NMR spectroscopy applied in the identification of organic substances and medicinal drugs

Abstract

NMR spectroscopy is one of the most powerful available for studying the structure of molecules and identification of drugs. NMR involves the absorption of radiowaves by the nuclei of some combined atoms in a molecule that is located in the magnetic field. An NMR spectrum is acquired by varying or sweeping the magnetic field over a small range while observing the resonance signal from the sample. Due to NMR spectra we can confir the structure of compounds . Aims : The purpose of our investigation was to elaborate the method of interpreting 1H proton and 13C carbonic spectra. Materials and methods: In the analysis were used the drugs like aspirin „Benzituron , Isohydrofural , Metiferon. The NMR spectra was registered at Fourier Transformation NMR spectrometer. The substances were dried for 2 hours at 1050 C, after that the samples is necessary to be dissolved in the deuterised water and be filtered through Millipore filter 0.2 pm under vacuum. The obtained solutions were transferred in glass tubes about 15 cm in long and 5 mm in diameter .As a reference standard is used TMS with the absorbance set at 0,0 ppm ,which is introduced in the tube with solution. Results: The NMR spectra of these substances give important and detailed information about molecules. Every spectrum is characterized by the chemical shift of peaks and spin-spin splitting of peaks . For example the chemical shift indicates the functional groups that are present, such as aromatics, ketones, amines, alcohols, aldehyde and so on. .The multiplicity of the resonances identifies the type of protons. The 1H protonic spectrum of Benzituron contain resonance signals of a high intensity which demonstrate the presence of hydrogen proton in the molecule. The signal at 3.4 ppm belong to metylen group (-CH2-) it is a diplet. The zone of resonance at 4.56 ppm correspond to amines group (NH2) and imines (NH),its represented as a common signal, due to superposition of peaks. The signal at 7.21,7.22;7.24; ppm included in multiplet are assigned to aromatic ring. Conclusions: There were examined the 1H -protonic and 13C- carbonic spectra of different substances in order to elaborate the rules for interpreting spectra. These spectra permits to confirm the structure of compounds, to identify the drugs.