparts physical and chemical stabilization to the entrapped
nanoparticles while ensuring optimal diffusion of the reactants
2
through the huge (600−800 m /g) inner porosity of the
organically modified silicate (ORMOSIL). Again, the relevance
of the latter aspect in the catalytic performance of doped
14
ORMOSIL has been studied and explained elsewhere.
In conclusion, given the low amount of Pd catalyst required
and the easy scalability of batch processes employing
15
ORMOSIL catalysts, the route may be open to widespread
employment of catalytic hydrogenation for alkenes reduction
both in industry and in the laboratory.
AUTHOR INFORMATION
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
This paper is dedicated with affection to Montpellier’s ENCSM
■
Professor Joel
progress of chemical catalysis through sol−gel materials.
̈
Moreau for his eminent contributions to the
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dx.doi.org/10.1021/op300079z | Org. Process Res. Dev. 2012, 16, 1230−1234