New activation methods used in green chemistry for the synthesis of high added value molecules

Abstract

In the chemical and pharmaceutical industry, molecular organic chemistry is undergoing a green revolution in order to avoid waste by developing a cleaner and safer chemistry. This change is subject to the new European regulation REACH. One of the major goals of organic synthesis is to design molecules with high added value by developing synthetic methods highly selective, economical and environmentally friendly. To satisfy the societal expectation new activation methods must be developed in order to shorten the synthesis, to respect the principle of atom economy and to substitute pollutants or toxic organic solvents. In this context, our group focuses its research on the synthesis of biologically active molecules, developing new environmentally friendly synthetic strategies and more energy-efficient alternatives such as microwaves, ultrasound, photochemistry or biotransformation. We present here how various activation methods used for the preparation of several high-value compounds can dramatically enhance yields and selectivity. First, we describe microwave-assisted syntheses of precursors of [ 11 C] PIB, a tracer used in PET imaging and amides intermediates of natural products. We describe also the selective reduction of nitro compounds using ultrasound activation and a facile pathway to obtain b 3 -chiral aminoacids by biotransformation using purified nitrilases. Finally the results concerning the alkylation of a-aldehydes, using visible light and dyes as catalysts without transition metal are discussed. Some general considerations concerning the activation methods and their impact on the environment and the energy saving are given.

General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis

“…; or (2) the heat generated in situ. Such physical activation methods offer challenging opportunities for developing clean, selective and Catalysts 2018, 8, 483 6 of 21 energy-efficient synthetic strategies for both the production of high value-added compounds [45,46] and pollutant abatement. Here, the synergy of these technologies with catalysis for selective oxidation reactions in liquid phase is emphasized through selected representative literature studies.…”

Water purification from metal ions in the presence of organic matter using electromagnetic radiation-assisted treatment

“…chemical, physical or biochemical changes in the behavior of the substance being microwaved when the system temperature remains constant (Yang et al, 2014;Yu et al, 2010). These effects originate from several sources such as an increase in polarization of the dipolar transition state (Veitía and Ferroud, 2014), and the interaction between the MW field and materials under treatment (de la Hoz et al, 2005). Athermal MW effects increase the vibration and 'wriggle' of the polar chains of molecules that lead to the breaking, or weakening, of chemical bonds.…”

Ultrasound-assisted pseudohomogeneous tungstate catalyst for selective oxidation of alcohols to aldehydes

“…Catalytic alcohol oxidation is a popular method to synthesize aldehydes, but despite the favorable outcome in many cases, establishing an eco-friendly method to producing these intermediates in high yield and selectivity still remain as a main challenge. In order to take a number of green chemistry criteria into practice, the amount of harmful and toxic solvents and reagents should be kept at the lowest level or be substituted with non-toxic and benign materials, additionally, the amount of energy consumption in reactions should be diminished 1 . It seems no exaggeration to say that among all of the new green activation methods up until now namely; Photochemistry 2 , 3 , Microwave 4 , Biotransformation 5 , 6 , and Ultrasound, no technique accommodates green chemistry principles in chemical transformations as ultrasound does.…”