A green solid acid catalyst 12-tungstophosphoric acid H3[PW12O40] supported on g-C3N4 for synthesis of quinoxalines

Article abstract of DOI:10.1007/s11164-020-04200-0

A green Keggin-type heteropoly-12-tungstophosphoric acid, (H₃[PW₁₂O₄₀].12H₂O) supported on graphitic carbon nitride g-C₃N₄ (HPW/g-C₃N₄-40), was developed for one-pot s

Full text of DOI:10.1007/s11164-020-04200-0

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-020-04200-0
A green solid acid catalyst 12‑tungstophosphoric
acid H3[PW12O40] supported on g‑C3N4 for synthesis
of quinoxalines
Murugan Kumaresan1 · Vadivel Saravanan1 · Ponnusamy Sami2 ·
Meenakshisundaram Swaminathan1
Received: 19 April 2020 / Accepted: 19 June 2020
© Springer Nature B.V. 2020
Abstract
A green Keggin-type heteropoly-12-tungstophosphoric acid, (H3[PW12O40].12H2O)
supported on graphitic carbon nitride g-C3N4 (HPW/g-C3N4-40), was developed for
one-pot synthesis of quinoxaline derivatives from 1,2-diketone and 1,2-diamines.
Use of green solvent, heterogeneous reaction condition, simple workup procedure,
short reaction time and reusability of the catalyst are the advantages of this protocol.
Keywords Heteropoly acid · Graphitic carbon nitride · Solid acid catalyst ·
Quinoxalines · Water as solvent
Introduction
Reactions that are performed in water have captured increased interest in synthetic
organic chemistry, and many researchers are attracted toward the use of green
solvent, environmentally friendly catalyst to reduce the environmental pollution
[1]. Development of water-tolerant solid acid catalysts gained much attraction as
they can be separated by simple fltration and recycled [2–4]. Quinoxalines, nitro-
gen-containing heterocyclic compounds, have received great attention because
of their possible applications in biological and material science. Fascinatingly,
quinoxaline derivatives show various biological activities such as antibacterial,
anti-infammatory [5, 6], anticancer [7], antiviral [8] and kinase inhibitors [9].
They have been reported for their applications in dyes [10], pharmaceuticals [11,
*
Meenakshisundaram Swaminathan
m.swaminathan@klu.ac.in
1
Nanomaterials Laboratory Department of Chemistry, International Research Center,
Kalasalingam Academy of Research and Education (Deemed To Be University), Tamil Nadu,
Virudhunagar, Krishnankoil 626126, India
2
Department of Chemistry, V.H.N.S.N. College (Autonomous), Tamil Nadu,
Virudhunagar 626001, India
Vol.:(0123456789)
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M. Kumaresan et al.
12], organic semiconductors [13, 14] and chemically controllable switches [15].
The diversifed biological responses and materialistic applications of the quinoxa-
line derivatives have attracted many researchers to investigate new protocols for
the synthesis of these derivatives through a simple eco-friendly and green route.
A number of methods for the synthesis of quinoxaline derivatives with diferent
catalysts I2 [16], acetic acid [17], MnO2 [18], POCl3 [19], zeolites [20], cerium
ammonium nitrate [21] and CuSO4. 5H2O [22] have been reported. In most of the
above methods, problems such as handling and disposal of inorganic acids and
hazardous solvents occur. It throws much light on the development of alternative
green catalysts for the synthesis of quinoxalines. Economic and green catalysts
are heterogeneous solid acid catalysts, which have chemical stability, non-toxic-
ity, non-corrosiveness, high selectivity, reusability and easy separation eliminat-
ing harsh work-ups.
Phosphorous acid anchored and sulfonic acid functionalized mesoporous mate-
rials were explicitly used as solid acid catalysts in organic synthesis [23–29].
