CHEMCATCHEM
COMMUNICATIONS
DOI: 10.1002/cctc.201300394
An Improved Method for the Complete Hydrogenation of
Aromatic Compounds under 1 Bar H2 with Platinum
Nanowires
Tingting Yu, Jiaqing Wang, Xinming Li, Xueqin Cao, and Hongwei Gu*[a]
The catalytic hydrogenation of aromatic compounds to form
cyclohexane derivatives represents a challenging area of re-
search in both the general synthetic and industrial fields of
chemistry.[1] Despite recent progress in the development of ho-
mogeneous catalysts for hydrogenolysis,[2–5] the properties of
heterogeneous systems are generally considered to be more
favorable and benign, including their lower cost, operational
simplicity, and ease of separation and recyclability. Conse-
quently, heterogeneous catalysts have been used in a broad
range of industrial applications, including the production of
pharmaceuticals, agrochemicals, fine chemicals, flavors, fra-
grances, and dietary supplements.[6] The complete hydrogena-
tion of aromatic compounds using current palladium,[7] ruthe-
nium,[8] and rhodium[9] metal catalysts, however, still requires
the use of dangerous reaction conditions (i.e. high H2 pres-
sures) and highly energetic pathways (>1008C) because of the
lack of active catalysts. Industrial applications in particular re-
quire high yields, high levels of selectivity and productivity,
low costs, and safety and environmentally benign processes
among other technical factors.
efficient method for the hydrogenation of aromatic com-
pounds is, therefore, still of considerable interest to the chemi-
cal industry and represents a significant challenge to synthetic
chemists. Herein, we report the development of a novel, effi-
cient, convenient, and environmentally benign approach to
the synthesis of cyclohexane derivatives from the correspond-
ing aromatic compounds using platinum nanowires as a cata-
lyst in conjunction with a Lewis acid co-catalyst (e.g., AlCl3).
PtNWs catalysts were obtained from the acidic etching of
FePtNWs under an air atmosphere.[12] (Figure 1, Figure S1 and
The use of well-defined metal nanostructured materials in
catalytic hydrogenation processes has recently become a rapid-
ly growing area of research, and numerous studies have been
devoted to the development of efficient and selective catalysts
for the hydrogenation of aromatic compounds and olefins, as
well as for reactions that are not catalyzed or are poorly cata-
lyzed by molecular species. For example, Somorjai and Yang[10]
reported the catalytic hydrogenation of pyrrole using platinum
nanocrystals and found that the activity and selectivity were
heavily dependent on the size and shape of the nanocrystals.
A similar phenomenon was also reported by Han et al.[5,11] with
palladium nanocrystals. Gu et al.[12] reported the direct catalytic
hydrogenation of nitroaromatic compounds with one-dimen-
sional platinum nanowires (PtNWs), together with the coupling
of carbonyl compounds with aromatic nitro compounds or the
hydrogenation of aromatic compounds under 1 MPa of initial
hydrogen pressure. The development of a simple, green, and
Figure 1. TEM images of PtNWs: A) at normal and B) high resolution.
S2) To demonstrate the catalytic activity of the PtNWs towards
aromatic hydrogenation, phenol was selected as a substrate
and hydrogenated under 1 atm of H2 pressure (1 atm=
0.101 MPa) in the presence of an AlCl3 co-catalyst to give
cyclohexanol and some related cyclohexane derivatives
(Scheme 1). This transformation represents an industrial pro-
cess of considerable importance because the product is used
as an intermediate in the production of nylon 6 and nylon 66.
Shown in Table 1 are the results for the hydrogenation of
phenol to form cyclohexanol, cyclohexanone, and cyclohexyl
acetate in the presence of different solvents, including water,
acetic acid, acetic acid/water, formic acid, methanol, and etha-
nol. Of the solvents tested, water provided the best results for
[a] T. Yu, J. Wang, Prof. X. Li, Prof. X. Cao, Prof. H. Gu
Key Laboratory of Organic Synthesis of Jiangsu Province
College of Chemistry, Chemical Engineering and Materials Science
Soochow University
Suzhou 215123 (P.R. China)
Fax: (+86)512-65880905
Supporting information for this article is available on the WWW under
Scheme 1. Phenol hydrogenation with PtNWs.
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 2 – 4
&
2
&
ÞÞ
These are not the final page numbers!