Effect of phosphorus amount on the particle size and catalytic performance of heterogeneous nickel(ii) schiff-base complex in aldol condensation reaction

Article abstract of DOI:10.1080/10426507.2013.787996

The organic-inorganic hybrid of citric acid, tetraethoxysilane (TEOS), and triethylphosphate (TEP) doped by a nickel Schiff-base complex was prepared by sol-gel method. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmittance electron microscopy (TEM), scanning tunnelling microscopy (STM), and infrared spectroscopy (IR). In order to determine the phosphorus amount effect on the catalytic activity of the prepared composites, the aldol condensation was used as a model reaction. The results revealed that the composite with 10% phosphorus is a better catalyst in comparison with other composites.

Full text of DOI:10.1080/10426507.2013.787996

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Phosphorus, Sulfur, and Silicon and the Related
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Effect of phosphorus amount on the particle size and
catalytic performance of heterogeneous nickel(II)
Schiff-base complex in aldol condensation reaction
Hossein Eshtiagh-Hosseini a & Taymaz Tabari a
a Dept. of Chemistry, Ferdowsi University of Mashhad, Mashhad, 917751436, Iran
Accepted author version posted online: 05 Apr 2013.
To cite this article: Phosphorus, Sulfur, and Silicon and the Related Elements (2013): Effect of phosphorus amount on the
particle size and catalytic performance of heterogeneous nickel(II) Schiff-base complex in aldol condensation reaction,
Phosphorus, Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2013.787996
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Effect of phosphorus amount on the particle size and catalytic performance of
heterogeneous nickel(II) Schiff-base complex in aldol condensation reaction
Hossein Eshtiagh-Hosseini* and Taymaz Tabari
Dept. of Chemistry, Ferdowsi University of Mashhad, Mashhad 917751436, Iran
Corresponding author:
Tel.: +98 511 8797022; fax: +98 511 8796416
E-mail address: heshtiagh@ferdowsi.um.ac.ir (H. Eshtiagh-Hosseini).
OH
R1
+ M
OH
OH
OM
O
R2CHO
R1
R1
O
R1=Me, R2=Ph, M= Catalyst
Abstract
The organic-inorganic hybrid of citric acid, tetraethoxysilane (TEOS) and triethylphosphate
(TEP) doped by a nickel Schiff-base complex was prepared by sol–gel method. The prepared
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composites were characterized by X-ray diffraction (XRD), scanning electron microscopy
(SEM), transmittance electron microscopy (TEM), scanning tunnelling microscopy (STM), and
infrared spectroscopy (IR). In order to determine the phosphorus amount effect on the catalytic
activity of the prepared composites, the aldol condensation was used as a model reaction. The
results revealed that the composite with 10% phosphorus is a better catalyst in comparison with
other composites.
Keywords: heterogeneous Schiff-base, Nano powder, green chemistry; aldol condensation.
Introduction
The aldol condensation is widely regarded as one of the most important C–C bond forming
reactions in organic synthesis, and which is generally catalyzed in the presence of strong acids or
bases. Under acidic conditions, an enol behaves as a nucleophile and attacks the active
protonated carbonyl group. Also, the aldol condensation under basic conditions includes the
nucleophilic addition of an enolate ion to another carbonyl group. Under acidic and basic
conditions the product of the aldol condensation can be dehydrated to form α, β-unsaturated
carbonyl compounds. So, either aldol condensation or the dehydration can be catalyzed by
conventional monofunctional catalysts with an acidic or basic center [1–4].
The first acid–base cooperative activation example was inspired in enzyme studies [5–10] and
inspired the recent preparation of bifunctional materials that possess acidic and basic groups. By
attaching both acidic and basic groups onto the surface of a support, these irreconcilable groups
can exist at the same time and concurrently catalyze reactions like an enzyme. The right choice
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of the acid–base couples, involving their strength and the relative position is the key of this
preparation.
