Spectrophotometric investigation of meto-clopramide and promazine palladium II complexes

The color reaction of metoclopramide or promazine and palladium [II] chloride has been investigated. The optimum reaction conditions, spectral characteristics, conditional stability constants and composition of the water-soluble complexes have been established. The structure of palladium [II] chelates in the solid state is also studied. A spectrophotometric method is proposed for the determination of metoclopramide and promazine hydrochlorides in pure forms and in pharmaceutical preparations. The method is simple, reproducible and accurate and is easily applied to the determination in tables and injection solutions

Acid-base properties of 2,4-dihydroxy benzaldehyde-3 [6-phenyl] pyridazinyl hydrazone [DBP3H] formation constants of some of it's complexes

The objective of this study was to present some details of the synthesis, properties and the analytical behavior of the new reagent; namely, 2,4-dihydroxy-benzaldehyde-3 [6-phenyl] pyridazinyl hydrazone [DBPzH] and its possible applications for the determination and detection of some cations. The finding was based on the evaluation of the dissociation constant of the reagent, the composition and formation constants of the complexes by spectrophotometric and potentiometric methods

Spectrophotometric studies on determination of sulphadimidine

Spectrophotometric studies have been made for the determination of Sulfadimidine by reacting with some aldehydes, as salicylaldehyde and cinnamaldehyde. The color intensity of the formed Schiff bases was found to depend upon the nature and concentration of acid and aldehyde used. The optimum temperature for color development was 50C and heating time was 30 minutes. The procedures were developed for determination of sulfadimidine in presence of sulfanilamide, sulfaguanidine and sulfasomidine. The method has been successfully used for the spectrophotometric determination of sulfadimidine alone and in the presence of some sulfonamides

Effect of solvents on the PKa values of some sulpha drugs

In the present investigation the ionization constants of sulfapyridine, sulfadimidine, sulfasomidine, sulfapyridazine, sulfamerazine, sulfadiazine and sulfamethoxazole were determined potentiometrically using five solvents with concentration ranging between 20 to 100%. Concerning with the solvents used the following regularity in PKa of different sulfa-drugs can be noted: Dioxane > dimethyl-formamide > methanol ethanol > acetone. The number of the solvent molecules [n] surrounding each drug molecule was determined. An attempt was made to detect the number of water molecules in the primary and secondary solvation zone [J] for the different solvent mixtures. Moreover, the relationship between the viscosity of three sulfa-drugs in ethanol-water mixture and their percentage have been evaluated

Chelating tendencies of some sulpha drugs

The acid dissociation constant of sulfadiazine, sulfamerazine and sulfasomidine in 50% ethanolic solution were determined by pH-metric titration at temperature 30C and in different ionic strength. Also, their formation constants with Cu[II], Zn[II], Ni[II], Co[II], Mn[II] have been studied. The free energies of the complexes formed were deduced and the relation between the stabilities of these complexes and the ionization potenital of the cautions were discussed

Cephalexin complexes with some 3d transition-metal ions

The protonation constants of cephalexin and the stability constants of its complexes with Fe [III], Cu [II], Ni [II] and Mn [II] have been determined by pH-metric titration in aqueous medium at 30 and 40 and 0.1 M ionic strength [KCI]. The metal-ligand formation constants [long beta 2] calculated, show the order as Fe [III]> Cu [II]> Ni [III]> Mn [II]. Thermodynamic parameters [delta G, delta H and delta S] calculated at 30C and 0.1 M ionic strength, show that the interaction of cephalexin and these metal ions is chelation-reaction between ionic species. Thus, the entropy change plays important role in giving the observed stability

Stability study of some complexes of sulphamethoxazole

The interaction of certain transition metal ions Cu [II], Zn [II], Ni [II], Co [II] and Mn [II] with sulphamethoxazole have been studied in 50% ethanol-water medium at 30 and different ionic strengths following Irving-Rossitti pH titration technique. The proton-ligand and metal-ligand formation constants [log K[H1] and log beta2] calculated, show the order of stability as [Cu [II] > [Zn [II] > Ni [II] > Co [II] > [Mn [II]. Thermodynamic parameters [delta G, delta H and delta S], calculated at 30 and 0.1 M [KC1] ionic strength

Determination of the dissociation constants of sulphasomidine, sulphadimidine and sulphapyridine using solubility and pH value

The relationship between the dissociation constant of a sparingly soluble acid [or basic] substance, its solubility, and the pH value of the solvent is stated. This relation is tested and confirmed by measurement of the solubility of an amphoteric substance [sulphasomidine, sulphadimidine and sulphapyridine] in buffer solutions ranging from pH [1.0-11.6]. The procedure is suggested as convenient for determining the dissociation constants of some sulpha drugs