Metal-free catalytic oxidation of sulfides to sulfoxides with ammonium nitrate, ammonium hydrogen sulfate and ammonium bromide as catalyst

Abstract

A oxidação catalítica geral e sem o uso de metais, de sulfetos alifáticos e aromáticos aos seus sulfóxidos correspondentes via combinação de nitrato de amônio (NH 4 NO 3 ), hidrogenossulfato de amônio suportado em sílica gel (NH 4 HSO 4 -SiO 2 ) e uma quantidade catalítica de brometo de amônio (NH 4 Br) na presença de SiO 2 aquoso (50%, m/m) foi investigada. As reações ocorreram em meio heterogêneo e seletivamente em curtos tempos de reação, em CH 2 Cl 2 a temperatura ambiente. Este procedimento é simples e eficiente comparado a outros métodos relatados.A general and metal-free catalytic oxidation of aliphatic and aromatic sulfides to their corresponding sulfoxides via combination of ammonium nitrate (NH 4 NO 3 ), supported ammonium hydrogen sulfate on silica gel (NH 4 HSO 4 -SiO 2 ) and a catalytic amount of ammonium bromide (NH 4 Br) in the presence of wet SiO 2 (50%, w/w) has been investigated. The reactions were carried out heterogeneously and selectively in short reaction times in CH 2 Cl 2 at room temperature. This protocol is mild and efficient compared to other reported methods.

Protection of Hydroxyl Groups as a Trimethylsilyl Ether by 1,1,1,3,3,3-Hexamethyldisilazane Promoted by Aspartic Acid as an Efficient Organocatalyst

“…In a continuation of our studies into the application of new catalysts in organic functional group transformations [16][17][18][19][20][21][22], we disclose here a new, efficient, and mild procedure for the trimethylsilylation of a wide variety of hydroxyl groups using HMDS in the presence of a catalytic amount of aspartic acid as an efficient organocatalyst under mild and heterogeneous conditions at room temperature.…”

Preparation of Alkyl Formates from Corresponding Alcohols using Ethyl Formate Catalyzed by Poly(4-vinylpyridinium tribromide) under Neutral and Solvent-Free Conditions

“…In continuing of our experiments on the application of new reagents or reagent systems in the organic functional group transformations [14][15][16][17][18][19][20][21][22] we became interested to prepare alkyl formates from the corresponding alcohols in the presence of a neutral catalyst. Recently we have introduce a new tribromide reagent (poly(4-vinylpyridinium tribromide), as green and none-toxic polymeric reagent (Fig.…”

Green and Metal-free Catalytic Oxidation of Urazoles into Triazolinediones by Guanidinium Nitrate and Catalytic Amounts of Silica Sulfuric Acid

“…1 In the last few years, heterogeneous systems [2][3][4][5] have become increasingly used in organic reactions, mainly because the reactions are carried out under mild conditions and the organic products are easily isolated from the reaction media. In addition, the stability and cheapness, high yields of the products, short reaction times, and reusability is other important advantages of these systems.…”