Electrophilic aromatic substitution. Part VI. Kinetics and mechanism of nitration of halogenobenzenes

The kinetics of nitration of the monohalogenobenzenes in sulphuric acid and in perchloric acid, and of many di- and poly-halogenobenzenes in sulphuric acid have been studied. Isomer proportions have been measured and partial rate factors evaluated. The polysubstituted compounds tend to be more reactive than would be expected from the additivity principle. Pentachlorobenzene is more reactive than 1,2,4,5-tetrachlorobenzene. The results are discussed in terms of H.M.O. theory and in terms of a simple electrostatic treatment.