Tetralin 1, 2-dihydronaphthalene, catalytic

Naphthalene can be reduced more easily than benzene. With sodium in alcohol, 1,4-dihydronaphthalene is formed. Catalytic hydrogenation gives tetralin (1,2,3,4-tetrahydronaphthalene). Further reduction to give perhydro-naphthalene (decalin) can be achieved on prolonged catalytic hydrogenation at relatively high temperatures and pressures ... 

It is interesting to note that catalytic reactions tending to equilibrate tetralin, 1,2-dihydronaphthalene and naphthalene (19,39) will serve to generate free radicals since 1,2-dihydronaphthalene rapidly undergoes molecular disproportionation with tetralin. For instance, at equilibrium a 0.5% solution of naphthalene in tetralin (typical of distilled tetralin) will generate ca. 10 2 mol percent 1,2-dihydronaphthalene at 400°C, which will, in turn, form ca. 10 7 M tetralyl radicals (see above). 

Naphthalene is reduced to 1,4-dihydronaphthalene by sodium and alcohol. Isomerization of this product to 3,4-dihydronaphthalene occurs with sodamide in liquid ammonia. Tetrahydronaphthalene (tetralin) is formed from naphthalene by sodium in amyl alcohol or by reduction with nickel-aluminum alloy and aqueous alkali. Catalytic hydrogenation of naphthalene can be stopped at the tetralin stage over copper chromite, Raney nickel, or alkali metal catalysts. cis-Decahydronaphthalene is produced by high-pressure hydrogenation of tetralin over Adams catalyst, whereas a mixture of cis- and trans-decalins is obtained from naphthalene under the same conditions. ... 

Aromatic Rings. - The ability of electrolytic reduction of naphthalene to produce dihydronaphthalene offers an advantage over the catalytic process, which can only be halted at the tetralin stage. It is believed that Hoechst are carrying out pilot plant studies with a view to producing 1,4-dihydro-naphthalene and 1,4-dihydronaphthalic esters commercially by electrolytic reduction of naphthalene and naphthyl esters. 

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