The Keggin heteropoly acids (HPAs) possess hierarchical structures, and their
primary structure corresponds to the cluster heteropolyanion [PW12O40]3− (diam-
eter of the cluster equal to ca. 10 Å). The Keggin HPA has been explored widely
in catalysis due to its strong Bronsted acidity and its redox properties [30]. The
secondary structure of HPAs possesses counter cations and water molecules, and
acidic protons bridge these water molecules, which make HPAs as strong Bron-
sted acid catalyst. But these HPAs with transition metal oxygen clusters have low
specifc surface area [31]. Hence, the dispersion of HPA on solid supports will be
much useful to enhance its catalytic activity. Choice of the support has a strong
efect on the activity of the composite. Graphite carbon nitride has gained sig-
nifcant attention in diferent felds such as photocatalysis, solar cells, sensing,
solar fuel production and catalysis because of its structure and fascinating elec-
tronic properties [32–37]. The tri-s-triazine ring structure and the high degree of
condensation make graphite carbon nitride highly stable with respect to thermal
and chemical attack. Thermal gravimetric analysis (TGA) on g-C3N4 reveals its
thermal stability up to 600 °C even in the air [38–40]. Graphite carbon nitride
(g-C3N4) was reported to be an efcient solid acid catalyst for the condensation
of anthranilamide with aldehydes or ketones for one-pot synthesis of 2,3-dihy-
droquinazolin-4(1H)-ones in good to excellent yields [41]. Sulfamic acid gra-
phitic carbon nitride (g-C3N4/NHSO3H) was used for the synthesis of quinazoline
derivatives by the condensation reaction of benzaldehyde, 2‐ aminotetrazole and
dimedone [42]. Graphitic carbon nitride was reported to be a good hydrophilic
material [43]. A good dispersion of the HPAs occurs on a hydrophilic surface and
increases its activity, but on a hydrophobic support dispersion of HPAs decreases
and lowers its activity and selectivity [44]. This stimulated our interest to prepare
HPA supported on C3N4 for the synthesis of quinoxaline derivatives. Moreover,
hybrid of two solid acid catalysts can provide synergic and cooperative behaviors
toward clean and favorable products with high yields. In the present work, we
developed a solid acid catalyst heteropoly acid H3[PW12O40].12H2O supported on
graphitic carbon nitride (g-C3N4) and report a simple method for the synthesis of
quinoxaline derivatives in a green solvent water.
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A green solid acid catalyst 12‑tungstophosphoric acid…
Experimental
Materials and methods
1,2‑Diketones and 1,2‑diamines were purchased from Sigma‑Aldrich and used
without further purifcation.
Fourier transform infrared (FT-IR) spectra were recorded by an IR Afnity-1 Shi-
1
madzu FT-IR spectrophotometer. H and 13C-NMR spectra were recorded on a
Bruker 300 MHz NMR instrument with CDCl3 as solvent and TMS as an inter-
nal reference. Elemental analyses were performed with Elementar Vario EL III
equipment (Elemantar, Germany). High-resolution mass spectrum (HR-MS) of
the selected product was obtained using the maXis Impact 282,001.00081 Mass
Spectrometer (Bruker, Billerica, MA). The powder difraction patterns of the
catalysts were studied using X’Pert–PRO X-ray difractometer with Cu-Kα radi-
ation. HR-SEM and EDX analysis were performed using FEI Quanta FEG250-
High-Resolution Scanning Electron Microscope. Transmission electron micros-
copy (TEM) images are obtained on JEOL Hitachi-600. Brunauer–Emmett–Teller
(BET) surface area analysis was performed from the nitrogen adsorption iso-
therms at 77 K with a Micromeritics Model ASAP 2020 instrument. All sam-
ples were degassed at 383 K under vacuum for 6 h. The average pore diameter
and pore volume were calculated based on the Barrett–Joyner–Halenda (BJH)
method.
Preparation of catalysts
Preparation of heteropoly‑12‑tungstophosphoric acid, H3[PW12O40].12H2O
The parent Keggin anion was prepared by a literature method [45]. In a typical prep-
aration, 1 g sodium tungstate dihydrate (Na2WO4.2H2O) and 0.16 g disodium hydro-
gen phosphate (Na2HPO4.H2O) were dissolved in 15 mL of boiling water. Concen-
trated HCl (8 mL) was added dropwise to this solution with constant stirring. The
resulting suspension was cooled and transferred to a separating funnel, and 20 mL of
diethyl ether was added. The mixture was shaken until three layers were formed on
standing. NaCl crystals was added, and the bottom layer was removed and washed
several times, frst with water, then with ether and then evaporated to dryness with a
slow stream of air over conc. sulfuric acid. The white product, H3[PW12O40].12H2O
(HPW) was obtained.
Preparation of g‑C3N4
The g-C3N4 was prepared by literature method [46]. In a typical synthesis, 5.0 g of
melamine powder was put into a covered crucible, heated to 550 °C and held for 4 h
at a heating rate of 2.2 °C min−1. After the reaction, the alumina crucible was cooled
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M. Kumaresan et al.
to room temperature. The yellow color polymeric g-C3N4 product was then collected
and ground into powder (Yield=3.8 g).
