The Enantioface-differentiating (Asymmetric) Hydrogenation of the C=O Double Bond with Modified Raney Nickel. XXXIV. The Adsorption Mode of 2-Hydroxy Acid on Raney Nickel

Article abstract of DOI:10.1246/bcsj.53.1019

The adsorbed species of the modyfying reagent and the surface states of the catalyst caused by the modification of a Raney nickel with 2-hydroxy acid at various pH regions were investigated.The adsorption mode of 2-hydroxy acid was proposed in each modifying-pH region; that is, (1) in a pH region intrinsic to the solution of the free 2-hydroxy acid, nickel salt of 2-hydroxy acid was adsorbed on the catalyst surface corroded by the acid; (2) under weakly acidic conditions, nickel salt and sodium salt of 2-hydroxy acid were adsorbed on the catalyst surface partially corroded by the acid; (3) under neutral conditions, the sodium salt was adsorbed on the surface of the fresh Raney nickel, and (4) under strongly basic conditions, the sodium salt and NaOH were adsorbed on the surface of the fresh Raney nickel.