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Adipic Acid

Updated: 2026-08-25

Overview

Adipic acid (IUPAC name: hexanedioic acid) is an important organic compound with the formula (CH2)4(COOH)2. As the most commercially significant dicarboxylic acid, it serves as a fundamental building block in polymer chemistry. First synthesized in the late 19th century, industrial production began in the 1930s with the advent of nylon manufacturing. The compound naturally occurs in beet juice but is predominantly produced synthetically for commercial applications. Modern production methods typically involve the oxidation of cyclohexane or cyclohexene. As an intermediate in numerous chemical processes, adipic acid plays a crucial role in multiple industries, from textiles to food production.

Physical and Chemical Properties

Adipic acid appears as a white, odorless crystalline powder with a slightly acidic taste. The compound exhibits good thermal stability, decomposing only at temperatures above 230°C. Its solubility profile shows moderate water solubility (14 g/L at 20°C) that increases significantly with temperature, along with good solubility in polar organic solvents. Chemically, adipic acid behaves as a typical dicarboxylic acid, capable of forming salts, esters, and amides. The two carboxyl groups allow for polymerization reactions, particularly important in nylon 6,6 production. The acid has pKa values of 4.43 and 5.41, making it a relatively weak acid suitable for buffering applications.

Main Applications

Approximately 90% of adipic acid production is dedicated to nylon 6,6 manufacturing, where it reacts with hexamethylenediamine to form the polymer. The automotive and textile industries represent major end-users of nylon products made from adipic acid. Other significant applications include polyurethane production (as a chain extender), plasticizers for PVC, and unsaturated polyester resins. In food processing, adipic acid serves as an acidity regulator (E355) in gelatin desserts, powdered drinks, and baking powders. Emerging uses include biodegradable polymers and pharmaceutical intermediates.

Safety and Storage

Adipic acid is generally considered low in toxicity (LD50 oral rat: 3600 mg/kg) but requires standard chemical handling precautions. The main hazards include potential eye and skin irritation from dust, and respiratory irritation from airborne particles. Appropriate PPE (safety glasses, gloves, dust masks) should be used when handling the powder form. For storage, keep containers tightly closed in a cool, dry, well-ventilated area away from strong oxidizers and bases. Bulk storage should prevent moisture absorption and caking. The material is stable under normal conditions but may form combustible dust concentrations in air.

B2B Procurement Guide

Industrial buyers should specify required purity levels, which typically range from 99.5% to 99.9% for most applications. Food-grade specifications require additional testing for heavy metals and other contaminants. Packaging options include 25kg bags, 500kg supersacks, or bulk shipments for large-scale users. Consider regional production capabilities when sourcing, as transportation costs can significantly impact pricing. Verify supplier certifications (ISO, REACH compliance) and request material safety data sheets. For long-term contracts, price escalation clauses can help manage market volatility in raw material costs.

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