Methods for improving yields of cyclic acid from linseed oil

Liquid C-18 saturated monocarboxylic acids, which are termed “cylic acids” because they contain a ring structure, have been prepared by the action of excess sodium hydroxide on linseed oil in ethylene glycol at elevated temperatures, followed by distillation and hydrogenation of the resulting free fatty acid monomers and by separation of the straight-chain components by low-temperature crystallization from acetone. In a survey of other possible catalysts and reaction conditions, cyclic acid yields were improved from the previously reported 32.4 g to 43.5 g of cyclic acid per 100 g of linseed fatty acids by removing water from the starting materials and using the monosodium derivative of ethylene glycol as catalyst. The corresponding amount of polymer formed decreased because of a decrease in hydroxylation and subsequent polyester formation. Presented at the AOCS meeting, in Chicago, Ill., 1961. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.