Catechol derivative urushiol’s reactivity and applications beyond traditional coating

Catechol compounds such as tannic acid and dopamine have been widely found in plants, marine mussels and human beings due to they play critical roles in governing activities such as growth, fruit ripeness, and emotion of life. They have been made into functional materials through benefitting from the outstanding reactivities of catechol group. Urushiol is a liquid mixture of catechol compounds with a side chain of C15–17 tri- or bi- or mono-ene. It naturally originates from sap of lacquer tree (Rhus verniciflua Stokes). Due to its curability under ambient conditions and waterproof performance, it has long been mainly used as a durable and aesthetic coating for woodwares in ancient and modern oriental countries. As research interest is growing for catechol compounds in recent years, many novel reactions and functions have been developed for urushiol. In this mini-review for the research on urushiol in the last decade, we mainly focus on the various reactions occurring on urushiol’s benzene ring, phenolic hydroxyl group and alkenyl side chain, and on its functional materials ranging from photocatalyst to adhesive to biomedical materials, advanced coatings, and biological activities including allergy and chemoprevention. As more interesting functions derived from urushiol are conceived, this great renewable compound would certainly enable us to fulfill ambitious goals in making more advanced materials and products for a sustainable economy and society.