Studies on Cyclic Compounds Separated from Heated Oils and Fats. III

Studies on Cyclic Monomer Obtained from Heated Linseed Oil in the Absence of Catalyst and Solvent

Abstract

In the previous papers, the authors reported the aromatic ο-substitution products which were formed by the disproportionation of the cyclohexadiene compounds produced in heated linseed oil in the presence of alkali or in heated ethyl β-eleostearate.
In these experiments, linseed oil was heated at 275°C for 12 hrs in the presence of carbondioxide without use of catalyst and solvent. Heated linseed oil fatty acid methyl esters were prepared by the routine method. Cyclic monomers were obtained from the vacuum distillate (187°C/0.21.5 mmHg) of the esters by urea adduct separation.
In the IR spectrum of the cyclic monomer fraction, the absorptions of aromatic ο-substituents and cyclohexadiene compounds were not observed, and in the GLC, there was a very small peak at position corresponding to cyclohexadiene compound and there was no any aromatic compound peak. Main parts of the cyclic monomers were cyclohexene compounds.
The cyclic monomer fraction was processed by the following procedures, (1) dehydrogenation, (2) aromatization with N-bromosuccinimide and (3) further heating (275°C, 6 and 12 hrs).
The results of these procedures showed that ; (1) aromatic ο-substitution products appeared slightly, (2) cyclohexadiene and aromatic ο-substituted compounds were produced in both and (3) the cyclic monomer fraction did not change further except polymerization.
As above mentioned, in the case of heating in the absence of alkali, both cyclohexadiene compounds and aromatic ο-substitution products were not produced, because the disproportionation reaction did not occur on the cyclohexene rings.