Ozone-mediated polyol synthesis from soybean oil
Polyols from vegetable oils can replace petroleumbased polyols in the preparation of polyurethanes and polyesters in a wide range of applications. However, previous preparation methods are either too costly, inefficient, or yield secondary alcohols, which are less reactive than the desired primary alcohols. The objectives of this study were to prepare primary soy-based polyols by a new catalytic ozonolysis process and to characterize the composition of the product mixture. In this new process, the polyols were prepared by passing ozone through a solution of soybean oil and ethylene glycol in the presence of an alkaline catalyst. Unlike conventional ozonolysis that yields aldehydes and carboxylic acids by spontaneous decomposition of the ozonide intermediates, the ozonides in our method reacted with the hydroxyl group of the glycol to form an ester linkage with a terminal hydroxy group. Statistical analysis of the product mixture indicates that the resulting polyol mixture is more uniform than the original TG mixture, having (2-hydroxy)nonanoate as the major component of the new hydroxyl functional TG. The chemical structure of the polyols produced was further characterized by iodine number and 13C NMR and FTIR spectroscopy, which confirmed the cleavage of the double bonds, the presence of hydroxyl groups, and the formation of new ester linkages.