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S. Kheirjou et al. / C. R. Chimie xxx (2016) 1e6
aqueous or pH-controlled reactions [13]. Several salts
of oxone have been reported, such as tetra-n-butyl-
ammonium-peroxy-monosulfate (n-Bu4NHSO5, TBA-OX),
tetra-n-pentyl-ammonium-peroxy-monosulfate, tetra-n-he
xyl-ammonium-peroxy-monosulfate and benzyl-triphenyl-
phosphonium-peroxy-monosulfate. Recently, Lie et al. [14]
have demonstrated TBA-OX as an effective reagent for the
oxidation of alcohols in CH2Cl2 or H2O.
These tremendous advantages of TBA-OX have
encouraged us to choose it as an oxidant in our study.
There are several reagents available for the oxidation of
sulfides and alcohols, but most of them are not satisfac-
tory for medium to large scale synthesis due to the low
content of effective oxygen, formation of environmentally
unfavorably co-products, and high cost [15]. An aqueous
solution of TBA-OX is an excellent oxidant in terms of
being environmentally friendly, safe in storage and oper-
ation [14,15].
Scheme 1. Oxidation of alcohols with n-Bu4NHSO5 catalyzed by copper (II)
phthalocyanine nanoparticles.
2. Experimental
1H and 13C spectra were determined on a Varian Mer-
cury 300 MHz or a Bruker AM-400. Gas chromatographic
analyses were performed on a Hewlett Packard 6890 in-
strument equipped with a FID detector and an HP-1 (either
a 10 m  0.2 mm i.d. or a 25 m  0.2 mm i.d.) capillary
column.
2.1. Preparation of the nano-CuPc
In this work, copper (II) phthalocyanine nanoparticles
were used as a catalytic system. Phthalocyanines (Pcs)
constitute a remarkably versatile and robust class of com-
pounds with diverse technological applications [16e18].
Phthalocyanine transition metal complexes are important
industrial pigments which have been considered as po-
tential oxidation catalysts due to their facile preparation on
a large scale, chemical and thermal stabilities. Metal-
lophthalocyanines have been used as efficient biomimetic
catalysts for the oxidation, reduction, and other reactions of
different organic compounds. However, the low solubility
of metallophthalocyanine catalysts is the most important
problem that is often encountered by the catalyst in
different reactions [8].
The extensive use of toxic and volatile organic solvents
in these oxidation systems has reduced considerably the
practical importance of biologically inspired oxidation
catalysis. The discarding of harmful organic solvents is a
problem in chemical industries which accounts for about
80% of their wastes [13]. Therefore, using non-toxic sol-
vents in aqueous media can play a significant role in these
reactions and a new challenge could be done to make such
a process in aqueous solutions or under solvent free con-
ditions [19e23].
Copper (II) phthalocyanine was synthesized according
to literature procedures [27e30]. Then, copper phthalocy-
anine nanoparticles up to 42 nm were prepared pursuant to
the following procedures. Briefly, 0.15 g CuPc was first
dissolved in 5 ml 98% concentrated sulfuric acid, and then
the solution was added drop-by-drop into a 300 ml
aqueous solution containing 0.45 g hexadecyltrimethyl
ammonium-bromide in an ultrasonic ice-water bath.
Isolation of phthalocyanine nanoparticles from a solution
phase was done by using a simple centrifuge.
The obtained nanoparticles were washed immediately
with hydrochloric acid twice, to remove bromide and then
washed with deionized water three times. The final prod-
ꢀ
uct was dried at 40 C under vacuum.
Characterization of copper (II) phthalocyanine nano-
particles was performed with a SEM as shown in Fig. 1
[31,32]:
Confirmation of the catalyst structure was done by
elucidating UV (Fig. 2). Fig. 2 shows the absorption spec-
trum of CuPc and its related nanoparticles. Other metal
phthalocyanines have very similar absorption spectra in
the visible spectral region; these bands were assigned to
p
/p transitions of the macrocyclic p-system [33].
Nanoinorganic materials are an interesting subject of
research because of their unique physical and chemical
properties [24]. Over hundred papers describing inorganic
nanoparticle reactions with different materials have
appeared in chemical literature studies in recent years.
Nanoparticles have recently emerged as efficient alterna-
tives for the immobilization of homogeneous catalysts.
Nevertheless, difficulties in recovering the nanoparticles
from the reaction mixture result from effective dispersion
in solution by forming stable suspensions, which limit their
wide applications [25,26].
In continuation of our interest in exploring the oxida-
tion of organic compounds [27e30], this study aims to
report a mild and effective heterogeneous strategy for the
aqueous oxidation of alcohols by n-Bu4NHSO5 and copper
(II) phthalocyanine as catalysts (Scheme 1). However, to the
best of our knowledge, the use of copper (II) phthalocya-
nine nanoparticle catalysts for the oxidation of alcohols has
not been previously reported.
Fig. 1. SEM images of copper (II) phthalocyanine nanoparticles with average
diameters of 42 nm.
Please cite this article in press as: S. Kheirjou, et al., Selective aqueous oxidation of alcohols catalyzed by copper (II) phthalo-