Preparation of H3[PW12O40]/g‑C3N4
A series of HPW supported g-C3N4 catalyst were prepared by varying loading
amount of HPW, namely 5, 10, 20, 30 and 40% on to the g-C3N4 by ultra-sonication
method [47]. In a typical procedure, 0.4 g of HPW was dissolved in 20 mL of water
and 0.6 g of dry g-C3N4 was added to the solution and kept in a sonication bath for
1 h. Then, it was fltered, washed with water, dried in an air oven at 110 °C for 12 h
and calcined at 285 °C for 4 h to give 0.8 g of HPW/g-C3N4-40 with 40% loading
of HPW. In a similar manner, HPW/g-C3N4-5, HPW/g-C3N4-10, HPW/g-C3N4-20
and HPW/g-C3N4-30 were prepared by tuning the weight percentage of HPW and
g-C3N4.
General procedure for the preparation of quinoxaline derivatives
The method for the preparation reported in the literature [22] was followed for the
preparation of quinoxaline derivatives. A mixture of 1,2-dicarbonyl compound
(1 mmol) and 1,2-diamine (1 mmol) was dissolved in water (5 mL). To this clear
solution, catalytic amount (0.03 g) of 40% HPW/g-C3N4-40 was added and the
resulting reaction mixture was stirred at room temperature for about 30 min. The
progress of the reaction was monitored by TLC using petroleum ether–ethyl acetate
(7:3) solvent mixture as eluent. After the completion of the reaction, the reaction
mixture was heated. As the product dissolves in ethanol, the catalyst was separated
easily from the reaction mixture by simple fltration. The product, obtained by the
evaporation of ethanol, was washed several times with water, dried in air oven. By
this way, fourteen quinoxaline derivatives were prepared using various substituted
1,2-diketones and substituted 1,2-diamines.
Results and discussion
Catalyst characterization
Among the HPW/g-C3N4-5, HPW/g-C3N4-10, HPW/g-C3N4-20, HPW/g-C3N4-30
and HPW/g-C3N4-40 catalysts, the catalytic efciency of HPW/g-C3N4-40 was
found to give better yield than others, and therefore, HPW/g-C3N4-40 had been
characterized.
FTIR analysis
The FT IR spectrum of the recrystallized sample of HPW is shown in Fig. 1 which
matches with the IR spectrum of heteropoly-12-tungstophosphoric acid reported
by Rocchiccioli-Deltchef et al. [48, 49]. The main characteristic features of the
Keggin structure are observed at 1080–1060 cm−1 (νas P–Oa), at 990–960 cm−1
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A green solid acid catalyst 12‑tungstophosphoric acid…
Fig. 1 FTIR spectra of HPW, g-C3N4, and 5, 10, 20, 30 and 40% HPW/g-C3N4. HPW-heteropoly-
12-tungstophosphoric acid; g-C3N4-graphitic carbon nitride
(νas M–Od), at 900–870 cm−1(νa M–Od–M) and at 810–760 cm−1 (νas M–Oc–M),
respectively (M = W or Mo). The broad range of absorption band from 3300 to
3000 cm−1 is related to the stretching vibration of NH groups [33]. The peak at
882 cm−1 is for CN heterocyclic triazine units in g-C3N4 [50]. The broadbands
from 1128 cm−1 to 1631 cm−1 can derive from the stretching vibration of CN
heterocycle [51]. The FTIR spectrum of HPW/g-C3N4-40 (Fig. 1) exhibited the
characteristic bands of Keggin-type HPW as well as that of g-C3N4, and the band
positions were slightly shifted to the lower frequency which confrms the impreg-
nation of HPW into the g-C3N4 moiety and thereby confrms the formation of
HPW/g-C3N4-40.
XRD analysis
The powder XRD patterns of g-C3N4 and HPW/g-C3N4 catalysts are illustrated in
Fig. 2. The intense difraction peaks are observed for the g-C3N4 in the 2θ region
of 27.4° (002) corresponding to interplanar stacking peaks of aromatic architecture
[47, 52]. It can be seen that the XRD curve of 5% HPW/g-C3N4 is very similar to
that of g-C3N4·XRD peaks of HPW starts appearing 10% HPW and peaks of both
HPW and g-C3N4 are clearly seen from 20% loading of HPW indicating the high
dispersion of HPW anions on the microporous g-C3N4 support. However, the dif-
fraction intensity of HPW/g-C3N4 is slightly decreased compared to that of pristine
g-C3N4 and small deviation of 2θ value is observed. It clearly suggests the formation
of HPW/g-C3N4. The crystalline size and strain were calculated using Scherrer for-
mula, which are 27.4 nm and 0.02, respectively, for HPW/g-C3N4.
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M. Kumaresan et al.
