ZIEGLER SYSTEMS AS HYDROGENATION CATALYSTS .1. COBR2 LI[ALH(O-T/BUTYL)3]3 SYSTEM AS A CATALYST FOR THE HYDROGENATION OF ANTHRACENE/

The system Li[AIH(0-t-butyl)3]/CoBr2 in THF is a very active catalyst for the hydrogenation of anthracene. The rising activity with increasi ng concentration of the reducing agent can be described in terms of th e formation of a 1:1 adduct between the catalyst and the reducing agen t. If the catalyst is kept in a hydrogen atmosphere prior to the addit ion of the substrate, its activity decreases rapidly. During the addit ion of the components of the catalyst, at most 0.5 mol H-2/Mol CoBr2 a re generated at once, followed by slow H-2 generation which can be des cribed as two parallel first-order reactions. From the immediate H-2 g eneration it can be deduced that CoBr2 is reduced to Co(I) and that th e catalyst contains unchanged reducing agent.