Multiple studies have explored the above concepts and designs [11–14]. The acid–base
bifunctionalized SBA-15 catalysts for aldol condensations were prepared via a one pot procedure
with primary alkylamines and various organic acids [12]. The results showed that catalysts
including primary alkylamines in cooperation with carboxylic acid groups were exceptional for
the aldol condensation and pointed out that matching of these components are very important for
total conversion. Furthermore, the amphoteric mesoporous silica including carboxylic acids and
amino groups was prepared and exhibited efficient catalysis for the aldol condensation reaction
[15,16]. On the other hand, the previous studies have mentioned that decreasing the strength of
the acidic part leads to a more efficient aldol condensation with primary alkylamines. Also
silanols can participate in acid–base cooperativity [17,18]. However, silanols on the surface of
pure silica based mesoporous materials are considered very weak acids [19]. Besides, one of the
basic challenges and ultimate goals for the reactions of organic molecules is to carry out the
reactions in water [20, 21] because, instead of organic solvents, water is inexpensive, safe and
leads to the development of environmentally green chemical process [22–23].
In the previous report, we examined physically grafted nickel (II) Schiff-base complex as an
efficient nanocatalyst in oxidation of thiols and alcohols to related products [24]. In this work,
the nickel(II) Schiff-base complex was grafted in the matrices of supports with a different mole
ratio of phosphorus to silica. Then, the effect of the phosphorus amount on the particle size of
composites and catalytic activity was investigated in the aldol condensation reaction. The results
showed that the presence of phosphorus in the supports led to changes in the particle size of the
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composites. Also, by decreasing the particle sizes, the catalytic activity increased. Furthermore,
the related products of aldol condensation obtained reaction with high yields and selectivity over
the catalyst.
Results and Discussion
IR spectroscopy
The spectrum of the heterogeneous Schiff-base complex with various amounts of phosphorus
after heating at 150 °C is given in Figure. 1. The samples showed the broadband at 1077 cm-1
that related to stretching of Si-O-Si bond. The bands at 1100 cm-1 and 1230 cm-1 are due to P-O-
Si and P-O-P vibrations, respectively [25], which indicate the presence of phosphorus in the
silica network. Comparison between the spectra in Fig. 1a and Fig. 1b shows several additional
bands in Fig. 1b. So, two bands appeared in 2929 and 2851 cm−1 are derived from CH2 in the
moiety of ligand. Furthermore, the bands from 1700 to 1750 cm-1 are attributed to the stretching
vibrations of the two kinds of carbonyl in the structure of composite without phosphorus (Fig.
1b). Also, the bands at 1637 and 1400 cm-1 are assigned to vibrational stretching of CN and CS
bonds of the complex in the matrices of support, respectively.
[Insert Figure 1]
XRD analysis
The XRD performed after the composites were heated at 150 °C for 2h and are shown in Fig. 2.
Furthermore, the XRD pattern of grafted complex in the matrices of SiO2 is compared with XRD
pattern of the composites with various amounts of phosphorus. Furthermore, the XRD of the
grafted complex in the matrices of silica shows two peaks at 2θ of 38 and 43. On the other hand,
it seems in the presence of the complex and without phosphorus, the silica phase is broadened
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and amorphous (Fig. 2a). Also, the XRD pattern of the sample with 5% phosphorus shows the
peaks at 2θ of 30, 36 and 43 indicating the presence of nickel complex in the matrices of support.
Also, this pattern shows a peak at 2θ of 21 that related to SiO2-P2O5 matrices (Fig. 2b). Thus, the
presence of phosphorus in the media leads to change in intensity and shift of the peaks at 2θ 38
and 43. Moreover, the peaks of nickel complex were observed in the XRD pattern of composite
with 10% phosphorus at 2θ of 30, 36 and 43. Also, the individual peak of SiO2-P2O5 composite
appeared in 2θ of 21. However, the XRD patterns of composites with 5 and 10 percent
phosphorus are shown different intensity (Fig. 2c). Furthermore, the peaks of complex were
observed in the XRD pattern of composite with 15% phosphorus. Also, the SiO2-P2O5 peak was
observed at 2θ of 21 (Fig. 2d).
The d values of the grafted complexes are relevant to the presence and amount of phosphorus.
