Honors Theses

Date of Award

Spring 4-13-2021

Document Type

Undergraduate Thesis


Chemistry and Biochemistry

First Advisor

Nathan Hammer

Second Advisor

Gerald Rowland

Third Advisor

Steven Davis

Relational Format



Diacetyl, otherwise known as 1,2-butadione or biacetyl, is a flavor additive used in microwave popcorn, and more importantly as of late, e-cigarettes. The compound is known to cause lung disease for those who have been exposed to a large quantity of the buttery smelling molecule. As such, the characterization of diacetyl’s vibrational modes when it interacts with water are pivotal to understanding the effects it has on human lung tissue. In this research, the intermolecular interactions between water and diacetyl and the effects they have on one another’s vibrational modes are explored. While some experimental data is presented, the spectra obtained are not sufficient for extensive comparison to theoretical computations. Therefore, the focus of this work is on the theoretical optimization and simulated spectra of diacetyl and water complexes ranging from 1/1 to 1/5 Diacetyl/Water ratios, with the increase in water molecules assisting in the understanding of how diacetyl behaves when it is solvated in the human body. By using the B3LYP and MP2 methods with aug-cc-pVTZ basis set and tight convergence, a total of three 1/1, ten 1/2, twelve 1/3, twenty-three 1/4, and thirty-nine 1/5 Diacetyl/Water complexes were optimized. Use of rCCSD(T) single-point energy calculations, as well as B3LYP-D3, M06-2X, M06-2X-D3, and 𝜔-B97XD methods, the energetics of the lowest energy structures were confirmed. The simulated spectra of the lowest energy structures were investigated, and trends were gathered for the lowest energy structures from the one to five water complexes. These simulated spectra showed that the carbonyl stretching frequency of diacetyl shifted to lower energy and increased in the splitting between the symmetric and asymmetric motions as the number of water molecules increased. The stretching motions of the methyl group also increased in the range of frequencies that described their motions.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.



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