2
M. KUMARI ET AL.
Introduction
Nanotechnology is one of the most versatile areas of current research and wide range
applications.
[
1–3]
Their unique properties arise from particularly their high surface to volume ratio.
Various methods have been reported for their synthesis, among them the biological
methods, plant mediated synthesis of nanoparticles are more attractive because of its
[
4–12]
simplicity, easy availability and stability of the resulting products.
Nowadays, they
have attracted great deal of attention due to catalytic application such as synthesis of
[
13]
[14]
[15,16]
spirooxindoles,
carbonitriles,
4-H chromenes,
decahydroacridine 1,8 dio-
[
17]
[18]
[19]
nes,
oxidation of sulfides to sulfoxides,
etc.
synthesis of propargylamines,
quinoxa-
[
20]
line,
Nanoparticles fill the gap between homogeneous and heterogeneous catalysis, but
recovery by normal filtration technique limits their widespread utility which results in
their loss disturbing the economics and sustainability of these nanocatalytic proto-
[
21]
cols.
In recent decades magnetic nanopartciles (MNPs) have gained popularity due
to their ease of preparation and surface functionalisation, facile separation via magnetic
[
22]
force as well as low toxicity and price.
Bare MNPs due to their inherent instability
and hydrophobic nature results in big clusters over time in the absence of any surface
[
23]
coating which reduces their surface energy.
Therefore it needs to be minimized by
surface immobilization of MNPs with biocompatible organic and inorganic materials
which protects them from being oxidized and provides them stability against damage
[
24,25]
during or after being used in organic transformations.
Surface functionalization of
3
-
MNPs with PO4 , sulfate and carboxylate are attractive surface modifications which can
be easily accomplished. It is observed that carboxylate binding to MNPs is the strongest
preventing leaching out during reaction, as well as protecting the bare NP’s against
damage hence it can be used undoubtedly in catalysis with good stability.
Schiff bases are some of the most widely used organic compounds. They are used as
intermediates in organic synthesis
stabilisers. Recently they have been utilized for optical recording technology,
electrical conductor, electrode materials, and micro-electronic equipment,
[
26]
[
27]
[28]
[29]
pigments & dyes,
catalysts,
and a polymer
[
30]
[31]
as
[
32]
organic
[
33]
batteries or electrochromic display devices.
The Schiff’s base of 4-amino antipyrine is
considered to be pyrazolone derivatives and are reported to demonstrate biological, clin-
[
34]
ical, pharmacological and analytical applications.
Synthesis of Schiff’s base is often
carried out with or without acid catalyzed by various previously reported synthetic
[
35]
[36]
[37]
methods like microwave assisted,
irradiation by UV,
ultrasonication,
etc. The
main drawback of these reported methods is the utilization of large amount of solvent
and longer reaction time. Therefore there is need to vary or modify the conventional
methods which are not eco-friendly and less efficient. Separation of the catalyst and
final product from the reaction mixture is one of the most vital aspects of synthetic pro-
tocols. Catalytic recovery by filtration is relatively inefficient. Another technique,
extractive isolation of products also requires excessive amount of organic solvents. The
development of versatile and efficient procedures for the preparation of these types of
compounds by using a new catalyst and active ongoing research area, and there will be
a scope for further improvement towards lower-reaction times, improved yields and
milder-reaction conditions. In view of this MNP@CA has been prepared by the