A mutarotation mechanism based on dual proton exchange in the amorphous d-glucose

Włodarczyk, P.; Paluch, Marian; Włodarczyk, Agnieszka; Hyra, Marta

doi:10.1039/c3cp54833c

Cited by 10 publications

(5 citation statements)

References 16 publications

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“…Having in mind the results of inter- and intramolecular investigations performed with the use of BDS and FTIR techniques, we decided to examine experimentally the progress of mutarotation in the supercooled state, both above and below the T c . Recently, many articles on the monitoring of mutarotation in the vicinity of the glass transition temperature with the use of dielectric spectroscopy have been published 21 – 24 , 26 , 36 . In these papers, it was reported that the changes in dielectric spectra get much smaller and are barely detectable with increasing temperature.…”

Section: Resultsmentioning

confidence: 99%

Unexpected Crossover in the kinetics of mutarotation in the supercooled region: the role of H-bonds

Wolnica

Dulski

Kamińska

et al. 2018

Sci Rep

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Intra- and intermolecular studies on the molten L-sorbose have been carried out at variable temperature conditions to determine the crosover temperature (Tc). In addition, isothermal time-dependent FTIR and Raman measurements were performed to probe the pace of mutarotation and activation energy of this reaction in the studied saccharide, which varied from 53–62 kJ/mol up to 177–192 kJ/mol below and above Tc, respectively. To explain the change in activation barrier for the mutarotation a complementary analysis using difference FTIR spectra collected around Tc = 365 K in the hydroxyl region has been done. It was found that the alteration of kinetic parameters and molecular dynamics around Tc are strictly related to the variation in the strength of H-bonds which above Tc are significantly weaken, increasing the freedom of rotation of functional groups and movement of individual molecules. That phenomenon most likely affects the proton transfer, underlying molecular mechanism of mutarotation, which may lead to the significant increase in activation barrier. The new insight into a molecular aspect of the mutarotation around Tc has created an opportunity to better understanding the relationship between physics of condensed matter and the potential role of H-bonds dynamics on the progress of the chemical reaction in highly viscous systems.

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Section: Resultsmentioning

confidence: 99%

Unexpected Crossover in the kinetics of mutarotation in the supercooled region: the role of H-bonds

Wolnica

Dulski

Kamińska

et al. 2018

Sci Rep

Self Cite

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“…In contrast, they also suggested that in the supercooled liquid phase (above T g ), mutarotation initiates via mutual proton transfer between two neighboring sugar molecules. 28 From the perspective of the above discussion, we expect that the application of pressure could enhance the degree of cooperative motion in a supercooled state near glass transition and eventually translate a stronger sugar-sugar interaction which will support intermolecular proton transfer.…”

Section: Introductionmentioning

confidence: 99%

Evidence of pressure induced intermolecular proton transfer via mutarotation: the case of supercooledd-fructose

Cecotka

Tripathy

Paluch

2015

Phys. Chem. Chem. Phys.

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This paper describes a systematic investigation on the role of pressure in mutarotation kinetics of supercooled d-fructose using dielectric spectroscopy. The structural relaxation time acts as a suitable dynamical observable to monitor the mutarotation process that enables the construction of the kinetic curves. The reaction kinetic shapes have been analyzed using the Avrami model. At low temperature, sigmoidal kinetic curves are noted, which correspond to the high concentration of furanosidic forms. The magnitude of activation energy of the process significantly decreases with increasing pressure and is comparable to the solvated systems at 100 MPa. A potential connection between cooperative motion and the origin of intermolecular proton transfer via mutarotation at elevated pressure is also discussed. These experimental observations have fundamental significance on theoretical explanation of the mechanism involving mutarotation in sugars.

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“…In solution or in the liquid state, mutarotation is generally fast and an equilibrium tautomeric composition is rapidly reached. In the amorphous solid state, mutarotation has been found to require a much higher activation energy, so mutarotation kinetics is quite slower. ,− While there is almost no molecular mobility in crystals, Tombari et al have postulated that mutarotation can also occur in this ordered physical form through the mediation of vacancies and defects. It then causes local amorphizations, which could ultimately lead to the liquefaction of sugars well below their known melting points .…”

Section: Introductionmentioning

confidence: 99%

Impact of Amorphization Methods on the Physicochemical Properties of Amorphous Lactulose

et al. 2019

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The influence of the amorphisation technique on the physico-chemical properties of amorphous lactulose has been investigated. Four different amorphisation techniques have been used: quenching of the melt, milling, spray-drying and freeze-drying, and amorphous samples have been analysed by DSC, NMR, and powder X-ray diffraction. Special attention has been paid to the tautomeric composition and to the glass transition of amorphised materials. It has been found that the tautomeric composition of the starting physical state (crystal, liquid or solution) is preserved during the amorphisation process and has a strong repercussion on the glass transition of the material. The correlation between these two properties as well as the plasticizing effect of the different tautomers have been clarified by molecular dynamic simulations.

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A mutarotation mechanism based on dual proton exchange in the amorphous d-glucose

Cited by 10 publications

References 16 publications

Unexpected Crossover in the kinetics of mutarotation in the supercooled region: the role of H-bonds

Unexpected Crossover in the kinetics of mutarotation in the supercooled region: the role of H-bonds

Evidence of pressure induced intermolecular proton transfer via mutarotation: the case of supercooledd-fructose

Impact of Amorphization Methods on the Physicochemical Properties of Amorphous Lactulose

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