Comparatively Speaking: Fatty Acids vs. Ozone Acids

Natural acids can be made by saponification of either triglycerides (Figure 1) or methyl esters (Figure 2), followed by acidulation (Figures 3 and 4). The reaction sequence, whether by methyl esters or triglycerides, has two steps. The first step is saponification with base and the second is acidulation. If a triglyceride is used, glycerin results as the by-product. Similarly, if methyl ester is used, methanol is the by-product. The reaction produces a monosubstituted fatty acid identical to the feedstock going into the reaction. For fatty acid nomenclature, see Table 1.

Ozone acids are produced by the reaction of unsaturated acids with ozone, as seen in Figure 5. Ozonolysis of oleic acid is the major source for pelargonic and azelaic acids. The reaction is interesting since it produces a diacid and a lower molecular weight monofunctional acid.

The process was developed and patented in the 1950s by Emery, now Cognis. The process notably produces both diacid and odd carbon chain acids, which are not readily available from nature.

Any unsaturated acid can be subjected to the process to cleave the double bond and produce a diacid and pelargonic acid. The reaction of erucic acid results in pelargonic acid and brassylic acid 13-carbon diacid.

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