Sodium toluene-4-sulfonate as a reusable and ecofriendly catalyst for greener synthesis of 5-aminopyrazole-4-carbonitrile in aqueous medium

Article abstract of DOI:10.1002/jhet.4077

In these environmentally conscious days there is need to use eco-friendly greener technologies, such as solvent free, microwave, ultrasound and use of room temperature. Here report an efficient and green protocol for the synthesis of 5-aminopyrazole-4-carbonitrile from three component condensation of phenyl hydrazine, aldehyde, and malononitrile using NaPTS as catalyst in aqueous medium. Use of water has emerged as a versatile solvent for organic reaction; it is readily available, inexpensive, environmentally benign, neutral and natural solvent. Multicomponent reactions in water are of outstanding value in organic synthesis and green chemistry. The significant features of this article are short reaction time, provide excellent yield, removal of toxic solvent and use of water as green solvent.

Full text of DOI:10.1002/jhet.4077

Sodium toluene-4-sulfonate as a reusable and ecofriendly catalyst for Greener Synthesis
of 5-aminopyrazole-4-carbonitrile in aqueous medium
Aboli Sapkal, Santosh Kamble*
Department of Chemistry, Yashavantrao Chavan Institute of Science (Autonomous), Satara,
Maharashtra, India
Email: santosh.san143@gmail.com
Abstract:
In these environmentally conscious days there is need to use eco-friendly greener technologies,
such as solvent free, microwave, ultrasound and use of room temperature. Here report an
efficient and green protocol for the synthesis of 5-aminopyrazole-4-carbonitrile from three
component condensation of phenyl hydrazine, aldehyde, and malononitrile using NaPTS as
catalyst in aqueous medium. Use of water has emerged as a versatile solvent for organic reaction;
it is readily available, inexpensive, environmentally benign, neutral and natural solvent.
Multicomponent reactions in water are of outstanding value in organic synthesis and green
chemistry. The significant features of this article are short reaction time, provide excellent yield,
removal of toxic solvent and use of water as green solvent.
Keywords: Green Synthesis, Hydrotrope, Aqueous medium, Pyrazole.
Introduction:
[1]
Heterocyclic compound having a significant & unique position in medicinal chemistry
.
Synthesis of such heterocyclic compound have acquired high priority in the pharmaceutical
field[2-4] because they shows a wide range of interesting biological activities, such as
antimicrobial[5], anti-inflammatory[6], antioxidant[7] , antiviral[8], antibacterial[9], anticancer[10]
,
anticonvulsant[11] , cardiovascular[12], antihypertensive[13], antipyretic[14], antibiotic[15], anti-
hyperglycemic activity[16]. Among these heterocyclic compounds, the five membered
heterocyclic aromatic ring compound having lots of applications in pharmaceutical field [17-18]
.
Out of which Nitrogen-containing five membered heterocyclic are abundant in natures and they
This article has been accepted for publication and undergone full peer review but has not been
through the copyediting, typesetting, pagination and proofreading process which may lead to
differences between this version and the Version of Record. Please cite this article as doi:
10.1002/jhet.4077
This article is protected by copyright. All rights reserved.

