Highly Efficient and Green Oxidation of Nitrotoluenes with Dioxygen as Oxidant in a Novel Homogeneous and Recyclable Catalytic System

Abstract

A novel homogeneous and recyclable catalytic system was applied in the oxidation of nitrotoluenes to nitrobenzoic acids with the isolated yield of 93%. In this method, the catalytic system could be easily separated from the aqueous phase by simple decantation and could be reused in subsequent runs without apparent change in activity.

Aerobic Copper-Catalyzed Organic Reactions

“…The process was later demonstrated to proceed in an ionic solvent (Scheme 2b). 19 Although slightly higher temperature was necessary, simple acidification of the aqueous layer conveniently provided the pure product and allowed recycling of the ionic liquid solvent, lending the process amenable to large scale industrial applications. Notably, other metal catalysts gave superior results in this transformation and only one substrate was demonstrated with the copper catalyst.…”

Fluorine-functionalized ionic liquids with high oxygen solubility

“…8,9 In oxidative catalysis, dissolved oxygen is used as oxidant for the oxidation of various reagents, such as alcohols, olens, nitrotoluene and cysteine. [10][11][12][13][14][15][16][17][18][19][20] For the latter reaction, Shan et al observed that the performance of the catalyst was directly proportional to the solubility of oxygen and that a higher oxygen concentration resulted in higher yields. Ionic liquids with dissolved oxygen have also been used in metal-free catalytic systems for the depolymerization of lignin model compounds and lignin, 21,22 or as solvent for transition-metal catalyzed oxidation of lignin model compounds.…”

A metal-free aerobic oxidation of nitrotoluenes catalyzed by N,N′,N″-trihydroxyisocyanuric acid (THICA) and a novel approach to the catalyst

“…This signal then disappeared upon addition of 2,4-DNT to the solution. This proved that our system was based on a radical process rather than a mechanism based on a carbon anion under basic conditions [5,7]. Thus, our oxidation system can be applied to a much wider range of substrates, as compared with the literature [5,7].…”

“…For oxidation in our system, the acid yield reached nearly 100%, showing the potential industrial application value of our catalytic system. Additionally, when compared to the literature [5][6][7]13], nitrotoluenes were oxidized successfully into carboxylic acids in this system with yields of almost 100%, which were not affected by the position of the nitro group (runs 3-5). According to the literatures [34,35], the bond energy of m-nitrotoluene is about 2 kJ/mol larger than the p-nitrotoluene.…”

“…For example, She [5,6] reported the catalyzed oxidation of p-nitrotoluene to its carboxylic acid with a maximum yield of 90% using metalloporphyrins (metals include Fe, Co and Mn) as biomimetic catalysts. With iron phthalocyanine as the catalyst in ionic liquids [7], onitrotoluene and p-nitrotoluene, as well as dinitrotoluene (DNT), which is much more difficult to oxidize, were turned into their corresponding carboxylic acids in good yields. Nevertheless, mnitrotoluene and toluene could not be oxidized in this system, which was explained by a mechanism of ionization where toluene and m-nitrotoluene were not able to participate [5,7].…”