The d values of composite in absence of phosphorus is 2.39 Å with 60% intensity, with 5%
phosphorus is 2.65 Å with 48% intensity, with 10% phosphorus is 2.99 Å with 75% intensity and
finally with 15% phosphorus is 4.08 Å with 29.45% intensity. The widening of the lattice
parameter with increasing of phosphorus amounts can be attributed to the interfacial stress that
originates from the lattice mismatch [26]. Powder XRD patterns of grafted nickel (II) complex
show the sharp peaks that indicate the crystalline phase existence. The crystallite sizes were
calculated using XRD peak broadening of the (110) peak using Scherer's formula:
0.9
(1)
Dhkl

hkl coshkl
Where Dhkl (nm) is the particle size perpendicular to the normal line of (hkl) plane, βhkl is the full
width at half maximum, θhkl (Rad) is the Bragg angle of (hkl) peak, and λ (nm) is the wavelength
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of X-ray. The calculated particle size of grafted Schiff-base complex in composite matrices with
various amounts of phosphorus was around 8-30 nm. The XRD pattern showed high crystalline
phase in all composites but the composite with 10% phosphorus showed higher crystalline phase
than other composites, which might lead to higher catalytic activity.
[Insert Figure 2]
SEM
In order to analyze the morphology of the composites surface before and after the addition of
phosphorus, SEM micrographs were used. As shown (Fig. 3a), the catalyst was loose, and had
various caves, holes, pores and channels with different shapes and sizes in every particle, and
each particle irregularly consisted of several smaller particles. In addition, as shown in Fig. 3b
the morphology of surface of catalyst changed completely with the addition of 5% phosphorus
Furthermore, in Fig. 3c, 10% phosphorus composite, the surface morphology shows micropores
with ordered shape and different size. Also, in Fig. 3d, the surface morphology in the presence of
15% phosphorus was changed in comparison with other composites and had different pores in
shape and size.
[Insert Figure 3]
TEM
TEM observations of the silica/nickel complex and the composites reveal that most of the nickel
complex particles are dispersed within the matrix and their size distributions are quite narrow
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(Fig. 4). The average size of nickel complex particles evaluated from measurements on the TEM
micrographs was 5~25 nm. There was also a great difference in the average size of the particles
among the composites in the presence or absence of phosphorus. In the composite without
phosphorus, crystallinity is low and the average size of particles is not clear (Fig. 4a). As shown
in Fig. 4b, with 5% phosphorus, the crystallinity of the matrices is increased and the average size
is 5-10 nm but the distribution of particles is not ordered. On the other hand, in Fig. 4c with 10%
phosphorus, crystallinity is high and the particle distribution is totally ordered with average size
of 5 nm. Moreover, in the presence of 15% phosphorus (Fig. 4d), the average size is 20nm, and
the particle distribution is ordered. Furthermore, TEM clearly showed that there were many
microspores and secondary channels between the layers of the catalyst, which would increase the
surface area and provide enough space for substrate access to the active sites of catalyst, which
might be one of the main factors for excellent catalytic activities and properties of the
heterogeneous catalysts. On the other hand, the much more catalytic activity of the composite
with 10% phosphorus is relevant to smaller and fine distribution particles of nickel complex.
[Insert Figure 4]
STM
STM images (1000 nm×1000 nm) of composite nanoparticles (Fig. S 1 Supplemental Materials)
can be used to determine the particles size and height. The distribution of particles on the surface
of composite without phosphorus are mapped obviously and the height of the bright spots is
higher than the dark ones (Fig. S 1a). Five particles were selected for quantitative measurements
and results showed that their average size and height obtained were around 25 nm and 22 nm,
respectively (Fig. S 1b). Also, the distribution of particles obviously mapped in the composite
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with 5% phosphorus and the height of bright dots is higher than dark dots (Fig. S 1c). Five
particles were selected for particle size measurements and revealed that their average size and
height were around 12nm and 2nm, respectively (Fig. S 1d). Also, the distribution of particles on
the surface of composite with 10% phosphorus are mapped clearly and the height of bright dots
is higher than dark dots (Fig. S 1e). Three particles were selected for particle size measurements
and the average size and height obtained were around 7nm and 2nm, respectively (Fig. S 1f).
