ZS-1 Zeolite as a Highly Efficient and Reusable Catalyst for Facile Synthesis of 1-amidoalkyl-2-naphthols Under Solvent-Free Conditions

Article abstract of DOI:10.1007/s10562-021-03684-8

Efficient and reusable ZS-1 zeolite as a novel catalyst was successfully synthesized by the hydrothermal method. Characterizations of catalysts were carried out using diverse analysis techniques such as XRD, FT-IR, FESEM, EDAX, HRTEM, BET, and NH₃

Full text of DOI:10.1007/s10562-021-03684-8

Catalysis Letters
https://doi.org/10.1007/s10562-021-03684-8
ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile
Synthesis oꢀ 1‑amidoalkyl‑2‑naphthols Under Solvent‑Free Conditions
1
1
1
1
1
Sudarshan S. Dipake · Sachin P. Gadekar · Premkumar B. Thombre · Machhindra K. Lande · Anjali S. Rajbhoj ·
Suresh T. Gaikwad1
Received: 4 March 2021 / Accepted: 27 May 2021
©
The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2021
Abstract
Efcient and reusable ZS-1 zeolite as a novel catalyst was successꢀully synthesized by the hydrothermal method. Characteri-
zations oꢀ catalysts were carried out using diverse analysis techniques such as XRD, FT-IR, FESEM, EDAX, HRTEM, BET,
and NH TPD. Promoted as an environment-ꢀriendly protocol ꢀor the ꢀacile synthesis oꢀ various substituted 1-amidoalkyl-
3
2
-naphthols through the reaction oꢀ β-naphthol, aldehyde, and amides under solvent-ꢀree conditions. This catalyst provides
many advantages such as shorter reaction times, operational simplicity, reusability, an excellent yield oꢀ the product, ꢀacile
work-up, and easily recoverable. Moreover, the recovered catalyst can be recycled and reused ꢀor the next ꢁve runs without
signiꢁcant loss oꢀ catalytic activity.
Graphic Abstract
Keywords ZS-1 (Zirconium silicate) · 1-amidoalkyl-2-naphthols · Multicomponent reaction (MCR) · Solvent ꢀree
conditions · Zeolite catalyst
1
Introduction
The production oꢀ pesticides, pharmaceuticals, and petro-
chemicals on large scale is responsible ꢀor chemical pollu-
tion in the development oꢀ green chemistry [1]. Nowadays,
the development oꢀ eco-ꢀriendly technologies is the most
laborious task in the contemporary chemistry and chemi-
cal industry. With these objectives, reducing the wastes
*
Suresh T. Gaikwad
gaikwadsuresh12@gmail.com
1
Department oꢀ Chemistry, Dr. Babasaheb Ambedkar
Marathwada University, Auranagabad 431004, Maharashtra,
India
Vol.:(0
1
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3

