Adipic Acid

Abstract

Adipic acid, hexanedioic acid, 1,4-butanedicarboxylic acid, mol wt 146.14, HOOCCH2CH2CH,CH2COOH, is a white crystalline solid with a melting point of about 152°C. Little of this dicarboxylic acid occurs naturally, but it is produced on a very large scale at several locations around the world. The majority of this material is used in the manufacture of Nylon-6,6 polyamide, which is prepared by reaction with 1,6-hexanediamine. Adipic acid is a colorless, odorless, sour-tasting crystalline solid that undergoes reactions including esterification, amidation, reduction, halogenation, salt formation, and dehydration. It also undergoes several industrially significant polymerization reactions. Adipic acid historically has been manufactured predominantly from cyclohexane. However, much research continues to be directed to alternative feedstocks, especially butadiene and cyclohexene, as dictated by shifts in hydrocarbon pricing. Air quality regulations may exert further pressure for alternative routes as manufacturers seek to avoid NOx abatement costs. When dispersed as a dust, adipic acid is subject to normal dust explosion hazards. The material is an irritant, especially upon contact with the mucous membranes. Protective goggles or face shields should be worn when handling the material. The material should be stored in corrosion-resistant containers, away from alkaline or strong oxidizing materials. Adipic acid is a very large-volume organic chemical and is one of the top 50 chemicals produced in the United States in terms of volume, although demand is highly cyclic. Adipic acid for nylon takes ∼60% of U.S. cyclohexane production. Adipic acid is relatively nontoxic.