2002 Denver Annual Meeting (October 27-30, 2002)

Paper No. 9
Presentation Time: 3:30 PM


IKAN, Raphael, Organic Chemistry, The Hebrew Univ of Jerusalem, Givat Ram Campus, Jerusalem, 91904, Israel, raphael@vms.huji.ac.il

Our first comprehensive study was to determine the fate of naturally occurring lipids and pigments of a marine sediment originating in Tanner Basin when exposed to elevated temperatures (65°-200°C) for varying periods of time (9-64 days).

Analysis of the heat-treated sediment revealed the presence of a-ionene and 2,6-dimethylnaphthalene which are thermal degradation products of b-carotene. Chlorins, originating from chlorophylls were converted to nickel-porphyrins of both DPEP and etio-series.

Several isoprenoid compounds which were not present in the original sediment were identified as phytol, dihydrophytol, C 18-isoprenoid ketone, phytanic and pristanic acids, C 19 and C 20 monolefins and the following alkanes, 2,6,10-trimethylpentadecane, pristane and phytane.

These results furnished insight into the mechanisms of converting precursors to products as related to the genesis of petroleum constituents.

Another topic under investigation was about the involvement of melanoidins (formed via thermal interaction between carbohydrates and amines, amino acids and proteins, namely Maillard Reaction) as partial constituents of humic acids was supported by spectroscopic, chromatographic, thermogravimetric, pyrolytic, oxidative, ESR and isotope analyses of humic acids and melanoidins.

It has been suggested that in some cases the heterocyclic moieties are among the main building blocks of humic substances rather than the aromatic benzeniod ones. In support of this idea it was claimed that significant portions of the sediments of Lake Haruna (Japan) and Lake Hula (Israel) are composed of melanoidins and pseudomelanoidins.

I count myself lucky for having been able through your generosity and courtesy to be a visiting scientist at your Department in UCLA and for yours and Helen's warm and friendly hospitality at your home during our visits in Los Angeles.

Yael and I would like to wish you and Helen a lot of good health and happiness for many years to come.