A study on the progress of mutarotation above and below the Tg and the relationship between constant rates and structural relaxation times. Issue 31 (26th July 2017)

• Record Type: Journal Article
• Authors: Wolnica, K.; Dulski, M.; Kaminska, E.; Cecotka, A.; Tarnacka, M.; Wrzalik, R.; Kaminski, K.; Paluch, M.
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 31(2017)
• Page Start: 20949
• Page End: 20958
• Publication Date: 2017-07-26
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c7cp02046e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Comprehensive FTIR studies on the progress of mutarotation ind -fructose mixed with maltitol have been carried out over a wide range of temperatures, both above and below the glass transition temperature T g . Abstract : Comprehensive FTIR studies on the progress of mutarotation ind -fructose mixed with maltitol have been carried out over a wide range of temperatures, both above and below the glass transition temperature T g . In addition to the analysis of single bands, we have developed a completely new approach considering the full spectral range to follow the overall progress of the reaction. We have found that at the calorimetric T g, there is a clear change in the temperature dependence of constant rates. The activation barrier for mutarotation changes from around 59 kJ mol −1 (the supercooled state) to around 249 kJ mol −1 (the glassy state). This dramatic variation in the activation barrier is consistent with the change in the mechanism of this specific chemical conversion, as theoretically considered by Wlodarczyk et al. [ Phys. Chem. Chem. Phys., 2014, 16, 4694–4698]. Alternatively, it can also be connected to the change in the viscosity of the sample. Additionally, we investigated the relationship between constant rates ( k ) of mutarotation, structural relaxation times ( τ α ), and dc conductivity ( σ dc ) above and below the glass transition temperature. It was found that there was a linear correlation between all these quantities; they scale with various exponents changing at T g . Our results also indicate that a single activation barrier might not be sufficient to describe the mutarotation process.