R. Jay
Mar 1, 1964
Citations
2
Influential Citations
200
Citations
Quality indicators
Journal
Analytical Chemistry
Abstract
SIR: The determination of the oxirane ring in organic compounds has generally involved reaction with excess hydrochloric acid in a vayiety of solvents. Because the reaction LS slow, a t least a 15-minute reaction time is generally allowed before back titrating the excess acid. The determination of aziridines also requires back-titration techniques (1, 4) . Durbetaki (2) described a direct titration of epoxies with anhydrous hydrogen bromide in acetic acid. While this method is rapid and capable of good results, the reagent, which fumes profusely in air, requires special handling and freque it restandardizations for accurate analyses, The following method employs a stable, readily available, titrant which can be used for the direct titration of oxiranes and certain aziridines. The sample is dissolved in chloroform and titrated to a crystal violet end point with standard perchloric acid (in acetic acid or dioxane) in the presence of an excess of a soluble quaternary ammonium bromide or iodide. For epoxides eithereagent can be used, but the quaternary bromide is satisfactory for virtually all the materials usually encountered and is recommended over the iodide because of economy and better cd,orability. With aziridines, however, the iodide is preferred as it gives more rapid reactions and sharper end point3.