TS-1 zeolite as a Lewis acid catalyst for solvent-free one-pot synthesis of 1,3-thiazolidin-4-ones

Article abstract of DOI:10.1007/s11164-018-3599-2

Abstract: Titanium silicate (TS-1) zeolite heterogeneous catalyst is synthesized by the hydrothermally discontinuous method and is characterized by using XRD, SEM, TEM, and NH₃–TPD techniques. The catalytic activity of the TS-1 type zeolite was tested for one-pot solvent-free synthesis of 1,3-thiazolidine-4-ones. The present technique illustrates many benefits, including eco-friendly reaction conditions, environmentally helpful, short response time, simplicity, straightforward separatation, catalyst reusability and high yields of the products. Furthermore, the catalyst was utilized for four recycle reactions and it has been found that the catalyst shows consistent chemical process activity. Graphical abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s11164-018-3599-2

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TS-1 zeolite as a Lewis acid catalyst for solvent-free one-pot
synthesis of 1,3-thiazolidin-4-ones
Sachin P. Gadekar1 Machhindra K. Lande1
•
Received: 14 July 2018 / Accepted: 14 September 2018
Ó Springer Nature B.V. 2018
Abstract
Titanium silicate (TS-1) zeolite heterogeneous catalyst is synthesized by the
hydrothermally discontinuous method and is characterized by using XRD, SEM,
TEM, and NH3–TPD techniques. The catalytic activity of the TS-1 type zeolite was
tested for one-pot solvent-free synthesis of 1,3-thiazolidine-4-ones. The present
technique illustrates many benefits, including eco-friendly reaction conditions,
environmentally helpful, short response time, simplicity, straightforward separata-
tion, catalyst reusability and high yields of the products. Furthermore, the catalyst
was utilized for four recycle reactions and it has been found that the catalyst shows
consistent chemical process activity.
Graphical abstract
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11164-
018-3599-2) contains supplementary material, which is available to authorized users.
&
Machhindra K. Lande
mkl_chem@yahoo.com
1
Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad,
Maharashtra 431004, India
123

S. P. Gadekar, M. K. Lande
Keywords Lewis acid Á Titanium silicate (TS-1) Á 1,3-Thiazolidin-4-ones Á Zeolite
catalyst Á Synthesis
Introduction
In last 2–3 decades, researchers have had much more interest in the synthesis of
heterocyclic (mainly O, N, S, containing) compounds, because of increasing
demand of pharmaceutical products, agrochemicals, veterinary products and use of
everyday life. Also, they are used in sanitizers, antioxidants, as corrosion inhibitors,
as co-polymers, and dyestuff. They are used as catalysts, as well as vehicles in the
synthesis of other organic transformation. Some heterocyclic compounds found in
natural products, antibiotics (penicillins), alkaloids (morphine), etc. have many
applications in heterocyclic moiety [1, 2]. Here, we have synthesized 1,3-
thiazolidin-4-ones heterocyclic compounds, which has much more importance in
medicinal chemistry (Fig. 1).
4-Thiazolidinone derivatives are a promising class of heterocycles, which
represent a class of chemical products with interesting pharmacological and
biological activities such as antidiabetic activity, anticonvulsant, DNA cleavage
[3, 4], anti-histaminic [5], antifungal [6], antihypersensetive [7], anti-infective [8],
antitubercular [9], antiviral [10], anti-cancer, antituberculotic [11, 12], antimicrobial
[13], antioxidant [14], analgesic [15], antiviral, anti-HIV [16, 17], in ibuprofen anti-
inflammatory drugs [18, 19], antimicrobial [20, 21]; toxicological 4-thiazolidinone
derivatives are genotoxically safe [22].
In a recent trend, one-pot synthesis methodology has taken on a major role in
organic transformation attributable to its many benefits including atom economy,
high yield property, minimum latency and least by-products as compared to
classical artificial methods [23]. Nitrogen, sulfur-containing heterocyclics are the
building blocks of natural products and drug molecules; nearly 60% of unique small
molecule drugs contain a nitrogen heterocycle [24, 25]. Considering these wide and
versatile applications, few catalytic methods have been developed for the synthesis
of biologically active 1,3-thiazolidin-4-ones derivatives, such as DIPEA in the
presence of toluene 24–36 h, SnCl2 and acetic acid 14 h [18, 19, 26], nano Cd-Zr4-
[PO4]6, [24, 25], N-methyl pyridinium tosylate [27], ammonium persulfate [28],
ionic liquid [bmim] OH [29], Bi[SCH2COOH]3 [30] acid catalysed [31] silica
supported Co-Fe2O4@SiO2/PrNH2 [32], Y[OTf]3 [33]. Although reported methods
are quite efficient, some suffer from one or more types of limitations such as more
reaction time, harsh reaction conditions, carcinogenic or hazardous materials,
volatile organic/other solvents, homogeneous catalyst separation, low yield and use
of an expensive catalyst. Some of the reported catalysts are not reusable and some
methods require special conditions, such as microwave or sonication, require high
temperature, homogeneous-phase reactions, etc. [29, 34]. Hence, to overcome these
limitations, it is necessary to find sustainable, efficient, eco-friendly and cost
effective protocols for synthesis of 1,3-thiazolidin-4-ones derivatives. So, we have
developed a TS-1 catalyst and firstly reported here a sustainable, eco-friendly, cost
123

