amines. Typically the reduction of aldoximes gives both primary amines and secondary amines; however, reaction conditions can be altered (such as the addition of potassium hydroxide in a 1/30 molar ratio) to yield solely primary amines. In general, oximes can be changed to the corresponding amide derivatives by treatment with various acids. This reaction is called Beckmann rearrangement. In this reaction, a hydroxyl group is exchanged with the group that is in the anti position of the hydroxyl group. The amide derivatives that are obtained by Beckmann rearrangement can be transformed into a carboxylic acid by means of hydrolysis (base or acid catalyzed). And an amine by Hoffman degradation of the amide in the presence of alkali hypoclorites. Beckmann rearrangement is used for the industrial synthesis of caprolactam (see applications below). The Ponzio reaction (1906) concerning the conversion of m-nitrobenzaldoxime to m-nitrophenyldinitromethane using dinitrogen tetroxide was the result of research into TNT analogues: In the Neber rearrangement certain oximes are converted to the corresponding alpha-amino ketones. Oximes can be dehydrated using acid anhydrides to yield corresponding nitriles. Certain amidoximes react with benzenesulfonyl chloride to make substituted ureas in the Tiemann rearrangement: Uses In their largest application, an oxime is an intermediate in the industrial production of caprolactam, a precursor to Nylon 6. About half of the world's supply of cyclohexanone, more than a million tonnes annually, is converted to the oxime. In the presence of sulfuric acid catalyst, the oxime undergoes the Beckmann rearrangement to give the cyclic amide caprolactam: Metal extractant Oximes are commonly used as ligands and sequestering agents for metal ions. Dimethylglyoxime (dmgH2) is a reagent for the analysis of nickel and a popular ligand in its own right. In the typical reaction, a metal reacts with two equivalents of dmgH2 concomitant with ionization of one proton. Salicylaldoxime is a chelator in hydrometallurgy. Amidoximes such as polyacrylamidoxime can be used to capture trace amounts of uranium from sea water. In 2017 researchers announced a configuration that absorbed up to nine times as much uranyl as previous fibers without saturating. Other applications Oxime compounds are used as antidotes for nerve agents. A nerve agent inactivates acetylcholinesterase by phosphorylation. Oxime compounds can reactivate acetylcholinesterase by attaching to phosphorus, forming an oxime-phosphonate, which then splits away from the acetylcholinesterase molecule. Oxime nerve-agent antidotes are pralidoxime (also known as 2-PAM), obidoxime, methoxime, HI-6, Hlo-7, and TMB-4. The effectiveness of the oxime