Fig. 2 XRD patterns of g-C3N4, HPW and 5, 10, 20, 30 and 40% HPW/g-C3N4 catalyst
Fig. 3 HR–SEM images of the a HPW, b, c g-C3N4 and d HPW/g-C3N4-40 catalyst. Note: HPW, heter-
opoly-12-tungstophosphoric acid; g-C3N4, graphitic carbon nitride
1 3

A green solid acid catalyst 12‑tungstophosphoric acid…
SEM analysis
The morphology and surface nature of the g-C3N4 and 40% HPW/g-C3N4-40 were
analyzed by SEM micrographs. Upon impregnation of HPW into the g-C3N4, the
surface was occupied by HPW, which is clearly indicated in Fig. 3. The SEM micro-
graph of HPW/g-C3N4-40 showed the 2D lamellar structure where a good disper-
sion of HPW and spherical particles of g-C3N4 are seen.
Compositional analysis
The elements present in the HPW and HPW/g-C3N4-40 were evidenced by EDX
analysis as depicted in Fig. 4. The EDX results of HPW (Fig. 4a) revealed the
presence of O, W and P. Furthermore, the EDX of HPW/g-C3N4-40 in Fig. 4b
showed the presence of O, W, P, C, N which clearly confrmed the formation of
HPW/g-C3N4-40.
TEM analysis
The surface morphology of HPW/g-C3N4-40 was analyzed by TEM micrographs as
illustrated in Fig. 5. The TEM images at diferent magnifcations of HPW/g-C3N4-40
reveal that HPW particles are uniformly attached to the surfaces of g-C3N4 sug-
gesting the formation of nanocomposite. The corrugated, transparent and ultrathin
sheet-like nanostructures of as-prepared g-C3N4 powder can be visibly observed by
TEM images. The concentric rings in SAED pattern reveal a good crystallinity of
the nanocomposite.
BET analysis
The surface area of HPW supported on g-C3N4 for optimized catalyst HPW/
g-C3N4-40 was determined by the BET method using nitrogen adsorp-
tion–desorption. The g-C3N4 was reported with a type IV isotherm pattern with
Fig. 4 EDX of a HPW and b HPW/g-C3N4-40. Note: HPW, heteropoly-12-tungstophosphoric acid,
g-C3N4, graphitic carbon nitride
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M. Kumaresan et al.
Fig. 5 HR–TEM images of the HPW/g-C3N4-40 catalyst at diferent magnifcations and locations and
SAED pattern
Fig. 6 Nitrogen sorption isotherms (a) and pore size distribution (b) of HPW/g-C3N4-40
a distinct hysteresis loop starting at 0.6 partial pressure, which is characteristic
of mesopores [53]. The HPW/g-C3N4-40 in Fig. 6a also has a type IV hyster-
esis loops starting at 0.4 partial pressure, which designate that the mesoporous
structure of g-C3N4 can be kept after loading HPW. The BET surface area and
pore volume of the HPW/g-C3N4-40 catalyst were found to be 15.338 m2 g−1 and
18.968 cm3 g−1. These results demonstrate that the g-C3N4 support still retains its
mesoporous structure after loading HPW [53, 54].
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A green solid acid catalyst 12‑tungstophosphoric acid…
Table 1 Catalyst screening
Run
Catalyst
Catalyst amount
Yielda%
for one-pot two component
synthesis of quinoxalines
1
2
3
4
5
6
7
g-C3N4
HPW
0.03
0.03
0.03
0.03
0.03
0.03
0.03
58
42
62
74
88
92
98
5% HPW/g-C3N4-5
10% HPW/g-C3N4-10
20% HPW/g-C3N4-20
30% HPW/g-C3N4-30
40% HPW/g-C3N4-40
Reaction conditions: benzil (1 mmol), o-phenylenediamine
(1 mmol), catalyst 0.03 gin water, Stirring at r.t, 30 min
aIsolated yields
Table 2 Efect of solvents on
the condensation reaction of
benzil and o-phenylenediamine
catalyzed by 40% HPW/g-
C3N4-40
Run
Solvent
Yielda (%)
1
2
3
4
5
6
7
8
9
THF
Toluene
DMF
CHCl3
CH3CO2Et
CH2Cl2
CH3CN
EtOH
28
32
74
76
78
82
84
94
92
98
MeOH
H2O
10
Reaction conditions: benzil (1 mmol), o-phenylenediamine
(1 mmol), 40% HPW/g-C3N4-40, 0.03 g in solvent, Stirring at room
temperature, 30 min
aIsolated yields
Synthesis of quinoxlines
Condensation of one mole of benzil (1,2-diketone) with one mole of o-phenylen-
ediamine (1,2-diamine) in water in the presence of catalyst was taken as a stand-
ard reaction for the optimization study for the synthesis of 2,3-diphenylquinoxaline.
