The Reaction of Azoxybenzenes with Aluminum Chloride

Abstract

Treatment of azoxybenzene [1] with AlCl₃ in CS₂ gave 4-chloroazobenzene [2] as main product, and azobenzene [3] and 4, 4'-dichloroazobenzene [4] as by-products (Table 1). The reaction of 2-chloro-ONN-azoxybenzene with AlCl₃ yielded a mixture of 2, 4- and 2, 4'-dichloroazobenzenes as the main products. Azobenzenes were chlorinated with AlCl₃ in the presense of azoxy compounds to give 4-chloroazobenzenes. It may be interpreted that dichloro azo cornpound [4] is formed by subsequent chlorination of the initial product [2] with AlCl₃ and the unchanged azoxy compound. The reaction of 4, 4'-dibromoazoxybenzene with AlCl₃ in CS₂ gave 4-bromo-4'-chloroazobenzene (18%) and 3, 4'-dibromo-4-chloroazobenzene (10%), together with 4, 4'-dibromoazobenzene (38%) and 4, 4'-dibromo-2-chloroazobenzene (19%). Meanwhile, [1] was treated with AlCl₃ in nitromethane to give [2] (60%) and [3] (18%), besides 2-hydroxyazobenzene (2%) and 4-hydroxyazobenzene (9%).