Decarboxylating Tryptophan

[Student]

Yes, those yields are legitimate, but rather than a cork, a test tube with a screw cap was used and the cap was left slightly loose. I suggested the cork because that will work with common test tubes. Occasionally the heat needed to be lowered during the reaction to reduce solvent loss, but usually not.

[urushibara]

Foxy, you didn't read right, that's terpentine (or tetralin or something similar) with butanone, not xylene.
I know naaaathing.

[Student]

No, Foxy read correctly. Decarboxylation occurs in either xylene or turpentine under the conditions specified. The confusion may be about how to reflux the reaction mixture without a condenser. In this case, the wall of the test tube above the liquid surface serves as an air condenser. Air condensers are very effective with high boiling liquids, and even xylene boils high enough in this case to be made to work. The important thing is to keep the vapor part way up the tube, so that air doesn't reach the liquid nor does vapor climb to the mouth of the tube (heating the entire tube to xylene's bp) and escape. Of course there is nothing wrong with using a reflux condenser if you have one.

[foxy2]

"The important thing is to keep the vapor part way up the tube, so that air doesn't reach the liquid"

I HIGHLY doubt that effectively keeps air out,
Why not just purge with inert gas and tape a ballon to the top?  Or maybee you would need to use a nitrile glove so it has some xylene resistance.
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[Lilienthal]

Did you use real turpentine oil or decaline / tetraline (thinner)? Did you use other methods to be sure it's tryptamine?

[Student]

The reason I think that the solvent vapor is excluding air is that when the reaction is simmered it turns dark and deposits solid and no product can be isolated. When the reaction is boiled more rapidly, the solution only becomes yellow and there is no solid whatsoever deposited below the surface of the liquid, and crystals of product form upon cooling. I haven't used an inert atmosphere because it doesn't seem to be necessary, and I wanted to keep the procedure as simple as possible.

The turpentine was from a can from the hardware store labeled "Turpentine", though I haven't analyzed or purified it or measured the temperature of reflux. The xylene was distilled once. The product melted a bit low, but it was crude product after all, and it smelled the way a tryptamine ought and was one spot on TLC. It also dissolved well in hot solvents, unlike the side product I got when the reaction was exposed to air.

You may be surprised that the reaction works even in xylene, which boils lower than any successful reaction solvent reported so far. If a regular ketone like butanone were used, the reaction would fail, as expected, since the temperature is 60 degrees below tetralin's bp, and even in tetralin the reaction takes hours. A week of reflux with butanone in xylene lead to no apparent decarboxylation.  

[Lilienthal]

Sounds great! Which type of mint oil did you use? Spearmint contains 50% or so of carvone (unsaturated ketone) while peppermint is mostly menthol (?) (useless).

[Student]

Why, yes, carvone is an unsaturated ketone (an enone)!    I forget the brand of spearmint oil, but it is the pure, essential oil used in aromatherapy. My first success was by extracting crushed caraway seeds with xylene and using the xylene for the reaction, but the product wasn't as pure.

[foxy2]

Yes you found the right OTC ketone!
It definately appears that enone's allow the decarboxylation to happen at lower temps.  The references without them appear to bee more along the lines of brute force(high temp) decarboxylations.


Here is a thought
I'll bet that useing menthol(5-methyl-2-(1-methylethyl)-Cyclohexanol) as the solvent would dramatically speed things up.  Its close to cyclohexanol in structure and boils at 212C, while turpentine boils at about 155C.  Or limonene, BP=176C and you can get pure otc.

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[Student]

The Merck has 154-170 for turpentine, and if it were distilled you could take your pick within that range. The reaction with turpentine was done after 10 hours, but it may have been done well before then. I just didn't get around to checking it. I don't think menthol would be worth the expense and difficulty of evaporating from the crystals, but at least it would smell nicer.  One improvement I though of was using a dienone. Maybe the trend would continue, and decarboxylation would be fast in toluene? I couldn't find any OTC dienones. Beta-ionone, used in perfumery, is the closest. However, Rhodium just suggested benzalacetone as a catalyst

Post 277174

(Rhodium: "Re: New Tryptophan Decarboxylation Reference", Tryptamine Chemistry), and although it isn't as convenient as carvone, dibenzalacetone is made by the same method, and that is a dienone.

[foxy2]

"The Merck has 154-170 for turpentine, and if it were distilled you could take your pick within that range."

Not Really
Trust me, this would bee WAY WAY WAY more work than just buying a higher boiling solvent.  You cannot easily separate compounds with such a narrow boiling range.  Limonene is citrus solvent, you can find it sold 100% and that smells 1000 times better than turpentine, Oranges.