The reactions were performed with catalysts g-C3N4, HPW, HPW/g-C3N4-5 (5%
HPW), HPW/g-C3N4-10, HPW/g-C3N4-20, HPW/g-C3N4-30 and HPW/g-C3N4-40.
The results obtained in terms of the yield of product are collected in Table 1, and it
reveals the catalytic ability of HPW/g-C3N4-40 over other catalytic materials, indi-
cating that 40% loading of HPW is optimum for efcient condensation. The 40%
HPW-loaded g-C3N4 catalyst produced 98% yield and 30% HPW-loaded g-C3N4
catalyst produced 92% yield where as the yield of other tested catalysts are compara-
tively low. Hence, 40% HPW-loaded g-C3N4 composite is more efcient than HPW
and g-C3N4 catalysts.
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M. Kumaresan et al.
Table 3 Efect of reusability of
40% HPW/g-C3N4-40 catalyst
on the yield of quinoxalines
Run
Cycle
Yielda (%)
1
2
3
4
5
0
1
2
3
4
98
96
94
88
86
Reaction conditions: benzil (1 mmol), o-phenylenediamine
(1 mmol), 40% HPW/g-C3N4-40, 0.03 g in water, Stirring at r.t,
30 min
aIsolated Yields
Fig. 7 XRD (a) and HR–SEM (b) images of the HPW/g-C3N4-40 reusability of the catalyst. Note: HPW,
heteropoly-12-tungstophosphoric acid; g-C3N4, graphitic carbon nitride
The reaction was also examined in various solvent systems, such as THF, toluene,
DMF, chloroform, ethylaceto acetate, CH2Cl2, CH3CN, ethanol, methanol and H2O.
The results are collected in Table 2. As far as EtOH and MeOH solvent systems are
concerned, the condensation reaction is almost completed with signifcant yield of
product. In case of water solvent system, the completion of reaction took place in
30 min with excellent yield of 98%. Considering the yield and hazardous nature of
the solvents, water was selected as solvent for the present investigation. Further, the
possibility of recycling the catalyst was also examined. After the completion of the
reaction, ethanol was added in excess to extract the organic product.
Reusability of the catalyst
Further, the possibility of recycling the catalyst was also examined. After the com-
pletion of the reaction, ethanol was added in excess to extract the organic product.
The solid catalyst was recovered by simple fltration. The catalyst was washed with
distilled water and ethanol and dried in air oven at 110 °C for 5 h. The catalyst
1 3

A green solid acid catalyst 12‑tungstophosphoric acid…
recovered by this manner was reused directly without any treatment for fve times.
The results conclude that no appreciable loss in catalytic activity was observed
(Table 3). To know the stability of the catalyst during the reusability, we have taken
the XRD and SEM of the used catalyst after the reaction. As shown in Fig. 7a, b,
there is no signifcant change in the structure of the catalyst.
Catalytic activity of 40% HPW/g‑C3N4‑40 toward the synthesis of quinoxaline
derivatives
Based on the results of the optimization study, fourteen quinoxaline derivatives were
prepared by using various substituted 1,2-diketones and substituted 1,2-diamines.
The generalized reaction protocol is depicted as Scheme 1. The products were char-
acterized by melting point measurement, FTIR, 1H and 13C-NMR spectroscopy and
elemental analysis. The results in terms of the reaction times and product yields are
1
listed in Table 4. The analytical data (melting point, FTIR, H and 13C-NMR, ele-
mental analysis data) of the products are given as supplementary material. It appears
that 1,2-diketones substituted with electron-withdrawing groups underwent the reac-
tion in a faster manner and show good yield of products in comparison with 1,2-dik-
etones with electron-donating substituents.
The plausible mechanism proposed for the generation of quinoxaline using 40%
HPW/g-C3N4-40 as catalyst is given as Scheme 2. HPW has very strong Bron-
sted acidity with three labile protons, and it is dispersed on a hydrophilic surface
of g-C3N4. Thermal gravimetric analysis on g-C3N4 reveals its thermal stabil-
ity up to 600 °C [2]. Graphite carbon nitride is also an efcient solid acid catalyst
[41]. Hybrid of HPW and g-C3N4 with 40% HPW-loaded nanocomposite, HPW/
g-C3N4-40, serves as an efcient solid acid catalyst when compared to HPW and
g-C3N4. The condensation reaction of 1,2-diamine with 1,2-dicarbonyl compound
follows the regular acid catalyzed condensation mechanism [55, 58, 59]. It is
assumed that initially 40% HPW/g-C3N4-40 bound the diketone through its acid pro-
ton sites (I) and thereby facilitates the nucleophilic attack of electron-rich nitrogen
Scheme 1 Synthesis of quinoxaline derivatives using 40% HPW/g-C3N4-40 as catalyst
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M. Kumaresan et al.
