Thesis
Development of rapid and inexpensive derivatisation methods for methylphosphonic acid
Honours, Murdoch University
2019
Abstract
This study probed alternative methods towards rapid and inexpensive in-field derivatisation of methylphosphonic acid (MPA), the final hydrolysis product of several chemical warfare nerve agents, for detection by gas chromatography-mass spectrometry (GC-MS).
Initially, research focused on acetylation as a derivatisation method, with attempted preparation of a reference sample of diacetyl methylphosphonate. This was unsuccessful with reduction of the acetyl carbonyl group during synthesis and detection of diethyl methylphosphonate instead.
The research subsequently focused on esterification of methylphosphonic acid with methanol or ethanol. Preparations employed the use of dicyclohexyl carbodiimide as a coupling reagent, and silica chloride or sulfuric acid as catalysts. The coupling reagents and catalysts utilised had limited success, with no dialkyl methylphosphonate ester derivates detected via GC-MS.
Dialkyl derivatives were successfully prepared by conversion of MPA to methylphosphonyl dichloride using thionyl chloride, and subsequent reaction with alcohols. Conversion of methylphosphonyl dichloride to corresponding dialkyl methylphosphonates occurs rapidly with derivatives being detected within 10 minutes for primary alcohols (methanol, ethanol, and butan-1-ol) and within 20 minutes for secondary alcohols (propan-2-ol), while benzyl alcohol did not react. Dialkyl methylphosphonates were identified by analysis of reaction products using GC-MS and nuclear magnetic resonance (NMR) spectroscopy. This method applied here acts as a proof of concept, providing a promising platform for future exploration. Alkylation of methylphosphonic acid with alcohols provides an inexpensive and relatively non-hazardous alternative to current widely accepted derivatisation methods in supporting the rapid in-field detection of chemical warfare nerve agents.
Details
- Title
- Development of rapid and inexpensive derivatisation methods for methylphosphonic acid
- Authors/Creators
- Jolene Anthony
- Contributors
- Kate Rowen (Supervisor)John Coumbaros (Supervisor)James Speers (Supervisor)
- Awarding Institution
- Murdoch University; Honours
- Identifiers
- 991005540922707891
- Murdoch Affiliation
- School of Medical, Molecular and Forensic Sciences
- Language
- English
- Resource Type
- Thesis
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