HPA decorated Halloysite Nanoclay: An efficient catalyst for
the green synthesis of Spirooxindole derivatives
| Majid M. Heravi
| Masoumeh Malmir
| Baharak Masoumi
Gas Conversion Department, Faculty of
Petrochemicals, Iran Polymer and
Petrochemical Institute, PO Box
14975‐112, Tehran, Iran
Department of Chemistry, School of
Science, Alzahra University, PO Box
1993891176, Vanak, Tehran, Iran
Samahe Sadjadi, Gas Conversion
Department, Faculty of Petrochemicals,
Iran Polymer and Petrochemical Institute,
PO Box 14975‐112, Tehran, Iran.
Majid Heravi, Department of Chemistry,
School of Science, Alzahra University, PO
Box 1993891176, Vanak, Tehran, Iran.
A novel heterogeneous catalyst, HPA@HNTs‐IMI‐SO
H, was designed and
synthesized based on functionalization of halloysite nanotubes with ionic
liquid and subsequent incorporation of heteropolyacid. The structure of
the catalyst was studied and confirmed by using SEM/EDX, FTIR, XRD,
ICP‐AES, TGA, DTGA and BET. Moreover, the catalytic activity of
H was investigated for promoting ultrasonic‐assisted
three‐component reaction of isatines, malononitrile or cyanoacetic esters
and 1,3‐dicarbonyl compounds to afford corresponding spirooxindole in high
yields and short reaction time. The reusability of the catalyst was also studied.
Notably, the catalyst could be recovered and reused for three reaction
runs. However, reusing for fourth reaction runs led to the decrease of the
catalytic activity. Considering leaching test results, that observation was
attributed to the leaching of heteropolyacids, which can be induced by
halloysite, hybrid, ionic liquid, nanocatalyst, spirooxindole
1 | INTRODUCTION
Spirooxindole derivatives such as are biologically‐
attractive heterocycles which can be found in alkaloids
and pharmaceuticals. The synthesis of these compounds
is an appealing target in the organic synthesis due to their
diverse biological activities including fungicidal, anti-
convulsant, herbicidal and anti‐cancer properties.
Spirooxindoles can also be used as a key intermediate
for the synthesis of clinical pharmaceuticals.
many attempts have been devoted to disclose efficient
protocols for the synthesis of spirooxindoles. In this line,
the utilities of many catalysts such as triethylamine,
piperidine, ethylenediamine diacetic acid, L‐Proline,
chiral phoshoic acid
and potassium tetrachloroaurate
trihydrate have been proved.
Heteropolyacids, HPAs, belong to a class of inorganic
compounds that are composed of cations and polyanion
clusters. The unique feature of HPAs and their salts is that
they can exert both acidic (Bronsted acidity(and redox
This outstanding property renders these
catalysts bi‐functional and broadens their applications as
efficient catalysts in catalytic processes.
the non‐toxic and non‐corrosive entity of HPA, they can
be very promising for developing green protocols for the
synthesis of various chemicals. However, HPAs are highly
soluble in water and most organic solvents which is a
drawback from the green chemistry and industrialization
point of views. To circumvent this issue, immobilization
of HPA on heterogeneous supports such as zeolites and
clays has been suggested.
Halloysite nanotubes, HNTs, are naturally oc-
curring clays with the general formula of
The HNTs tubes are relatively
long (~ 100 nm to 4000 nm).
Moreover, the external
diameters of HNTs range from 30 to 190 nm while their
Received: 18 July 2017 Revised: 28 August 2017 Accepted: 30 August 2017
Appl Organometal Chem. 2018;32:e4113.
Copyright © 2017 John Wiley & Sons, Ltd.wileyonlinelibrary.com/journal/aoc 1of12