MODIFYING EFFECTS OF POLYOXYETHYLENE STEARATES ON THE RATE OF ACID-CATALYZED HYDROLYSIS OF ACETYLSALICYLIC ACID | ||
| Bulletin of Pharmaceutical Sciences Assiut University | ||
| Article 3, Volume 12, Issue 1, June 1989, Pages 52-67 PDF (445.75 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/bfsa.1989.71454 | ||
| Authors | ||
| S. Ismail; A. A. Mohamed; M. G. Abd-El-Mohsen | ||
| Department of Pharmaceutics, Faculty of Pharmacy, Assiut University, Assiut, Egypt | ||
| Abstract | ||
| The hydrolysis of acetylsalicylic acid, ASA, in buffered solution of Polyoxyethylene stearates (Myrj 52, Myrj 53,and Myrj 59) has been studied at 37°C and over a pH range 1 through 2. The observed rate constant, Kobs, for ASA was found to be reduced markedly with an increase in Myrj concentration. The distribution coefficient of ASA between the micellar and pseudo aqueous phases has been estimated. It was found to be parallel with both the length of POE chain and the hydrogen ion concentration. The data revealed that the hydrolysis of ASA occurred mainly in the bulk aqueous phase, but at lower pH value, the contribution of hydrogen ion catalyzed reaction within the micelles becomes significant. The hydrolytic rate constant for ASA within the micelles, Km, has been calculated and was found to increase in the following ranked order: Myrj 52 > Myrj 53 > Myrj 59. | ||
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