Anthracenes 1,2,3,4,5,6,7,8-octahydro

Using the optimum conditions for the reduction of anthracene to 33 (entry 2, Table 5) and adding a base catalyzed isomerization step for the conversion of 33 to 34 it was possible to increase the cathodic yields of the octahydro-(3J) and decahydro-(i<5) products. The one pot sequence is shown below ... 

Polycyclic aromatic hydrocarbons, such as anthracene and phenanthrene, can be reduced at elevated temperatures (80°C) at constant current to different hydroderivatives in an aqueous medium containing (TBA )OH (2.1 M). The following products were obtained in yields depending on the number of FmoP and the cell construction 9,10-dihydroanthracene, hexahydro-, octahydro-, and decahydroanthracenes. Phenanthrene can be reduced under similar conditions no isomerization step is necessary to obtain octahydro- and decahydrophenanthrene [43,51]. 

Hydrogenation of anthracene (30) over Raney nickel, platinum or palladium also gives 9,10 dihydroanthracene (31) as the initial product but a rhodium catalyst gives the octahydro product, 32, in which both terminal rings are saturated (Eqn. 17.28). Further hydrogenation takes place under the conditions used to saturate alkylbenzenes with the predominant product the cis ring junction isomer. 

The direct synthesis of anthraquinone from phthalic anhydride and benzene has been reported to proceed over zeolite Beta [50] in a shape selective manner. In a conventional anthraquinone synthesis, anthracene is used as a feedstock for oxidation. Once there is a shortage of it in the market, additional anthracene could be produced by isomerization of its isomer, viz. phenanthrene. This, however, is not possible by direct isomerization of the trinuclear aromatic system but involves the partially (symmetrically) hydrogenated species. Consequently, isomerization of symmetrical octahydrophenanthrene to symmetrical octahydro-anthracene was studied by Song and Moffatt [51]. As sketched in Figure 3, a high yield of symmetrical octahydroanthracene can be obtained over zeolite H-mordenite (ngj/nyy = 8) at 250 °C (liquid phase, decalin as solvent). These examples show that (shape selective) catalysis on zeolites is more and more expanding into the conversion of polycyclic aromatics, and we foresee continued interest and success in this field of zeolite catalysis. 

Ring-shift isomerization of 1,2,3,4,5,6,7,8-octahydro-phenantrene (syn-OHP) to 1,2,3, 4,5,6,7,8-octahydro-anthracene (syn-OHAn) was studied on several hydrogen- and Me-exchanged Y zeolites (Song and Moffatt 1993). La,H-Y zeolite (8.4 wt% La203) appears to be an active and selective catalysts. Thus, a selectivity to syn-OHAn of 44.9% at a conversion of 74.93% at 250°C (yield of 30.43) have been reported. However, the catalytic behaviour was strongly influenced by the solvent, and the best catalytic behaviour was obtained using decaline as solvent. 

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