Catalytic oxidation of sulfides to sulfoxides using sodium perborate and/or sodium percarbonate and silica sulfuric acid in the presence of KBr Davood Habibi a, * , Mohammad Ali Zolfigol a , Malihe Safaiee a , Atefeh Shamsian a , Arash Ghorbani-Choghamarani b a Faculty of Chemistry, Bu Ali Sina University, Department of Chemistry, Abbas Abad Street, Hamedan 6517838683, Iran b Department of Chemistry, Faculty of Science, Ilam University, P.O. Box 69315516, Ilam, Iran article info Article history: Received 7 September 2008 Received in revised form 1 December 2008 Accepted 7 December 2008 Available online 5 February 2009 Keywords: Sulfides Sulfoxides Sodium perborate (SPB) Sodium percarbonate (SPC) Silica sulfuric acid KBr abstract Chemoselective catalytic oxidation of sulfides has been developed. A variety of aliphatic and aromatic sulfides are subjected to the sulfoxidation reaction by treatment of sodium perborate (SPB) and/or sodium percarbonate (SPC), silica sulfuric acid (SSA) and catalytic amounts of KBr in the presence of wet SiO 2 (50% w/w) in dichloromethane at room temperature with moderate to good yields. Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction Development of heterogeneous catalysts for fine chemicals syn- thesis has become a major area of research [1]. Also important as- pect of clean technology is the use of environmentally friendly catalysts [2]. Nowadays the research is focused on the more versa- tile, more selective, and more reactive catalyst [3]. Sulfides oxidation is one of the most important organic pro- cesses, since the corresponding sulfoxides are valuable synthetic intermediates for the synthesis of chemically and biologically important and significant molecules [4–6]. Sulfoxides are also valuable in the C–C bond-formation [7] and molecular rearrange- ments [8,9]. Additionally some of the biologically active sulfoxides play important roles as therapeutic agents such as anti-ulcer [10,11], antibacterial [12], and etc. Although sulfides can be easily oxidized by a wide variety of oxidizing reagents [13–17], but unfortunately, some of these re- agents are not satisfactory for the selective oxidation of sulfides to the sulfoxides because of several reasons such as over oxidation to sulfones, low selectivity, low yields of products, toxicity, and expensive reagents or catalysts. Hydrogen peroxide is a cheap and environmentally friendly oxi- dant [18], but the handling of its concentrated solutions is not desirable for safety problems. Sodium perborate (SPB) and sodium percarbonate (SPC) are both cheap, large-scale industrial chemicals that are nontoxic and relatively stable solids and are thus simple to handle on a large-scale and permit accurate dosage [19]. They are being produced mainly as solid ingredients of domestic washing formulations in which they act as sources of H 2 O 2 in solution for stain bleaching [20]. Sodium perborate (SPB) and sodium percar- bonate (SPC) are versatile oxidizing agents, which have been used extensively for oxidation of different types of organic compounds [21–24]. 2. Results and discussion Recently we have shown that the bromonium ion (Br + ) can effectively be applied for oxidation of different types of organic compounds [25–29]. Therefore we became interested to introduce a new catalytic media, based on in situ generation of Br + using so- dium perborate and/or sodium percarbonate and catalytic amounts of potassium bromide in the presence of an activator for the effective oxidation of sulfides to sulfoxides. In continuation of our studies on the synthesis and application of hydrogen peroxide adduct reagents [30], we decided to apply SPB and SPC as excellent and safe source of H 2 O 2 . SPB and SPC are environmentally friendly oxidizing agents, but the low oxidizing power of these reagents is the main drawback to their application. Therefore, an appropriate activator should be 1566-7367/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.catcom.2008.12.066 * Corresponding author. Tel.: +98 811 8282807; fax: +98 811 8257407. E-mail address: davood.habibi@gmail.com (D. Habibi). Catalysis Communications 10 (2009) 1257–1260 Contents lists available at ScienceDirect Catalysis Communications journal homepage: www.elsevier.com/locate/catcom