[NMR studies on cetirizine hydrochloride].
OBJECTIVE
To study the NMR phenomena of cetirizine hydrochloride and assign all proton and carbon signals in NMR spectra.


METHODS
To record the 1D and 2D NMR spectra of cetirizine hydrochloride while changing the experimental temperature and adding D2O into the solution.


RESULTS
More than one NMR signal or broad peak resulting from piperazine and the attached groups with N atom were given in DMSO-d6 solution at room temperature. "Coalescence" or narrowing had occurred for the proton and carbon signals when the experimental temperature was increased or D2O was added into the solution.


CONCLUSIONS
Compared with the NMR "time scale", there are more than one conformation of cetirizine hydrochloride in DMSO-d6 solution at room temperature. The different conformation will be exchanged fast while temperature rise and the stable conformation will be existed while D2O was added into the solution.
Li
Qian
Q
Center for Instrumental Analysis, China Pharmaceutical University, Nanjing 210009, China.
Shen
Wen-bin
WB
Zou
Qiao-gen
QG
D017332:Cetirizine / Q000737:chemistry*; D003903:Deuterium; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011487:Protein Conformation; D013696:Temperature
D003903:Deuterium; D017332:Cetirizine