1,4‐Pentanediol as an Alternative Biomass‐Derived Medium for the Phosphine‐Free Heck Coupling Reactions

> 0.9) were observed between the substituents' Hammett σ constants and performance. Taking advantage of the products' significant temperature-dependent solubility in 1,4-PDO, facile product separation via simple filtration can be achieved, avoiding high-solvent-consuming column chromatography and facilitating solvent recovery. Using this approach, 24 products were synthesized and isolated with moderate to high yields (53-83%) and high purities (>90%). Solvent and catalyst recycling were demonstrated over three cycles. This protocol reduces the E-factor by more than 90% relative to conventional Heck conditions, highlighting its potential for sustainable synthetic applications.