Energetics of the interaction of d-fructose and d-glucose with sodium hydroxide in aqueous ethyl alcohol, acetone, and 1,4-dioxane media
✍ Scribed by Satya P. Moulik; Dipti Basu
- Publisher
- Elsevier Science
- Year
- 1984
- Tongue
- English
- Weight
- 414 KB
- Volume
- 132
- Category
- Article
- ISSN
- 0008-6215
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✦ Synopsis
Both D-glucose and D-fructose bind NaOH at 303 K in aqueous medium, with association constants of 24 and 25 L.mol-', respectively. The polarity of the medium significantly affects the association process. Calculation has shown that, at 303 K, 1 ,Cdioxane, acetone, and ethyl alcohol can totally stop the association process between D-glucose and NaOH at dielectric constants of 52.2,44.6, and 53.5, respectively, whereas the respective dielectric constants of the solvents required for completely stopping the association process between D-fructose and NaOH are 54.6, 47.0, and 55.0. At equidielectric levels, the changes in free energy for the binding process are more or less similar, whereas the enthalpy and entropy changes differ. In this regard, acetone is the most, and 1 ,Cdioxane the least, effective of the three solvents. In the mixed media, the binding process ends with an altered solvent structure. The ordering of the environment, that is, the AS", exactly compensates the enthalpy, AH", with a compensation temperature of 298 K. Except for acetone-water at E 74.5, the energetics of the binding process for both of the carbohydrates are similar in all of the mixed media. The carbohydrate-base complexes are, therefore, physicochemically similar.