Merck

1H and 13C NMR characteristics of β-blockers.

Magnetic resonance in chemistry : MRC (2011-04-15)
Monika Agnieszka Zielińska-Pisklak, Dariusz Maciej Pisklak, Iwona Wawer
ABSTRACT

The β-blockers are important drugs and decades of clinical experience proved their high medical status. However, to the best of our knowledge, there is no complete assignment of (1)H and (13)C NMR resonances of popular representatives: acebutolol, alpenolol, pindolol, timolol and propranolol and the published NMR data on carvedilol and atenolol are incorrect. Therefore, (1)H and (13)C NMR spectroscopy was applied for the characterization of a series of β-adrenolytics: carvedilol (1), pindolol (2), alprenolol (3), acebutolol (4), atenolol (5), propranolol (6) and timolol (7). Two-dimensional NMR experiments (COSY, HMQC, HMBC, NOESY) allowed the unequivocal assignment of (1)H and (13)C spectra for solution (DMSO-d(6) ). Salts and bases can be easily distinguished based on (13)C chemical shifts which are within 65.0-65.5 ppm (OC2) and 46.9-47.0 (NC3) for hydrochlorides and larger, ca. 68.4 ppm (OC2) and 50.3-52.6 (NC3) for bases. NMR data of 1-7 should be included in pharmacopoeias.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Pindolol, ≥98% (TLC), powder
Supelco
Acebutolol hydrochloride, analytical standard
Acebutolol hydrochloride, European Pharmacopoeia (EP) Reference Standard