On the Interaction of Noscapine (Narcotine) with Ammonium Tellurate in Sulphuric Acid

The purpose of this study is to clear up what is happening in the test tube during the interaction of ammonium tellurate with noscapine in sulphuric acid (Brociner test). The approach is a Theoretical Organic Chemistry Study based on the chemical deportment of reagent and substrate, the reaction medium, and experimental conditions. This point out that a redox process is going up, with the following results: meta-telluric acid is formed in situ whose protonation yields the reactive species. Reaction with the methylenedioxy group present in noscapine affords an oxonium salt. Reaction proceeds when a water molecule forms a hemiacetal and an organometallic ester, a tellurate. Acidolysis of the latter gives rise to a concerted mechanism involving five electron-shifts. This way the following compounds are formed: tellurious acid, an ortho-benzoquinone, and formaldehyde. Tellurium dioxide results by acid catalyzed dehydration of tellurious acid.