抄録
Oleic acid (cis-9-octadecenoic acid) was converted to monocarboxylic acids and γ- and δ-lactones by heating at 200°C under free oxygen. The monocarboxylic acids showed a C9 acid predominance in the presence of Na-montmorillonite in contrast to a C8 acid predominance in the absence of the clay. The γ-lactones showed a C6 lactone predominance in the former case and C4 and C8 lactone predominances in the latter case. Accordingly, it was postulated that the catalytic cracking of oleic acid in the presence of the clay produced mainly the C9 acid that, in turn, generated the C6 lactone by thermal oxidation. The molecular distribution patterns of the monocarboxylic acids and the γ-lactones in the range of C4 to C12 produced by the heating in the presence of the clay resemble those found in the Neogene Shinjo sediments. Therefore, unsaturated monocarboxylic acids with a C-C double bond at C9 were probably important precursors of the monocarboxylic acids and the γ-lactones found in the sediments.
