GLUTARIC ACID, or Normal Pyrotaric Acid, HO2C·CH2·CH2·CH2·CO2H, an organic acid prepared by the reduction of α-oxyglutaric acid with hydriodic acid, by reducing glutaconic acid, HO2C·CH2·CH:CH·CO2H, with sodium amalgam, by conversion of trimethylene bromide into the cyanide and hydrolysis of this compound, or from acetoacetic ester, which, in the form of its sodium derivative, condenses with β-iodopropionic ester to form acetoglutaric ester, CH3·CO·CH(CO2C2H5)·CH2·CH2·CO2C2H5, from which glutaric acid is obtained by hydrolysis. It is also obtained when sebacic, stearic and oleic acids are oxidized with nitric acid. It crystallizes in large monoclinic prisms which melt at 97.5° C., and distils between 302° and 304° C., practically without decomposition. It is soluble in water, alcohol and ether. By long heating the acid is converted into its anhydride, which, however, is obtained more readily by heating the silver salt of the acid with acetyl chloride. By distillation of the ammonium salt glutarimide, CH2(CH2· )2NH, is obtained; it forms small crystals melting at 151° to 152° C. and sublimes unchanged.