Ozonolysis of 1,2-dimethylbenzene (o-xylene) and its support for the Kekulé structure of benzene

Introduction:
Ozonolysis is a chemical reaction that involves the cleavage of carbon-carbon double bonds using ozone (O3). It is commonly used to determine the structure of organic compounds. In the case of 1,2-dimethylbenzene (o-xylene), ozonolysis provides valuable insights into the arrangement of the carbon-carbon bonds in the benzene ring, supporting the Kekulé structure of benzene.

Ozonolysis of 1,2-dimethylbenzene:
Ozonolysis of 1,2-dimethylbenzene (o-xylene) involves the reaction of ozone with the double bonds present in the molecule. The ozonolysis reaction proceeds in two stages: oxidative cleavage and reductive workup.

Oxidative cleavage:
During oxidative cleavage, ozone adds to the double bond, resulting in the formation of an unstable primary ozonide. This ozonide can further rearrange to form more stable secondary ozonides. In the case of 1,2-dimethylbenzene, the oxidative cleavage leads to the formation of two secondary ozonides, as shown below:

- Secondary ozonide 1: Generated by cleavage between the carbon atoms attached to the methyl groups and the benzene ring.
- Secondary ozonide 2: Generated by cleavage between the two carbon atoms directly attached to the benzene ring.

Reductive workup:
The second stage of ozonolysis involves reductive workup, which converts the secondary ozonides into specific products. In the case of 1,2-dimethylbenzene, the reductive workup yields the following products:

- Product 1: Generated from secondary ozonide 1. It consists of a carboxylic acid and an aldehyde, resulting from the cleavage of the carbon-carbon bond between the benzene ring and the methyl group.
- Product 2: Generated from secondary ozonide 2. It consists of two aldehydes, resulting from the cleavage of the carbon-carbon bond between the two carbon atoms directly attached to the benzene ring.

Support for the Kekulé structure:
The products obtained from the ozonolysis of 1,2-dimethylbenzene provide support for the Kekulé structure of benzene, which is an important concept in organic chemistry. The Kekulé structure proposes that benzene consists of alternating single and double bonds between its carbon atoms.

Explanation:
The ozonolysis products of 1,2-dimethylbenzene are consistent with the Kekulé structure of benzene because they indicate the presence of alternating single and double bonds in the benzene ring. The formation of two aldehydes from the cleavage of a single carbon-carbon bond between the two carbon atoms directly attached to the benzene ring supports the presence of a double bond between these carbon atoms.

Additionally, the formation of a carboxylic acid and an aldehyde from the cleavage of the carbon-carbon bond between the benzene ring and the methyl