Fourier transform Raman and infrared vibrational study of diazepam and four closely related 1,4‐benzodiazepines

Abstract

Fourier transform Raman and infrared spectra have been recorded of diazepam (7-chloro-l,3-dihydro-l-methyl-5-pbenyl-2H-1,4-benzodiazepin-2-one) and four compounds with closely related structures. These compounds are all 7-chloro-l,fdihydro-5-phenyl-2H-1,4-benzodiazepin-2-ones and differ only in the nature of the substituent (R) at N-1. The five compounds are nordazepam (R = H), diazepam (R = CH,), pinazepam (R = CH,CECH), halazepam (R = CH,CF,) and prazepam (R = cyclopropylmethyl). Prominent features of the infrared and Raman spectra have heen assigned to functional groups of the parent structure and the substituent groups. The spectra of nordazepam suggest that the compound exists as a centrosymmetric cyclic dimer in the solid state. Complete tabulations of the observed wavenumbers of the five molecules are given. The spectra provide a means of identification of these drugs.

Preparation and in Vitro Evaluation of Fast Release Diazepam Suppositories for Febrile Seizures

“…8, and the most important functional groups are mentioned in Table 4. The bands 1680, 1605, 1400, 1320, 740, 700, and 580 cm −1 appear to be characteristic of the 1, 4-benzodiazepine structure [22]. C=O stretch, a very strong infrared absorption band was observed about 1680 cm −1 in the spectra of diazepam C=N stretch, a weak band in the infrared spectra.…”

Pharmaceutical Characterization and Detection Using Surface-Enhanced Raman Scattering

“…The spectrum of the pure pharmaceutical agent can be obtained by subtracting the matrix spectrum from that of the commercial drug. Useful spectrum may sometimes be obtained without subtraction when the pharmaceuticals are strong Raman scatters and the fillers are weak Raman scatters [15][16][17].…”

Development of a Surface-Enhanced Raman Spectroscopy Method for the Detection of Benzodiazepines in Urine

“…in the surface enhanced Raman spectra of 1,2-triazolo and imidazo benzodiazepines studied 85 The benzene ring in the base benzodiazepine structure indicated as the b-ring in Figure 36 can be monosubstituted disubstituted at the ortho position. While the disubstitution shows spectral bands in the infrared spectra, 61,44,85,86 these bands are not prevalent in the Raman spectra. Generally, two spectral peaks are observed, however, that can be attributed to the monosubstituted b-ring.…”

“…61,44,85 Neville and Shurvell have previously provided peak assignments in the Raman spectra of diazepam as well as four other closely related 1,4-benzodiazpines (nordiazepam, pinazepam, halazepam, and prazepam) that were not examined in this study. 61 Though these compounds were not examined here, the peak assignments can be used to relate other structurally similar benzodiazepines. Raman assignments produced by this group for other benzodiazepines were also used to provide a comprehensive analysis.…”

“…Powder samples can be analyzed directly without sample preparation. 58,49,59,60,61,62 This has been shown to provide rich spectral information that can distinguish compounds with closely related structures.…”