Question

Can you identify the NH2+ stretch and any other stretches that show the product is the protonated ammonium chloride salt?

IR (neat) of Bupropion Hydrochloride 100 cm 1000 500 400 2000 3000 2000 1500 IR2011-88654TK Wavenumber[cm-11 Wave number (cm) and Transmittance (T%) 3067 85 1690 45 1281 80 1079 78 781 79 513 73 2925 3 1560 39 1240 54 1005 74 753 83 2854 12 1459 33 1212 66 903 75 739 58 2676 60 1403 74 1170 80 864 88 706 78 2454 80 1377 51 1134 66 800 80 672 77

Answer 1

FT-IR spectra of secondary amine (R₂NH) shows only a single weak band in the NH stretching region at ~3300-3000 cm^-1, as they have only one N–H bond. When this secondary amines get protonated it will form (R₂NH₂⁺) protonated salt. Definitely the FT-IR spectra of   protonated secondary amine (R₂NH₂⁺) salt differ from those of the corresponding secondary amine (R₂NH). There is a characteristic bands observed at in the region 1695 to 1550 cm⁻¹, which are due to NH₂⁺ deformation vibrations, are characteristic of secondary amine salts, and can be used to detect the presence of a secondary amino group in the original molecule. In bupropion hydrochloride salt there is a characteristic bands observed at 1690 cm⁻¹ and 1550 cm⁻¹ are associated with N-Hdeformation vibrations of NH₂⁺ moity.