There's no widely circulated, peer-reviewed procedure that lays out mCPBA oxidation of mitragynine in full detail—but it has been reported anecdotally and used in research contexts for selective oxidation of indole systems, and it's theoretically sound. That said, most documented lab procedures for converting mitragynine to 7-OH focus on Oxone or PIFA (phenyliodine(III) bis(trifluoroacetate)) rather than mCPBA.
If you want something concrete,
this patent is your best bet: US Patent US20210148049A1 –
Selective Oxidation of Mitragynine to 7-Hydroxymitragynine. It outlines a method using Oxone in acetone/water, with a good yield and high selectivity. That's probably the best-documented route currently known.
The THF/water system works well with PIFA because PIFA is soluble in polar solvents. The aqueous component helps stabilize intermediates and can aid in selectivity. In theory, a similar system
could work with mCPBA, but mCPBA is more commonly used in DCM or acetonitrile. Water can hydrolyze excess mCPBA or form m-chlorobenzoic acid, potentially affecting the yield and selectivity.
If trying a THF/H₂O route with mCPBA, it would be experimental territory, not something that's well documented for mitragynine.
Went looking into some alternative reactions that can yield 7-OH-- id like your opinion on this one
(In suitable reaction vessel) Dissolve mitragynine extract in alcohol.
Add a few drops of rose Bengal, ~4 drops for every 5 grams mit
(You can probably skip this part if inclined to chemistry; do not do this step unless you are ready to immediately follow it in <5 minutes by the sequential steps, as this reaction can form byproducts when reacting with gasses other than oxygen, and singlet oxygen is so cancerous it's not even funny, so wear a gas mask, yeh? A cheap one off temu works, if anything just replace the filter)
Submurge vessel in ice bath
Run tubing attached to oxygen tank into reaction vessel
Put an upside down beaker over top of the vessel down into the ice bath, sealing off the access to normal air, while allowing the tubing to run under the 'beak'
Bubble all air out with oxygen tank.
Reflux over stirbar (still in ice bath) for 8-36 hours
[depending on how long you have and extent to which you are trying to oxidize the mitragynine. Obviously on the lower end of that spectrum, theres going to be higher mit contamination in the final product as less will have time to react]
Use a large excess of citric acid, like a super saturated water solution of it, and add roughly an equal part of this as there is reactant to the vessel.
This destroys the catalyst.
Reflux on low at room temperature for 2-5 mins
Dry on hot plate (set on low)
While drying best to throw a capsule of quercetin in to quench any remaining singlet oxygen after the citric acid- better safe than sorry!
After this you'll be left with a black, tarry residue, that, if youve correctly done the process, should be 7-hydroxy-Mitragynine citrate
To purify, this should probably be dissolved in water, freebased with a KOH or NaOH and the alkaloid potion extracted into a suitable Nonpolar solvent
Though in theory, this should be safe to consume without this step if you successfully quenched the singlet oxygen.