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Adipic acid, hexanedioic acid, 1,4‐butanedicarboxylic acid, mol wt 146.14, HOOCCH 2 CH 2 CH 2 CH 2 COOH, 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. During the 1970s and 1980s, however, much research has been directed to alternative feedstocks, especially butadiene and cyclohexene, as dictated by shifts in hydrocarbon markets. Growing concern with air quality may exert further pressure for alternative routes as manufacturers seek to avoid NO x 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 about 60% of U.S. cyclohexane production. Adipic acid is relatively nontoxic.

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A 53 year old obese male presented with the signs and symptoms of acute appendicitis and a family history suggesting the possibility of a malignant hyperthermia trait. In spite of spinal anaesthesia the patient developed malignant hyperthermia during the appendicectomy and the attack was successfully aborted with the early use of dantrolene sodium (Dantrium, Norwich Eaton).

A 28‐year‐old man presented with painful progressive necrosis of the skin of his left leg which was associated with general toxicity and a high fever. A working diagnosis of necrotizing arachnidism was made, but no improvement followed two weeks of therapy with analgesics, antibiotics and antihistamines. His symptoms responded rapidly to prednisolone therapy, and a diagnosis of pyoderma gangrenosum was confirmed by biopsy. This subsequently proved to be associated with early acute myelomonocytic leukaemia.