Analysis of Ozonides and Peroxidic Compounds from Methyl Oleate
O. E. Ledea, J. Moleiro, M. Diaz, D. Jardines, A. Rosado(1),
Ozone Research Center, Cuba.
1 – National Center for Scientific Research, Cuba.
Methyl oleate ozonation, in hexane (non participating solvent) at
a concentration of 0.3 M and in presence of protic substances,
such as ethanol and water, was carried out. A bubbling reactor at
25 C, with an ozone dose of 50 mg per gram of sample was used.
Proton Nuclear Magnetic Resonance (H1-NMR) and Gas
Chromatography/Mass Spectrometry (GC/MS) techniques, in order to
identify the reaction products in all the studied conditions, were
used. During ozonation of methyl oleate in hexane, the
corresponding ozonides/oligomeres were identified. It was design a
simple procedure for GC/MS determination of ozonides, combining
the quantitative methylation with the analysis of the thermal
decomposition products of the ozonides. The procedure used for
this determination was not previously reported. The ozonides were
separated from the reaction mixture by means of the high
performance liquid chromatography (HPLC), using an isocratic
system. On the other hand, when ethanol is used as additive, the
ethoxy-hydroperoxides were identified as major products. Ozonides,
in smaller proportion, are observed too. For the analysis of these
compounds by GC/MS, the same procedure for the determination of
ozonides, was used. The gas chromatography profile obtained is
discussed in detail and it is corroborated by the H1-NMR analysis.
The analysis of the reaction products, when water was used as
additive, revealed only the presence of aldehydes (hexanal,
nonanal and 9-oxo-methyl nonanoate) for both techniques. The
obtained products, in all cases, can be explained taking into
account the Crieggee mechanism.
Source: 2nd International Symposium on Ozone Applications
Havana, Cuba – Mach 24-26, 1997.