Kinetics of solid state stability of glycine derivatives as a model for peptides using differential scanning calorimetry
Kinetics of solid state stability of glycine derivatives as a model for peptides using differential scanning calorimetry
Received 26 November 2001; revised 21 December 2001; accepted 21 December 2001. Available online 29 May 2002.
M. I. Abd-Elrahman, , a, M. O. Ahmedb, S. M. Ahmedb, T. aboul-Fadlc and A. El-Shorbagic
Biophysical Chemistry
Volume 97, Issues 2-3 , 19 June 2002
ScienceDirect
a Department of Physics, Faculty of Science, Assiut University, Assiut 71516, Egypt
b Department of Industrial Pharmacy, Faculty of Pharmacy, Assiut University, Assiut, Egypt
c Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt
Abstract
Kinetics of solid state stability of seven derivatives of 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) of glycine as a model for amino acids and peptide drugs were studied using differential scanning calorimetry (DSC). Each DSC curve for each derivative showed an endothermic peak followed by an exothermic one, which could be attributed to the melting and decomposition, respectively. The decomposition activation energy of each derivative was calculated using the Augis and Bennet, Kissinger equations and Mahadevan approximation. Also, the melting activation energies as well as the thermodynamic parameter (enthalpy) for the investigated derivatives were evaluated. The relative stability of the derivatives in the solid state according to the calculated values of the decomposition activation energy, frequency factors and half-life for each derivative could be determined.
Author Keywords: Organic crystals; Chemical synthesis; Calorimetry; Thermal analysis
Corresponding author. Tel.: +20-8834-6901; fax: +20-8831-2564; email: mostafa.ia@eudoramail.com
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