An efficient method for the oxidation of urazoles with [NO+·crown·H(NO3)2−]

Exploiting Urazole's Acidity for Fabrication of Hydrogels and Ion-Exchange Materials

In this study, the acidity of urazole (pKa 5-6) was exploited to fabricate a hydrogel in two simple and scalable steps. Commercially available poly(hexamethylene)diisocyanate was used as a precursor to synthesize an urazole containing gel. The formation of urazole was confirmed by FT-IR and 1H-NMR spectroscopy. The hydrogel was characterized by microscopy imaging as well as spectroscopic and thermo-gravimetric analyses. Mechanical analysis and cell viability tests were performed for its initial biocompatibility evaluation. The prepared hydrogel is a highly porous hydrogel with a Young's modulus of 0.91 MPa, has a swelling ratio of 87%, and is capable of exchanging ions in a medium. Finally, a general strategy was demonstrated to embed urazole groups directly into a crosslinked material.

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.

Selective and Efficient Oxidation of Diaryl Carbazide to Diaryl Carbazone with NaNO2/NaHSO4• H2O/SiO2

Ten diaryl carbazide are shown to undergo selective and rapid oxidation to the diaryl carbazones using NaNO2/NaHSO4• H2O/SiO2 as a novel mild oxidising agent.

A Simple and Efficient Method for the Dehydrogenation of Symmetric Hydrazo Compounds with NaNO2/NaHSO4•H2O/SiO2

In this paper, 18 symmetric hydrazo compounds undergo rapid oxidation to corresponding azo compounds using NaNO2/NaHSO4•H2O/SiO2 as a novel oxidising agent under mild conditions for the first time.

Silica Sulfuric Acid/ NaNO2 as a Novel Heterogeneous System for the Nitration of Phenols under Mild Conditions

Nitrophenols can be obtained in moderate to high yields via nitrosation-oxidation of phenols with silica sulfuric acid, NaNO₂ and wet SiO₂ at room temperature. In situ generation of HNO₂ and a radical cation mechanism via the nitrous acid catalyzed (NAC) pathway appear to be applicable to phenol nitration using these reagents.