A Convenient Method for Selective Mono or Dinitration of Phenol under Mild Conditions

Nitration of aromatics with dinitrogen pentoxide in a liquefied 1,1,1,2-tetrafluoroethane medium

Regardless of the sustainable development path, today, there are highly demanded chemical productions still operating that bear environmental and technological risks inherited from the previous century. The fabrication of nitro compounds, and nitroarenes in particular, is traditionally associated with acidic wastes formed in nitration reactions exploiting mixed acids. However, nitroarenes are indispensable for industrial and military applications. We faced the challenge and developed a greener, safer, and yet effective method for the production of nitroaromatics. The proposed approach comprises the application of an eco-friendly nitrating agent, namely dinitrogen pentoxide (DNP), in the medium of liquefied 1,1,1,2-tetrafluoroethane (TFE) – one of the most non-hazardous Freons. Importantly, the used TFE is not emitted into the atmosphere but is effortlessly recondensed and returned into the process. DNP is obtained via the oxidation of dinitrogen tetroxide with ozone. The elaborated method is characterized by high yields of the targeted nitro arenes, mild reaction conditions, and minimal amount of easy-to-utilize wastes.

A green, safe, and economical method for the production of nitroaromatics is developed. The method comprises the use of the eco-friendly nitrating agent, dinitrogen pentoxide, and liquefied 1,1,1,2-tetrafluoroethane as the reusable reaction medium.

Electrochemistry as a Tool for Studies of Complex Reaction Mechanisms: The Case of the Atmospheric Aqueous-Phase Aging of Catechols

The ultimate goal in the understanding of complex chemical processes is a complete description of the underlying reaction mechanism. In the present study and for this purpose, a novel experimental platform is introduced that builds upon electrochemistry capable of generating reactive intermediate species at the electrode surface. The atmospherically relevant nitration of catechols is taken as a case example. First, we confirm the recently proposed nitration mechanism, advancing the understanding of atmospheric brown carbon formation in the dark. We are able to selectively quantify aromatic isomers, which is beyond the limits of conventional electroanalysis. Second, we identify a new pathway of nitrocatechol hydroxylation, which proceeds simply by oxidation and the addition of water. This pathway can be environmentally significant in the dark aqueous-phase formation of secondary organic aerosols. Third, the developed methodology is capable of selectively detecting a wide range of nitroaromatics; a possible application in environmental monitoring is proposed.

An Efficient Method for the Oxidation of 1,4-Dihydropyridines under Mild and Heterogeneous Conditions via in Situ Generation of NOCl

A combination of inorganic chloride salts [e.g. AlCl3, ZrCl4, and ZnCl2] and sodium nitrite in the presence of wet SiO2 was used as an effective oxidising agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives under mild and heterogeneous conditions in moderate to excellent yields.

Chemoselective N-nitrosation of secondary amines under mild and heterogeneous conditions via in situ generation of NOCl

A combination of inorganic chloride salts [e.g. WCl6, AlCl3 and ZnCl2] and sodium nitrite in the presence of wet SiO2 were used as an effective nitrosating agent for the nitrosation of secondary amines to their corresponding nitroso derivatives under mild and heterogeneous conditions in moderate to excellent yields.

An Efficient and Chemoselective Method for the Oxidation of 1,4-dihydropyridines under mild and heterogeneous conditions

A combination of inorganic acidic salts or oxalic acid dihydrate and sodium nitrate in the presence of wet SiO2 was used as an effective oxidising agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives at 40–50 oC with excellent yields.

Highly Efficient Nitration of Phenolic Compounds using Some Nitrates and Oxalic Acid under Solvent-Free Conditions

Nitrophenols can be obtained by direct nitration of phenols with some nitrates and oxalic acid at room temperature in moderate to high yields under solvent-free conditions. A small amount of water proved to be important in the initial period of the reaction.