Σύνθεση μεθαμφεταμίνης από εφεδρίνη με τη χρήση I2 και H3PO2

[xp7291]

I have a question. In Figure 12, the pH value has reached 12, which means free alkali can be produced. Why do we need to add sodium thiosulfate? In Figure 13?

 

[darthseres]

A simple technical/theoretical question... The reaction is an oxidation/reduction... Considering that the main elements are Iodine, Phosphorus and Ephedrine... what exactly is the precise role of each element? Which one is oxidized? Which one is reduced? And the third?... I'm a new student, forgive my ignorance