DOI: 10.1002/cctc.201600977
Full Papers
Evaluation of AgPd Nanoshells in Dual Catalysis: One-Pot
Silane Oxidation and Reduction of Organic Compounds
Camila M. Kisukuri, Jo¼o L. M. S. Reis, Thenner S. Rodrigues, Pedro H. C. Camargo,* and
[a]
Leandro H. Andrade*
AgPd nanoshells (AgPd NSs) were used as dual catalysts for
hydrogen production and reduction of organic compounds in
a one-pot protocol. AgPd NSs were very efficient catalysts for
the reduction of several functional groups, including alkenes,
alkynes, imines, nitro compounds, and azides. Excellent chemo-
selectivities were observed for a,b-unsaturated ketones, esters,
and cinnamonitrile. Also, deuterium-labeled compounds were
prepared by using D O instead of H O. A packed-bed reactor
2 2
containing the immobilized AgPd NSs in silica (AgPd/SiO ) was
2
designed to be used in continuous-flow conditions. An opti-
mized flow system with AgPd NSs was able to give the desired
compounds in high conversions with 30–60 min residence
time (tR).
Introduction
[
30]
Bimetallic nanomaterials can have improved catalytic perfor-
mances as compared to their monometallic analogues owing
to synergism effects between the two metals. Therefore, a new
set of catalysts prepared by combining two different metal
components can enable, at least in principle, unique catalytic
properties, better selectivity, durability, and activity compared
coupling reaction. Rh/Pd and Pt/Pd nanoparticles were also
used as catalysts for alcohol oxidation and catalytic
[31]
reforming.
In addition to catalytic applications, we have recently shown
the potential of bimetallic nanomaterials as a supporting mate-
rial for enzyme immobilization to prepare biometallocatalysts
[
1–7]
[32]
to their monometallic counterparts.
For example, galvanic
with both metallic and enzymatic activities.
Motivated by
replacement reactions can produce bimetallic nanoshells (NSs)
displaying hollow interiors. This reaction is driven by the differ-
ence in reduction potentials between two metals, which
occurs if a metal (sacrificial template) reacts with metal ions
the very interesting results with bimetallic nanoshells, we de-
veloped a study focused on the utilization of AgPd NSs as dual
catalysts for the reduction of several organic compounds
(alkenes, alkyne, imines, nitro compounds, and azides) with hy-
drogen (H ), hydrogen deuteride (HD), or deuterium (D ) pro-
[
8]
having a higher reduction potential. This leads to the oxida-
tion and dissolution of the template with concurrent reduction
2
2
duced from silane oxidation. For this purpose, a one-pot proto-
col under batch and continuous-flow conditions was demon-
strated. Notably, silanes are easily available as a source for hy-
[
8,9]
and deposition of the more noble metal at its surface. Nota-
bly, nanomaterials came into prominence in the field of cataly-
sis because of the variations in the electronic band structure
drogen production and can be safely handled in open air, re-
[
10–14]
[33–35]
and surface-to-volume ratios as a function of size.
sulting in an environmentally friendly protocol.
Besides, to
A large number of bimetallic catalysts have been reported
for a range of transformations, including hydrogenolysis, cou-
the best of our knowledge, reports on the use of bimetallic
nanoparticles as catalysts for HD/D production and reduction
2
[15–27]
pling reaction, reforming reactions, and silane oxidation.
For example, Wang et al. used Pt/Co bimetallic nanoparticles
of organic compounds to deuterium-labeled compounds are
scarce.
[
28]
for the hydrogenolysis of 5-hydroxymethylfurfural,
Gawande et al. used Ag/Ni nanoparticles for hydrogen transfer
and
Results and Discussion
[
29]
from isopropanol oxidation to acetophenone. Son et al. em-
ployed Pd/Ni nanoparticles as catalysts for Sonogashira
AgPd NSs were prepared by using galvanic replacement reac-
2À
tion between Ag nanospheres and PdCl4 ions (Supporting In-
formation, Figure S1). This protocol afforded nanoparticles with
controlled sizes and compositions (39Æ3 nm in outer diame-
ters and 6Æ1 nm in wall thickness determined by SEM and
TEM, Figure S1 and S2; 28 wt% in terms of Pd as determined
by inductively coupled plasma optical emission spectroscopy,
[a] C. M. Kisukuri, J. L. M. S. Reis, T. S. Rodrigues, Prof. P. H. C. Camargo,
Prof. L. H. Andrade
Department of Fundamental Chemistry, Institute of Chemistry
University of S¼o Paulo
Av. Prof. Lineu Prestes, 748
0
5508-000, S¼o Paulo, SP (Brazil)
[32]
ICP–OES).
E-mail: camargo@iq.usp.br
With the AgPd NSs in hands, we investigated different
organosilane compounds as substrates for hydrogen produc-
tion at room temperature. Dimethyl(phenyl)silane (1a),
ChemCatChem 2016, 8, 1 – 7
1
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&
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