Toward Sustainable Synthesis of PA12 (Nylon-12) Precursor from Oleic Acid Using Ring-Closing Metathesis

The efficient reaction conditions for ring-closing metathesis of homoallyloleamide (2) for the synthesis of PA12 (Nylon-12) precursor (4) are presented. Systematic screening of a series of commercially available metathesis catalysts identified a catalyst that promotes the reaction at low temperature (60 °C), enabling use of nonhalogenated solvents, ethyl acetate and hexanes. The catalyst was adsorbed on mesoporous silica gel to aid its postreaction recovery and reuse, which was demonstrated in hexanes up to three cycles without significant loss of reaction conversion (>90%). The identification of reaction-compatible green solvents as well as the demonstration of the potential for recycling of the supported catalyst are steps further toward establishing environmentally sustainable production of the polyamide precursors from oleic acid.