journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: a b s t r a c t 2-(Ethylamino)-1-(4-methylphenyl)propan-1-one (shortly named 4-MEC) (1a), 1-(1,3-benzodioxol-5-yl)-2-(methylamino)propan-1-one (shortly named methylone or 3,4-methylenedioxymethcathinone) (1b), 1-(3,4-dimethylphenyl)-2-(methylamino)propan-1-one (1c), 2-methylamino-1-(4-methylphenyl)pro-pan-1-one (shortly named mephedrone; 4-MMC or 4-methylmethcathinone) (1d) and 2-(methyl-amino)-1-phenylbutan-1-one (shortly named buphedrone) (1e) and their aminium salts (2a–e), are examples of cathinones which were characterized by FTIR, UV–Vis, multinuclear NMR spectroscopy. By single crystal X-ray diffraction method structures of 2a, 2b, 2c and 2d were determined. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, ethyl, N-methyl or N-ethyl groups. The diastereotopic methylene protons of 1a appear as an ABX 3 , and 1e and 2e appear as an ABMX 3 system. The geometries of the studied compounds were optimized in singlet states using the density functional theory (DFT) method with B3LYP functional. Electronic spectra were calculated by TDDFT method. In general, the predicted bond lengths and angles are in good agreement with the values based on the X-ray crystal structure data. Ó 2011 Elsevier B.V. All rights reserved.