Studying Effect of temperature on stability constants of some azo dyes resulting from reaction of reagent (o-phenylenediamine) is ozonized with a number of chalcones

Ahmeed, Hiba Salah; Sulyman, Ebtahag Z.; Al-Niemi, Mohammad Mahmoud Hussein

doi:10.33899/berj.2025.187031

	Studying Effect of temperature on stability constants of some azo dyes resulting from reaction of reagent (o-phenylenediamine) is ozonized with a number of chalcones
College Of Basic Education Research Journal
Volume 21, Issue 1, March 2025, Pages 678-689 PDF (771.8 K)
Document Type: Research Paper
DOI: 10.33899/berj.2025.187031
Authors
Hiba Salah Ahmeed^* ¹; Ebtahag Z. Sulyman^* ¹; Mohammad Mahmoud Hussein Al-Niemi^* ²
¹Department of Chemistry, College of Education for Girls, University of Mosul, Mosul, Iraq
²Department of Chemistry, College of Education for Pure Sciences, University of Mosul, Mosul, Iraq
Abstract
Our research initially includes preparing five aromatic chalcones, diagnosing them physically using melting points and color changes, diagnosing them using an infrared (IR) device, as well as diagnosing them chemically using appropriate chemical tests. In addition to preparing reagent (ortho-phenylene diamine). Then study their interaction with each other and formation of azo dyes and follow them spectroscopically using an electronic spectrophotometer (UV+visible) at natural (PH) for each dye. And at six temperatures (273, 283, 293, 303, 313, 323k). Then the optimal conditions for formation of each azo dye were determined at each temperature along with molar ratios of its components, so they were all (reagent 1: 2 chalcone) using mole ratio method. Then degree of agglomeration was calculated with values of stability constants of resulting dye at each temperature, and it was within (negative) range. In addition, it was inversely proportional to increase in temperature because reaction of its formation exothermic. From studying absorption spectrophotometrically at six temperatures, we were able to calculate enthalpy of reaction (∆H). Its negative value indicates that reaction is exothermic, and this is confirmed by decrease in stability constants of prepared dyes when reaction is heated. The Gibbs free energy was also calculated at all temperatures, and it was negative, indicating spontaneity of reaction. While entropy values (∆ S) were negative, indicating regularity of product compared to reactants, with presence of some anomalies.

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