Condensation of Oleic Acid with Formaldehyde

Abstract

Condensation products of oleic acid and paraformaldehyde in acetic acid solution were saponified and then fractionated by recrystallization, and the following two substances were obtained [1 part of oleic acid reacted with 2 parts of formaldehyde effectively in 1 hr when 1% of HClO₄ was used as a catalyst (Fig. 3)].
One of them had mp 117-118°C and seemed to have pyranol-4 structure because of its characteristics (Table 1 & Fig.-1) and it was considered as 3-octyl-4-hydroxy-5-carboxyhexyltetrahydropyran (or 3-heptyl-4-hydroxy-5-carboxyheptyltetrapyran). Pigulevskii assumed in his report about the same reaction that the product had pyranol-3 structure.
And the other was C₁₈H₃₆O₃, mp 70-71°C, A.V. 184.5, and from the IR spectrum (shown in Fig.-2), it was considered as monohydroxystearic acid (mixture of 9-and 10-hydroxy acids).
As the catalyzers, perchloric acid was most effective, and sulfuric acid and borontrifluoride etherate were also fairly effective (Table 3).