Demethylation Kinetics of Aspartame and L-Phenylalanine Methyl Ester in Aqueous Solution
- 1 January 1993
- journal article
- Published by Springer Nature in Pharmaceutical Research
- Vol. 10 (8) , 1174-1180
- https://doi.org/10.1023/a:1018920402644
Abstract
The kinetics of demethylation of aspartame and L-phenylalanine methyl ester were studied in aqueous solution at 25°C over the pH range 0.27–11.5. The pseudo-first-order rate constant for aspartame was resolved into individual contributions from methyl ester hydrolysis and diketopiperazine formation. pH – rate profiles were quantitatively described by chemically reasonable kinetic schemes. Aspartame is maximally stable at pH 4 (t90 = 53 days at 25°C); phe-nylalanine methyl ester, at pH 3. The potentiometrically measured pKa values were pKa1 3.19 and pKa2 7.87 fr aspartame and pKa 7.11 for phenylalanine methyl ester.Keywords
This publication has 3 references indexed in Scilit:
- Solvent Effects on Chemical Processes. V: Hydrophobic and Solvation Effects on the Solubilities of Substituted Biphenyls in Methanol/Water MixturesJournal of Pharmaceutical Sciences, 1993
- Solvent Effects on Chemical Processes, I: Solubility of Aromatic and Heterocyclic Compounds in Binary Aqueous—Organic SolventsJournal of Pharmaceutical Sciences, 1992
- Stability of Aspartame in Water:Organic Solvent Mixtures with Different Dielectric ConstantsJournal of Pharmaceutical Sciences, 1991