are present in various biological motifs & they having great significance to life because of their
structural units present in many natural products such as vitamins, nucleic acids, amino acid,
herbicides, and dyes [19]. Therefore, for the synthesis of such heterocyclic compound several
methods are presented including multi-component reactions (MCRs) [20-23]. Synthesis by MCRs
is more accepted aspect because it is effective, required less energy, decrease cost, time &
generation of by-products [24-28]. Therefore, the formation of new MCRs with green procedure
has attracted more attention, especially in the field of medicinal chemistry, organic synthesis and
material science [29-32]. Synthesis of heterocyclic scaffolds is performed via MCRs in the presence
of various green tools & catalyst gives good results [33-38]
.
Out of which Pyrazole is one of the good example of Nitrogen containing heterocycles which is
biologically active class of compound [39]. Therefore pyrazole derivatives are synthesized by
many ways such as using sodium ascorbate [40], CuO/ZrO2 recyclable catalyst [41], prepared by
using 1,3 diketone, acid chloride in base and organic solvent[42], it is also prepared by using other
catalyst such as Sc(oTf)3[43], zirconium sulfophenyl phosphate [44] , Y-zeolite [45] , Zn[L-proline]2
[46]
[48]
, H3PW12O40 [47], eosin-Y
& potassium phthalimide (PPI) [49]. All this reported
methodologies require harsh reaction conditions viz. organic solvent, metal framework catalyst,
acids and also bases but this reaction conditions are not sustainable to the environment,
expensive, hazardous, time consuming. Therefore now days researchers focused on develop
[50]
more eco-friendly, less hazardous, environmentally safe methodologies, such as ionic liquid
,
I2 in water [51], 1-methylimidazolium trinitromethanide {[HMIM]C(NO2)3}as a nano ionic liquid
(NIL) [52], PEG-400 and water under ultrasound waves [53] but preparation of ionic liquid & other
solvent are also little costly & cause environmental issue therefore we use here hydrotrope in
these synthesis which can full fill some of the conditions of green chemistry that is
environmentally safe, less hazardous, cost effective, easy handling, no any toxic solvent, that is it
is sustainable to environment [54]
.
Recent development shows Pyrazole derivatives have attracted more attention due to their
interesting pharmacological properties. This type of hetrocycles can be traced in a number of
well-established drugs belonging to different categories with diverse therapeutic activities. Some
of these drugs mentioned as follows-
This article is protected by copyright. All rights reserved.

Experimental:
General:
All the chemicals required for synthesis were commercially sourced and were used without
further purification. Melting points of products are measured on electrical melting point
1
13
apparatuses. IR spectra were obtained with lambda FT-IR 750 spectrometer. H NMR and C
NMR were recorded on a Bruker 400MHZ spectrometer using CDCl3as solvent and TMS is an
internal standard.
This article is protected by copyright. All rights reserved.

2.1. General procedure for the synthesis of 5-amino-pyrazole-4-carbonitrile:
Take equimolar ratios of malononitrile (1mmol), phenyl hydrazine hydrochloride (1mmol) and
substituted aldehyde (1mmol) in 10ml 40% aqueous NaPTS solution. This reaction mixture
stirred at room temperature for few minutes until the completion of reaction is monitored by
TLC in n-Hexane: Ethyl Acetate (7:3). The solid product separated by simple filtration. The
separated solid product was recrystallized from suitable solvent.
Result and Discussion:
Hydrotropes increases the solubility of sparingly soluble organic compounds [55]. Hydrotropes are
water- soluble and surface active compounds; they significantly increase the solubility of organic
solutes such as esters, alcohols, ketones, aldehydes, hydrocarbons, and fats [56-58]. It acts as carrier
for poorly soluble drugs & non-polar organic compounds [59]. The main feature is nature of
hydrotropes on which reaction medium depends & its minimum hydrotropic concentration
(MHC) above which maximum solubility of reactants. As the hydrotroe increases solubility of
compounds there is direct interaction between reactants those are insoluble in aqueous medium.
The mechanism by which insoluble & sparingly soluble compounds are soluble in water is
aggregation & MHC [60]. There is difference between self aggregation of hydrotrope & micelle
that is presence of minimum hydrotrope concentration (MHC) analogues to critical micelle
concentration (CMC) [61]. Most hydrotropic solutions precipitate the solute on dilution with
[62]
distilled water therefore recovery of product and re-use of hydrotropic solvent is easy
.
Hydrotropes are used for many purposes such as drug solubilization, detergent formulations,
health care, in household applications [63], also used as extracting agent. Overall hydrotrope has
various advantages such as eco-friendly; non-flammable, less toxic, inexpensive that is
hydrotrope follow the green chemistry principle. Therefore here use one of the hydrotrope is
sodium paratoulenesulfonate (NaPTS) for synthesis of Pyrazole derivatives (Scheme-1).
This article is protected by copyright. All rights reserved.