S. S. Dipake et al.
together with the use oꢀ renewable ꢀeedstocks, environmen-
tally harmless solvents, reagents, and eꢂectively recoverable
catalysts are an important guideline to attain more sustain-
able approaches according to the green chemistry principles
multicomponent reaction (MCRs) under solvent-ꢀree condi-
tion attracted as a new approach ꢀor the synthesis oꢀ biologi-
cally active molecules, without the isolation oꢀ any interme-
diates and thus reducing reaction time with energy resulting
in atom economy and high selectivity [18, 19].
[
2–4].
In this aspect, heterogenous catalysts have been oꢀ great
The synthesis oꢀ amidoalkyl naphthols derivatives is an
attractive example oꢀ these MCRs. 1-Amidoalkyl-2-naph-
thols derivatives bearing 1,3-amino oxygenated ꢀunctional
groups have gained remarkable attention due to their imma-
nent role as essential building blocks ꢀor a variety oꢀ bio-
logically active natural products, potent drugs, and synthetic
pharmaceuticals including several nucleoside antibiotics and
HIV protease inhibitors [20]. In literature survey reveals that
the established method ꢀor the preparation oꢀ amidoalkyl
naphthols has been carried out by a three-component con-
densation oꢀ diverse aldehydes, 2-naphthols and amides in
presence oꢀ a variety oꢀ catalyst such as Ba (PO ) [21],
importance, they can be reused, cheap and one oꢀ the great
advantages is that they avoid the environmental contami-
nation related to commercial catalysts, such as H SO ,
2
4
HF, AlCl , BF , and H PO . Heterogeneous catalysis has
3
3
3
4
emerged as a useꢀul parameter to reduce waste, lower con-
tamination oꢀ the products with the active catalytic species,
avoiding toxic solvents, efcient separations, and recycling
oꢀ the catalysts [5–8]. Zeolite is a heterogeneous catalyst;
current zeolite catalysis research has ꢀocused on the synthe-
sis oꢀ SBA and MCM types oꢀ mesoporous silica. Unꢀor-
tunately, these mesoporous materials have low thermal
stability, poor surꢀace acidity, and restrictive application
as a catalyst or support. Literature study reports that, the
impregnation oꢀ transition metals, such as Ti, Zr, V, Fe, Cu,
Nb, and Mo inside the structure oꢀ some mesoporous sili-
cates ꢀor enhancing the catalytic perꢀormance in epoxidation,
transesteriꢁcation, and alcohol dehydration reactions [9, 10].
Zeolites establish a ꢀamily oꢀ crystalline microporous alumi-
nosilicates will promote many applications in a wide variety
oꢀ ꢁelds in science and technology [11–14]. However, broad-
ened the application oꢀ zeolite as a heterogeneous catalyst,
isomorphic substitution oꢀ isolated zirconium, niobium, and
tantalum metals species in tetrahedral coordination into the
3
4 2
graphene oxide [22], sulꢀonated poly naphthalene [23], sup-
ported heteropolyacid [24], b-CD-BSA [25], MSNs-HPZ-
SO H [26], phosphoric acid [27], NanoAl O [28], p-TSA
3
2
3
[29], NaHSO .SiO [30], and SiO -HClO [31]. However,
4
2
2
4
some oꢀ these reported procedures are not eco-ꢀriendly and
suꢂer ꢀrom one or more disadvantages yet, ꢀor example,
prolonged reaction time, use oꢀ volatile organic solvent,
additional ultrasonic irradiation, tedious work-up, by-prod-
ucts, and use oꢀ toxic, highly acidic, expensive catalysts.
Thereꢀore, it is desirable to introduce clean procedures, and
utilizing eco-benign reusable heterogeneous catalyst ꢀor
the synthesis oꢀ 1-amidoalkyl-2-naphthols derivatives is an
alternative procedure to construct these valuable organic
compounds is still in high demand.
ꢀ
ramework oꢀ silicate conꢀers lewis acid character to these
metal sites [15]. The compositions oꢀ Zirconium silicate are
also constructed to remove toxins, e.g., ammonium ions or
potassium ions ꢀrom the gastrointestinal tract at an elevated
rate without causing unwanted side eꢂects and also useꢀul
in the therapeutic reagent ꢀor the treatment oꢀ hyperkalemia
Herein, to achieve these objectives and continuation
our eꢂort in the synthesis oꢀ novel catalysts and their ef-
ciency in organic synthesis, we have developed a synthetic
strategy to design zirconium silicate and demonstrated its
eꢂectiveness as an efcient catalyst ꢀor the synthesis oꢀ
1-amidoalkyl-2-naphthols via a three-component reaction
oꢀ b-naphthol, various aldehydes, and amides under solvent-
ꢀree conditions. This novel highly reusable and efcient
catalyst exhibited excellent catalytic activity towards the
synthesis oꢀ 1-amidoalkyl-2-naphthols (Scheme 1) and it
possesses several promising ꢀeatures such as high surꢀace
area, good thermal stability, easy handling, easy work-up,
[
16]. Impregnated zirconia-containing material with high
surꢀace area and acidity was used as a catalyst in several
catalytic organic transꢀormation reactions [17]. Among vari-
ous techniques oꢀ green chemistry, multicomponent reac-
tions (MCRs) have been very classic and efcient methods
in modern synthetic chemistry. The Discovery and devel-
opment oꢀ novel and known MCRs are highly compatible
with the aims oꢀ sustainable and green chemistry. One-pot
Scheme 1 General development
ꢀ
or the synthesis oꢀ diꢂerent
1
-amidoalkyl-2-naphthols
1
3

ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile Synthesis oꢀ…
shorter reaction times, and easy puriꢁcation. The catalyst
can be reused without any signiꢁcant loss in catalytic ef-
ciency ꢀor ꢁve consecutive runs oꢀ model reaction.
diameters, acidic sites oꢀ catalyst calculated by NH TPD
3-
and total surꢀace area were measured using the BJH
method.
2
Experimental Section
2.2 Catalyst Preparation
2
.1 Materials and Instruments
ZS-1 (zirconium silicate) zeolites were synthesized by
using a hydrothermal method, which is shown in scheme 2.
Initially, mixed hydroxy precipitates were obtained by
hydrolysis oꢀ tetraethylorthosilicate (TEOS) and zirconium
nitrate salt solutions using tetra propyl ammonium hydrox-
ide (TPAOH) as a mild hydrolysing agent as well as a
structure-directing agent., In a typical procedure, required
amount oꢀ 0.57 g zirconyl nitrate as a zirconia source,
50 ml water and 27 ml oꢀ TPAOH as a structure-directing
regent were mixed. The resulting solution was stirred until
a clear solution was obtained at room temperature. Sub-
sequently, 26 ml oꢀ TEOS as a silica source and 20 ml oꢀ
ethanol were stirred ꢀor 30 min. Finally, the TEOS solution
and zirconia solution was mixed dropwise with vigorous
stirring. Aꢀter that desired volume oꢀ TPAOH was added
until the pH value became 10–12. The suspension was
stirred until the mixture was completely clariꢁed. Aꢀter
aging, the above suspension was transꢀerred in a Teꢃon-
lined autoclave ꢀor 24 h. at 175 °C ꢀor hydrothermal treat-
ment. Aꢀter the crystallization was completed, the crys-
tals were cooled. The obtained white solid product was
ꢁltered, subsequently, washed several times with a large
amount oꢀ DI water until the pH was 8. The obtained solid
product was then dried in a hot air oven ꢀor 2 h at 110 °C
and calcined at 550 °C ꢀor 5 h, suspension was prepared
ꢀor later use.
All chemicals included Tetraethylorthosilicate
TEOS, wt.%, 99.9), Tetra propyl ammonium hydrox-
ide (TPAOH, ~ 40 wt.% in water), anhydrous alcohol
EtOH, wt.%, 99%), Zirconium nitrate (Zr (NO) ), Ace-
(
(
3
tone (marked as ACT, wt.%, 99.5%), The used deion-
ized water (DI water, 18.2 MΩ) was Lab made and all
required organic regent were purchased ꢀrom Merck and
Sigma-Aldrich and used without ꢀurther puriꢁcation. All
the yield reꢀers to an isolated product aꢀter puriꢁcation.
The NMR spectra were recorded on a Bruker Advance
DPX 400 MHz instrument, the spectra were measured
in DMSO-d6 relative to TMS (0.00 ppm), The chemical
shiꢀts are indicated in parts per million (ppm) and tetra-
methyl silane (TMS) was used as an internal reꢀerence.
The powder X-ray diꢂraction patterns were measured with
a Bruker D8 Advance diꢂractometer using Cu-Ka irra-
diation. FE-SEM was taken by a Hitachi S-4160 photo-
graph to examine the shape and size oꢀ Zirconium silicate
zeolite, Elemental composition was recorded on Energy
Dispersive spectroscopy (EDS), High-resolution trans-
mission electron microscopy (HRTEM) were recorded on
JEOL JEM 2100 Plus, Fourier Transꢀorm Inꢀrared (FTIR)
Spectroscopy were recorded on Shimadzu, the speciꢁc
surꢀace area oꢀ catalyst was determined according to the
Brunauer–Emmett–Teller method while average pore
Scheme 2 Schematic diagram
ꢀor the synthesis oꢀ ZS-1 zeolite
1
3

