Zinc Choride Catalyzed Decomposition of 1,2-Dihydronaphthalene at 165 deg C. A Coal-Related Model Compound Study

Article abstract of DOI:10.1021/jo00348a011

The zinc chloride catalyzed decomposition of 1,2-dihydronaphthalene (1) at 165 deg C produces dimers of 1, tetralin, and naphthalene.Zinc chloride functions as a Friedel-Crafts type catalyst by coordinating with a hydroxyl from a water molecule and releasing a proton which initiates a carbonium ion reaction.The stoichiometric role of water has been established by measuring the activity of the zinc chloride-water complex as a function of the degree of hydration of the zinc chloride.The activity maximum occurs at a zinc chloride/water mole ratio of 1:1.Deuterium tracer experiments corroborate the role of water and also verify that the reaction occurs by a carbonium ion mechanism.The carbonium ion nature of the reaction is also inferred by the structures of the products.The 300-MHz 1H NMR spectra of the dimer products are consistent with the previously reported structures of the compounds.