Benzo thiophenes side-chain substituted

The dominant sulfur compounds in the gas oils of the heavy oil and bitumens are alkyl substituted benzo- and dibenzothiophenes, with a limited number of isomers. While some of these thiophenes have long side chains, those in the major fractions have short side chains. The dominance of short side chains might be ascribed to the maturation effects. The benzothiophenes in the deeper Medicine River oil are similar to those from the heavy oils, however, the same dibenzothiophenes are not found in significant amounts. 

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