Structure of ranitidine hydrochloride

Characterization of tautomeric forms of ranitidine hydrochloride: thermal analysis, solid-state NMR, X-ray

“…It was reported [7] that the enamine is the correct structure in the solid Form 2, however, the single crystal data of this study suggests that a mixture of nitronic acid and enamine is more probable structure (Fig. 6).…”

“…The crystal data of this study (Table 3) are fairly close to the work of Ishida et al [7] but the bond length and the interpretation of the structure are different.…”

“…Ishida et al [7] collected the crystal data and proposed molecular structure for the solid RANHCl without mentioning its polymorphic form. Based on their findings the hydrogen residing on nitrogen atom of the dimethylamino group is hydrogen bonded to chloride ion and the molecule is also disordered.…”

Natural abundance 14N and 15N solid-state NMR of pharmaceuticals and their polymorphs

“…(δiso = −22 ppm) nitrogen environments. 140 These assignments are corroborated by the observed correlations with the directly bound hydrogen atoms at 11.4(5) ppm (RR′R″NH + ) and 9.4(5) ppm (both RR′NH sites). The resonance at δiso = −281 ppm is assigned to the planar RR′NH nitrogen environment near the end of the alkyl chain (labelled site 1 in Figure S13).…”

“…39,132,[134][135][136][137][138][139][140] DFT calculations were completed using the CASTEP software package 147 (see Experimental Section for details). Molecular systems involved in strong intermolecular hydrogen-bonding interactions typically require structural optimization prior to calculation of the NMR parameters.…”