INSIGHT INTO PHOSPHINE EFFECTS ON THE HOMOGENEOUS HYDROGENATION OF AVERMECTINS TO IVERMECTIN CATALYZED BY IN-SITU FORMED RHODIUM COMPLEXES

PATRICIA D. ZGOLICZ; MARÍA I. CABRERA; RICARDO J. GRAU

REACTION KINETICS AND CATALYSIS LETTERS

SpringerLink

Año: 2008 vol. 93 p. 165 - 173

0133-1736

A kinetic study of the homogeneous catalytic hydrogenation of avermectins is reported for a series of isosteric p-substituted arylphosphines as ligands. The activity of the rhodium complexes formed in situ from [RhCl(COD)]2 increased with increasing the electron-donor capacity of the P(p-XC6H4)3: P(p-ClC6H4)3 < P(C6H5)3 < P(p-CH3C6H4)3 < P(p-OCH3C6H4)3. As expected, this trend was also observed when using preformed complexes thereof. Linear correlations based on Hammett and Kabachnik treatments are provided as useful tools to guide the exploration work towards improved [RhCl(COD)]2/P(p-XC6H4)3 catalytic systems.