Scheme 1. Synthesis of 5-amino-pyrazole-4-carbonitrile.
CHO
R
NH
R'
N
NH2
NC
aq. 40%NaPTS
R.T.
N
+
+
R'
CN
R
CN
H2N
Table-1.1: Screening of conditions for synthesis of 5-amino-pyrazole-4-carbonitrile:
Entry
Solvent/ Catalyst
Time
Yield
1
2
3
4
Water
48hrs
24hrs
trace
trace
40%
92%
Ethanol
Water + Ethanol(1:1)
Water + 40% NaPTS
24hrs
30 min
Initially focused on selection of green methodology for synthesis of present scheme (Table1.1).
Initially we use water as green solvent but yield was very low and also require long reaction
time, then we choose the another solvent is water: ethanol(1:1) then also yield is poor due to
lower solubility of organic compound in aqueous medium. Then we select hydrotrope that
increase the solubility of sparingly soluble compounds in aqueous medium. Hydrotropes are
surface active agent they increase solubility in many fold access. We select hydrotrope which is
NaPTS at various concentrations out of which 40% NaPTS gives expected yield in 5-10 minutes
at room temperature (Table 1.2). We screen the reaction condition by using reactant as aldehyde
(1mmol), malononitrile (1mmol), and phenyl hydrazine (1mmol) and got the maximum yield in
5ml 40% aq. NaPTS at room temperature. Then use different derivatives of benzalaldehyde with
electron donating and withdrawing group getting good to excellent yields of corresponding
pyrazoles as shown in (Table 1.3).
This article is protected by copyright. All rights reserved.

Table-1.2: Optimization concentration of Hydrotrope for synthesis of 5-amino-pyrazole-4-
carbonitrile:
SR. NO.
Hydrotrope (% w/v)
Temp.(0C)
Time
Yield %
1.
2.
3.
4.
5.
6.
7.
8.
9.
10 % NaPTS
20 % NaPTS
30 % NaPTS
40 % NaPTS
50 % NaPTS
60 % NaPTS
40 % NaPTS
40 % NaPTS
40 % NaPTS
240C
240C
240C
240C
240C
240C
500C
800C
1000C
24 hrs
180 min
100 min
30 min
100 min
100 min
60min
-
10
50
92
90
85
70
70
75
80 min
100 min
The plausible mechanism of the product formation is conceptualized in Fig1. The water added to
hydrotrope, water molecules hydrate the hydrotrope head groups & decreasing the electrostatic
attraction between these groups. The two head groups move apart and displace the water
molecules interacting hydrophobic parts. This may be the driving force for two hydrophobic
parts to interact and force the reactant molecule to solubilize & get interact with each other. Then
water molecules get eliminated & easily absorbed by the hydrophilic head groups. As a result, of
the overall effect there is a rate enhancement of the reaction & reaction proceeds in aqueous
medium due to hydrotropism.
This article is protected by copyright. All rights reserved.

Fig.1. A Plausible reaction mechanism for synthesis of 5-amino-pyrazole-4-carbonitrile in
aqueous hydrotropic medium.
Recyclability of Hydrotrope:
The reuse of catalyst is very important step in synthesis because reuse of catalyst directly effects
on cost & also environment. Therefore easy recovery & reuse of catalyst is necessary these is
possible by using hydrotrope, because it is reuse only after the reaction is complete, filter the
product & give washing to product & collect the filtrate along with product because that filtrate
contain the hydrotrope, then keep the filtrate for evaporation after that our catalyst i.e.
hydrotrope is recover & which is ready for reuse. We check the recyclability of that hydrotrope
by 5 times obtain the good result with loss of small amount of yield which is shown in fig. 2.
This article is protected by copyright. All rights reserved.

Fig.2 Recyclability of Hydrotrope.
This article is protected by copyright. All rights reserved.

Table-1.3: Synthesis of 5-amino-pyrazole-4-carbonitrile derivatives in 40% hydrotrope in
aqueous medium.
M.P. ( oC)
Entry
Aldehyde
Product
Yield (%)
CHO
N
N
156-158
92
1
CN
H2N
Cl
CHO
N
127-128
175-177
158-160
92
92
92
2
3
4
N
Cl
CN
H2N
NO2
CHO
N
N
O2N
CN
H2N
CHO
N
N
NO2
H2N
O2N
CN
OMe
CHO
N
106-109
160-162
90
80
5
6
N
MeO
CN
H2N
CHO
OH
N
N
H2N
HO
CN
This article is protected by copyright. All rights reserved.

