SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF NEW AZOMETHINES SYNTHESIZED FROM 4-FORMYL-1-PHENYL-3-ARYL(HETERYL)PYRAZOLES

The target l-phenyl-3-aryl(heteryl)pyrazole-4-idenaminocarboxylic acids and their esters (Ilia - lilt) were obtained by nucleophilic addition of the corresponding aminobenzoic acids and their ethyl esters (IIa - lid) to 3-aryl(heteryl)-4-formylpyrazoles (Ia - le). The yields and physicochemical characteristics of the synthesized compounds are presented in Table 1. The proposed structures of all these compounds were confirmed by the results of elemental analyses and IR spectroscopic measurements. Compounds Ilia and IIIn were additionally characterized by 1H NMR spectra. The IR spectra of compounds containing carboxyl groups show absorption bands corresponding to C=O stretching vibrations in the region of 1680-1700cm -I, bands due to C=N vibrations ( 1620 - 1630 cm- I), and bands characteristic of O-H bonds (3390-3450cm -I) and C=C and C=N bonds in aromatic and heterocyclic rings (1540 - 1590 cm- i). The IR spectra of ethyl esters are characterized by a shift of the bands of C=O vibrations to 1740 - 1750 cm- z and by the vanishing of absorption bands belonging to the OH groups. The spectra of compounds Illr- IIIt containing coumaryl substituents show additional absorption bands of the C=O bonds at 1740 cm- I. The IH NMR spectra of compounds Ilia and llIn contain singlet signals from the protons of azomethine groups in the region of 9.34 (Ilia) and 9.25 ppm (llln) and the signals from protons of the HC groups in position 5 of the pyrazole ring at 8.92 (Ilia) and 8.87 ppm (llIb). Protons of the aromatic (heterocyclic) substituents give typical signals in the region of 7.33-8.41 ppm.