J. Chil. Chem. Soc., 61, Nº 1 (2016)
SiO2@FeSO4 NANO COMPOSITE AS NANOCATALYST FOR THE GREEN SYNTHESIS 1,1-DIACETATES FROM
ALDEHYDES UNDER SOLVENT-FREE CONDITIONS
MOSTAFA KARIMKOSHTEH*1,2, MARZIYEH BAGHERI1, BEHZAD ZEYNIZADEH1
1Department of chemistry, Faculty of Science, Urmia University, Urmia 57159-165, Iran
2Institute of Young Researchers in Nanotechnology, Razavi Khorasan, Mashhad, Iran
ABSTRACT
Aldehydes compounds selective converted to 1,1-diacetates as protective reagent with SiO2@FeSO4 nano composite as effective nano catalyst at room
temperature under solvent-free condition and acetic anhydride (Ac2O) as acetylation reagent. This method provides several advantages, such as low cost of the
nano catalyst, high yields, short reaction time, chemoselective protection of aldehydes and operational simplicity. Aromatic and aliphatic, simple and conjugated
aldehydes were protected with excellent yields. In addition, chemoselective reductive acetylation of aldehydes over ketones was achieved perfectly with the
reagent at room temperature.
Keywords: Aldehydes, 1,1-Diacetates, SiO2@FeSO4 catalyst, Acetic anhydride, Solvent-free
pure products. TLC using silica gel 60 GF254 aluminum sheet was applied for
determination of the purity of substrates and products as well as monitoring
the reaction.
Method1, typical experimental procedure for the preparation of
1,1-diacetates:
In a typical procedure, a mixture of benzaldehyde (106mg, 1mmol), Ac O
(306mg, 3 mmol) and SiO @FeSO catalyst (53mg, 0.25mmol) was stirred2at
room temperature for 10 m2in. After4completion of the reaction, as indicated by
TLC, diethylether was added and the mixture was washed successively with
1 M NaOH solution (10 mL), brine (10 mL) and H2O (10 mL). the organic
layer was separated and dried (Na SO4). Evaporation of the solvent under
reduced pressure furnished almost2 pure product. Further purification was
achieved by column chromatography (silica gel, ethylacetate: hexane = 1:9)
or recrystallization from EOAc: hexane to afford a pure product in 98% yields
(Table 2).
1. INTRODUCTION
The term nanotechnology is employed to describe the creation and
exploitation of materials with structural features in between those of atoms
and bulk materials, properties of materials of nanometric dimensions are
significantly different from those of atoms as well as those of bulk materials.1
Nanocomposite is a multiphase solid material where one of the phases has
one, two or three dimensions of less than 100 nanometers (nm), or structures
having nano-scale repeat distances between the different phases that make
up the material. The properties of nano-composite materials depend not only
on the properties of their individual parents but also on their morphology
and interfacial characteristics. Experimental work has generally shown that
virtually all types and classes of nanocomposite materials lead to new and
improved properties when compared to their macrocomposite counterparts.2,3
In organic reaction protection of functional groups during synthesis
compounds are essential.4 One of the important functional groups is aldehydes,
because of easy converted to other organic groups for examples, alcohol,5
carboxylic acids,6 aldoximes.7 moreover, the diacetates of α,β-unsaturated
aldehydes serve as an important precursor for Diels–Alder reactions. Some
industrial uses of these compounds have also been reported.8 Examples of
the reagents and catalysts that have been developed for this purpose include
SelectfluorTM ,9 MWCNTs-C-PO3H2 ,10 PEG–SO3H ,11 Si-[SbSipim][PF6] ,12 PS/
TiCl4 ,13 ZSM-5-SO3H ,14 [Ti(salophen)(OTf)2]15 and [bmpy]HSO4 .16
2.2. Selected spectral data of the products:
1,1-Diacetoxy-1-(2,4-dichlorophenyl)-methane (1). solid:85-87 oC; IR
(KBr) υmax 3080,3017, 2937, 1763, 1430, 1375, 1235, 1194, 1078 cm-1; 1H
NMR (CDCl3, 300 MHz) δ 2.15 (s, 6H), 7.3-7.33 (m, 1H), 7.43 (s,1H), 7.5-7.53
(d, j=8.4 Hz, 1H), 7.92 (s, 1H); 13C NMR (CDCl , 75.46MHz ) δ 20.64, 86.64,
127.40, 128.73, 129.80, 132.01, 133.89, 136.23, 3168.24.