S. S. Dipake et al.
2
.3 General Procedure for the Synthesis
3 Catalyst Characterizations
of 1‑amidoalkyl‑2‑naphthols
The FTIR spectra oꢀ the as-synthesized hierarchical ZS-1
−1
The reaction was carried out at 1 mmol level ꢀor the aryl
aldehyde, benzamide\acetamide (1.3 mmol), b-naphthol
zeolite samples were obtained in the range oꢀ 1300–400 cm
which is shown in Fig. 1. All the peaks exhibited the typi-
cal MFI ꢀramework topology oꢀ zeolite. The IR spectra oꢀ
the synthesized sample clearly showed the characteristic
absorption bands at 1662, 1226, 1068, 798, 626, 547, 428,
(
1 mmol) in the presence oꢀ zirconium silicate catalyst
was stirred at the appropriate time in a 25 ml round bot-
tom ꢀlask (R.B) in an oil bath at 110 °C under solvent-
−
1
ꢀ
ree condition. Progress oꢀ the reaction was monitored
and 401 cm which were assigned to diꢂerent vibrations
oꢀ tetrahedral and ꢀramework atoms in the ZS-1 zeolite.
by thin-layer chromatography (TLC) with ethyl acetate:
ether (4: 6) as a solvent system. Complete disappearance
oꢀ starting material within 30 min was observed by TLC
spots. Aꢀter the completion, the reaction mixture was
cooled to room temperature. 10 ml acetone was added
to the reaction mixture and the catalyst was separated
by ꢀiltration, the contents were poured onto the crusted
ice and the product was precipitated with ice-cold water.
The precipitate was collected by vacuum ꢀiltration and
washed with ice-cold ethanol under vacuum to remove
residual impurities. The crude product was recrystallized
in hot ethanol ꢀor aꢀꢀording the desired 1-amidoalkyl-
−
1
The well-deꢁned IR bands at 798 and 1226 cm region
are characteristic oꢀ symmetric and asymmetric stretching
vibration oꢀ T–O respectively, (where T is Si or Zr) while
−
1
the vibrational band at 547 cm conꢁrms the presence oꢀ a
double ꢁve-ring member oꢀ pentasil structure [32, 33]. The
−
1
sharp absorption band appearing at 798 cm is ascribed to
Si–O–Si symmetric stretching vibration band. The bands
−
1
at 1226 cm have been assigned to the internal asymmet-
ric stretching vibration oꢀ Si–O–T linkage respectively and
−
1
band at 1068 cm was attributed to the asymmetric stretch-
ing vibration or ꢀormation oꢀ Si–O–Zr bonds. [32, 34]. The
−
1
2
-naphthols derivative with a good yield. Later on, the
band around 1068 cm is assigned to the SiO asymmetric
4
separated catalyst was washed several times with acetone
and transꢀerred in an oven ꢀor 2 h at 200 °C ꢀor activation.
The ꢀurther activated catalyst was used ꢀor the next ꢀour
cycles ꢀor Scheme 1.
vibrations oꢀ internal tetrahedra and the band ꢀound around
−
1
820–780 cm corresponds to the symmetric stretching oꢀ
−
1
a T-O. The bands appearing at 626, 563, and 428 cm may
be due to the vibrations oꢀ the Zr-O bending mode. [35, 36]
The powder X-ray diꢂraction patterns oꢀ ZS-1 zeolite
synthesized by a hydrothermal method are shown in Fig. 2.
Fig. 1 FTIR spectrum oꢀ ZS-1
zeolite
1
3

ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile Synthesis oꢀ…
Fig. 2 XRD pattern oꢀ ZS-1
The synthesized materials exhibit the characteristic X-ray
diꢂraction pattern oꢀ the ZSM-5 type and MFI topology
with the peaks at 2θ =7.9°, 8.88°, 14.83°, 23.15°, 23.96°,
Figure 4 shows that the crystals are well-dispersed in the
ZS-1 zeolite sample. Most large crystals have pseudo-hex-
agonally prismatic shapes with crystal sizes oꢀ 1–5 µm. The
high magniꢁcation oꢀ FE-SEM images (Fig. 4a, b) clearly
show that the average length oꢀ a large ZS-1 zeolite crystal
is about 3.58 µm. and thickness is around 592.9 nm.
To get more details, the ZS-1 sample was studied by
High-resolution transmission electron microscopy (HR-
TEM). ZS-1 zeolite shows lattice ꢀringes (micropores) with
consistent regular orientations over the entire crystal region
and some irregular orientations oꢀ lattice ꢀringes observed
are due to the broken mesopores structure (Marked by red
cycle). We can observe that the broad size distribution oꢀ
mesopores 2.2 nm was precisely ꢀormed due to the decom-
position oꢀ several micropores oꢀ 0–1 nm. Based on HR-
TEM images Fig. 4c and d results, it can be concluded that
the micropores and mesopores were dispersed inside a crys-
tal oꢀ ZS-1 zeolite [41–43].
2
4.62°, and 29.95° that are associated with (001), (010),
(
[
200), (220), (022), (221) and (400) planes, respectively
32, 33, 37]. According to international zeolite association
data (IZA), ZSM-5 type zeolite ꢀalls under MFI topological
structure. The intense peak oꢀ ZS-1 observed at 2θ= 7.9°
is very close to the IZA standard data value [38] in Fig. 2.
the ZS-1 sample showed characteristic two diꢂraction peaks
between 6 and 10° (2θ) and three diꢂraction peaks between
the range oꢀ 22–25° (2θ) indicating the MFI topological
structure [39, 40]
Figure 3 provides the N2 adsorption–desorption isotherm
oꢀ as-synthesized ZS-1 zeolite sample is very close to type
IV with an H3 p/p hysteresis loop at a relative pressure (p/
o
p ) oꢀ 0.01–1.0. Adsorption isotherm at low relative pres-
o
sure region (p/p <0.2) corresponds to the N2 ꢁlling in the
o
micropores and the hysteresis loop is slightly broad at rela-
EDAX mapping data represent the homogeneous disper-
sion oꢀ Zirconium (red), Silicon (green), and Oxygen (blue)
in the ꢀramework oꢀ synthesized ZS-1 zeolite material which
is shown in Fig. 5. The EDAX spectra reveal that the per-
centage weight oꢀ zirconium, silicon, and oxygen elements
are 27, 32, and 41 % respectively introduced into the ZS-1
zeolite structure (Fig. 6).
tive pressure p/p oꢀ 0.45–1.0 demonstrate the presence oꢀ
o
mesopores, which can be attributed to the intercrystalline
voids created by the accumulated materials shown in Fig. 4
HR-TEM image [33, 39]. which was ꢀurther proved by the
as-synthesized ZS-1 zeolite has a BET surꢀace area (355.670
2
m /g), micropores pore volume 0.061 cc/g, and average pore
diameter (3.36511e+00 nm) respectively.
Figure 7 shows the temperature-programmed desorption
The morphological characteristic oꢀ the ZS-1 zeolite
has been studied using FE-SEM and HR-TEM techniques.
oꢀ ammonia (NH -TPD) curve oꢀ ZS-1 zeolite material. Two
3
peaks in the range between 200 and 600 °C were presented
1
3

