Author Topic: novel newbee tryp decarb question session  (Read 5500 times)

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  • Guest
Another failure with Student's procedure
« Reply #20 on: July 08, 2004, 08:58:00 PM »
This is the translation of the first post in that thread, by Erny, who tried Student's procedure and failed.

(Earnest Bee)
12-13-03 16:52

Post 476610 (missing)

(Erny: "Äåêàðáîêñèëèðîâàíèå òðèïòîôàíà a la Student", Russian HyperLab)

Decarboxylation of tryptophan a la student

The procedure, outlined in

did not bring a desired result when performed under our conditions.

15 g of tryptophan, 150 ml of the turpentine, purchased in the economic store, and 30 drops of pharmaceutical peppermint essential oil were placed into a 250ml Erlenmeyer flask and the mixture was heated to reflux while stirring magnetically. After 18 hours of reflux, unreacted tryptophan was filtered off on the Buechner and washed with 70 ml of dichloromethane. The yellow turpentine motherliquor and dichloromethane washing were pooled and extracted with 5% aqueous HCl, this was basified with potassium hydroxide to pH ~12 and extracted with approximately 100 ml of benzene. Extracting this again with 5% aqueous HCl showed no amines were present at all.

The unreacted tryptophan had a white color and it weighed 14.2 g, that, taking into account losses on filtering, it appears that no decarboxylation reaction took place at all, and generally tryptophan remained unchanged in the reaction mixture.

If someone has positive ideas as how to tackle the decarboxylation of tryptophan, express them, if you please.

You HyperLab bees should share abit more information like this with us  :) .
From now on you can expect me to come looking in there from time to time  ;) ...

EDIT: Of course, there is not enough ketone present here too, since peppermint essential oil contains anywhere from 10-50% menthone..


  • Guest
IIRC, the ketone acts as a catalyst.
« Reply #21 on: July 08, 2004, 11:33:00 PM »
IIRC, the ketone acts as a catalyst. So you don't actually need equimolar amounts of ketone.


  • Guest
as I understand it
« Reply #22 on: July 08, 2004, 11:47:00 PM »
The tryptophan forms an unstable ketimine with the ketone, which readily decarboxylates giving the imine of tryptamine. After hydrolysis you have tryptamine and ketone again.

But some ketones like acetophenone will give stable imines with tryptamine, which will not readily hydrolize unless you heat them in an acidic or basic environment.

I don't know about menthone, but the imine from tryptamine and acetone should be much more readily hydrolyzed. If the imine from menthone and tryptamine would not be readily hydrolyzed, it wouldn't be much of a catalyst.

Next to this, there is the additional problem, that with some ketones, transamination may occur.


  • Guest
These recent posts explains a lot of stuff
« Reply #23 on: July 09, 2004, 01:21:00 AM »

Post 509761 (missing)

(Nicodem: "Mechanism of decarboxylation literature", Tryptamine Chemistry)

Post 509782 (missing)

(Rhodium: "Catalytic transamination/decarboxylation cycle", Tryptamine Chemistry)


  • Guest
« Reply #24 on: July 09, 2004, 01:52:00 AM »
P.S. The use of the organic (?) solvents, acetic acid and bicarbonate is compulsory, an attempt at the acidification by sulfuric acid, and the extraction of resin by petroleum ether did not succeed, since resins and tryptamine in it were left mostly undissolved.
Attempts to directly basify the solution and to immediately extract tryptamine with benzene lead to the isolation of red noncrystallizing resin:

WTF, would never guessed, so on that note i have to ask;
can one assume that good old 5% acetic is fine for this?


  • Guest
Thanks, bees
« Reply #25 on: July 09, 2004, 02:48:00 AM »
Thanks all, here it is some my comments.


Your reaction mixture seems to be reddish right from the start. What's the trick to get it working?

The reaction brings some reddish color immidiately after heating to 150 C. Some tryptophan dissolves, evolution of CO2 starts and mix brings some reddish. No special tricks.


How have you tested if it is indeed tryptamine and not a cyclization product?

I haven't measure the melting point of the product (i haven't a thermometer :(), but all phys-chem properties shows that it is tryptamine. Moreover, it was alkylated with EtBr and the products was show the activity. I planned some experiments in future, where all will be measured right.

Nice translation, thanks.

don't see one on the pictures

Yes, the stirring was completed by hands when the foam rised up to condenser.

