Les réactions de Friedel et Crafts d'acylation des hydrocarbures aromatiques polycycliques. IX. L'acétylation de l'anthracène et de ses homologues méso-méthylés

A study of the influence of various reaction parameters (solvent, temperature, nature and quantity of the catalyst and of the acylating agent) on the yield and isomeric orientation of the acetylation of 9-methyl- and 9,10-dimethylanthracene relative to that of anthracene itself. reveals the importance of the rearrangement of the meso-substitution product vis à vis that of products substituted in other positions. Analysis of the conditions necessary for reversibility indicates that an excess of the catalyst is the main factor responsible. The experimental results allow one to propose a mechanism for this rearrangement which does not involve the prior dissociation of the acylating agent during acylations by acid anhydrides.