| Abstrakt: |
Carbonaceous meteorites contributed polycyclic aromatic hydrocarbons (PAHs) to the organic inventory of the primordial Earth. Low molecular weight PAHs (e.g. anthracene) may have been important precursors for the production of oxy-PAHs (e.g. quinones) with potential to function as redox species within emergent biochemical systems (e.g. primitive membranes). Mineral surfaces were likely important catalytic phases for such reactions in prebiotic environments. To better understand the interactions of meteoritic PAHs and terrestrial minerals in this context, we assessed the kinetics of anthracene (ANTH) conversion to anthraquinone (ANTHQ) in the presence of montmorillonite clay (MONT) at 250, 200, 150, and 100oC. No ANTHQ production was observed in the absence of MONT at any temperature or at temperatures below 100oC in the presence of MONT during the interval assessed. ANTHQ production was detectable by 2, 6, 12, and 60 min of incubation at 250, 200, 150, and 100 oC, respectively. Plots of ANTHQ production were fitted with linear curves yielding zero order rate constants of 0.312 µg min-1 (r2 = 0.994; P < 0.05), 0.274 µg min-1 (r2 = 0.984; P < 0.05), 0.139 µg min-1 (r2 = 0.990; P < 0.05), and 0.0099 µg min-1 (r2 = 0.987; P < 0.05) at 250, 200, 150, and 100 oC, respectively. Computed rate constants were fitted with a logarithmic curve (r2 = 0.995; P < 0.001). ANTHQ production efficiency was on the order of 0.001% at all temperatures. Work is ongoing to assess additional kinetic parameters and their effects on MONT-catalyzed ANTH conversion to ANTHQ. [ABSTRACT FROM AUTHOR] |
