ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Bromine formation in solid NaBr/KNO₃ mixture and assay of this reaction via bromination of activated aromatics

Ida Rahu, Ott Kekišev, Jaak Järv, and Peeter Burk

University of Tartu, Tartu, Estonia

E-mail: ida@ut.ee

Abstract: Bromine formation in the mixture of solid NaBr and KNO₃ was observed and the process was studied in different acidified organic solvent–water mixtures by monitoring the bromination of acetanilide and other compounds, containing activated aromatic substituents. This assay is based on fast bromination reaction of these aromatic compounds, as differently from the assay of Br₂, the brominated aromatics can be easily determined by conventional gas chromatography–mass spectrometry (GC–MS) methods. It was found that bromine was generated autocatalytically on the surface of salt crystals and the reaction was characterized by a lag period, the duration of which depended on reaction conditions, and importantly on the type of the organic solvent in the reaction mixture. As the bromine formation could be easily controlled by reaction conditions, it was suggested that the studied reaction might have practical applications as an environmentally friendly and economically feasible bromination method. It was also shown that the bromination of aromatics followed the mechanism of classical electrophilic aromatic substitution reaction.

Keywords: Feasible in situ method of bromine formation ; Reaction with solid salts ; Eco-friendly reagents ; Bromination of activated aromatics 

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-018-0526-3

Chemical Papers 72 (11) 2893–2898 (2018)