Unimolecular, Bimolecular, and Intramolecular Hydrolysis Mechanisms of 4-Nitrophenyl beta-D-Glucopyranoside
Amani Alhifthi, Spencer J Williams
JOURNAL OF ORGANIC CHEMISTRY | AMER CHEMICAL SOC | Published : 2021
1,2-trans-Glycosides hydrolyze through different mechanisms at different pH values, but systematic studies are lacking. Here, we report the pH-rate constant profile for the hydrolysis of 4-nitrophenyl β-D-glucoside. An inverse kinetic isotope effect of k(H3O+)/k(D3O+) = 0.65 in the acidic region indicates that the mechanism requires the formation of the conjugate acid of the substrate for the reaction to proceed, with the heterolytic cleavage of the glycosidic C-O bond. Reactions in the pH-independent region exhibit general catalysis with a single proton in flight, a normal solvent isotope effect of kH/kD = 1.5, and when extrapolated to zero buffer concentration show a small solvent isotope ..View full abstract
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Awarded by Australian Research Council
This work was supported by a grant from the Australian Research Council (DP180101957 and DP210100233). A.A. thanks Jazan University for financial support and thanks the Saudi Arabian Cultural Mission (SACM).