CHO
OMe
OMe
7
128-130
92
N
OMe
N
MeO
OMe
H2N
OMe
CN
CHO
MeO
OMe
N
OH
N
120-122
130-132
104-106
92
90
8
9
H2N
CN
OH
CHO
Cl
Cl
N
Cl
N
H2N
Cl
CN
NMe
CHO
N
92
10
N
CN
NMe2
H2N
CHO
Cl
N
CH3
N
124-126
121-123
92
H2N
Cl
CN
Me
11
12
CHO
MeO
OMe
92
N
OMe
N
OMe
CN
H2N
This article is protected by copyright. All rights reserved.

HO
CHO
Br
N
OH
13
178-180
80
N
Br
CN
H2N
Spectroscopic data for some target compounds are as follows:
1) 5‑Amino‑1,3‑diphenyl‑1H‑pyrazole‑4‑carbonitrile(1):
White solid, melting point: 156-158oC. IR (KBr): ῡ = 3320.82, 3290, 2930, 2210, 1580, 1600,
1240 cm-1. 1H NMR (400 MHz, CDCl3): δppm 6.87 (d, 1H ), 7.11(dd, 2H), 7.13-7.26(m, 5H),
7.37(d,1H), 7.65(S, 2H), 7.68(d,1H). 13C NMR (100MHz CDCl3): δppm 112.71, 120.07,
126.15, 128.40, 128.58, 129.28, 135.26, 137.24, 143.33, 144.61, 144.75, 146.80.
2) 5-amino-3-(2-hydroxyphenyl)-1-phenyl-1H-pyrazole-4-carbonitrile(6):
Yellow solid, melting point: 160-162oC. IR (KBr): υ= 3446.17, 3320.82, 3207.04, 2927,
1
2188.81, 1598.70, 112.79, 1150.01 cm-1. H NMR (400 MHz, CDCl3): δppm 6.90-7.00 (m,
13
4H), 7.15-7.49 (m, 5H), 7.83 (s, NH2), 10.84 (s, 1H). C NMR (100MHz CDCl3): δppm
112.58, 116.57, 118.46, 119.46, 120.86, 129.52, 129.53, 129.99, 135.26, 137.24, 141.17,
143.33, 146.61, 156.98.
3) 5-amino-3-(4-nitrophenyl)-1-phenyl-1H-pyrazole-4-carbonitrile(3):
Red solid, melting point:175-177oC. IR (KBr): υ 3467.38, 3303.43, 2950, 2360.11, 1580.70,
1
1210.05, 750.17 cm-1. H NMR ( 400 MHz, CDCl3): δppm 6.95 (d, 1H), 7.15-7.26 (m, 5H),
7.78 (S, NH2), 7.98 (d, 1H),8.23 (dd, 2H). 13C NMR (100 MHz,CDCl3): δppm 112.60, 119.81,
124.43, 125.76, 126.96, 127.52, 129.01,130.51, 130.74, 132.81, 144.54, 146.59.
This article is protected by copyright. All rights reserved.

