Nanocatalysis is recently growing field and is crucial component of “sustainable technology and organic transformations” applicable to almost all types’ catalytic organic transformations [1,2-6]. Among nanocatalysts, several forms such as magnetic nanocatalysts, nano mixed metal oxides, core-shell nanocatalysts, nano-supported catalysts, graphene-based nanocatalysts have been employed in catalytic applications [3,7,8]. Magnetic nanocatalysts stand apart in this group of reusable nanocatalysts due to their low preparation cost, excellent activity, great selectivity, high stability, efficient recovery, and good recyclability (Figure 1).

Figure 1: Characteristics of nanocatalysts

The field of benign organic synthesis has lately embraced various innovative scientific developments accompanied by improved and effective synthetic practices that avoid the use of toxic reagents reactants [9,10]. The tuning of important organic transformations and these newer generation of nanocatalysts worked very well together to achieve important products [11-13]. These versatile semi heterogeneous nanocatalysts with high surface area are the best alternatives to conventional catalysts, the highest catalytic activity, selectivity, and stability can be achieved by their shape, size, composition, and nature of nanocatalyst structure [8,14,15]. These noteworthy advantages of nanocatalysts are depending on the nanosize effect; catalytic performance generally increases with decreasing size of nanostructures. Though, when the size of the active site is reduced to nanoscale dimensions, the surface free energy is greater than before. This results in the aggregation of the particles into small bunches and reduces the catalytic productivity. Also, the isolation and recovery for the catalysts become difficult as their size decreases to nanoscale dimensions; in most cases, separation through traditional filtration is not an easy task. So, it is important to used appropriate support materials/nanomaterial to design an effective, reusable and recycling nanocatalysts [16].

Till date these nanostructured materials are employed in various types of organic transformations including hydrogen transfer reactions, chemo-selective oxidations, coupling reactions, oxidative aminations, asymmetric hydrogenations, C-H activations, Mannich reactions Oxidative esterification’s and more. A wide variety of nanostructures including morphology dependent nanocatalysts, magnetic nanocomposites, graphene-supported nanocatalysts, hybrid nanostructured catalysts, integrated nanocatalysts and core-shell nanocatalysts were employed for various catalytic applications (Figure 2) [1,17].

Figure 2: Applications of Nanocatalysts

Notable development has been made using these nanocatalysts in terms of diversity of the organic reactions, activity, selectivity, and reusability. Still, the leaching of metal in nanocatalysts under harsh conditions or continuous flow reactions in flow reactor remains the major concern yet to be solved. The design and development of new more robust, and advanced multifunctional nanomaterials and imperative protocols for decoration of homogeneous metals, organic ligands or catalysts entities are still requisite in order to overcome these difficulties.

In conclusion, it is believed that these well-defined nanostructures with various energy sources such as microwave technology, ball- milling, ultrasonication and recently emerged microwave-continuous flow reactors, will help the accomplishment of benign and sustainable chemical processes.