S. S. Dipake et al.
Fig. 3 N2 adsorption and
desorption isotherms oꢀ ZS-1
Catalyst
in the NH -TPD curves. It is postulated that the two diꢂerent
the amount oꢀ catalyst; available active site oꢀ catalyst will
be increase and product yield also increase. There is no
ꢀurther increase in percentage yield oꢀ product (Table 1)
while increase in amounts oꢀ catalyst above 0.05 gm. In
model reaction we ꢀound that 0.05 gm oꢀ catalyst amount
was sufcient ꢀor 95% yield in a 30 min. The reaction does
not sufciently proceed in the absence oꢀ a catalyst aꢀter
180 min at 110 °C. The temperature eꢂect was studied at
various temperatures such as 80, 100, 110 and 120 °C with
ZS-1 as a catalyst in a solvent ꢀree condition. Model reac-
tion at 80 °C proceeded but with low yield. An enhance-
ment oꢀ temperature ꢀrom 80 to 110 °C showed increase in
activity oꢀ catalyst which in enhancement oꢀ resulted the
product yield with signiꢁcant reduction in reaction time,
3
types oꢀ acidic sites exist in the ꢀramework oꢀ ZS-1 zeolite
i.e., weak acidic sites and strong acidic sites. The peak range
oꢀ temperature approximately 200–350 K is due to the pres-
ence oꢀ weak acidic sites (Bronsted acidic sites), while the
peak in between temperature range 420–600 °C is due to the
strong acidic sites (Lewis acidic sites) which are present in
the ZS-1 zeolite ꢀramework.
4
Result and Discussion
4
.1 Catalytic Activity of ZS‑1 in Synthesis
of 1‑amidoalkyl‑2‑naphthols
ꢀ
urther increase in temperature did not aꢂect the percent-
Aꢀter characterization oꢀ ZS-1, catalytic efciency was
investigated in the exclusive synthesis oꢀ the 1-ami-
doalkyl-2-naphthols analogues, it is a classic example oꢀ
a three-component reaction. (Scheme 1) Initially, our study
was aimed to determine the appropriateness oꢀ ZS-1 cata-
lyst ꢀor the synthesis oꢀ 1-amidoalkyl-2-naphthols by using
aldehyde, b-naphthol and benzamide/acetamide preꢀerred
as the model reaction. We examined the diꢂerent rection
conditions like eꢂects oꢀ diverse catalyst amount, tempera-
ture and solvent on model reaction. In order to calculate
the appropriate amount oꢀ catalyst, we increase the catalyst
amount ꢀrom 0.01 to 0.05 gm and observed that increase
age yield. Thereꢀore, best result was achieved at 110 °C,
which was chosen as the optimum reaction temperature
(Table 2).
To compare the eꢂects oꢀ various solvents concerning
reaction time and percentages yield with the solvent-ꢀree
conditions we have carried out the model reaction in the
presence oꢀ solvents such as Water, EtOH, PEG, Chloro-
ꢀorm, and DMF, almost all the reactions with solvent were
less advantageous than the absence oꢀ solvent. Hence,
solvent-ꢀree was regarded as the best condition ꢀor model
reaction. it is cost-eꢂective and environmentally benign. In
all the reactions, pure products were obtained by aqueous
1
3

ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile Synthesis oꢀ…
Fig. 4 FE-SEM images oꢀ ZS-1
(
a, b) and HR-TEM images oꢀ
ZS-1 (c, d, e, f)
1
3

S. S. Dipake et al.
Fig. 5 EDX Elemental mapping
composition oꢀ ZS-1, FE-SEM
(
a), Zirconium (b), Silicon (c),
Oxygen (d)
Fig. 6 EDAX Spectra oꢀ ZS-1
1
3

ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile Synthesis oꢀ…
Fig. 7 NH -TPD oꢀ ZS-1
3
quenching ꢀollowed by ꢁltration, washing with the water,
and recrystallization in ethanol as shown in Table 3.
Aꢀter optimizing the reaction conditions, we examined
structurally aromatic aldehydes bearing either electron-
withdrawing and electron-donating groups. It is observed
that the substrate with electron-withdrawing group took
short time with high yield as compared to the electron-
donating group.
Michael addition oꢀ amide on ortho-quinone methide inter-
mediate (III).
4.2 Reusability and Reproducibility of ZS‑1 Zeolite
Catalyst
Aꢀter the reaction was completed, the major drawback ꢀor
other catalysts in separation and recovery. Investigate the
reusability oꢀ ZS-1 catalyst ꢀor the reaction benzaldehyde,
β-naphthol, and benzamide/acetamide as model substrates
(Scheme 1). Aꢀter the completion oꢀ the reaction, the catalyst
was easily separated by ꢁltration and washed with acetone
3–4 times. Then catalyst was dried and activated in a vac-
uum oven ꢀor 2 h at 200 °C. Finally, the recycled catalyst
was reused in mentioned reaction ꢀor another successive ꢁve
cycles without any signiꢁcant loss oꢀ reactivity and yield.
Thus, it could be evidence that the ZS-1 catalyst is a suit-
able catalyst ꢀor this reaction with high reactivity and good
reusability as shown in Fig. 8.
The efciency oꢀ the present ZS-1 catalyst was com-
pared with some other reported catalysts ꢀor the synthesis oꢀ
1
-amidoalkyl-2-naphthols as summarized in Table 4. ZS-1
showed a much higher catalytic activity concerning the reac-
tion times and product yield. Thereꢀore, Table 4 result sug-
gests that the present protocol with ZS-1 catalyst is much
efcient and promising than the previously reported catalytic
methods ꢀor the synthesis oꢀ 1-amidoalkyl-2-naphthols.
The proposed reaction mechanism ꢀor the synthesis oꢀ
1
-amidoalkyl-2-naphthols mediated by ZS-1 catalyst is
depicted in Scheme 3 [10, 14]. Considering the nature oꢀ
the ZS-1 catalyst, it decreases the electron density oꢀ the car-
bonyl group oꢀ aldehydes. Intermediate (II) is ꢀormed by the
nucleophilic attack oꢀ b-naphthol to the carbonyl group oꢀ
activated aldehydes. Then, the ortho-quinone methide (III)
intermediate was ꢀormed by the condensation oꢀ the water
molecule. Aꢀterward, ortho-quinone methide (III) interme-
diate activated by catalyst ZS-1 and aꢂords the expected
5 Conclusion
In summary, we have synthesized ZS-1 zeolite as a catalyst
by using a hydrothermal pathway. Synthesized catalyst mate-
rial was characterized by various characterization techniques
1
-amidoalkyl-2-naphthols desired product (IV) through the
such as FT-IR, XRD, FESEM, HRTEM, EDS, NH TPD,
3
1
3