TS-1 zeolite as a Lewis acid catalyst for solvent-free…
O
O
tBut
OH
O
S
N
N
HO
S
S
O
N
H2N
tBut
N
R
anti-inflammatory drugs
antihypertensive
agents
Anti -HIV
S
O
O
O
S
O
S
R1
O
N
N
N
N
S
S
HN
O H
N
R1
Br
Cl
Anticancere agents
antimicrobial agents
Anticonvulsant agents
Fig. 1 Biologically important thiazolidin-4-ones derivatives
effective, efficient protocol for synthesis of 1,3-thiazolidin-4-ones derivatives. It has
a heterogeneous solid acid catalyst, as well as strong Lewis and Bronsted acidic
properties [35–37]. Titanium silicate [TS-1] zeolite is an alternative active
heterogeneous Lewis acid catalyst possessing unique properties such as high
surface area, high thermal stability, non-toxicity, reusability, and ease of handling,
hence is utilized in various industrial processes such as oxidation, epoxidation,
alkylation, acylation and cyclic condensation reactions [38–40]. In view of the ever
increasing importance of green/sustainable synthetic protocol, it was aimed to
develop eco-friendly, efficient catalytic methods for organic synthesis.
Experimental
Preparation TS-1
A Lewis acid catalyst, titanium silicate (TS-1), was prepared by using the reported
method [41]. Titanium tetrabutoxide (Ti[OBu)4] 1.16 mL was mixed in 30 mL of
solvent (dry alcohol) and stirred vigorously, Tetraethyl ortho-silicate (TEOS)
24.37 mL and 20% tetrapropyl ammonium hydroxide (TPA-OH) 25 mL was added
with vigorous stirring, resulting mixture was stirred for 10 min at 30–35 °C to
obtain silica sol. The prepared titanium containing gel was added into the silica sol
with constant stirring at 70–75 °C for 60–120 min to remove excess solvent. The
final transparent gel maintained basic pH, and was transferred to the autoclave,
autogenously pressure at 175 °C for 24 h discontinuously, then treated hydrother-
mally under static condition. The solid product was filtered, dried at 100 °C for 1 h,
123

