Hydrogenation of Polycyclic Aromatic Ring Systems

Raney nickel and platinum, palladium, and rhodium catalysts have been used to accomplish the hydrogenation of polycyclic aromatics. Hydrogenation of fused polycyclic arenes leads to the cis- or fran -substituted cyclohexane derivatives. The cis product is usually obtained again this can be understood in terms of the mechanism proposed for aromatic hydrogenation (vide supra). 

24) [22]. With other than Pt catalysts, e. g. Ru/C, more severe reaction conditions are required, although even higher stereoselectivities ( 95 %) are achievable [23]. 

Solvent effects are sometimes important in the hydrogenation of substituted naphthalenes, e. g. 2-naphthol [24]. Use of Rh-on-alumina catalysts in acetic acid results in a mixture of decalone and cis-decalol, whereas changing the solvent to methanol or ethanol gives ds-decalol as the predominant product. 

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