Investigating the Kinetics of Montmorillonite Clay-Catalyzed Conversion of Anthracene to 9,10-Anthraquinone in the Context of Prebiotic Chemistry
Carbonaceous meteorites contributed polycyclic aromatic hydrocarbons (PAHs) to the organic inventory of the primordial Earth where they may have reacted on catalytic clay mineral surfaces to produce quinones capable of functioning as redox species in emergent biomolecular systems. To address the feasibility of this hypothesis, we assessed the kinetics of anthracene (1) conversion to 9,10-anthraquinone (2) in the presence of montmorillonite clay (MONT) over the temperature range 25 to 250 °C. Apparent rates of conversion were concentration independent and displayed a sigmoidal relationship with temperature, and conversion efficiencies ranged from 0.027 to 0.066%. Conversion was not detectable in the absence of MONT or a sufficiently high oxidation potential (in this case, molecular oxygen (O2)). These results suggest a scenario in which meteoritic 1 and MONT interactions could yield biologically important quinones in prebiotic planetary environments.
KeywordsPAH Anthracene 9,10-Anthraquinone Montmorillonite Kinetics Prebiotic
The authors thank Drs. Dale Droge and Scott McKay (Dakota State University (DSU)) for insightful conversations and financial support, and Nancy Presuhn (DSU) for administrative assistance. This work was supported by a Barry M. Goldwater Scholarship award to HLJ, a DSU College of Arts and Sciences faculty research grant to MOG, and a DSU Student Research Initiative (SRI) research grant to BKP. This work was further supported by the DSU College of Arts and Sciences as part of an undergraduate research-in-teaching initiative in MOG’s Organic Chemistry I & II (CHEM 326 & 328) courses. LMB’s research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. BPT’s research was carried out at the University of Tulsa.
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