The ozonization of pyridine and some of its homologues in connection with the bond structure of pyridine

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Abstract
The ozonization of pyridine, 4‐ethylpyridine, 2,6‐dimethylpyridine, 2,4,6‐trimethylpyridine, 2,3‐dimethylpyridine, 3,4‐dimethylpyridine and 2,3,4‐trimethylpyridine is described.The products formed upon hydrolysis of the ozonized bases were found to consist of glyoxal derivatives, acids, ammonia and peroxides. Probably, acid amides are also present.The glyoxal derivatives could be isolated and identified in the form of the corresponding bis‐(p‐nitrophenyl)‐hydrazones. The formation of glyoxal, methylglyoxal and diacetyl from 2,3‐dimethylpyridine, 3,4‐dimethylpyridine and 2,3,4‐trimethylpyridine proved these bases to react as if consisting of a mixture of their Körner‐Dewar forms.This result, which is analogous to that which is found in the ozonolysis of benzene homologues, may be explained by assumptions based on the theory of resonance.A tentative scheme is given for the primary reactions involved, which is in full agreement with experimental evidence but which has not been proved with certainty.The conversion of the pyridine bases was found to proceed very slowly as compared with the corresponding reaction in the benzene series, the major part of the starting material being recovered.Some of the main results of this investigation have already been described by us in a preliminary communication2).