Síntese e caracterização de cloridratos de 4,5-diidro-1H-pirazol-1-carboximidamidas sob condições sonoquímicas

Abstract

This work describes the synthesis of a new series of 4,5-dihydro-1H-pyrazole-1-carboximidamide hydrochlorides obtained under sonochemical conditions by the cyclocondensation reaction between 1-(2-hydroxyphenyl)enones and aminoguanidine hydrochloride. Altogether, thirteen new substances were synthesized with yields from 15.5% to 83.2% and were subjected to antimicrobial evaluation by minimum inhibitory concentration test (MIC). The tests were carried out with purpose of verifying the antimicrobial potential of the synthesized substances, which the substance 5-(4-bromophenyl)-3-(2-hydroxyphenyl)-4,5-dihydro-1H-pyrazole-1-carboximidamide hydrochloride showed the best result aganist Gram-positives bacteria S. aureus and E. faecalis with MIC of 7.8 μg.L˗1, minor concentration when compared to the chloramphenicol standard used in this work. The use of ultrasound has proved to be effective since the substances were synthesized in short reaction times and without chromatographic purification. Products were characterized by infrared spectroscopy and 1H and 13C NMR. The data were consistent with the proposed structures. The structure of 3-(2-hydroxyphenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carboximidamide hydrochloride was determined by X-ray diffraction.