S. P. Gadekar, M. K. Lande
and calcined at 500 °C for 4 h under air atmosphere. The subsequent material was
normally cooled, portrayed and called Lewis acid catalyst titanium silicate (TS-1).
General procedure for one-pot synthesis of 1,3-thiazolidin-4-ones
A mixture of substituted 4-chloro benzaldehydes (0.140 g, 1 mmol), thioglycolic
acid (0.092 g, 1 mmol) and 4-chloro anilines (0.127 g, 1 mmol), 0.05 g of TS-1
catalyst, was magnetically stirred, then gradually the temperature was increased,
and refluxed at 110 °C. The progress of the reaction was monitored by TLC using
ethyl acetate/ether as a solvent system. The reaction mixture was quenched with
crushed ice and extracted with ethyl acetate (3 9 25 mL). Simultaneously, the
catalyst was recovered for next batch reaction. The organic extracts were washed
with brine (3 9 25 mL) and dried over anhydrous sodium sulfate. The solvent was
evaporated under reduced pressure to afford the corresponding crude compounds.
The obtained crude compounds were recrystallized using ethanol to afford pure
products (3a–i).
Results and discussion
In continuation, the synthesised catalyst was characterised by powder X-ray
diffraction patterns of TS-1 calcined at 500 °C, as is shown in Figs. 2 and 3, and
show intense peaks at 2h° = 14.63, 21.81, 22.76, 22.59, 24.04, and 26.62 with
corresponding planes (112), (023), (150), (511), (250), (004). The planes (150) and
(511) indicate the presence of ordered orthorhombic, MFI topology TS-1 framework
[42, 43]. The SEM and TEM images suggest that the prepared catalyst has uniform
spherical particle size and hexagonal shape with ordered morphology; similarly,
they show high acidity, calculated by NH3–TPD analysis, shown in Table 1. For the
synthesised catalyst TS-1, the total acidity (Lewis and Bronsted) is calculated by
using the following formula.
Volume of NH3 Desorbed
Acidity ¼
m mol/gm
22:4256
Optimization of reaction conditions
In order to find the optimum loading of the catalyst in the reaction of 4-chloro
benzaldehydes (1 mmol), thioglycolic acid (1 mmol), 4-chloro anilines (1 mmol),
and TS-1 catalyst, initially, many protic and aprotic solvents and acceptable times
were screened with loading calcined TS-1 catalyst reflux condition, and the results
are summarized in Table 2. A model reaction (3b) has completely different quantity
of calcined TS-1 catalyst screened with reflux condition and the results are
summarized in Table 3. In the absence of a catalyst the reaction didn’t give
satisfactory results of the specified product (3b) within the stipulated time.
However, reaction yields were found more in solvent-free conditions as compared to
other solvents. It has been found that refluxing the reaction mixture at 110 °C for
123

TS-1 zeolite as a Lewis acid catalyst for solvent-free…
3500
3000
2500
2000
1500
1000
500
B
0
10
20
30
40
50
2θ
Fig. 2 Powder XRD pattern of TS-1 calcined at 500 °C
Fig. 3 SEM and TEM patterns of TS-1 calcined at 500 °C
Table 1 Total acidity of TS-1 catalyst
Peak
no.
Temperature
(°C)
Volume (mL/g
STP)
Peak
height
Acidity (mmol/ Total acidity (mmol/
g)
g)
1
2
238.5
423.3
2.99301
7.89957
0.08150
0.04531
0.1334
0.3522
0.4856
123

S. P. Gadekar, M. K. Lande
Table 2 Effect of various
solvents in the synthesis of 3b
Entry
Solvent
Yield (%)a
1
3
4
5
6
7
Water
Trace
35
Ethanol
PEG
40
THF
50
Chloroform
Solvent-free
60
90
aIsolated yield
Table 3 Effect of the amount of
TS-1 on modal reaction 3b
Catalyst (mg)
Time (min)
T (°C)
Yield (%)a
–
500
60
30
30
30
30
60
rt
–
–
110
110
110
110
110
120
Trace
20
10
30
50
70
50
50
90
90
90
aIsolated yield
10–30 min with loading 0.05 g of TS-1 is an appropriate reaction condition for the
synthesis of 1,3-thiazolidin-4-ones derivatives.
In order to explore the scope and importance of the present method, under
optimized conditions, electronically diverse TS-1 catalyst was tested for the
synthesis 1,3-thiazolidin-4-ones derivatives, and the results are summarized in
Table 4. It was found that substituted aryl aldehyde and substituted aniline with
electron donating and withdrawing groups. It was found that the electron
withdrawing groups give maximum yield as compared to the electron donating
groups. After optimizing reaction conditions, efforts have been made towards the
recovery and reusability of the catalyst (Scheme 1).
The plausible reaction mechanism for the formation of 1,3-thiazolidin-4-ones has
been depicted in Fig. 4. (I) A more reactive lone pair of RCHO interacts with Lewis
acid catalyst to enhance electrophilicity and nucleophile RNH2 interacts immedi-
ately. Simultaneously, the catalyst acts as a Bronsted base and accelerates the
reaction to form a carbon–nitrogen bond (C=N) (III). Respectively, the catalyst
again acts as a Lewis acid to interact (III) and enhance electrophilicity (C=N). The
thioglycolic acid –SH group acts as nucleophile. Simultaneously, the catalyst acts as
a Bronsted base to accelerate reaction forward (IV) of intermediates, then rearranges
and cyclization and dehydration give compounds (V), target molecule 1,3-
thiazolidin-4-ones (3a–i).
123

