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

Oxidative bromination of non-activated aromatic compounds with AlBr₃/KNO₃ mixture

Ida Rahu and Jaak Järv

Institute of Chemistry, University of Tartu, Tartu, Estonia

E-mail: ida@ut.ee

Received: 10 June 2019  Accepted: 16 October 2019

Abstract:

Bromination of non-activated aromatic compounds with reaction mixture containing KNO₃ and AlBr₃ was studied in liquid substrates and in solvent. Aluminium bromide has three different roles in this reaction mixture. First, it is a source of bromide ions, which are essential in oxidative bromination application. Second, it acts as a catalyst, and lastly, it forms acidic environment via its hydrolysis, which is necessary for enhancement of the oxidising properties of nitrate ions. It was shown that when changing the reaction conditions, different side reactions (like nitration or Friedel–Crafts type arylation) can occur. However, it is possible to guide the reaction path and receive the desired outcome by choosing the suitable reaction conditions. In addition, it was shown that there has to be water content in this reaction mixture as the bromine formation rate depends on it, while there exists an optimal volume of water, where bromine formation is the fastest.

Keywords: Bromination of non-activated aromatics; Oxidative bromination; Lewis acid catalyst; In situ bromine formation

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-019-00965-w

Chemical Papers 74 (4) 1219–1227 (2020)