4) 5-amino-1-phenyl-3-(3,4,5-trimethoxyphenyl)-1H-pyrazole-4-carbonitrile(7):
Cream colour solid, melting point:128-126oC.IR (KBr): ῡ = 3413, 3364, 2930, 2220, 1610,
1
1245, 1140 cm-1. H NMR (400 MHz, CDCl3): δppm 3.930 (s, 3H), 3.389 (s, 6H), 6.88 (d,
13
2H, ArH), 7.19-7.28 (m, 5H, ArH), 7.66(s, 2H). C NMR (100MHz CDCl3): δppm 112.60,
117.57, 119.46, 121.07, 127.2, 129.4, 130.7, 137.9, 143.2, 148.12, 150.0, 154.7.
5) 5-amino-3-(4-methoxyphenyl)-1-phenyl-1H-pyrazole-4-carbonitrile(5):
Light brawn solid, melting point:106-109oC. IR (KBr): ῡ = 3446.17, 3320.82, 292741,
1
1598.17, 1480.17, 1272.78, 1159.01, 750.04. H NMR (400 MHz, CDCl3): δppm 3.910(S,
3H), 6.89(d, 2H, ArH), 7.60(d, 2H, ArH), 7.30-7.60(m, 5H, ArH), 7.71(s, 2H). 13C NMR
(100MHz CDCl3): δppm 53.6, 112.60, 114.8, 116.34, 121.20, 126.2, 127.4, 129.01, 129.85,
130.07, 145.8, 152, 155.
6) 5-amino-3-(4-chlorophenyl)-1-phenyl-1H-pyrazole-4-carbonitrile(2):
Cream colour solid, melting point: 127-128oC. IR (KBr): ῡ = 3446.17, 3313.11, 2229.11,
1
1594.84, 1488.78, 1255.43, 748.25. H NMR (400MHz, CDCl3): δppm 7.45-7.68 (m, 4H,
ArH), 7.30-7.60 (m, 5H), 7.72 (s, 2H). 13C NMR (100MHz,CDCl3): δppm 118.45,120.86,
122.4, 126.5, 127.98, 129.25, 129.88, 130.45, 133.23, 144.46, 148.01, 153.01.
Conclusion:
The present protocol describe environmental friendly synthesis of 2-amino Pyrazole 5-
carbonitrile. Due to harsh reaction conditions dangerous side effect on environment need to
develop such safe methods therefore here we use hydrotrope in aqueous medium which is a
green methodology. These methodogy having lot of advantages such as less hazardous, cost
effective, time saving and mild reaction condition. Present protocol suggests a promising green
approach for the synthesis of 5-aminopyrazole-4-carbonitrile.
SUPPORTING INFORMATION
Supporting information may be found online in the Supporting Information File of this article.
This article is protected by copyright. All rights reserved.

Acknowledgment:
We gratefully acknowledge the financial support from the Rayat Institute of Research and
Development (RIRD) and Y.C.I.S. Satara (Autonomous). As well as Department of Science
Technology–Science and Engineering Research Board (DST-SERB) and University Grants
Commission (UGC) as major research project.
ORCID
Santosh B Kamble https://orcid.org/0000-002-4668-1628
References:
1] A. Majumder, R. Gupta & A. Jain. Green Chemistry Letters and Reviews 2013, 6, 151.
2] F. Hosseini & M. Mohammadi-Khanaposhtani & H. Azizian & A. Ramazani & M. B.
Tehrani & H. Nadri & B. Larijani & M. Biglar & H. Adibi & M. Mahdavi. Structural
chemistry 2020, 31, 999.
3] M. Khoobi, S. Emami, G. Dehghan, A. Foroumadi, A. Ramazani and A. Shafie. Arch.
Pharm. Chem. Life Sci. 2011, 344, 588.
4] S. T. Fardooda, A. Ramazania, F. Moradniaa, Z. Afsharia, S. Ganjkhanlua, F. Y. Zarea.
Chemical Methodologies 2019, 3, 632.
5] R. Nagamallu, A. K. Kariyappa. Bioorganic & Medicinal Chemistry Letters 2013, 23,6404.
6] S. Prekupec, D.Makuc, J. Plavec, L. Suman, M. Kralj, K. Pavelic, J. Balzarini, E.D. Clercq,
M. Mintas, S. Raic-Malic, J. Med. Chem. 2007, 50, 3037.
7] N. Renuka , H. K. Vivek , G. Pavithra , and K. Ajay Kumar. Russian Journal of Bioorganic
Chemistry 2017, 43, 197.
8] S.Mavel , J. L. Renou, C. Galtier , R. Snoeck, G. Andrei, J. Balzarini, E. D. Clercq, and A.
Gueiffier . Arzneim.-Forsch./Drug Res. 2001, 51, 304.
9] S. Emami ,A. Foroumadi , M. A. Faramarzi , and N. Samadi. Arch. Pharm. Chem. Life Sci.
2008, 341, 42.
10] D. Havrylyuk , L. Mosula , B. Zimenkovsky , O. Vasylenko , A. Gzella , R. Lesyk.
European Journal of Medicinal Chemistry 2010, 45, 5012.
11] S. N. pandeya , A. S. Raja. J Pharm Pharmaceut Sci. 2002, 5, 266.
This article is protected by copyright. All rights reserved.

