Aromatic sulfonation 86. Sulfonation of pyrene, 1‐methylpyrene and perylene

Abstract

Abstract The mono‐ and di‐sulfonation of pyrene ( 1a ), 1‐methylpyrene ( 1b ) and perylene ( 2 ), with SO 3 in nitromethane at 0°C, has been studied. The monosulfonation of 1a, 1b and 2 leads to the almost exclusive formation of the 1‐, the 6‐ + 8‐ and the 3‐sulfonic acid, respectively, which is in agreement with predictions based on the calculated localization energies for the various positions of the respective arenes. The sulfonation of pyrene‐1‐sulfonic acid yields the 1,3‐disulfonic acid as the main product while that of both 1‐methylpyrene‐6‐ and ‐8‐sulfonic acid mainly yields the 6,8‐disulfonic acid. Perylene‐3‐sulfonic acid yields almost exclusively the 3,9‐ and/or the 3,10‐disulfonic acid. The positional reactivity orders of the pyrenesulfonic acids are determined by the (electronic) directing effect of the sulfonic acid substituent, while that of perylene‐3‐sulfonic acid is determined by the localization energies of the parent arene.