Effects in Mutarotation Reactions

Isotope Effects in Mutarotation Reactions 1. Basis for Effects of Water and Deuterium Oxide [Pg.28]

Differences in the rate of mutarotation of sugars in water and in deuterium oxide provide a valuable means for studying mutarotation reactions.135,224,233 237,238 The difference in rates arises from a combination of kinetic and solvent isotope-effects, and is usually expressed as a ratio,knlkD, called the isotope effect. Kinetic isotope-effects are caused by differences in the energy required for alteration of the normal and the isotopic bonds in the corresponding transition states solvent isotope-effects can exist when the isotopic compound is used both as a reactant and as a solvent. [Pg.28]

The observed isotope-effect,fen/km may have values smaller than, equal to, or greater than unity. A kinetic isotope-effect is large when [Pg.28]

More HSD is formed in D20 than HSH in H20, because D30 is a stronger acid than H30 . Hence, reactions that take place by this mechanism are faster in deuterium oxide than in water. [Pg.29]

Sugar Temp- erature, degrees Species Ratio Refer- ences [Pg.30]

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