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Molecular orbital and transition sta...

Felipe, Mihali Abraham A.

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Molecular orbital and transition state theory modeling of isotope exchange in aqueous systems.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Molecular orbital and transition state theory modeling of isotope exchange in aqueous systems./
Author:	Felipe, Mihali Abraham A.
Description:	210 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1137.
Contained By:	Dissertation Abstracts International64-03B.
Subject:	Geochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3084284
ISBN:	0496320912

Molecular orbital and transition state theory modeling of isotope exchange in aqueous systems.
Felipe, Mihali Abraham A.

Molecular orbital and transition state theory modeling of isotope exchange in aqueous systems. - 210 p.

Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1137.

Thesis (Ph.D.)--Yale University, 2003.

Molecular orbital (MO) modeling combined with transition state theory (TST) provides a means to describe the progress of reactions at the atomic scale and to estimate the order of magnitude of reaction rate constants. In this thesis, the combined method, referred to as MO-TST, is used to elucidate the geochemically relevant kinetics of three isotope exchange reactions in two aqueous systems: the oxygen and hydrogen exchange between orthosilicic acid and water, and the carboxylic carbon exchange between acetic acid and bicarbonate.

ISBN: 0496320912Subjects--Topical Terms:

539092
Geochemistry.

Molecular orbital and transition state theory modeling of isotope exchange in aqueous systems.
LDR:03260nmm 2200313 4500 001 1843660
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020 $a 0496320912
035 $a (UnM)AAI3084284
035 $a AAI3084284
040 $a UnM $c UnM
100 1 $a Felipe, Mihali Abraham A. $3 1931882
245 1 0 $a Molecular orbital and transition state theory modeling of isotope exchange in aqueous systems.
300 $a 210 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1137.
500 $a Advisers: Danny M. Rye; James D. Kubicki.
502 $a Thesis (Ph.D.)--Yale University, 2003.
520 $a Molecular orbital (MO) modeling combined with transition state theory (TST) provides a means to describe the progress of reactions at the atomic scale and to estimate the order of magnitude of reaction rate constants. In this thesis, the combined method, referred to as MO-TST, is used to elucidate the geochemically relevant kinetics of three isotope exchange reactions in two aqueous systems: the oxygen and hydrogen exchange between orthosilicic acid and water, and the carboxylic carbon exchange between acetic acid and bicarbonate.
520 $a The isotopes of hydrogen and oxygen are extensively used in studies where water interacts with rocks or evolves from a source body. These isotopes are generally assumed to exchange between water and dissolved silica species at higher rates than fluid transport or mineral silica-water exchange; however, there is no established basis for this assumption and the magnitudes of the exchange rates have not been measured. MO-TST modeling of water and orthosilicic acid reveal that these reactions are indeed relatively fast, with computed reactant half-lives of <1 s at room temperature. The results furthermore show how such fast exchanges may proceed: through concerted proton transfers facilitated by water molecules, and by way of symmetric transition states (hydrogen) or intermediates (oxygen) through symmetric reactions.
520 $a Carbon isotopes are key tools for understanding an important topic in oil exploration and production---the sources and history of short chain organic acids in oil field waters. Lately, carbon isotope studies on individual short chain organic acids have found evidence suggesting the pH dependent mixing of dissolved inorganic carbon signatures with the carboxyl group of the acids. However, there is no generally recognized reaction by which this exchange takes place. MO-TST is used to determine the feasibility of two proposed symmetric pathways for the exchange: one by way of malonic acid, and another by a hydroxylated derivative of malonic acid. The results show rates consistent with experimental data and the correct pH dependence suggesting that these are good candidates for the exchange reactions. The rate determining steps found are also concerted proton transfers facilitated by water molecules.
590 $a School code: 0265.
650 4 $a Geochemistry. $3 539092
650 4 $a Chemistry, Physical. $3 560527
690 $a 0996
690 $a 0494
710 2 0 $a Yale University. $3 515640
773 0 $t Dissertation Abstracts International $g 64-03B.
790 1 0 $a Rye, Danny M., $e advisor
790 1 0 $a Kubicki, James D., $e advisor
790 $a 0265
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3084284