Moreover, the distribution of particles on the surface of the composite with 15% phosphorus are
mapped clearly and the height of the bright spots is higher than dark spots (Fig. S 1g). Six
particles were selected for particle size measurements and the average size and height obtained
was around 14nm and 5.8 nm, respectively (Fig. S 1h). The results revealed that the particle size
of composites is reduced by loading of phosphorus to the media of composites. Also, in the
composite with 15% of phosphorus, the average size of particles is increased in comparison with
the composite with 10% phosphorus.
Catalytic Properties
The aldol condensation of benzaldehyde with acetophenone was investigated. The control
experiment elucidated that no condensation product could be obtained in the absence of catalyst.
Then, the aldol condensation was examined using the catalysts in the protocols of the Scheme 1.
The aldol condensation carried out for optimization of the reaction variables such as amount of
phosphorus in catalyst, temperature, appropriate amount of catalyst and length of the reaction
time.
[Insert Scheme 1]
Effect of phosphorus amount
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The effect of phosphorus amount in catalytic performance was examined in the aldol
condensation. Also, the selectivity of the chalcone was studied at room temperature by varying
the amount of phosphorus in the catalyst at the constant amount of benzaldehyde and
acetophenone. At various amounts of phosphorus in catalyst, different conversion rates and
selectivity were observed (Table 1). For example, in the absence of phosphorus, conversion of
benzaldehyde was 40%, which increased up to 80% by increasing the amount of phosphorus to
5% in the catalyst. Also, when the amount of phosphorus increased to 10%, the conversion of the
benzaldehyde increased up to 100%. However, when the amount of phosphorus increased to
15%, the conversion was decreased, but the selectivity was as same as 10% phosphorus. The
conversion rate of benzaldehyde and acetophenone to chalcone was increased with further
increasing amount from 5% to 10%. On the other hand, in the presence of catalyst with 15%
phosphorus no more conversion was occurred. The selectivity also followed the similar trend.
The maximum selectivity (100%) of chalcone was observed in the presence of 10% Phosphorus.
Therefore, the composite with the 10% phosphorus was used as catalyst of aldol condensation
for next reactions. In regards to XRD, TEM and STM results, decreasing the particle size of the
composite with 10% phosphorus leads to an increase of catalytic activity.
[Insert Table 1]
Effect of temperature
The effect of temperature on aldol condensation of benzaldehyde and acetophenone was
◦
monitored by varying the reaction temperature from 15 to 75 C at a constant amount of
benzaldehyde and catalyst (Table. 2). The higher conversion of benzaldehyde and acetophenone
◦
(100%) with 100% selectivity of chalcone was observed at 55 C. The conversion of
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benzaldehyde in the aldol condensation in lower temperatures was also observed but the
conversion rate and selectivity were low. No more conversion and selectivity was observed at
higher temperatures.
[Insert Table 2]
Recyclability of catalyst
The used catalyst was regenerated by washing with water and ethanol. The regenerated catalyst
was used for the aldol condensation of benzaldehyde and acetophenone under similar condition.
From the data given in Fig. 5, it is observed that the catalyst was reproducible up to nine cycles
without any significant loss in its activity for aldol condensation of benzaldehyde.
[Insert Figure 5]
Effect of catalyst amount
The effect of amount of catalyst on the conversion and selectivity of chalcone was studied by
varying the amount of catalyst at constant amount of benzaldehyde at room temperature. At e
lower amount of catalyst, the lower conversion of benzaldehyde was observed (Table. 3). For
example, using 0.02 g of catalyst, resulted in 50% conversion of benzaldehyde which, by
increasing the amount of catalyst to 0.05 g, increased conversion up to 80%. However, further
increases in the amount of catalyst to 0.1 g, the conversion of the benzaldehyde increased up to
100%. By increasing the amount of catalyst to 0.2 g And more, also provides 100% conversion,
but the time that required to complete the reaction is the same as 0.1 g catalyst. The selectivity of
the chalcone also followed the similar trend. The maximum selectivity (100%) of chalcone was
observed in the range of 0.1–0.2 g of catalyst. The comparative study of the catalytic activity
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between the reported composite and the immobilized nickel salt in the silica network were
carried out. The results showed that the composite has higher catalytic activity than grafted
nickel salt. The aldol condensation studied in the optimal condition showed higher yields of
products (Table 4).
