ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Abinitio and PCILO investigations of the antiarrhythmic tocainide, its cation and hydrochloride

M. Remko

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Comenius University, CS-832 32 Bratislava

Abstract: The quantum-chemical PCILO and ab initio SCF methods (STO-3G basis) were applied to the conformational analysis of antiarrhythmic tocainide (2-amino-2',6'-propionoxilidine) (B) and its cation (BH⁺). For В the conformation with N—H...N hydrogen bond, corresponding to the mutual cis arrangement of both nitrogen atoms of—N—CO—CH—N— fragment, has been found to be most stable. On the other hand, for BH⁺ the most stable conformation is stabilized by the bifurcated intramolecular hydrogen bond of the N⁺— H...0 = C type formed by two protons of—NH₃⁺ group of drug and carbonyl oxygen. The proton affinity was determined by means of ab initio SCF (STO-3G and MINI-1 bases, respectively) and PCILO methods. The STO-3G calculated energy of intermolecular hy­drogen bond N⁺—H...Cl^- in the tocainide hydrochloride is very high (507.8 kJ mol^-1). The gross atomic charges resulting from the STO-3G ab initio calculations for B, BH⁺, and BHCl were compared.

Full paper in Portable Document Format: 432a267.pdf

Chemical Papers 43 (2) 267–278 (1989)