Davies, Kevin William
(2009)
Reaction Volumes of Photoinitiated Reactions, and Their Use As Probes of Reactive Intermediates.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Photoacoustic calorimetry is a sensitive method for measuring the enthalpies, kinetics, and changes in volumes for reactions that generate transient intermediates through photoexcitation. This work focuses on building a better understanding of ΔVrxn, to ascertain the importance of accounting for ΔVrxn when measuring enthalpies of reaction via photoacoustic methods. ΔVrxn for three metal carbonyls has been measured. The results presented herein show that to obtain high-quality thermochemical information from photoacoustic measurements, it is necessary to account for the contribution of ΔVrxn. Neither the magnitude nor the sign of this contribution may be predicted without either the direct measurement of ΔVrxn or (as an outcome of the research described in this dissertation) computationally. Failure to account for this contribution may results in errors in the measured ΔHrxn by as much as 79% [e.g. (CH3OC)Mn(CO)5 in octane].This dissertation also lays the groundwork for the use of ΔVrxn to distinguish between possible structures of short-lived intermediates though a combination of photoacoustic measurements and computational chemistry. A protocol is described that will allow molecular dynamics simulations to be used to determine the solvated volume of a molecule, and to combine several of these measurements to allow the volume change accompanying a reaction to be determined computationally. Simulations conducted via this protocol are in good agreement with our experimental results. These simulations will allow experimental results to provide a new window into the nature of short-lived intermediates, and the mechanistic of their reactions. Several unsuccessful molecular dynamics simulations are also described in order to identify cases where simulations may not provide accurate data and how these issues may be addressed.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
27 January 2009 |
| Date Type: |
Completion |
| Defense Date: |
22 August 2008 |
| Approval Date: |
27 January 2009 |
| Submission Date: |
20 November 2008 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
high-pressure photoacoustic calorimetry; linear alkane photoacoustic calorimetry |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-11202008-105240/, etd-11202008-105240 |
| Date Deposited: |
10 Nov 2011 20:05 |
| Last Modified: |
15 Nov 2016 13:51 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/9738 |
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