Write down the products of ozonolysis of 1, 2-dimethylbenzene (o-xylene). How does the result support Kekulé structure for benzene?

Explanation

1,2-dimethylbenzene (o-xylene) may be regarded as a resonance hybrid of the following Kekule structures I and II. Their ozonolysis takes place as shown below:

Thus, in all three products are obtained. These cannot be obtained by any one of the Kekule.s structures. This shows that toluene and hence benzene is a resonance hybrid of the two resonating structures.