S. S. Dipake et al.
Table 1 Synthesis oꢀ 1-amidoalkyl-2-naphthol derivatives by using ZS-1 as catalyst (110 °C)
Entry
1
Aldehyde
Time (min)
30
Yield(%)a
95
M.P.(°C)b
234–236
Lit.m.p.(°C)c
235–236 [24]
Productd
CHO
OH
NH O
2
3
4
35
32
32
95
94
92
237–238
177–178
183–185
239–241 [44]
176–177 [45]
185–187 [5]
CHO
OH
NH O
NO2
O N
2
CHO
OH
NH O
Cl
Cl
CHO
OH
NH O
Br
Br
1
3

ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile Synthesis oꢀ…
Table 1 (continued)
Entry
5
Aldehyde
Time (min)
35
Yield(%)a
92
M.P.(°C)b
190–191
Lit.m.p.(°C)c
192–193 [46]
Productd
CHO
OH
NH O
Me
Me
6
7
30
40
35
95
92
92
193–194
221–223
205–206
195–196 [45]
220–223 [24]
206–208 [47]
CHO
F
OH
NH O
F
CHO
OH
OH
NH O
HO
0
8
CHO
OMe
OH
NH O
MeO
1
3

S. S. Dipake et al.
Table 1 (continued)
Entry
Aldehyde
Time (min)
35
Yield(%)a
92
M.P.(°C)b
22–224
Lit.m.p.(°C)c
221–223 [48]
Productd
09
10
11
12
CHO
OH
NH O
CH3
Me
Me
40
35
30
90
92
95
240–242
229–230
239–241
243–245 [5]
229–231 [5]
242–244 [48]
CHO
OH
NH O
CH3
OH
HO
CHO
OH
NH O
CH3
Br
Br
CHO
OH
NH O
CH3
Reaction condition: aldehyde (1 mmol), β-naphthol (1 mmol), benzamide/acetamide (1.3 mmol) and the (0.05 gm) catalyst was stirred at 110 °C
ꢀ
or the appropriate time under solvent ꢀree condition
Isolated yield
M.P
Lit. M.P
Product
a
b
c
d
and BET. Then, the synthesized catalyst was employed as a
novel zeolite catalyst in an efcient, one-pot multicomponent
synthesis oꢀ 1-aminoalkyl-2-naphthols derivatives oꢀ diverse
aromatic aldehydes, b-naphthol, and benzamide/acetamide,
under solvent-ꢀree conditions. It provides several promising
advantages such as high yields, easy handling, easy work-
up, shorter reaction times, and easy puriꢁcation. The cata-
lyst can be easily separated ꢀrom the reaction mixture by
1
3

ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile Synthesis oꢀ…
Table 2 Catalytic activity oꢀ
ZS-1 zeolite catalyst in the
reaction β-naphthol, aldehyde
and benzamide/acetamide
Catalyst (Wt.)a
Solventb
Temp(°C)c
Time (min.)d
Yield (%)e
Entry
1
2
3
4
5
6
7
8
9
0
Solvent ꢀree
Solvent ꢀree
Solvent ꢀree
Solvent ꢀree
Solvent ꢀree
Solvent free
Solvent ꢀree
Solvent ꢀree
Solvent ꢀree
Solvent free
110
110
110
110
110
110
Rt
80
100
120
180
180
180
120
60
10
30
45
60
80
95
Trace
50
60
0.01
0.02
0.03
0.04
0.05
0.05
0.05
0.05
0.05
30
180
180
60
1
0
30
95
Reaction condition: aldehyde (1 mmol), β-naphthol (1 mmol), benzamide/acetamide (1.3 mmol)
a
Weight oꢀ catalyst
Solvent
Temperature (°C)
Time (min)
b
c
d
e
Isolated yield
Table 3 Eꢂect oꢀ various solvent ꢀor the synthesis oꢀ 1-amidoalkyl-
-naphthols derivatives
ꢁltration and can be reused without any signiꢁcant loss in
catalytic efciency ꢀor ꢁve consecutive cycles oꢀ model reac-
tion (Scheme 1). Hence, highly reusability and economic
applicability, it is ꢀacile and environmental benign ꢀor the
synthesis oꢀ biologically active substituted 1-aminoalkyl-
2
Solventa
Conditionb
Time (Min.)c
Yield (%)d
Sr. No
1
2
3
4
5
Water
Ethanol
PEG
Chloroꢀorm
DMF
Reꢃux
Reꢃux
Reꢃux
Reꢃux
Reꢃux
180
180
180
180
180
Trace
20
30
35
40
2
-naphthols derivatives.
Supplementary Inꢀormation The online version contains supplemen-
tary material available at https://doi.org/10.1007/s10562-021-03684-8.
Reaction condition: aldehyde (1 mmol), β-naphthol (1 mmol), benza-
mide/acetamide (1.3 mmol)
Acknowledgements One oꢀ the authors, Mr. Sudarshan S. Dipake,
grateꢀully thankꢀul to the Council oꢀ Scientiꢁc and Industrial Research
(CSIR), New Delhi ꢀor the award oꢀ ꢀellowship and the Department oꢀ
Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurang-
abad-431004 (M.S.), India. ꢀor support and providing the necessary
laboratory ꢀacility.
a
Solvent
Condition
Time (min.)
b
c
d
Isolated yield
Table 4 Comparison oꢀ the
catalytic activity oꢀ ZS-1 zeolite
catalyst with some reported
catalysts ꢀor the one pot three
multicomponent reaction oꢀ
aldehyde (1 mmol), β-naphthol
Catalysta
Time(min.)b
Yield(%)c
Entry
Condition/(°C)
Reꢀerence
1
2
3
4
5
6
7
8
9
ZS-1
Solvent ꢀree/110
Solvent-ꢀree/110
Solvent ꢀree/125
Solvent ꢀree/20
Solvent ꢀree/125
Solvent ꢀree/80
solvent-ꢀree/125
solvent-ꢀree/100
solvent-ꢀree/100
30
30
60
120
180
240
300
50
95
80
84
85
78
88
88
92
94
Our work
[28]
[49]
[50]
[51]
[52]
[29]
[10]
[14]
Nano Al O
2
3
Montmorillonite K-10 clay
Silica sulꢀuric acid
(
(
1 mmol), benzamide/acetamide
1.3 mmol) and ZS-1 (0.05gm)
K CoW O ·3H O
5
12 40
2
under solvent ꢀree condition
Thiamine HCl
p-TSA
HPA/Py-Fe3O4
H4SiW12O40/TPI-MCM-41
40
a
Diꢂerent catalyst
Time (min.)
Isolated yield
b
c
1
3

S. S. Dipake et al.
Scheme 3 Proposed reaction mechanism ꢀor the synthesis oꢀ 1-amidoalkyl-2-naphthols
Fig. 8 Recyclability oꢀ ZS-1
zeolite catalyst
Author Contributions SSD-conduct the whole experiment, writing an
editing. ASR-review and editing. STG-writing, review, and editing.
original draꢀt. SPG-investigation. PBT-investigation. MKL-review and
1
3

ZS‑1 Zeolite as a Highly Efcient and Reusable Catalyst ꢀor Facile Synthesis oꢀ…
Data Availability Manuscript including all data correct and
10. Mahdizadeh Ghohe N, Tayebee R, Amini MM (2019) Synthesis
and characterization oꢀ mesoporous Nb-Zr/KIT-6 as a produc-
tive catalyst ꢀor the synthesis oꢀ benzylpyrazolyl coumarins.
Mater Chem Phys 223:268–276. https://doi.org/10.1016/j.match
emphys.2018.10.067
unpublished.
Declarations
1
1. Yang G, Pidko EA, Hensen EJM (2013) Structure, stability, and
lewis acidity oꢀ mono and double Ti, Zr, and Sn ꢀramework sub-
stitutions in BEA zeolites: a periodic density ꢀunctional theory
study. J Phys Chem C 117:3976–3986. https://doi.org/10.1021/
jp310433r
Conꢀlict oꢀ interest The authors declare that there is no conꢃict oꢀ in-
terests regarding the publication oꢀ this paper.
Consent to Participate All Authors are agreed ꢀor submission.
Consent ꢀor Publication Agreed to submission.
1
1
2. Dipake SS, Lande MK, Rajbhoj AS, Gaikwad ST (2021) Zeolite
ZSM-11 as a reusable and efcient catalyst promoted improved
protocol ꢀor synthesis oꢀ 2,4,5-triarylimidazole derivatives
under solvent-ꢀree condition. Res Chem Intermed. https://doi.
org/10.1007/s11164-021-04423-9
3. Gadekar SP, Dipake SS, Gaikwad ST, Lande MK (2018) Solid
acid TS-1 catalyst: an efcient catalyst in Knoevenagel conden-
sation ꢀor the synthesis oꢀ 5-arylidene-2,4-thiazolidinediones/
Rhodanines in aqueous medium. Res Chem Intermed 44:7509–
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