The most common method of producing Dextromethamphetamine (Crystal Meth) is supposedly the Nagai Method, where Pseudoephedrine, Hydriodic acid and Red Phosphorous are refluxed overnight, producing a mixture of Dextromethamphetamine, water and Red Phosphorous which may be reused.
The thing is, I don't quite understand how the Red Phosphorous ends up in the mixture as though it were acting as a catalyst.
The best mechanism I could think up was the following:
Pseudoephedrine + Hydriodic acid --> Iodoephedrine + Water
Iodoephedrine + Hydriodic acid --> Methamphetamine + Iodine
Using no Red Phosphorous at all.
The only use of Red Phosphorous I can see here would be to convert the Iodine back to Hydriodic acid, which would give Phosphoric acid as a byproduct, not Red Phosphorous.
What exactly is the Red Phosphorous supposed to be doing here?
EDIT: I notice that this question is very similar to mine, however whilst the answer to that question does address the use of the Red Phosphorous (Phosphoric acid is produced as I had assumed), it unfortunately doesn't explain how it ends up back as Red Phosphorous in the end.
Disclaimer: I am merely interested from a theoretical standpoint and have no intention of making Dextromethamphetamine. Just saying.
