Chemo-enzymatic functionalization of gallic and vanillic acids: synthesis of bio-based epoxy resins prepolymers

The chemo-enzymatic epoxidation of allylated gallic and vanillic acids with lipase B from Candida antarctica and aqueous hydrogen peroxide in the presence of caprylic acid was investigated. The use of 1 molar eq of caprylic acid and 1.8-2 molar eq of H2O2 per allylic double bond led to a high degree of conversion to epoxides (89% yield for allylated gallic acid and 87% yield for allylated vanillic acid) comparatively to the hazardous peracid mCPBA (1.5-3.2 molar eq per double bond allowed 75-85% yield). The epoxidized products obtained could be used in the formulation of novel bio-based epoxy resins.