• Adipic acid, from an industrial perspective, it is the most important dicarboxylic acid: : about 2.5 billion kilograms of this white crystalline powder are produced annually, mainly as a precursor for the production of nylon. . Adipic acid otherwise rarely occurs in nature. About 60% of the 2.5 billion kg of adipic acid produced annually is used as monomer for the production of nylon by a polycondensation reaction with hexamethylene diamine forming nylon 66. . Other major applications also involve polymers; it is a monomer for production of polyurethane and its esters are plasticizers.