Benign by design: catalyst-free in-water, on-water green chemical methodologies in organic synthesis

Abstract

Catalyst-free reactions developed during the last decade and the latest developments in this emerging field are summarized with a focus on catalyst-free reactions in-water and on-water. Various named reactions, multi-component reactions and the synthesis of heterocyclic compounds are discussed including the use of various energy input systems such as microwave- and ultrasound irradiation, among others. Organic chemists and the practitioners of this art both in academia and industry hopefully will continue to design benign methodologies for organic synthesis in aqueous media under catalyst-free conditions by using alternative energy inputs based on fundamental principles.

Sustainable Nanocatalysts for Organic Synthetic Transformations

“…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][12][13].…”

Recent developments in copper nanoparticle-catalyzed synthesis of 1,4-disubstituted 1,2,3-triazoles in water

“…A number of homogeneous copper catalysts have been employed for the click reaction of azides and alkynes. [33][34][35][36][37] In spite of the high selectivity, important productivity, improved yield and simplicity of optimization of the reported homogeneous catalysts, they suffer from the difficulty of separating the copper catalyst from the products, which produces environmental barriers to broadening their scope, thus limiting their extensive use in a number of applications. Elimination of trace quantities of catalyst from the end product is important because metal contamination can cause toxicity, especially in the pharmaceutical industry.…”

Microwave-promoted synthesis of cyclic imides

“…Employment of this novel strategy has given rise to the so-called "Green Chemistry", and the application of such strategy is now fostered to minimize the use of nonrenewable resources as well as polluting solvents, which are known to generate secondary toxic products, and to reduce the emission of harmful gases. 62 In the context of the Green Chemistry, 65,66 solvent-free 67,68 and water-mediated [69][70][71] MW-assisted reactions acquire a relevant role.…”