That last part of the sentence, is that correctly translated?

Yes, this is correct.

The general output not of schitan, since with the experiments separation of candy (tryptamine) from govna resin) product threw out itself on nemnogu into the toilet.

Politicaly correct translation is: "The total yield was not calculated, since during of the reaction workup (purifying the tryptamine from the resin byproducts), much of the reaction mixture was discarded"

The use of the organic (?) solvents


You didn't tell us what your final yield was

The total yield i obtained was 2g (from 20g tryptophan). But much, very much of the reaction mixture was discarded when i was tried to remove resins by recrystallization, A/B reextraction, trying various solvents, etc. You can obtain good results with using of inert gas and provided instructions. (My workup was completed during 2 days, without protection reaction mixture from air: slightly reddish reaction mixture makes intensively red after these days. Oxidation?)

Future questions are welcome. Thanks again.

P.S. Sorry for my terrible english.


  • Guest
Decarboxylation with cyclohexen-2-one
« Reply #26 on: July 09, 2004, 12:25:00 PM »
The first attempt of tryptophan decarboxylation was described at

Post 478376 (missing)

(Erny: "Äåêàðáîêñèëèðîâàíèå òðèïòîôàíà - áåòà âåðñèÿ", Russian HyperLab)

Here I'll describe the second:

In a 250 ml erlenmeyer flask there were added 15 g of D,L-tryptophan along with 150 ml of cyclohexanol and 2 ml commercial cyclohexen-2-one. A reflux condenser was attached and the RM was brought to reflux while stirring magnetically. Warm water was used in the reflux condenser as, when using cold water, cyclohexanol crystallized in it. After 2,5 h of reflux only about a half of the tryptophan had dissolved, and the RM was orange. It was cooled to approx 50°C and as the air went into the flask the RM turned brown. 50 ml of petroleum ether (2) and 200 ml of diluted hydrochloric acid were added, layers were separated and the slightly acidic water layer (3) was evaporated to give 9 g of brown sparkling crystalline mass. After grinding it with acetone, filtering on buechner and washing with acetone it became pink, was turned into freebase and recrystalized from benzene (4). 3,7 g of white sparkling sugar-like crystals were obtained. It's mp was correct and DMT was made from it a la Shulgin wia the ethylformiate/LAH route.


1. In the first attempt 15 g of tryptophan, 1,5 ml of cyclohexen-2-one and 150 ml of cyclohexanol were used. Reaction time was 6,5 h and the final yield of tryptamine - 3,3 g.
2. Petroleum ether was added for the better separation of phases.
3. To evaporate the acidic solution was a great mistake: when almost all of the water was gone, pH was already <2 and it dropped the yield more than twice (as can be seen from the amount of hydrochloric acid used to neutralise the tryptamine during the extraction).
4. Dichloromethane may be used instead of benzene. The best solvent for the extraction of tryptamines is EtOAc.
5. The solvents/reagents were not dried and, as the water is present in the equilibrium amine + ketone <__> imine + H2O, drying may also improve the yield.


  • Guest
It has been shown (UTFSE for different melting
« Reply #27 on: July 09, 2004, 01:36:00 PM »
It has been shown (UTFSE for different melting points of tryptamine) that recrystallization from acetone produces the corresponding imine, not the free tryptamine.

Any imine of tryptamine is prone to cyclization under acidic conditions, resulting in tetrahydro-beta-carbolines which are still amines and behave like amines.

Maybe the conjugated doublebond from alpha-beta-unsaturated ketones inhibita this cyclization a bit.  Howower, I would suggest to remove any trace of ketone before acidifying the workup solution.


  • Guest
Decarboxilation in o-xylol
« Reply #28 on: July 21, 2004, 02:14:00 PM »
Hi all.
SWIM successfully decarboxilated tryptofan in o-xylol.
There is description it synthesis:
3g pure tryptofane suspended in 10ml o-xylol and about 3ml acetophenone. Its mixture refluxed 25-35 hours(with interruptions),almost tryptophane was dissolved. Rm cooled to 50-60C and tryptamine was extracted  3*10ml 10%HCl at heating( In order to Shiff-base hydrolized heating need.).Acid solution was basified and tryptamine  was extracted with  CHCL3. Solvent was distilled on water bath and tryptamine (about1.2-1.3g) was yielded. that is tryptamine was successfully methylated and ethylated  to dmt,det.