Despite its heavy use on agricultural lands and as a post-harvest fruit and vegetable treatment, transformation reactions of H-phosphonate (phosphite", HPO<sub>3</sub><sup>2-</sup>) are poorly documented. Distinguishing H-phosphonate from structurally-related pesticides (e.g., its ethyl ester), impurities (e.g., pyrophosphite and isohypophosphate), and oxidation products (orthophosphate and pyrophosphate) is an extraordinary analytical challenge. We have developed capillary electrophoresis with indirect photometric detection for this purpose. Oxidation of all the P(III)-containing compounds listed above to corresponding P(V) compounds by oxygen, iron and manganese oxyhydroxides, and even some organic moieties (e.g., benzoquinones, alpha-keto carboxylates) is thermodynamically favorable. Properties of P(III)-containing compounds affecting aqueous speciation, e.g., oxyanion Lewis basicity that controls protonation, metal ion coordination, and adsorption, largely explain differences in oxidation rates. Much of what we've learned can be used to help understand technologies employing P(III)-containing species (e.g., metal plating, corrosion control, polymer stabilization) and shed light on sources and sinks across redox gradients in the environment.

Oxidation of H-phosphonate and other overlooked P(III)-containing oxyanions: Interconnections between speciation and reactivity

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.