Infrarotspektroskopische Untersuchungen von Barbituraten

Structural Features, Phase Relationships and Transformation Behavior of the Polymorphs I−VI of Phenobarbital

“…The main differences in the IR spectra can be attributed to distinct NH 3 3 3 OdC interactions and NH out-of-plane vibrations. On the basis of these vibrations, the spectra of 5,5-disubstituted barbiturates have been classified into several groups, 45,22 which we extended and already showed in a previous report 38…”

Infrared identification of barbiturates with particular reference to the occurrence of polymorphism

“…The effects of polymorphism on infrared spectra of barbiturates were noted by Cleverley & Williams (1959b) and by Paulig, Gansau & others (1963). Goenechea (1966) tabulated frequencies for N-H, C-H and C=O stretching absorptions of 21 barbiturates and suggested that these were suitable for the identification of the individual substances ; he also noted that the greatest differences between the spectra of polymorphic modifications were found in the N-H and C-H stretching absorptions, and commented that for analytical purposes consideration must be given to the method of purification. The C=O stretching absorptions were used by BouchC, Coclers & Delahaut (1966) for the quantitative estimation of individual barbiturates, examined as potassium bromide discs ; for this purpose the sample preparation procedure was rigorously controlled to ensure that the same crystalline form was reproducibly obtained.…”

Characterization of Hydrogen Bonding between Selected Barbiturates and Polyethylene Glycol 4000 by IR Spectral Analysis

“…Since the 2-carbonyl is free both in the solid state and in ether, the frequency change should be small. The 4-and 6-carbonyl groups, hydrogen bonded in the solid state but free in ether solution, should show much greater frequency changes, leading to an assignment in agreement with that of Goenechea (25).…”