Table 4 Product and yield of quinoxalines derived by the condensation reaction of various 1, 2-diketones
and 1, 2- diamine compounds using 40% HPW/g-C3N4-40 as catalysta
Entry
Substrates
Product
Yieldb
(%)
1,2-diketones 1, 2- diamines
3a
O
N
N
H2N
H2N
98
O
3b
3c
3d
3e
O
N
N
Cl
H2N
H2N
Cl
96
92
93
96
O
N
N
CH3
O
O
H2N
H2N
CH3
N
N
OCH3
O
O
H2N
H2N
OCH3
N
N
NO2
O
O
H2N
H2N
NO2
CH3
CH3
CH3
H2N
H2N
3f
N
O
O
94
96
N
CH3
CH3
CH3
O
O
N
N
Cl
H2N
Cl
3g
H2N
CH3
CH3
1 3

A green solid acid catalyst 12‑tungstophosphoric acid…
Table 4 (continued)
Entry
Substrates
Product
Yieldb
(%)
1,2-diketones 1, 2- diamines
CH3
CH3
3h
N
N
CH3
O
H2N
H2N
CH3
94
92
O
CH3
CH3
CH3
CH3
3i
3j
N
N
OCH3
O
O
H2N
H2N
OCH3
CH3
CH3
CH3
CH3
N
N
NO2
O
O
H2N
H2N
NO2
96
98
CH3
Br
CH3
Br
3k
N
O
O
H2N
H2N
N
Br
Br
Br
Br
3l
N
N
Cl
O
H2N
Cl
98
O
H2N
Br
Br
Br
Br
3m
3n
N
CH3
O
O
H2N
H2N
CH3
94
96
N
Br
Br
Br
Br
N
N
NO2
O
O
H2N
H2N
NO2
Br
Br
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M. Kumaresan et al.
Table 4 (continued)
aReaction conditions: benzil (1 mmol), o-phenylenediamine (1 mmol), 40% HPW/g-C3N4-40, 0.03 g in
water, Stirring at r.t, 30 min
bIsolated yields
of o-phenylenediamine on electron defcient carbonyl carbons of diketone to form
(II) followed by the removal of two molecules of water to form an adduct (III). In
the fnal step, transfer of protons to 40% HPW/g-C3N4-40 forms the product qui-
noxaline and regenerates the catalyst. Higher efciency of HPW/g-C3N4-40 is due
to the larger number of acidic sites than HPW and g-C3N4. Graphite carbon nitride
plays a vital role in providing a good support and in increasing the acidic sites for
the reaction.
A comparative account of efciency of 40% HPW/g-C3N4-40 with other reported
catalysts for the synthesis of quinoxaline derivatives, namely 2, 3-diphenylquinoxa-
line, is given in Table 5. The data clearly assert the versatility of the present protocol
using 40% HPW/g-C3N4-40 as catalyst over the other catalysts.
Scheme 2. A plausible acid catalyzed mechanism for the synthesis of quinoxaline derivatives using 40%
HPW/g-C3N4-40 catalyst
1 3

A green solid acid catalyst 12‑tungstophosphoric acid…
1 3

M. Kumaresan et al.
Conclusion
The paper describes a simple and efcient method for the synthesis of quinoxa-
line derivatives using a green catalyst heteropoly acid, 12-tungstophosphoric acid,
40% H3[PW12O40].12H2O supported on graphitic carbon nitride (g-C3N4), HPW/g-
C3N4-40. This method ofers several advantages such as short reaction time, excel-
lent yield of products, operational simplicity and the usage of green solvent water.
Easy recovery and reusability of the catalyst make it more advantageous.
Acknowledgements The authors thank the Nanomaterials Laboratory, Department of Chemistry, Inter-
national Research Center, Kalasalingam Academy of Research and Education Krishnankoil, Virudhuna-
gar-626126, India, and The Managing Board of Virudhunagar Hindu Nadars’ Senthikumara Nadar Col-
lege (Autonomous), Virudhunagar 626001, India, and Precision Laboratory for the facilities provided.
