258
Issue of isolation of catalyst and final products from the reaction medium makes
the catalytic system non-reusable as well as the complete procedure difficult, which
become the considerable threat in the progress of novel ambitious synthesis and
methodologies. Genuinely, the generation of waste and accordingly a disadvantage
in terms of chemical and ecological expenses is correlated with this process. In
order to develop reusable catalytic systems for organic synthesis from both academic and industrial viewpoints, resource conservancy and ecological preservation
are absolutely significant commercial and environmental motives. In this view, the
advancement of an effective, eco-friendly, recyclable and reusable catalytic system
has become indispensable for the tenable development of a chemical business [48,
49]. Nevertheless, recycling of metals can be challenging which demands for scientific investigation so that greater can be attained with a lesser amount of metals.
In this perception, heterogeneous catalysis can conquer the above shortcomings
as it offers the vision for simplicity of separation and recycling of the metal-catalyst
accompanied by easy product purification as well as possibly continuous or numerous treatments of final products [50, 51], which signifies the primary advantage over
homogeneous catalysis. Also, it possesses the similar reaction mechanisms with
their homogeneous counterparts, accompanied by even considerable turnover numbers (TONs) and/or turnover frequencies (TOFs) [52, 53]. An additional fascinating
feature is the feasibility to utilize heterogeneous catalytic systems to attain a precise
selectivity in sites, or a shift in selectivity, and perhaps an enhancement in the catalytic activity. This could in assumption be achieved by the development of hybrid
molecular frameworks. Heterogeneous catalysis has become a key aspect in the
progress of tenable procedures in fuel and fine chemical production, where chemical productivity has to be linked with financial and ecological requirements. Some
of these procedures, for example, catalytic hydrogenations are one of the most primitive reactions in this direction which are nowadays usually introduced as green
chemistry [54]. Indeed, it has become one of the greenest sectors of the chemical
manufacturing in the past decades. So, the progress of reusable heterogeneous catalytic systems is immensely fascinating not only as such systems permit for an easy
separation by filtration and therefore possible to recycle [50, 55], but also for designing innovative chemical procedures.
Considering the above preferences and in order to promote more reasonable
straight C–H activation reactions, the application of heterogeneous catalytic systems is notably appealing, even though the inactivity of the C–H bond has turned
this auspicious execution somewhat challenging [56, 57]. In this section, we have
provided certain instances of the expeditious current advancement in selective C–H
activations using heterogeneous catalytic systems.
2.1 C–H Arylation
In 2014, Parsharamulu et al. designed a three-dimensional mesoporous silica in
combination with a highly diffused palladium nanoparticle composite catalyst
(PS-3). The large surface area innovative heterogeneous PS-3 catalyst was employed
D. S. Deshmukh et al.
Issue of isolation of catalyst and final products from the reaction medium makes
the catalytic system non-reusable as well as the complete procedure difficult, which
become the considerable threat in the progress of novel ambitious synthesis and
methodologies. Genuinely, the generation of waste and accordingly a disadvantage
in terms of chemical and ecological expenses is correlated with this process. In
order to develop reusable catalytic systems for organic synthesis from both academic and industrial viewpoints, resource conservancy and ecological preservation
are absolutely significant commercial and environmental motives. In this view, the
advancement of an effective, eco-friendly, recyclable and reusable catalytic system
has become indispensable for the tenable development of a chemical business [48,
49]. Nevertheless, recycling of metals can be challenging which demands for scientific investigation so that greater can be attained with a lesser amount of metals.
In this perception, heterogeneous catalysis can conquer the above shortcomings
as it offers the vision for simplicity of separation and recycling of the metal-catalyst
accompanied by easy product purification as well as possibly continuous or numerous treatments of final products [50, 51], which signifies the primary advantage over
homogeneous catalysis. Also, it possesses the similar reaction mechanisms with
their homogeneous counterparts, accompanied by even considerable turnover numbers (TONs) and/or turnover frequencies (TOFs) [52, 53]. An additional fascinating
feature is the feasibility to utilize heterogeneous catalytic systems to attain a precise
selectivity in sites, or a shift in selectivity, and perhaps an enhancement in the catalytic activity. This could in assumption be achieved by the development of hybrid
molecular frameworks. Heterogeneous catalysis has become a key aspect in the
progress of tenable procedures in fuel and fine chemical production, where chemical productivity has to be linked with financial and ecological requirements. Some
of these procedures, for example, catalytic hydrogenations are one of the most primitive reactions in this direction which are nowadays usually introduced as green
chemistry [54]. Indeed, it has become one of the greenest sectors of the chemical
manufacturing in the past decades. So, the progress of reusable heterogeneous catalytic systems is immensely fascinating not only as such systems permit for an easy
separation by filtration and therefore possible to recycle [50, 55], but also for designing innovative chemical procedures.
Considering the above preferences and in order to promote more reasonable
straight C–H activation reactions, the application of heterogeneous catalytic systems is notably appealing, even though the inactivity of the C–H bond has turned
this auspicious execution somewhat challenging [56, 57]. In this section, we have
provided certain instances of the expeditious current advancement in selective C–H
activations using heterogeneous catalytic systems.
2.1 C–H Arylation
In 2014, Parsharamulu et al. designed a three-dimensional mesoporous silica in
combination with a highly diffused palladium nanoparticle composite catalyst
(PS-3). The large surface area innovative heterogeneous PS-3 catalyst was employed
D. S. Deshmukh et al.