Optimization of Phosphomolybdic Acid Synthesis using 31p NMR Data

Krukovsky, Ivan M.; Шелоумов, А. М.; Golubev, O. V.; Loginova, A. N.; Фадеев, В. В.

doi:10.1007/s10812-020-00995-3

Cited by 6 publications

(2 citation statements)

References 19 publications

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“…Figure shows the representative 31 P NMR spectra obtained from these three systems, while the spectra of the full series are shown in Figures S9–S11 in the Supporting Information. The degradation of Keggin POM {PMo 12 } in water with increasing pH has been reported in the literature, and the 31 P NMR spectra obtained in this study (see Figure ) are comparable to those published. − The four main identified POM species resulting from the {PMo 12 } decomposition in the pH range of 0–7 are PMo 11 O 39 7– ({PMo 11 }), A-PMo 9 O 31 (H 2 O) 3 3– (A-{PMo 9 }), B-H 2 PMo 9 O 34 7– (B-{PMo 9 }), and P 2 Mo 5 O 23 6– ({P 2 Mo 5 }) (see Table ).…”

Section: Resultssupporting

confidence: 87%

“…The degradation of Keggin POM {PMo12} in water with increasing pH have been reported in the literature, and the 31 P NMR spectra obtained in this study (see Figure 5) are comparable to those published. [42][43][44][45] The four main identified POM species resulting from the {PMo12} decomposition in the pH range 0-7 are PMo11O39 2). In the presence of two eq.…”

Section: Titration Of Cds With Pomsmentioning

confidence: 99%

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Improvement of the Hydrolytic Stability of the Keggin Molybdo- and Tungsto-Phosphate Anions by Cyclodextrins

et al. 2022

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Keggin-type molybdo-and tungsto-phosphate polyoxoanions are among the most popular polyoxometalates (POMs), but suffer from their limited stability at low pH in aqueous solution. Their superchaotropic properties generate strong supramolecular complexes with cyclodextrins (CDs) which significantly affect the hydrolytic stability of POM. This chaotropically-driven stabilization effect was systematically monitored by 31 P NMR spectroscopy covering a wide range of pH (from 0 to 8) and varying the nature of the CD (a-, b-, and g-form).A shift of ca. two pH units of the stability domains of these POMs were found in the presence of two eq. g-CD compared to pure water, leading to keep intact the PW12O40 3anion without any decomposition up to pH 3.5 (versus 1.5 in pure water) and pH 2.5 for PMo12O40 3which begins to decompose even at pH 0 in pure water. The effect of the smaller CDs (a-and b-form) is much less pronounced (only 0.5 pH units shift of stability domain) confirming the importance of host-guest size matching to form a sandwich-type inclusion complex, and thus protect the POM structure against basic hydrolysis. Such complexation was further supported by 183 W and 1 H NMR spectroscopy. Finally, using quantitative 31 P NMR analyzes, the new speciation and formation constants of phosphomolybdates and phosphotungstates in the presence of cyclodextrins are determined and compared to those previously reported in pure water or in 50:50 water/1,4-dioxane mixture.

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Section: Resultssupporting

confidence: 87%

Section: Titration Of Cds With Pomsmentioning

confidence: 99%

Improvement of the Hydrolytic Stability of the Keggin Molybdo- and Tungsto-Phosphate Anions by Cyclodextrins

et al. 2022

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Effect of phosphomolybdate anionic redox species on the redox flow polymer electrolyte fuel cell performance

Naruse,

Muroyama,

Matsui

et al. 2023

Journal of Power Sources

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Nature of Glucose Epimerization Catalyzed by Mo-Containing Bulk Catalysts in Aqueous Phase

Liu,

He,

Jiao

et al. 2024

ACS Catal.

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The nature of Mo-catalyzed glucose epimerization in the aqueous phase was elaborately studied. We herein formulate the thermodynamic properties (e.g., Δ r H T , Δ r G T , and K eq.T ) of the reversible epimerization by collecting the equilibrium composition. The isotopic tracing and NMR spectra show that the overall tautomerization network encompasses the reversible epimerization and isomerization and the irreversible degradation of all hexoses. The leaching tests and kinetic and spectroscopic studies reveal that glucose epimerization catalyzed by Mo-containing solid catalysts in the aqueous phase resembles homogeneous catalysis. All catalysts enable a near-equilibrium yield of mannose (28%) at 373 K except MoP but undergo a different kinetic course of which MoN is the best catalyst according to the apparent kinetic parameters. The molybdenum species dissolved in an aqueous solution evolves into the truly active centers of the Mo VI −O−Mo VI bridged polymolybdates. Moreover, we propose that a single Mo center as Lewis acidic site coordinates with the aldoses to form a bidentate complex, which thereby contributes two different mechanisms to generate the epimers, viz., the intramolecular 1, 2-carbon exchange and two-step isomerization. The former proceeds through a three-membered cyclic transition state (TS C ) that mediates the simultaneous cleavage of the bond between C-2 and C-3 and formation of the bond between C-1 and C-3, whereas the latter undergoes two hydride transition states (TS H-1 and TS H-2 ) via the hydride transfer twice, leading to the chiral inversion of the configuration at C-2. Last but not least, the presence of phosphates in an aqueous solution leads to the deactivation of Mo-based catalysts because of the interplay between glucose and phosphates.

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Optimization of Phosphomolybdic Acid Synthesis using 31p NMR Data

Cited by 6 publications

References 19 publications

Improvement of the Hydrolytic Stability of the Keggin Molybdo- and Tungsto-Phosphate Anions by Cyclodextrins

Improvement of the Hydrolytic Stability of the Keggin Molybdo- and Tungsto-Phosphate Anions by Cyclodextrins

Effect of phosphomolybdate anionic redox species on the redox flow polymer electrolyte fuel cell performance

Nature of Glucose Epimerization Catalyzed by Mo-Containing Bulk Catalysts in Aqueous Phase

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