A High-Performance Renewable Thermosetting Resin Derived from Eugenol

A renewable bisphenol, 4,4′‐(butane‐1,4‐diyl)bis(2‐methoxyphenol), was synthesized on a preparative scale by a solvent‐free, Ru‐catalyzed olefin metathesis coupling reaction of eugenol followed by hydrogenation. After purification, the bisphenol was converted to a new bis(cyanate) ester by standard techniques. The bisphenol and cyanate ester were characterized rigorously by NMR spectroscopy and single‐crystal X‐ray diffraction studies. After complete cure, the cyanate ester exhibited thermal stability in excess of 350 °C and a glass transition temperature (Tg) of 186 °C. As a result of the four‐carbon chain between the aromatic rings, the thermoset displayed a water uptake of only 1.8 % after a four day immersion in 85 °C water. The wet Tg of the material (167 °C) was only 19 °C lower than the dry Tg, and the material showed no significant degradation as a result of the water treatment. These results suggest that this resin is well suited for maritime environments and provide further evidence that full‐performance resins can be generated from sustainable feedstocks. For the clove of it: Eugenol, an abundant natural phenol and the primary component of clove oil, is converted to a thermoset resin without the use of bisphenol A, which has estrogenic effects. This is achieved by using a high yield, two‐step reaction, in which the intermediate bisphenol is generated through a solvent‐free process with low catalyst loading. The structure–property relationships resulting from the presence of atypical substituents on the aromatic rings of the eugenol‐derived resin are also discussed.