Procedure: (Example) 10 grams of harmaline dissolved in 10% aqueous hydrochloric acid had zinc dust added gradually (with occasional shaking). The mixture was heated on a water bath until the yellow coloration disappeared. After filtering off any unreacted zinc, ammonium chloride was added to prevent precipitation of zinc hydroxide. Addition of ammonia caused an immediate precipitation of white material. This was shaken into Ethyl acetate; which recovered THH. (See Siddiqui et al. 1983 for their version of this procedure.) (This should also work for harmine) Siddiqui et al. 1983 reported that the addition of NH4Cl prior to basification with Ammonia increased the yield for this reaction from 50% to around 80% (by preventing the precipitation of Zinc hydroxide).
I pretty much followed what it says except the Hcl solution was weaker (2 N, that's about 6%) and used DCM instead of Ethyl acetate. Sorry for the quality of the pictures but that's the best I could do with my camera.
This conversion came up so many times before but I never realised how simple and straightforward it was untill Infundibulum pointed it out, thanks for that.
Harmine/Harmaline freebase was aquired with the usual Manske method, which was repeated quite a few times (too many times as it turned out from the yield), till the water turned out clear and freebased with ammonia. I think 69Ron mentioned before that something else gets through the Manske precip. other than Harmine/Harmaline, and if freebased with a hydroxide it only precipitates the two.
700 mg of the freebase was put into 200ml Hcl water, heated and stired untill dissolved. Added zinc little by little by little untill there was no more change in colour (which happened very quickly), the whole thing stired and kept at 80 C throughout.
Here I added the ammonium chloride, wasn't sure how much to ad so I made it 10 gramms. There was some precipitation that wouldn't dissolve in DCM at freebasing, but it didn't seem to affect the yield(?).
The freebase:
The outside ring is unreducted harmaine/harmaline, it would not dissolve in cold Hcl water, but did in warm. The ammount of it was very small compared to the white freebase.
The Hcl salt:
The yield was 690 mg, that's 87% percent yield of freebase by weight.