A Sustainable Tandem Catalysis Approach to Plant Oil‐Based Polyols via Schenck‐Ene Reaction and Epoxidation

Abstract

Novel polyols are synthesized in a one‐pot, tandem reaction approach. First, singlet oxygen is used as oxidant in the photochemical Schenck‐Ene reaction to obtain allyl hydroperoxides of triglycerides, which are reacted in situ to the corresponding epoxy alcohols catalyzed by titanium(IV) isopropoxide. Subsequent acidic epoxide ring‐opening with perchloric acid yields a triglyceride‐based polyol. Under basic conditions applying aqueous sodium hydroxide solution, cleavage of the ester bonds of the triglyceride and epoxide ring‐opening occur simultaneously resulting in a fatty acid‐based polyol.Practical Applications: Polyols, especially also based on renewable fatty acids, are valuable monomers for the synthesis of polyurethanes, polyester‐ and alkyd‐resins. With the here reported method, a maximum of three hydroxyl groups per double bond of the unsaturated triglyceride can be introduced, which cannot be realized with the methods reported to date.A tandem catalytic system of Schenk‐Ene reaction and in situ epoxidation efficiently leads to plant oil derived epoxy alcohols, which can be converted to triglyceride or fatty acid based polyols. Most interestingly, three OH‐groups per double bond of the fatty acid can be obtained via this route.