Abstract

H. M. Arafa

DOI : http://dx.doi.org/10.13005/ojc/300429

In this work captopril an antihypertensive (KPL) drug, was investigated using thermal analysis (TA) measurements (TG-DTA) in comparison with electron impact (EI) mass spectral (MS) fragmentation at 70 eV. Semi-empirical molecular (MO) calculations, using PM3 method in the neutral and positively charged forms of the drug. These include molecular geometry, bond order, charge distribution, heats of formation and ionization energy. The behavior of the drug under drug TA decomposition, reveal a moderate stability up to 160C^o before a completely decomposition in the range 160-240 C^o. The initial decomposition is due to COOH + CH₃ loss, followed by SH loss. On the other hand, the molecular ion can easily fragmented by CO₂ loss followed by SH loss. This is the best-selected pathway comparable with decomposition using TA. MO-Calculation is used to declare these observations.

Captopril; thermal analysis; electron impact; MO calculation

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