References
1. C.J. Li, T.H. Chan, Organic Reactions in Aqueous Media (Wiley, NY, 1997)
2. K. Ravi, B. Krishnakumar, M. Swaminathan, Res. Chem. Intermediat. 41, 5353 (2015)
3. B. Krishnakumar, M. Swaminathan, Catal. Commun. 16, 50 (2011)
4. K. Ravi, B. Krishnakumar, M. Swaminathan, Bull. Chem. Soc. Jpn. 86, 370 (2013)
5. W. He, M.R. Meyers, B. Hanney, A. Spada, G. Blider, H. Galzeinski, D. Amin, S. Needle, K. Page,
Z. Jayyosi, H. Perrone, Bioorg. Med. Chem. Lett. 13, 3097 (2003)
6. Y.B. Kim, Y.H. Kim, J.Y. Park, S.K. Kim, Bioorg. Med. Chem. Lett. 14, 541 (2004)
7. C.W. Lindsley, Z. Zhao, W.H. Leister, R.G. Robinson, S.F. Barnett, D. Defeo-Jones, R.E. Jones,
G.D. Hartman, J.R. Huf, H.E. Huber, M.E. Duggan, Bioorg. Med. Chem. Lett. 15, 761 (2005)
8. M. Loriga, S. Piras, P. Sanna, G. Paglietti, Farmaco Quinoxaline Chem. Part 7(52), 157 (1997)
9. A. Gazit, K. Yee, A. Uecker, F.D. Bohmer, T. Sjoblomd, A. Ostman, J. Waltenberger, G. Golomb, S.
Banai, M.C. Heinrich, A. Levitzki, Bioorg. Med. Chem. Lett 11, 2007 (2003)
10. N.D. Sonawane, D.W. Rangnekar, J. Heterocycl. Chem. 39, 303 (2009)
11. A. Gazit, H. App, G. McMahon, J. Chen, A. Levitzki, F.D. Bohmer, J. Med. Chem. 39, 2170 (1996)
12. U. Sehlstedt, P. Aich, J. Bergman, H. Vallberg, B. Norden, A. Graslund, J. Mol. Biol. 278, 31 (1998)
13. S. Dailey, W.J. Feast, R.J. Peace, I.C. Sage, S. Till, E.L. Wood, J. Mater. Chem. 11, 2238 (2001)
14. D.O. Brien, M.S. Weaver, D.G. Lidzey, D.D.C. Bradley, Appl. Phys. Lett. 69, 881 (1996)
15. M.J. Crossley, L.A. Johnston, Chem. Commun. 1122 (2002)
16. R.S. Bhosale, S.R. Sarda, S.S. Ardhapure, W.N. Jadhav, S.R. Bhusare, R.P. Pawar, Tetrahedron.
Lett. 46, 7183 (2005)
17. Z. Zhao, D.D. Wisnoski, S.E. Wolkenberg, W.H. Leister, Y. Wang, C.W. Lindsley, Tetrahedron.
Lett. 45, 4873 (2004)
18. S.A. Raw, C.D. Wilfred, R.J.K. Taylor, Org. Biomol. Chem 2, 788 (2004)
19. C. Venkatesh, B. Singh, P.K. Mahata, H. IIa, H. Junjappa, Org. Lett 7, 2169 (2005)
20. M.A. Bodaghifard, A. Mobinikhaledi, M. Zendehdel, Z. Ayalvar, Rev. Roum. Chim. 60, 345 (2015)
21. S.V. More, M.N.V. Sastry, C.F. Yao, Green Chem 8, 91 (2006)
22. M.M. Heravi, S. Taheri, K. Bakhtiari, H.A. Oskooie, Catal. Commun. 8, 211 (2007)
23. H. Sepehrmansouri, M. Zarei, M. Zolfgol, A.R. Moosavi-Zare, S. Rostamnia, S. Moradi, Mol.
Catal. 481, 110303 (2020)
24. E. Doustkhah, J. Lin, S. Rostamnia, C. Len, R. Luque, X. Luo, Y. Bando, K.C.W. Wu, J. Kim, Y.
Yamauchi, Y. Ide, Chem. Eur. J. 25, 1614 (2019)
25. F. Jalili, M. Zarei, M. Zolfgol, S. Rostamnia, A.R. Moosavi-Zare, Micropor. Mesopor. Mat. 294,
109865 (2020)
26. M. Zarei, M. Zolfgol, A.R. Moosavi-Zare, E. Noroozizadeh, S. Rostamnia, Chem. Select 3, 12144
(2018)
27. J. Sun, X. Liu, X. Zhu, H. Wang, S. Rostamnia, J. Han, Catalysis 7, 127 (2017)
28. E. Doustkhah, S. Rostamnia, J. Colloid Interface Sci. 478, 280 (2016)
1 3

