Geometric isomerism in some unsaturated aliphatic ketones

If ketones are prepared by heating unsaturated fatty acids at a high temperature in the presence of a metal or metallic oxide catalyst, some stereoisomeric change and movement of the double bond accompany ketonization. The ketones, oleone and erucone of the cis-cis-class, described in the literature as products of reactions of this kind, are shown to have been mixtures of isomers with trans-trans-forms predominating. Oleone and erucone, containing no detectable amounts of trans-material can be prepared either from the corresponding acyl chloride and triethylamine, or by condensation of the methyl or ethyl ester of the appropriate acid in xylene using sodium ethoxide as catalyst. These ketones are readily converted to the tetrahydroxy ketones and thence by oxidation to ketodibasic acids, useful as intermediates for the preparation of cyclic ketones.