TY - JOUR
T1 - Organic functional group transformations in water at elevated temperature and pressure
T2 - Reversibility, reactivity, and mechanisms
AU - Shipp, Jessie
AU - Gould, Ian
AU - Herckes, Pierre
AU - Shock, Everett
AU - Williams, Lynda
AU - Hartnett, Hilairy
N1 - Funding Information:
We thank the members of the Hydrothermal Organic Geochemistry (HOG) group for lengthy discussions on this research. We also thank Zach Smith, Jesse Coe, Katie Noonan, and Alex Hamilton for help in the laboratory and the rest of Carbon and Nitrogen Dynamics (CaNDy) Lab for edits and discussion on this manuscript. We also appreciate the help from Gordon Moore for lending his expertise in welding capsules, Loÿc Vanderkluysen for help formatting Fig. 3 , and Chris Glein for providing thermodynamic calculations. This work was funded by NSF grant 0826588.
PY - 2013/3/1
Y1 - 2013/3/1
N2 - Many transformation reactions involving hydrocarbons occur in the presence of H2O in hydrothermal systems and deep sedimentary systems. We investigate these reactions using laboratory-based organic chemistry experiments at high temperature and pressure (300°C and 100MPa). Organic functional group transformation reactions using model organic compounds based on cyclohexane with one or two methyl groups provided regio- and stereochemical markers that yield information about reversibility and reaction mechanisms. We found rapidly reversible interconversion between alkanes, alkenes, dienes, alcohols, ketones, and enones. The alkane-to-ketone reactions were not only completely reversible, but also exhibited such extensive reversibility that any of the functional groups along the reaction path (alcohol, ketone, and even the diene) could be used as the reactant and form all the other groups as products. There was also a propensity for these ring-based structures to dehydrogenate; presumably from the alkene, through a diene, to an aromatic ring. The product suites provide strong evidence that water behaved as a reactant and the various functional groups showed differing degrees of reactivity. Mechanistically-revealing products indicated reaction mechanisms that involve carbon-centered cation intermediates. This work therefore demonstrates that a wide range of organic compound types can be generated by abiotic reactions at hydrothermal conditions.
AB - Many transformation reactions involving hydrocarbons occur in the presence of H2O in hydrothermal systems and deep sedimentary systems. We investigate these reactions using laboratory-based organic chemistry experiments at high temperature and pressure (300°C and 100MPa). Organic functional group transformation reactions using model organic compounds based on cyclohexane with one or two methyl groups provided regio- and stereochemical markers that yield information about reversibility and reaction mechanisms. We found rapidly reversible interconversion between alkanes, alkenes, dienes, alcohols, ketones, and enones. The alkane-to-ketone reactions were not only completely reversible, but also exhibited such extensive reversibility that any of the functional groups along the reaction path (alcohol, ketone, and even the diene) could be used as the reactant and form all the other groups as products. There was also a propensity for these ring-based structures to dehydrogenate; presumably from the alkene, through a diene, to an aromatic ring. The product suites provide strong evidence that water behaved as a reactant and the various functional groups showed differing degrees of reactivity. Mechanistically-revealing products indicated reaction mechanisms that involve carbon-centered cation intermediates. This work therefore demonstrates that a wide range of organic compound types can be generated by abiotic reactions at hydrothermal conditions.
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U2 - 10.1016/j.gca.2012.11.014
DO - 10.1016/j.gca.2012.11.014
M3 - Article
AN - SCOPUS:84872356933
SN - 0016-7037
VL - 104
SP - 194
EP - 209
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -