Synthesis, Characteristics and Physico-chemical Study of Some Dichloro Pyrazoles

Abstract

Some new 3,5-Diaryl-1-substituted pyrazoles have been synthesized by the action of isonicotinic acid and thio-semicarbazide on 3-iodo flavanones in pyridine medium. 3-iodo flavanones obtained from 2-hydroxy-3,5-dichloro chalcones and ICl in acetic acid. Structure of these compounds has been established by chemical and spectral analysis (NMR & IR). Purity of these heterocycles was checked by TLC. The interaction of Cu(II), Co(II) with 1-carboxamido-3-(2-hydroxy-3,5-dichloro pheyl)-5-(4-methoxy phenyl) pyrazole (L1), 1-thiocarbaxomedo-3(2-hydroxy-3,5-dichloro pheyl)-5-(4-methoxy phenyl) pyrazole (L2) have been carried out by employing Bjerrum -Calvin pH metric titration technique, at 27oC in 70 % dioxane-water medium. The data obtained can be used for the determination of proton ligand formation numbers (n). From the formation curve, the proton-ligand stability constant pK values have been evaluated using half integral method. The metal ligand formation numbers (n) are estimated by using Irving Rossotti’s expression.Metal-Ligand stability constants for 1:1 complex & 1:2 complex have been calculated which are designated by letters log K1 & log K2 respectively.