Abstract δ-Stearolactone was prepared from oleic acid using concentrated sulfuric acid under various conditions in the presence of polar, nonparticipating solvents. δ-Stearolactone was formed in as high as 15∶ 1 ratios over the thermodynamic product, ψ-lactone, in the presence of methylene chloride, 100% wt/vol, at room temperature with two equivalents of sulfuric acid for 24 h. This procedure is applicable to other olefinic fatty acids such as ...