Study on the Reaction of Higher Fatty Acid Methyl Esters with Metallic Sodium. III.

Abstract

Claisen condensation of higher fatty acid methyl esters was studied by using sodium methylate as the condensing agent. The condensation resulted in high yields of β-keto esters at reduced pressure, however it was difficult to proceed at normal pressure. Some properties of higher β-keto esters, including the reaction with hydroxylamine hydrochloride and KOH ethanol solution were discussed. The ketonic decomposition of higher β-keto esters was so quantitative that this may be easily utilized to analysis. Claisen condensation of C6C18 fatty acid methyl esters was little affected by the chain length.By the infrared spectroscopic study, some structural informations were obtained. These are as follows : Higher β-keto esters have no resonance structures characteristic to enolic form, and the tautomerism is far on the side of ketonic form with increase of chain length. β-Keto esters derived from C12C18 fatty acid esters are almost in the ketonic state.Properties of higher ketones which were prepared quantitatively from ketonic decomposition products were studied.