Investigation of molecula structure - chirality relationship of ephedrine and pseudoephedrine drug using thermal analyses and mass spectrometry techniques combined with MO-calculations

ABSTRACT

Two diastercoisomers ephedra drugs namely; ephedrine [eph.] and pseudoephedrine [psi-eph.] hydrochloride, have been investigated for their chirality using thermal analysis [TA] measurement [TG/DTA] and electron ionization mass spectrometry [EI-MS] at 70 eV. Monte Carlo conformational search technique was used for exploration of conformational space of ephedrine and psi-eph., using Amber force field molecular mechanics method. MO-calculations were performed using semi-empirical PM3 procedure on the obtained conformational sample for investigation of the different molecular properties. The calculations include bond length, bond order, charge distribution, ionization energy and heat of formation, in neutral and positively charged forms for the two drugs. The effect of diastereoisomerism on thermal analysis decomposition behavior of these drugs was studied. The obtained data confirmed the chirality and declared the structure reactivity relationship of these drugs