12] A. V. Velikorodov, I. N. Tyurenkov, M. V. Timchenko and V. N. Perfilova. Pharmaceutical
Chemistry Journal 2006, 40, 8.
13] A. Ma. Vela´zquez , L. Martı´nez , V. Abrego , M.A. Balboa , L.A. Torres , B. Camacho ,
S. Dı´az-Barriga , A. Romero , R. Lo´pez-Casta~nares , E. Angeles. European Journal of
Medicinal Chemistry 2008, 43, 486.
14] N. Uramaru, H. Shigematsu, A. Toda, R. Eyanagi, S. Kitamura and S. Ohta. Journal of
Medicinal Chemistry 2010, 53, 8727.
15] M. A. Wegman, M. H. A. Janssen, F. V. Rantwijk, R. A. Sheldon.Advance Synthetic
Catalysis 2001, 343, 559.
16] G. R. Bebernitz, G. Argentieri, B. Battle, C. Brennan, B. Balkan, B. F. Burkey, Michele
Eckhardt, Jiaping Gao, Prasad Kapa, R. J. Strohschein, H. F. Schuster, M. Wilson, and D.
D. Xu. J. Med. Chem. 2001, 44, 2601.
17] I. Yavari and A. Ramazan. Synthetic Communications 1997, 27, 1385.
18] H. Aghahosseini, A. Ramazani, K. Ślepokura, T. Lis. Journal of Colloid and Interface
Science 2018, 511, 222.
19] H. Aghahosseini, A. Ramazani, N. S. Jala er, . Ranjdoost, A. Souldozi, K. Ślepokura and
T. Lis. Org. Lett. 2019, 21, 22.
20] S. Gupta, M. Lakshman. Journal of Medicinal and Chemical Sciences 2019, 2, 51.
21] A. Ramazani, A. Rezaei, A. T. Mahyari, M. Rouhani, and M. Khoobi. Helvetica Chimica
Acta 2010, 93, 2033.
22] A. Ramazani and A. R. Kazemizadeh. Current Organic Chemistry 2011, 15, 3986.
23] A. Ramazani, Y. Ahmadi, M. Rouhani, N. Shajari, and A. Souldozi. Heteroatom
Chemistry 2010, 21, 368.
24] S. T. Fardood, A. Ramazani, Z. Golfar, S. W. Joo. Applied Organometallic chemistry
2017, 31, 3823.
25] . Hosseinzadeh & A. Ramazani & H. Ahankar & K. Ślepokura & T. Lis. Silicon 2018,
11, 2169.
26] A. Ramazani, A. T. Mahyari, M. Rouhani, A. Rezaei. Tetrahedron Letters 2009, 50,5625.
27] A. Ramazani, M. Rouhani, S. W. Joo. Ultrasonics Sonochemistry 2016, 28, 393.
28] A. Ramazania, S. T. Fardooda, Z. Hosseinzadeha, F. Sadrib, S. W. Joo. Iranian Journal of
Catalysis 2017, 7, 181.
This article is protected by copyright. All rights reserved.

