A thermodynamic study for the stability of some aromatic complexes formation derived from the reaction of 4-dimethyl amino benzaldehyde with diazotized dinitro aniline reagents.

Abstract

Abstract The basis of this research includes the preparation of aromatic azoimine complexes resulting from the coupling reaction (4) of Schiff bases with diazotized dinitroaniline reagent. Ultraviolet spectra, infrared spectra, and melting points are among the most important physical methods used to identification the right compounds prepared in this study. After that, the stoichiometric ratios of the components of the complex were determined using the molar ratio method, and we got a ratio of (1:1) for all the studied complexes. Finally, the factors that affect the stability constant values were studied, namely: A-Effect of acidity function: These stability constants were studied for each of the prepared complexes at each acidic function (pH) and different temperatures, and we obtained values for the stability constants, which are evidence of the preparation of stable azo complexes. B-The effect of temperature: These stability constants were calculated at a range of temperature (313–273oK) which allowed us to know that the reactions of formation of azo dyes are spontaneous and exothermic from the negative values of (∆G and ∆H) respectively, as well as the negative (∆S) value that supports what was mentioned previously. C-Effect of Structure: The location and the type of function group also has an effect on the values of the stability constants of the prepared complexes, and this was proved by the variation in the values of the stability constants.