A green solid acid catalyst 12‑tungstophosphoric acid…
29. S. Rostamnia, E. Doustkhah, J. Mol. Cata.l A-Chem. 411, 317 (2016)
30. N. Mizuno, M. Misono, Heterogeneous catalysis. Chem. Rev. 98, 199 (1998)
31. F.R. Pomilla, F. Fazlali, E.I. Garcia-Lopez, G. Marcìa, A.R. Mahjoub, I. Krivtsov, L.F. Liottae, L.
Palmisano, Mat. Sci. Semicon. Proc. 112, 104987 (2020)
32. J. Xu, G. Wang, J. Fan, B. Liu, S. Cao, J. Yu, J. Power Sources 274, 77 (2015)
33. S. Yan, Z. Li, Z. Zou, Langmuir 25, 10397 (2009)
34. X.L. Zhang, C. Zheng, S.S. Guo, J. Li, H.H. Yang, G. Chen, Anal. Chem. 86, 3426 (2014)
35. Y.P. Yuan, S.W. Cao, Y.S. Liao, L.S. Yin, C. Xue, Appl. Catal. B 140, 164 (2013)
36. X. Chen, J. Zhang, X. Fu, M. Antonietti, X. Wang, J. Am. Chem. Soc. 131, 11658 (2009)
37. A. Rashidizadeh, H. Ghafuri, H.R. EsmailiZand, N. Goodarzi, ACS Omega 4, 12544 (2019)
38. Y. Shi, S. Jiang, K. Zhou, C. Bao, B. Yu, X. Qian, B. Wang, N. Hong, P. Wen, Z. Gui, Y. Hu, R.K.K.
Yuen, Appl. Mater. Interfaces 6, 429 (2014)
39. Y. Wang, X. Wang, M. Antonietti, Angew. Chem. Int. Ed 51, 68 (2012)
40. X. Wang, K. Maeda, A. Thomas, K. Takanabe, G. Xin, J.M. Carlsson, K. Domen, M. Antonietti,
Nat. Mater. 8, 76 (2009)
41. H. Ghafuri, N. Goodarzi, A. Rashidizadeh, M. DouzandegiFard, Res. Chem. Intermediat. 45, 5027
(2019)
42. A. Hassankhani, S. Gholipour Rostamni, Polyhedron 175, 114217 (2020)
43. Y. Zhang, H. Jing, T. Wen, Y. Wang, Y. Zhao, X. Wang, X. Qian, W. Ying, Talanta 191, 509 (2019)
44. E.I. Garcia Lopez, G. Marci, L. Palmisano, I. Kritsov, F. Fazlali, I. Kritsov, A.R. Mahjoub, L.F.
Liotta, F.R. Pomilla, Mat. Sci. Semicon. Proc. 112, 104987 (2020)
45. G.B. Kaufman, P.F. Vartanian, J. Chem. Educ. 47, 212 (1970)
46. K. Katsumata, R. Motoyoshi, N. Matsushita, K. Okada, J. Hazard. Mater 260, 475 (2013)
47. L. Li, L. Li, T. Sun, X. Yu, L. Long, L. Xu, J. Yan, J. Solid State Chem. 274, 152 (2019)
48. C.R. Deltchef, M. Fournier, R. Franck, R. Thouvenot, Inorg. Chem. 22, 207 (1983)
49. C.R. Deltchef, M. Fournier, J. Chem. Soc. Faraday Trans. 87, 3913 (1991)
50. X. Chen, B. Zhou, S. Yang, H. Wu, Y. Wu, L. Wu, J. Pan, X. Xiong, RSC Adv. 5, 68953 (2015)
51. J.G. Yu, S.H. Wang, J.K. Low, W. Xiao, Chem. Phys 15, 16883 (2013)
52. Z. Zhao, Y. Sun, F. Dong, Nanoscale 7, 15 (2015)
53. J.C. Groen, L.A. Pefer, J. Perez-Ramirez, Micropor. Mesopor. Mat. 60, 1 (2003)
54. H. Wang, X. Zhang, J. Xie, Z. Zhang, P. Ma, B. Pan, Y. Xie, Nanoscale 7, 5152 (2015)
55. T.K. Huang, R. Wang, L. Shi, X. Lu, Catal. Commun. 9, 1143 (2008)
56. A.O. Dhokte, M.A. Sakhare, M.K. Lande, B.R. Arbad, J. Kor. Chem. Soc 57, 73 (2013)
57. A. Kamal, K. Suresh Babu, S.M.A. Hussainia Rasala Mahesh, A. Alarif, Tetrahedron Lett. 56, 2803
(2015)
58. A. Gharib, N.N. Pesyan, L.V. Fard, M. Roshani, Am. J. Heterocy. Chem. 1, 13 (2015)
59. J.J. Cai, J.P. Zou, X.Q. Pan, W. Zhang, Tetrahedron Lett. 49, 7386 (2008)
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