29] A. Ramazani, M. Khoobi, A. Torkaman, F. Z. Nasrabad, H. Forootanfar, M. Shakibaie,
M. Jafari, A. Ameri, S. Emami, M. A. Faramarzi, A.Foroumadi, A. Shafiee. European
Journal of Medicinal Chemistry 2014, 78, 151.
30] H. Ahankar, A. Ramazani, K. Ślepokura, T. Lisb and S. W. Joo. Green Chem. 2016,18,
3582.
31] J. Taran, A. Ramazani, H. Aghahosseini, F. Gouranlou, R. Tarasi, M. Khoobi & S. W.
Joo. Phosphorus, Sulfur, and Silicon and the Related Elements 2017, 192, 776.
32] Z. Hosseinzadeh, A. Ramazani, N. Razzaghi-ASL3, K. Slepokura, T. LI. Turk. J.
Chem. 2019, 43, 464.
33] H. Aghahosseinia, A. Ramazania. Eurasian Chem. Commun., 2020, 2, 410.
34] S. F. Motevalizadeh, M. Khoobia, A. Sadighic, M. Khalilvand-Sedagheha, M.
Pazhouhandeh, A. Ramazani, M. A. Faramarzie, and A. Shafiee. Journal of Molecular
Catalysis B: Enzymatic 2015, 120,75.
35] S. Rezayati, A. Ramazani. Res Chem Intermed. 2020, 46, 3757.
36] N. Varnaseri, F. Rouhani, A. Ramazania, A. Morsali. Dalton Transactions 2020, 49,
3234.
37] N. Fattahi, K. Triantafyllidis, R. Luque and A. Ramazani. Catalysts 2019, 9, 758.
38] E. Gholibegloo, T. Mortezazadeh, F. Salehian, H. Forootanfar, L. Firoozpour, A.
Foroumadi, A. Ramazani, M. Khoobi. Journal of Colloid and Interface Science, 2019,
556, 128.
39] P. N. Kalaria, S. P. Satasia and D. K. Raval. RSC Adv. 2014, 4, 32353.
40] H. Kiyani , M. Bomdad. Res chem Intermed. 2018, 44, 2761.
41] S. Maddila, S. Rana, R. Pagadala, S. Kankala, S. Maddila, S. B. Jonnalagadda. Catalysis
Communications 2015, 61, 26.
42] S. T. Heller & S. R. Natarajan.Organic Letters 2006, 6, 2675.
43] W. Xiong , J. X. Chen, M.C. Liu, J. C. Ding, H. Y. Wu, W. K. Su . J Braz.Chem.Soc. 2009,
20, 367.
44] M. Curini, O. Rosati, V. Campagna, F Montanari , G. Cravotto, M. Boccalini. Synlett
2005, 19, 2927.
This article is protected by copyright. All rights reserved.

45] R. Sreekumar, R. Padmakumar. Synthetic Communicaton 1998, 28, 1661.
46] M. Kidwai , A. Jain, R. Poddar . Journal of Organometallic Chemistry 2011,696, 1939.
47] X. Chen, J. She, Z. Shang, J. Wu, H. Wu, P. Zhang. Synthesis 2008, 21, 3478.
48] S. Yadav, P. Rai, M. Srivastava, J. Singh, K. P. Tiwaria and J. Singh. Tetrahedron Letters
2015, 56, 5831.
49] H. Kiyani & M. Bamdad. Hetrocycles 2017,94, 276.
50] M. Srivastava, P. Rai, J. Singh and J. Singh. RSC Adv. 2013, 3, 16994.
51] M. Srivastava, P. Rai, J. Singh and J. Singh. New J. Chem. 38, 302.
52] M. A. olfigol, F. Afsharnader , S. Bagher , S. Salehzadeh and F. Maleki. RSC Advances
2012, 5, 7555.
53] F. Nemati, S. H. Nikkhah, A. Elhampour. Chinese Chemical Letters 2015, 26, 1397.
54] M. Barge ,S. Kamble , A. Kumbhar , G. Rashinkar , R. Salunkhe. Monatsh Chem. 2013,144,
1213.
55] S. B. Kamble, A. S. Kumbhar, S. N. Jadhav and R. S. Salunkhe. Procedia Material
Science 2014, 6,1850.
56] V. G. Gaikar, P.V. Phathak. Sep. Sci. Technol. 1999, 34, 439.
57] S. E. Friberg, Hydrotropes. Surf. Sci. 1997, 2, 490.
58] X. Chen, J. C.Micheu. J. Colloid Interface Sci. 2002, 249,172.
59] N. S.Tavare, V. K. Jadhav. Chem. Eng. Data 1996, 41, 1196.
60] G. Horvath-Szabo, Q. Yin, S. E. Friberg. Colloid Interface Sci. 2001, 236, 52.
61] D. Balasubramanian, V. Shrinivas, V. G. Gaikar, M. M. Sharma. J. Phys. Chem. 1989, 93,
3865.
62] Mckee, H. Ralph. Journal of Industrial and Engineering Chemistry 1946, 38, 382.
63] S. E. Friberg, C. Brancewicz. Langmuir 1994,10, 2945.
This article is protected by copyright. All rights reserved.