DOI: 10.1002/chem.201405685
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Heterogeneous Catalysis
Nanoscaled Copper Metal–Organic Framework (MOF) Based on
Carboxylate Ligands as an Efficient Heterogeneous Catalyst for
Aerobic Epoxidation of Olefins and Oxidation of Benzylic and
Allylic Alcohols
Yue Qi, Yi Luan, Jie Yu, Xiong Peng, and Ge Wang*[a]
Abstract: Aerobic epoxidation of olefins at a mild reaction
temperature has been carried out by using nanomorphology
of [Cu3(BTC)2] (BTC=1,3,5-benzenetricarboxylate) as a high-
performance catalyst through a simple synthetic strategy. An
aromatic carboxylate ligand was employed to furnish a heter-
ogeneous copper catalyst and also serves as the ligand for
enhanced catalytic activities in the catalytic reaction. The
utilization of a copper metal–organic framework catalyst was
further extended to the aerobic oxidation of aromatic alco-
hols. The shape and size selectivity of the catalyst in olefin
epoxidation and alcohol oxidation was investigated. Further-
more, the as-synthesized copper catalyst can be easily
recovered and reused several times without leaching of
active species or significant loss of activity.
Introduction
nonuniform dispersity, which makes them prone to aggrega-
tion. Moreover, some of these composite structures lack the
desired stability and some of the metal active species tend to
leach from the support during the reaction.[33]
Olefin epoxidation is a highly important oxidation reaction, be-
cause the resulting epoxides are widely used in the production
of epoxy resins, paints, and surfactants, and they are highly
valued as synthetic intermediates in industrial processes.[1–4]
Olefin epoxidation can be carried out by using a variety of
oxidants, such as molecular oxygen,[5–6] hydrogen peroxide,[7–8]
alkyl hydroperoxides,[9,10] and iodosylbenzene.[11,12] The
utilization of molecular oxygen as an oxidant has attracted
much interest in the epoxidation of olefins recently, due to
its abundance in nature, ease of handling, and lack of toxic
byproducts during reaction.[13–16]
Therefore, heterogeneous catalysts with higher stability and
easier access to the metal ion are worth developing.[34]
Recently, metal–organic frameworks (MOFs) have emerged as
important functional materials because of their high surface
area, porosity, and chemical tenability.[35] Therefore, MOFs are
ideal candidates for heterogeneous catalysis. Some efforts
have been made using MOF as a catalyst.[36–38] Fujita et al. re-
ported the earliest example of MOFs, using ([Cd(bpy)2](NO3)2
bpy=2,2’-bipyridine) as a catalyst in an aldehyde cyanosilyla-
tion reaction in 1994.[39] However, areobic epoxidation of ole-
fins catalyzed by MOFs is limited.[40–42] Pramanik et al. reported
the aerobic epoxidation of alkenes with CuII/CoII/MnII-phenoxy
acetic acid derivative frameworks.[43] Garcia et al. reported the
aerobic epoxidation of cyclooctene with commercial [Fe(BTC)]
(BTC=1,3,5-benzenetricarboxylate).[44] However, in order for
the aerobic epoxidation reaction to be practical, higher yields,
selectivity, lower catalyst loadings, and shorter reaction time
are needed.
Various catalysts have been developed for the aerobic epoxi-
dation of olefins, amongst these are catalysts composed of
redox-active transition metals, such as V,[17,18] Mn,[19] Fe,[20–22]
Co,[23,24] and Cu,[25,26] etc. Most of the current transition-metal-
based catalysts (e.g. metal salts and metal-ion clusters) are ho-
mogeneous catalysts used in liquid-phase reactions, which are
difficult to separate from the products and reused. This leads
to waste and high costs in industrial production.[27] To employ
heterogeneous catalysts for easy recovery, homogeneous cata-
lysts are often immobilized on insoluble solid supports such as
polymer,[28] clay,[29] zeolite,[30] silica,[31] or titania.[32] However, the
catalytic metal loading on the supports exhibit random and
In this work, a highly efficient aerobic epoxidation of olefins
using copper MOF catalyst is achieved for the first time.
Trimesic acid is employed as the ligand for constructing the
framework of the copper-based heterogeneous catalyst, which
leads to a heterogeneous catalyst with extremely low metal-
active species leaching. The carboxylate also serves as an
organic ligand for the enhancement of catalytic activities in
the oxidation reactions. Several simple copper MOFs have
been synthesized and utilized as an efficient catalyst for
aerobic epoxidation, which is much cheaper and more readily
available than the porphyrin-derived MOF catalyst.[45,46] Nano-
[a] Y. Qi, Dr. Y. Luan, J. Yu, X. Peng, Prof. Dr. G. Wang
School of Materials Science and Engineering
University of Science and Technology Beijing
30 Xueyuan Road, Haidian district, Beijing, 100083 (P. R. China)
Fax: (+86)10-62327878
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201405685.
Chem. Eur. J. 2014, 20, 1 – 10
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ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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