The ozonization of 2,3‐dimethylnaphthalene; and of 1,4‐dimethylnaphthalene. a contribution to the problem of the bond structure of naphthalene

By the ozonization of 2,3-dimethylnaphthalene are formed glyoxal, methylglyoxal and dimethylglyoxal; these compounds have been identified by means of the oximes. The relative amounts of these oxidation products have been determined, the molecular ratio of dimethylglyoxal to methylglyoxal is about 1 : 0.1. By the ozonization of 1,4-dimethylnaphthalene are formed glyoxal and methylglyoxal; the relative amounts of these oxidation products have been determined, the total yields are low. The experimental evidence obtained does not support the assumption made by Marckwald, Fries, Fieser and other chemists, that naphthalene and its derivatives have the symmetrical structure (Erlenmeyer-Graebe structure) and that the single and double bonds between the carbon atoms of the bicyclic system are incapable of migrating. The experimental results can be interpreted in the simplest way by the assumption that 2,3-dimethylnaphthalene can react according to the three mesomeric forms and that 1,4-dimethylnaphthalene can react according to an unsymmetrical structure (Erdmann structure). It remains undecided whether 1,4-dimethylnaphthalene can also react according to the symmetrical structure; however, the assumption that 1,4-dimethylnaphthalene can react according to the three mesomeric forms is not contradictory to the observed facts.