A New Approach to the Chemistry of the Serullas Test for Morphine

Abstract

The tests for morphine are very important since this alkaloid is used in medicine for pain release but also it is a restricted drug due to abuse. The interaction of morphine with iodic acid has been used for its identification. In this communication the several redox reactions taking place during this test are explained in a new way. Activation of the organic-inorganic ester (mixed iodate) by protonation and water loosening creates a cationic intermediate with inverted polarity at the ortho-position. This innovation is important because there is no need to invoke electron back donation since this concept reverses the normal polarization of a functional group. Our novelty worked very well and explained the three successive redox steps taking place during the test, that is, until the oxidation to an ortho-quinone and iodine formation which is detected by reaction with starch gel giving Prussian blue colour.