Abstract

Palladium offers various applications in the field of fine chemicals, especially as a catalyst in carbon-carbon coupling reactions. Pd²⁺ ions which are attached to a suitable ligand, such as a hydrazone derivative, improve the catalytic performance of palladium (Pd(II)) as a catalyst. This study focused on the catalytic performance of two synthesized Pd(II)–hydrazone complexes (Pd-L₁ and Pd-L₂) as catalysts in the Heck reaction. The reaction of synthesized hydrazone ligands L₁ and L₂ in methanol with Pd(II) chloride produced Pd-L₁ and Pd-L₂ complexes, respectively. Structures of the synthesized compounds were confirmed by using Fourier transform infrared (FT-IR), ¹H and ¹³C nuclear magnetic resonance (NMR), and UV-Vis spectroscopies. The preliminary complexation study between Pd²⁺ cations and hydrazone ligands (L₁ and L₂) which showed stoichiometric of 1:1 and 1:2 formation corresponded to the metal-ligand ratio. Catalytic activity study of both complexes in the Heck reaction between 1-bromo-4-nitrobenzene and styrene at different catalyst loadings and reaction times was conducted and analyzed by using gas chromatography-flame ionisation detector (GC-FID) spectroscopy. The best catalytic activity was by using 0.5 mmol% Pd-L₁ catalyst loading at 60 min of reaction time, in DMA solvent, and Na₂CO₃ as a base.