[Insert Table 3]
[Insert Table 4]
Further studies are needed to clarify the mechanism of the reaction. However, by analogy with
iron carbonyl-mediated reactions, it is possible to consider a process via π-oxa allyl intermediates
and:or η1-oxygen bound catalyst enolate, which can either be trapped by an aldehyde or just
undergo a tautomerization to give the saturated ketone (Scheme 2). There is ample literature
precedence for π-oxa-η1 equilibria, the later depending on the ligands and the metal [27]. Further,
η1-oxygen bound catalyst enolate have already been prepared by another route and have also
been engaged in catalytic aldol reactions [28]. Based on the experimental results the proposed
mechanism for the aldol condensation in the presence of catalyst can be summarized as in
Scheme. 2.
[Insert Scheme 2]
Experimental
Chemicals were purchased from Merck, Aldrich and Fluka Chemical Companies. All yields refer
to isolated products. The reactions were monitored by thin‐layer chromatography (TLC) carried
out on silica plates. The products were characterized by comparison of their physical data with
those of known samples or by their spectral data. 1HNMR spectra were recorded in CDCl3 as the
solvent and TMS as internal standard. Also, The physicochemical characteristics of the
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composites were investigated by transmission electron microscopy (TEM), Scanning Electron
Microscope (SEM), scanning tunnelling microscopy (STM), X-ray diffraction analysis (XRD)
and IR spectroscopy.
Preparation of S-ethyl-β-N-(benzylidene)dithiocarbazate
Carbon disulfide (6.1 mL, 0.1 mol) was added to a cold mixture of hydrazine hydrate (5 mL, 1
mol) and KOH (5.6 g, 1 mol) in 20 mL of absolute ethanol making two phases. Then, ethyl
bromide (7.8 mL, 0.1 mol) is added slowly to the reaction mixture. Benzaldehyde (10.6 mL, 0.1
mol) solution in absolute ethanol (15 mL) was mixed with the above solution .The mixture was
heated on a water bath for approximately 1 h and then left to stand overnight. The yellow product
was separated by filtration, washed with ethanol and dried in a vacuum desiccator over silicagel.
The compound was recrystallized from ethanol [24].
Preparation of bis(S-ethyl-β-N-(benzylidene)dithiocarbazate)-nickel(II) complex
Nickel(II) nitrate hexahydrate (0.07 g; 0.22 mmol) in boiling ethanol (15 mL) was added to the
ethanolic solution of the ligand (0.1 g; 0.45 mmol) . The mixture was heated in a water bath for
30 min and left to stand overnight. The brown product was filtered off, washed with ethanol,
dried in a vacuum desiccator over silica gel [24].
Preparation of Nickel Schiff-base complex doped in porous P2O5–SiO2
The porous P2O5–SiO2 matrices were prepared by sol–gel method. Tetraethoxysilane (TEOS),
citric acid, triethylphosphate (TEP), Nickel Schiff-base complex, NH3.H2O, N,N-
dimethylformamide (DMF) and C2H5OH were used as starting materials. First, TEOS was pre-
hydrolyzed in H2O, DMF, NH3 and EtOH in the volume ratios of 1.5:1:0.015:0.0075:2 at
ambient condition. After vigorous stirring for 1 h, different amounts of TEP according to
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TEP/TEOS (mol%) in the starting compositions were mixed with the hydrolyzed sol. Then, citric
acid kept at 20 wt% of TEP/TEOS was added to the above solution. The obtained sols were kept
at 50 °C for gelation and drying. The dried hybrid gels were pulverized into fine powders, and
then heat-treated at 150 °C for 2 h to remove organic components and residual water. The
micropores and mesopores were appeared as citric acid was removed. Organic inorganic hybrid
was then added to Schiff-base complex solution, under a constant Si/Ni molar ratio of 1/0.01.
