Homocoupling reaction of p-tolylboronic acid with palladium-hydroxyapatite composite from chicken eggshell as the catalyst

Dea Putri Novianti, Muhamad Rashifari, Muhammad R. Ramadhan, Iis Intan Widiyowati, Puteri Khansa Salsabila, Ardanari Wahyu Waardhani, Muhamad Diki Permana, Atiek Rostika Noviyanti, Yudha P. Budiman
https://doi.org/10.1016/j.rechem.2025.102297

Abstract

Biaryl compounds, consist of two aromatic rings linked by a single bond, are crucial in the synthesis of antiviral drugs, antifungal agents, functional materials, and agrochemicals. Traditionally, these compounds are synthesized through cross-coupling reactions using two different types of aryl reagents. However, homocoupling reactions have emerged as a valuable alternative, enabling the production of symmetric biaryls from a single aryl substrate. This study explores the development of a heterogeneous palladium-hydroxyapatite (Pd-HAP) catalyst for the homocoupling of arylboronic acids. Hydroxyapatite, known for its hydroxyl-rich surface, high porosity, and strong acid-base sites, was selected as a cost-effective catalyst support. The research focused on optimizing solvent and temperature to maximize biaryl yields. Under optimal conditions ethanol as the solvent at 50 °C for 24 h, an 88 % yield of biaryl products was achieved. The recycled catalyst maintained a yield of 42 % after five reuses. These findings contribute to more sustainable and cost-effective approaches for biaryl synthesis.

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