Isophthalic acid, a benzene dicarboxylic acid, has the chemical formula C₈H₆O₄ and is an important industrial compound. It features two carboxylic acid groups (-COOH) positioned at the 1,3-positions on a benzene ring. Isophthalic acid is primarily used in the production of polyesters and resins, contributing to materials with enhanced thermal and mechanical properties. Its applications extend to coatings, fibers, and plasticizers, where it improves durability and resistance to hydrolysis. Additionally, isophthalic acid serves as a key intermediate in the synthesis of various chemicals, highlighting its significance in multiple industrial sectors.