Synthesis and application of monomers produced from oxidative cleavage of castor oil

Authors: Winfield, Demichael; Vermillion, Karl

Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: 2/14/2024
Publication Date: 4/29/2024
Citation: Winfield, D.D., Vermillion, K. 2024. Synthesis and application of monomers produced from oxidative cleavage of castor oil [abstract]. American Oil Chemists' Society Annual Meeting and Expo.

Interpretive Summary:

Technical Abstract: Vegetable oils are an attractive feedstock for producing sustainable polymers. Several types of chemistries can be employed to valorize vegetable oils into useful monomers or precursors. Oxidative cleavage of unsaturated fatty acids in vegetable oils can yield mono-, di-, and tri-carboxylic acids, which can be utilized for a variety of applications as monomers. This transformation can be achieved with a metal catalyst using hydrogen peroxide as the oxidant, or by ozonolysis followed by an oxidative workup. Oxidative cleavage of castor oil uniquely yields a ß-hydroxy acid, R-(3)-hydroxynonanoic acid, due to the hydroxy group present in ricinoleic acid. A variety of ß-hydroxy acids can be obtained through microbial fermentation, but the 9-carbon analogue is uncommon. This makes castor oil a valuable starting material for producing this analogue alongside other monomers. However, the presence of the hydroxy group also makes castor oil a challenging substrate for oxidative cleavage due to additional side reactions it can undergo. In this work, a method for oxidative cleavage of castor oil to obtain the aforementioned carboxylic acids is discussed. The reaction was performed by both ozonolysis and with tungsten based polyoxometalate catalysts. Tungsten catalysts provided higher selectivity and control over the reaction, affording oxidation products in good yield. Purity of the isolated products is affected by the chosen synthetic route and method. Applications of the products as a monomer for polyesters are discussed.