TS-1 zeolite as a Lewis acid catalyst for solvent-free…
Table 4 TS-1 catalyzed synthesis of 1,3-thiazolidin-4-ones derivatives
Entry
Mol. formula product
R
R1
Yield (%)b
M. P. Obs. (°C)
M. P. Lit. (°C)
3a
H
H
89
128–130
129–131 [44]
3ba
Cl
Cl
90
85
167–1688
106–107
168 [46]
Cl
S
N
O
Cl
3c
H
CH3
105–107 [44]
S
N
O
Me
S
3d
3e
NO2
H
90
90
127–130
129–131
105–106 [30]
133–134 [45]
O
N
NO2
H
NO2
S
N
O
NO2
Cl
3f
H
Cl
88
122–123
121–123 [30]
N
S
O
3g
3h
Cl
H
H
86
85
123–124
116–118
123–124 [30]
116–118 [44]
CH3
S
3i
Cl
OCH3
88
154–155
154 [46]
O
N
Cl
OMe
Reaction conditions: substituted aryl benzaldehyde 1,4-chloro aniline 2, and thioglycolic acid 3, and TS-1
(0.05 g) solvent-free
aModel reaction 3b
bIsolated yields
123

S. P. Gadekar, M. K. Lande
R'
O
R
H2N
H
TS-1, Neat.
110oC
+
N
R
R'
O
HOOCCH2SH
S
1
2
3a-i
R= H, Cl, Me, OMe, NO2
R' = H, Cl, OMe, NO2
Scheme 1 The synthetic pathway of compounds 3a–i
H2O
O
O
O
Si
O
O
Ti
O
O
O
Ti
O
O
Si
O
O
H
N
Ar
Ar1
O
O
S
Ar
H
O
(III)
(I)
TS-1
H
O
N
H
OH
Ar1
(II)
O
Ti
O
O
Si
O
OH
H
N
Ar1
O
Ar
N
S
O
O
Ar1
O
O
S
Ar1
O
(V)
(IV)
Ar
S
HO
HN
Ar1
Fig. 4 Proposed reaction mechanism of 1,3-thiazolidin-4-ones in the presence TS-1 catalyst
Fig. 5 Reusability test of TS-1
for synthesis of 3b
90.5
90
89.5
89
88.5
1 recycale 2 recycale 3 recycale 4 recycale
123

TS-1 zeolite as a Lewis acid catalyst for solvent-free…
Table 5 Catalytic performance of different reported catalysts for synthesis of 3b
S. no.
Catalyst
Conditions (°C)
Time (min)
Yield (%)
1
2
3
4
5
6
MCM-41
110
720
300
300
300
30
97 [47]
HClO4–SiO2
H2SO4–SiO2
TfOH–SiO2
Bi[SCH2COOH]3
TS-1
PhMe/100
PhMe/100
PhMe/100
70
85 [48]
55 [48]
72 [48]
75 [30]
Solvent-free, 110
30
90 Our results
Catalyst activation and reusability
Catalysts were insoluble in solvent; therefore, easy to separate and recover by
filtration. After completion of the reaction, catalysts were washed with acetone or
any polar solvent to collect the catalyst, which was then dried at 105 °C under
vacuum for 10 min. Reusability of the catalyst was also investigated for four
successive reaction of model reaction and found that the catalyst has retained almost
consistent activity. The catalyst was recycled (3b modal reaction) for four cycles
without loss of catalytic activity (Fig. 5).
To specify the benefits of planned methodology, results of various reported
strategies are compared with our results and are summarized in (Table 5). It was
found that the TS-1 catalyst promotes reaction more effectively than different
reported methodologies.
Conclusion
In the present study, synthesized Lewis acid catalyst TS-1 zeolite has highly Lewis
and Bronsted acidic sides and excellent catalytic properties. Its catalytic potency
was tested in one-pot solvent-free synthesis of 1,3-thiazolidin-4-ones via cyclic
condensation of various aldehydes, aniline and thioglycolic acid. The present
method offers remarkable advantages over reported methods such as the reusable
nature of TS-1, non-toxicity, non-corrosive nature and excellent yield of 1,3-
thiazolidin-4-ones, which makes the reaction more successful under environmental
benign conditions.
Acknowledgements We are grateful to the head of the Department of Chemistry, Dr. B.A.M., University,
Aurangabad, 431004 (MS), India for providing the laboratory facility. The corresponding author MKL is
thankful to UGC New Delhi (INDIA) for providing grant under major research Project Funding No.
43-184/2014 (SR). The authors are thankful to STIC Cochin and SAIF Chandigarh, IIT Madras
(Department of Chemistry), CDRI Lucknow characterization facilities.
123

S. P. Gadekar, M. K. Lande
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