Reductometric Titration and Quantum Chemical Study of Oxalohydroxamic Acid for Determination of Manganese in Ores and Alloys

Abstract

Oxalohydroxamic acid has been employed as a reductometric titrant for the determination of manganese in 2 N sulphuric acid. Stoichiometry of the reaction is established. One mole of oxalohydroxamic acid was found to consume 12 equivalents of KMnO4. The titre values are obtained by second derivative plots of potentiometric titrations. The effect of diverse ions, temperature, time, sulphuric acid concentration and concentration of reacting substances on the stoichiometry of the reaction were studied. The results obtained are reproducible. This study also presents molecular orbital/density functional theory (MO/DFT) for calculations of the electronic structure and reducing property of oxalohydroxamic acid for metal determination. A good agreement is found between the predicted properties of oxalohydroxamic acid and experimental and theoretical results.

An Exceptionally Stable Metal–Organic Framework Constructed from Chelate-Based Metal–Organic Polyhedra

“…Notably, although the p K a of the free hydroxamic acid is >8.5, polyhydroxamic acid polymers were previously shown to display negative zeta potentials above pH 3.8 . Further implicating the formation of defects, FTIR spectra of Fe-HAF-1 displayed O–H stretching vibrations as a broad peak at 3180 cm –1 similar to the H 4 BPTH linker (Figure S8), consistent with the presence of free hydroxamic acid groups . The possibility of mixed-valence Fe clusters (i.e., the presence of Fe 2+ species), which could also give rise to an overall negative charge, was ruled out by X-ray photoelectron spectroscopy (XPS) measurements (Figure S9).…”

“…51 Further implicating the formation of defects, FTIR spectra of Fe-HAF-1 displayed O−H stretching vibrations as a broad peak at 3180 cm −1 similar to the H 4 BPTH linker (Figure S8), consistent with the presence of free hydroxamic acid groups. 52 The possibility of mixedvalence Fe clusters (i.e., the presence of Fe 2+ species), which could also give rise to an overall negative charge, was ruled out by X-ray photoelectron spectroscopy (XPS) measurements (Figure S9). 53 Ionic MOFs have been explored as platforms for selective uptake of organic dyes.…”