o
1,1-Diacetoxy-3-phenyl-2-propene (15). solid: 84-86 C; IR (KBr) υ
3030, 2925, 1758, 1626, 1496, 1449, 1244, 1199, 1134, 1064, 997, 750, 6m9a2x
cm-1; 1H NMR (CDCl3, 300 MHz) δ 2.12 (s, 6H), 6.18-6.26 (m, 1H), 6.85-6.9
(m,1H), 7.31-7.55 (m, 6H); 13C NMR (CDCl3, 75.46MHz ) δ 20.89, 89.74,
121.72, 127.02, 128.68, 128.83, 129.07, 135.62, 168.75.
So in the course of our studies with nano catalyst 7 for effective synthesis,
organic compound, we observed that 1,1-diacetates synthesis of aldehydes
efficiently present of SiO2@FeSO4 catalyst at solvent-free condition with high
to excellent yield (Scheme 1). An important advantage of the use of SiO2@
FeSO4 catalyst is the possibility to use a small amount of catalyst.
1,1-Diacetoxy-1-naphthylmethane (16). solid: 114-118 oC; IR (KBr) υmax
3058, 2926, 1762, 1693, 1372, 1238, 1208, 1098, 1051, 1011, 920, 808 cm-1;
1H NMR (CDCl3, 300 MHz) δ 2.16 (s, 6H), 7.47-7.68 (m, 3H), 7.73-7.75 (d,
j=6.9 Hz, 1H), 7.87-7.93 (m, 2H), 8.27 (s, 1H), 8.29 (s, 1H); 13C NMR (CDCl3,
75.46MHz ) δ 20.90, 89.63, 124.14, 124.94, 126.03, 126.07, 126.98, 128.76,
130.29, 130.61, 130.84, 133.96, 168.77.
1,1-Diacetoxy ethane (17). Colorless liquid: 165–168 °C; IR (KBr) υmax
3465, 2984, 2937, 1762, 1433, 1374, 1243, 1123, 1084, 983, 917 cm-1;1H NMR
(CDCl3, 300 MHz) δ 1.28-1.30 (d, j=6.3 Hz, 3H), 1.86-2.17 (m, 6H), 6.85-6.89
(q, j=4.5 Hz, 1H); 13C NMR (CDCl3, 75.46MHz ) δ 20.29, 20.80, 21.19, 87.84,
170.01.
Scheme 1. Synthesis of 1,1-diacetates from aldehydes.
3. RESULTS AND DISCUSSION
2. Experimental procedure:
2.1. Chemicals and apparatus
Herein, we wish to apply SiO @FeSO catalyst in protected aldehyde to
1,1-diacetates compounds under so2lvent-fre4e condition.
Characterization of the SiO2@FeSO4 nano composite was investigated by
scanning electron microscopy (SEM). SEM image of the catalyst exhibited that
the spherical nanoparticles dispersed well (Figure 1).
We first examined the acylation of benzaldehyde usingAc2O in the absence
of SiO2@FeSO4 catalyst. The reaction was sluggish and no corresponding
1,1-diacetate was formed even after many hours. However, in the presence
All reagents and substrates were purchased from commercial sources with
the best quality and used without further purification. SiO2@FeSO catalyst
was prepared with high purity according to the reported procedur4es in the
literature .17 IR spectra were recorded on a Thermo Nicolet Nexus 670 FT-
IR spectrophotometer. 1H and 13C NMR spectra were recorded on a 300 MHz
Bruker Avance spectrometer in 300.13 an 75.46 MHz, respectively, and the
X-ray powder diffraction (XRD) patterns were recorded using Philips APD-
10 X-ray diffracto- meter with Cu Kα radiation. All yields refer to isolated
2780
e-mail: mostafakarimkoshteh@gmail.com