Abstract

OLAOYE, Oluwasegun E. et al. Catalytic Hydrogenation of Sorbic Acid using Pyrazolyl Palladium(II) and Nickel(II) Complexes as Precatalysts. S.Afr.j.chem. (Online) [online]. 2021, vol.74, pp.50-56. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2021/v74a9.

We have prepared several pyrazolyl palladium and nickel complexes ([(L1)PdCl₂](1), [(L2) PdCl₂](2), [(L3) PdCl₂](3), [(L1) NiBr₂](4), [(L2) NiBr₂](5) and [(L3) NiBr₂](6)) by reacting 3,5-dimethyMH-pyrazole (L1), 3,5-di-ferf-butyl-1ZÏ-pyrazole (L2) and 5-ferrocenyl-1Zf-pyrazole(L3) with [PdCl₂(NCMe)₂] or [NiBr₂(DME)] to afford mononuclear palladium and nickel complexes, respectively. These complexes were then investigated as pre-catalysts in the hydrogenation of 2,4-hexadienoic acid (sorbic acid). The active catalysts from these complexes demonstrate significant activities under mild experimental conditions. Additionally, the active catalysts show that the hydrogenation of sorbic acid proceeds in a sequential manner, where the less hindered C=C bond (4-hexenoic acid) is preferentially reduced over the more hindered C=C bond (2-hexenoic acid).

Keywords : Pyrazolyl catalysts; sorbic acid; hydrogenation; selectivity.

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