"I don't think menthol would be worth the expense and difficulty of evaporating from the crystals, but at least it would smell nicer"

The reason to use it is to do things faster, and smell helps.  No need to evap the menthol, just add say 1X toluene when the reaction is done.  Then you will have liquid menthol/toluene which you can extract the Tryptamine from with acidic water. (As shown below.)
Then you can evaporate off the toluene and recover your menthol.
toluene BP=111C
menthol BP=212C
And the Toluene azeotrope will dry the menthol, bonus.

https://www.thevespiary.org/rhodium/Rhodium/chemistry/tryptophan.html

Purification of Tryptamine

A good way to purify tryptamine without having to resort to distillation under strong vacuum is to dissolve the crude tryptamine hydrochloride in water, adjust the pH to between 7.6 and 8.2 and extract the solution with chloroform. The pH is then adjusted to 14 with NaOH and the pure tryptamine is filtered off with suction and air dried.

Also
Menthol can bee had easily for less than $30/kilo. 
That should last you a while.
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[urushibara]

Student was saying that excluding air from the reaction seems to assist it. I wonder if starting with hot acetone or giving it a good fuckin shake before fully sealing it up would be helpful in the same way for the pressure pipe. In one of the experiments swim did there was a dark brown insoluble mass formed. Though swim isn't sure that the dark brown stuff wasn't a byproduct of not cleaning the pipe from the first one.

Anyway, thankyou to the interested mathematician on the crystal board (lythande) the working burst pressure of swim's pipe was 1600psi, or 108 atm. It generated about 6.6atm at 250°C, according to my calculations, though it could be + or - 20%. Still well under half the burst pressure, and well under half the acetone decomposition temperature/pressure. Under by a factor of 6. I think that it could be called safe.

Swim's got some nice pure aminos planned for the near future, and some good scales to give a quantitative result. Tryptophan this time he says. Should provide a more conclusive experiment.
I know naaaathing.

[Student]

Your idea of using acetone under pressure is very inventive, and I wouldn't be surprised if it works. Pure acetophenone works, according to an abstract I saw once. Although shaking with the acetone will displace some of the air with acetone vapor, you could replace all the air by blowing propane, butane or carbon dioxide into the pipe before sealing it. Butane may be the most convenient. The only problem I see with your method for the hobbyist is that not everyone is as safety conscious as you are.

When I researched a better way to make tryptamine my goals were to use cheap OTC materials and to make the procedure as simple as possible, not for my own sake but for the benefit of the people who use this forum. I started with Drone's procedure using xylene and butanone, which are highly available, but it didn't work. I didn't know that menthol or limonene were commonly available, so I tried other solvents, and finally found success with xylene and turpentine when using an enone catalyst. The smell of these solvents, or the time needed for the reaction, were not major concerns. All the solvent except what evaporates from the crystals can probably be used directly for the next batch. There was no smell during the reaction. Tryptamine may not crystallize from menthol, in which case extraction would be mandatory rather than optional. If I use an Erlenmeyer flask for the reaction, all I have to do for work-up is pour out the solvent and leave the flask on its side for a few days until the cake of crystals on the bottom is dry. As long as this reaction requires heat, I don't see how the procedure could be further simplified.
  I just checked out the product from using turpentine. Even though it had several days to dry in a stream of air, it still smells or turpentine and is a bit gummy. The yield is above 90%, but it remains to be seem whether further drying will reduce this. I suspect that this turpentine may have a non-volatile residue and will require distillation before use. Limonene might be a nice alternative.

[urushibara]

Dwarfer seems to be convinced that 250°C in acetone is dangerous. I keep on seeing the figure 235°C and the word critical in msds' does this mean the acetone goes supercritical, or thermal? I thought acetone needed to be at 523°C to go thermal (chemical breakdown/oxidation boom).

Dwarfer also said that at 250 the pipe was at 1000psi. He didn't tell me what numbers he calculated from, or what formula. My calculations came out twice as 100psi, or 6.6atm. fuckin bastards with all these 500000 million bloody pressure units.

Oh it definitely works - and it seems also that the material doesn't have to fully dissolve, so long as it is pure aminos the acetone works on it anyway. From pulling the device out of the oven at 200, when it is gently jiggled it doesn't sound like there's anything in the pipe.

My experiments with amino acids have been somewhat messed up by the need to extract from tablets - at this point I am not sure about insoluble bits from the reaction, whether they are contaminants or what. Tyrosine produced something dark orange which didn't want to dissolve in acetone, separate from the freebase oil. The lysine too, had a solid un-changed element in the product. Again, I can't rule out that it was in fact CaCl or whatever, or lactose or whatever. The tabs don't specify 'no lactose'.

Can anyone tell me - is acetone supercritical at 250°C, or unstable and liable to cause a big boom? I have already established it can't flash on the basis of oxygen in the air that the acetone is dissolved in, it snuffs itself out.
I know naaaathing.

[Student]

Don't let the term "critical" scare you. It has a different meaning in this context than it does in nuclear physics!    In this case it means that the phase boundary between the liquid and gas phases disappears.

Even though you may not see your ingredient dissolve at room temperature, it is very likely dissolved at 250°C.