Leveraging the Photochemistry of N-Nitrosamines for Their Aqueous Detection, and Development of a Novel Hemi-Iptycene for Porous Polymers
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Beard-jcbeard-phd-chemistry-2023-thesis.pdf
Description
Thesis PDF
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4.78 MB
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083bf4dca67a1352821baf2867d6003a
Author(s)
Beard, Jessica C.
Advisor(s)
Swager, Timothy M.
Date Issued
September 2023
Publisher
Massachusetts Institute of Technology
Abstract
N-Nitrosamines are a class of compounds known for both the potent carcinogenicity of many of its members, and for their widespread occurrence in the human environment. Consequently, the development of methods for their detection is an active area of research. Chapter 1 provides an introduction to the structure, reactivity, and synthetic applications of N-nitrosamines with an emphasis on alkyl N-nitrosamines. The role of N-nitrosamines as water contaminants and the methods for their detection are also discussed.
In Chapter 2, two synthetic routes are used to synthesize several 9,9-disubstituted-9,10-dihydroacridines (DHAs). In one route, the final synthetic step consists of acid-promoted cyclization of a benzyl tertiary alcohol intermediate; for some substrates, elimination competes with the desired cyclization and leads to reduced yields. For N-substituted DHAs, however, they can instead be synthesized by Grignard addition to the parent acridinium, and portions of this route were adapted for rapid microwave conditions. The synthesized DHAs were evaluated as potential nitrosamine indicators and were found unsuitable for this application.
In Chapter 3, the detection of aqueous nitrosamines via photonitrosation of a naphtholsulfonate indicator is described. The initial photoreaction yields an ortho-naphthoquinone-oxime, and the colorimetric response is enhanced by the formation of an intensely green iron(II) complex. The sensitivity and selectivity of the resulting solution-phase assay are evaluated, and efforts towards a solid-supported assay are described. Additionally, the iron complex formed in the assay and the analogous commercial dye Naphthol Green B are characterized by Mössbauer and EPR spectroscopy, and the resulting characterization indicates that both compounds are low-spin iron(II) complexes.
In Chapter 4, the synthesis of a novel hemi-iptycene diacetylene monomer, whose core structure is derived from triptycene and diphenylfulvene, is described. The hemi-iptycene quinone precursor to the diacetylene monomer is constructed by the one-pot Diels–Alder cycloaddition–dehydrochlorination of 2-chlorotriptycene quinone with diphenylfulvene, which is performed as a neat melt. Other attempted synthetic routes to the quinone are described as well. Lastly, preliminary results from the Sonogashira polymerization of the hemi-iptycene monomer with two dihalide fluorene monomers are described.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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