The mixture was stirred overnight, and the solvent was removed using a rotary evaporator, then
the resulting olive green solid dried at 80ºC overnight. The product was washed with MeOH and
water until the washings were colorless. Further drying of solid product was carried out in an
oven at 80ºC for 8h. X-ray diffraction (XRD) pattern was recorded by an X-ray diffractometer
(Bruker D8 Advance) in 2θ range 20–60◦ using Cu Kα radiation of wavelength λ = 0.154 nm.
Nanostructural studies were performed using TEM and SEM techniques.
General procedure for aldol condensation
In a typical reaction, benzaldehyde (1mmol) and deionized water (5mL) were mixed in a 25cm3
glass batch. Subsequently, the catalyst powder (0.1 g) and acetophenone (1mmol) were added to
start the catalytic reaction. The progress of the reaction was monitored by TLC (eluent: ethyl
acetate/ n-hexane, 1:4). The catalyst was separated by a simple filtration and product was
obtained in high purity after evaporation of solvent. The final products were identified with the
1
1H NMR. H NMR (100 MHz, TMS, CDCl3) data are as follows: 7.72 (d, J = 16.0 Hz, 1H),
7.28–7.60 (m, 5H), 7.95–8.05 (m, 5H).
Conclusion
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In summary, nano-crystalline Ni(II)Schiff-base doped P2O5-SiO2 composites were
successfully prepared by sol-gel method using citric acid and subsequent thermal treatment
process. A peer study on the structural, morphological and catalytic properties of Ni(II)Schiff-
base doped P2O5-SiO2 composites was performed by various analytical techniques. XRD and
microscopic analysis indicate the catalyst that prepared by thermal treatment of the gel precursor
°
at 150 C, have suitable crystallinity. In addition, the present investigation has shown that the
synthesized Ni(II)Schiff-base doped P2O5-SiO2 composites can be a favorable material to C–C
bond-forming reactions in a wide range of aldehydse and ketons as initial materials. The
processing parameters such as amount of catalyst, the effect of various solvents, temperature and
different oxidant can all affect the C-C forming reaction. The results show that the prepared
powders could effectively formed C-C bond in high yield. Also the yield of the reaction with
stirring 30-180 minutes was 85-98% using 0.1 g/ 5 mL of catalyst. Moreover, this catalytic
system is clean, safe and operationally simple and also the yields of the products are high, so the
method meets the needs of contemporary green chemistry and is suitable for practical synthesis.
Acknowledgment
The authors acknowledge the financial support of Ferdowsi University of Mashhad (P/548).
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Figure 1: FTIR spectra of neat complex (a) and nickel(II) Schiff-base complex/ P2O5-SiO2
composites without phosphorus (b), Composite with 5% phosphorus (c), Composite with 10%
phosphorus (d) and Composite with 15% phosphorus (e).
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Figure 2: XRD pattern of nickel(II) Schiff-base complex/ P2O5-SiO2 composites. Composite
without phosphorus (a), Composite with 5% phosphorus (b), Composite with 10% phosphorus
(c) and Composite with 15% phosphorus (d).
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Figure 3: SEM image of nickel(II) Schiff-base complex/ P2O5-SiO2 composites. Composite
without phosphorus (a), Composite with 5% phosphorus (b), Composite with 10% phosphorus
(c) and Composite with 15% phosphorus (d).
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Figure 4: TEM image of nickel(II) Schiff-base complex/ P2O5-SiO2 composites. Composite
without phosphorus (a), Composite with 5% phosphorus (b), Composite with 10% phosphorus
(c) and Composite with 15% phosphorus (d).
Figure 5: Recyclability diagram of the catalyst
O
O
O
catalyst, rt
H2O
Ar
R2
R1
R2
Ar
H
R1=Ar, Me
R2= Ar, Me, Et, H
Scheme 1: Aldol condensation reaction
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OH
R1
+ M
OH
OH
OM
O
R2CHO
R1
R1
O
R1=Me, R2=Ph, M= Catalyst
Scheme 2: Mechanism of aldol condensation in the presence of catalyst
Table 1: Effect of phosphorus amount (by percent) on conversion and selectivity.
Selectivity%
Entry P% Conversion%
chalcone 3-hydroxy-1,3-diphenylpropan-1-one
1
2
0
5
40
80
60
40
0
100
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3
4
10
15
100
65
100
100
0
0
Reaction conditions: benzaldehyde and benzophenone = 1mmol, catalyst = 0.1g, T = 55 ◦C, time
= 1 h.
Table 2: Effect of reaction temperature on conversion and selectivity
Selectivity%
Entry T(°C) Conversion%
chalcone 3-hydroxy-1,3-diphenylpropan-1-one
1
2
3
4
5
6
7
15
25
35
45
55
65
75
40
65
30
30
70
70
50
20
0
80
50
100
100
100
100
80
100
100
100
0
0
Reaction conditions: benzaldehyde and benzophenone = 1mmol, catalyst = 0.1 g, time = 1 h.
Table 3: Effect of catalyst amount (by weight) on conversion and selectivity.
Selectivity%
Entry Catalyst (g) Conversion%
chalcone 3-hydroxy-1,3-diphenylpropan-1-one
1
0.02
30
70
30
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2
3
4
5
6
7
8
0.04
0.05
0.07
0.08
0.10
0.15
0.20
50
70
75
85
25
15
10
10
0
85
90
90
90
100
100
100
100
100
100
0
0
Reaction conditions: benzaldehyde and benzophenone = 1mmol, T = 55 ◦C, time = 1 h.
Table 4: Aldol condensation reaction
Entry
Substrate1
Substrate2
Time(min) Yield%
1
2
Acetophenone
Acetophenone
Acetophenone
Acetophenone
4-chlorobenzaldehyde
4-methoxybenzaldehude
4-nitrobenzaldehyde
2-hydroxybenzaldehyde
30
60
25
55
75
70
45
95
160
80
98
90
98
95
90
85
95
90
85
95
3
4
5
Acetophenone 3,4-dimethoxybenzaldehyde
6
Acetophenone
Acetophenone
Acetone
4-bromobenzaldehyde
benzaldehyde
7
8
4-chlorobenzaldehyde
4-methoxybenzaldehude
4-nitrobenzaldehyde
9
Acetone
10
Acetone
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11
12
13
14
Acetone
Acetone
Acetone
Acetone
2-hydroxybenzaldehyde
3,4-dimethoxybenzaldehyde
4-bromobenzaldehyde
benzaldehyde
145
180
180
115
90
85
80
90
Reaction conditions: catalyst = 0. 1g, solvent = H2O, T = 55 ◦C.
Supplemental Materials
Figure S 1: STM image of Composite without phosphorus.
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Figure S 2: STM images of nickel(II) Schiff-base complex/ P2O5-SiO2 of the composite without
phosphorus in the area of 1000 nm×1000 nm, Height profile along the white line.
Figure S 3: STM image of Composite with 5% phosphorus.
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Figure S 4: STM images of nickel(II) Schiff-base complex/ P2O5-SiO2 of the composite with
10% phosphorus in the area of 1000 nm×1000 nm, Height profile along the white line.
Figure S 5: STM image of Composite with 10% phosphorus.
Figure S 6: STM images of nickel(II) Schiff-base complex/ P2O5-SiO2 of the composite with
10% phosphorus in the area of 1000 nm×1000 nm, Height profile along the white line.
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Figure S 7: STM image of Composite with 15% phosphorus.
Figure S 8. STM images of nickel(II) Schiff-base complex/ P2O5-SiO2 of the composite with
15% phosphorus in the area of 1000 nm×1000 nm, Height profile along the white line.
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Figure S 9: 1H-NMR spectra of (E)-1-(4-methoxyphenyl)-3-phenylprop-2-en-1-one.
Figure S 10: 1H-NMR spectra of chalcone.
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