Heterogenization of palladium(II) chelates on a sibunite

Summary Heterogenized palladium(II) chelates have been prepared by a sibunite treatment of acetone or aqueous solutions of palladium complexes with alizarin red C, 4- anilino-pent-3-en-2-one,N, N-bis(acetylacetone)ethylenediamine, 1-phenyl-4-methylpent-4-en-1,3-dione and 1-phenyl-3-anilino-4-methylpent-4-en-1-one. The catalytic properties of these chelates in chloronitrobenzene hydrogenation have been studied. It was found that the catalytic activity approaches 159 mol H₂ (mol Pd min)^–1 depending on the chlorine atom position in the aromatic ring and the nature of the solvent. The catalysts do not lose their activity after five cycles. The products of chloronitrobenzene hydrogenation are chloroanilines (up to 90%), azo- and azoxychlorobenzenes (5–7%) as a result of incomplete reduction as well as small quantities (2–5%) of dehalogenated azo-, azoxybenzenes and aniline.