ISOLATION AND STRUCTURAL CHARACTERIZATION OF 10-OXO-OCTADECANOIC ACIDIN SOME LACUSTRINE SEDIMENTS FROM THE NORDLINGER-RIES (SOUTHERN GERMANY)

Unusually high concentrations of C16 and C18 10-oxo-carboxylic acids w ere identified in the free acid fractions of bitumens from sulphur-ric h black shales from the Nordlinger Ries (southern Germany). After isol ation, the structure of the C18 homologue was elucidated by mass spect ral interpretation, derivatization (formation of diol and conversion i nto diacetate), IR and C-13 NMR spectroscopy and comparison of spectra l data with those of closely related standards. These acids are assume d to be derived from oxidation of DELTA9 fatty acids, which are common constituents of microorganisms, possibly in the course of microbial s ulphate reduction which was a major redox process during early diagene sis in these sediments.