Unusual nucleophilic versus electrophilic aromatic substitution on nitroanilines

The reaction of the regioisomeric nitroanilines with KI and HNOs/bentonite system using microwave energy in solvent-free conditions is reported. In ac cordance with the obtained results, an unusual competence between nucleophi lic aromatic substitution versus electrophilic aromatic substitution was de tected. With the para isomer two products were obtained, one for each react ion type; however, with the meta-nitroaniline, only the nucleophilic substi tution product was detected, and finally with the ortho isomer in addition to the nucleophilic and electrophilic substitution products, we detected th e formation of 2,4-diiodonitrobenzene. In order to explain the achieved pro ducts, we propose that the last product is formed in two steps: firstly by a nucleophilic aromatic substitution, and secondly by an electrophilic arom atic substitution. (C) 2000 Elsevier Science B.V. All rights reserved.