engleski

Green Chemistry Methods in Pyrazole Synthesis

In this chapter a green chemistry synthetic methods of pyrazole derivatives will be revised. In general, green chemistry methods application in the synthesis of heterocyclic compounds has been in the focus of many researchers these days. Green synthetic methods and processes are an important approach for the synthetic chemists, tending to reduce the utilization or generation of toxic and environmentally adverse substances. In this manner, chemists are driven by the twelve principles of green chemistry in order to develop a benign chemical methods and processes. Conventional synthesis of pyrazoles often includes harmful or toxic organic solvents, catalysts or other compounds, which are characterized as a waste upon the completion of the reaction. In order to reduce the utilization of such toxic substances, new green chemistry synthetic approaches were developed. These methods include the utilization microwaves in the synthesis of desired compounds, in order to accelerate the reactions, to obtain products in high purity with higher yields and under milder conditions. Solvent-free synthesis is often employed in the synthesis of pyrazoles, providing the simplicity of the synthesis, less toxic substances (organic solvents), lower costs. Solvent-free synthesis is often performed in a combination with grinding and ball milling, mixing and heating or in combination with ultrasound and microwaves. Furthermore, a green approach in the synthesis of pyrazoles includes the application of ultrasound, as well, a method where the chemical effect is caused by the acoustic cavitation. An application of ionic liquids and deep eutectic solvents in the synthesis has also became very popular in the last decade, providing an excellent media for the synthesis of various pyrazole derivatives. Both ionic liquids and deep eutectic solvents are described as designer solvents, due to the tuneability of their physical and chemical properties depending on the components combined together. All these green methods have successfully been used in the synthesis of various pyrazole derivatives, individually or combined with other methods, and each will be described in details regarding their synthesis.

green chemistry ; pyrazole ; synthesis

nije evidentirano