SYNTHESIS OF DISODIUM 2-CARBOXI-INDOPHENOL DYE AND VERIFICATION OF ITS ANALYTICAL PROPERTY OF ACID-BASE INDICATOR

Abstract

Dyes are substances, almost always organic, very present in our lives, and have the function of adding color without the contact material losing its transparency, being widely used in the industrial field. This article deals with the replication of disodium 2-carboxy-indophenol dye synthesis through condensation between drug structures, Paracetamol and Aspirin, which was conducted by technical® chemistry students from a state school in The Middle Of Piracicaba, MG. However, modifications to the synthesis process were proposed and new tests were performed to verify the property of acid-base indicator of the dye. The results revealed that the synthesized dye has analytical property of undergoing protonation or deprotonation depending on the reaction medium, changing color in acidic medium and returning to its original color in alkaline medium. However, it proved to be inefficient in dilute acid solutions. It was also observed that it destabilizes easily and, because it is synthesized in concentrated alkaline medium, it is estimated that its interaction with other solutions may interfere in the results of volumetric analyses, for example, and its use in titrations is not feasible. However, further studies are needed to better conclude on the feasibility of its use in quantitative analyses. The synthesis performed is important, considering that it can contribute to elucidate doubts regarding the application of the dye produced and provide opportunities for promising studies in organic synthesis and analytical chemistry based on pharmacological active principles.