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Synlett 2011(6): 879-880  
DOI: 10.1055/s-0030-1259755
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© Georg Thieme Verlag Stuttgart ˙ New York

Sodium Bromate: An Eco-Friendly Brominating and Oxidizing Reagent

Jie Lu*
The College of Chemistry & Material Science, Hebei Normal University, Shijiazhuang 050016, P. R. of China
e-Mail: lujiechem@gmail.com;
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Publication History

Publication Date:
16 March 2011 (online)

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Introduction

Sodium bromate is commercially available as an inexpensive stable white crystal, and has been extensively used in organic synthesis as an eco-friendly brominating and oxidizing reagent. It decomposes at 381 ˚C with liberation of oxygen. It can oxidize primary alcohols to aldehydes, secondary alcohols to ketones, sulfides to sulfoxides, hydroquinones and polyaromatics to quinones, thiols to disulfides, iodobenzenes to iodoxybenzenes, and ω,ω-diols to dicarboxylic acids or lactones. Under different sets of conditions, the oxidation can result in the formation of esters and carboxylic acids. [¹] It has been used for oxidative cleavages of alkyl, trimethylsilyl, t-butyldimethylsilyl, tetrahydropyranyl ethers, and ethylene acetals to the corresponding carbonyl compounds. [²] [³] The transformations of benzylidene acetals to hydroxy esters with NaBrO3˙Na2S2O4 in EtOAc-H2O biphasic medium are readily accomplished. [4] [5] Even more interesting is the finding that the reaction of cyclic ethers with sodium bromate in the presence of catalytic amounts of hydrobromic acid gave lactones. [6] Sodium bromate can also serve as an effective bromohydroxylation reagent for alkenes, alkynes, and allylic alcohols. [7] It has also been reported to be a powerful brominating agent for aromatic compounds including phenols, anilines, aromatic ethers, and benzenes. [8] [9]