New Tryptophan Decarboxylation Reference

[foxy2]

Process for preparing tryptamine hydrochloride.
Eckstein, Marian; Misztal, Stanislaw; Terczynska, Anna; Adamus, Mieczyslaw. 
Pol.  (1985),    PL  130769 
Patent  written in Polish.

Abstract
In the manuf. of tryptamine-HCl (I) from DL-tryptophan in cyclohexanol, in the presence of alpha-tetralone or Tetralin contg. Tetralin peroxides, the decarboxylation step is performed by heating at 160-180° a suspension of DL-tryptophan in cyclohexanol.  To a boiling mixt. of 204 g DL-tryptophan in 440 g cyclohexanol, 160 g Tetralin contg. 9-10% peroxides was added dropwise during 0.5 h and the mixt. was refluxed until a clear soln. was obtained (3-4 h).  After cooling to 30° in the atm. of the CO2 produced in the reaction, the mixt. was dild. with 440 mL C6H6 or cyclohexane and filtered and the filtrate was treated with gaseous or ethanolic HCl.  The pptd. I was filtered off and washed with C6H6 contg. 18-20% EtOH, to obtain 159-170 g (82-85%) of the final product.
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[foxy2]

Tryptamine.    
Takano, Seiichi; Ogasahara, Kunio. 
JP  53147067  19781221 (Japanese Patent)

Abstract
Tryptamine (I) was prepd. by heating tryptophan (II) in the presence of RR1CO (R = H, alkyl, Ph; R1 = alkyl, Ph, 2-pyridyl).  This, a mixt. of 0.1 mol II and 0.06 mol MeCOPr in tetralin was heated 2.5 h at 220 - 50° to give 86.2% I. 
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[foxy2]

Tryptamine
JP  49011873  19740201  Patent  written in Japanese.

Abstract
Tryptamine (I) was prepd. by heating tryptophan (II) in Ph2CH2 at a temp. higher than the decompn. point of II.  Thus, 250 mg II in 10 g Ph2CH2 was refluxed at 280-90° under N and the product treated with C6H6 satd. with HCl to give 63% I.HCl. 
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[PrimoPyro]

Is it as simple as heating tryptophan in MEK then?

Edit: No, I see now. The temp is way too high. High pressure needed. Sorry.
Wir pumpen..... (Klatschen) Sie oben!

[Student]

MEK boils too low, but in chem. abstracts I saw a (russian) article which claimed 100% yield by reflux in acetophenone. I don't have the reference handy.

[foxy2]

Patent GB1008594

EXAMPLE 4
DL - Tryptophan (1.0 g.) was intimately mixed with 4-hydroxybenzophenone (1.0 g.) and heated on the oil bath to 210C when carbon dioxide was freely evolved. The residue on cooling was reflexed with 10% ethanolic sodium hydroxide for 3 hr. The solution was made just acid with aqueous hydrochloric acid and the precipitated sodium chloride filtered off. The filtrate was concentrated under reduced pressure to small bulk. Addition of aqueous picric acid precipitated impure tryptamine picrate which was dissolved in warm aqueous ethanol and passed through a column of Amberlite IRA 400 (OH) exchange resin.

The effluent was made acid with aqueous hydrochloric acid and evaporated to dryness under reduced pressure. The residue of tryptamine hydrochloride was recrystallised from ethanol and ether had m.p. 248C (decomp.) yield 32%.

Using 2,2¹-dihydroxybenzophenone with tryptophan as above, the yield of tryptamine hydrochloride was 41%.

The tryptamine hydrochloride may be isolated directly without preliminary conversion to the picrate, but the product requires further recrystallisation to climate the brown colour.

Results using o-hydroxyacetophenone as the ketone under the same conditions as described above are shown in the table.

o-hydroxyacetophenone   57%
o-methoxyacetophenone   50%
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[foxy2]

Schiff bases.  I.  Thermal decarboxylation of a-amino acids in the presence of ketones.    
Al-Sayyab, A. F.; Lawson, Alexander.       
J. Chem. Soc. C  (1968),   (4),  406-10.
 
Abstract
Schiff bases derived from a-amino acids and hydroxy-substituted aromatic ketones were prepd.  Their ir spectra suggest that their relative stability to hydrolysis as compared with those from ketones with no hydroxy-groups is due to hydrogen bonding.  The thermal decompn. of a-amino acids in the presence of ketones, followed by hydrolysis, produces the amines corresponding to the amino acids or the ketones (transamination) or both, depending on the nature of the amino acid and the ketone used and also on the method of hydrolysis.  In the case of amino acids with a quaternary a-carbon, transamination is the principal reaction.  The prepn. of tyramine, tryptamine, and histamine in good yield from the corresponding amino acids is described.
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[hest]

There is only one way. 5g tryp. 50mL cyclohexanol 0.5g cyclohex-en-on (cyclohex-a-non wont' doo the job).
Reflux for 1.5-2 h.
yeald 93-98%

But the alkylation off the amine could need some tuning.
H2CO (or asetone for the DIPT analog) NaBH4 in -15°C MeOH sounds good.

[foxy2]

I have a feeling that benzaldehyde might bee a decent catalyst for this reaction.  Sure not as good as cyclohex-en-on but it might work.
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[hest]

My exp. with methy-hexyl-keton is bad yeald 10%
In the article they write that it has to bee cyclohexenon ( they wonder why old cyclohex-a-on is much bether than new one
quinon might work ?

[halfapint]

My thoughts exactly, hest. Wondered whether benzoquinone might form a good ketone catalyst for this decarboxylation. Otherwise, there are many natural products, speaking specifically of essential oils, which contain high-boiling ketones, as has been mentioned.
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

[foxy2]

I think there is something special about ene-one's.
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[Rhodium]

NaOH-catalyzed condensation of acetone with benzaldehyde gives benzalacetone, which is an easily prepared enone. Use half the amount of benzaldehyde in the prep below, and the product will be benzalacetone instead of dibenzalacetone.

http://courses.chem.psu.edu/chem36/HTML/Experiments/Exp10.pdf

[urushibara]

Dare I say it (hmmm... I wonder)

Pressure Pipe, Acetone!

Dammit I don't have any tryptophan or a decent device to measure the mp/bp of the products... But I've got some pictures of tyrosine and lysine going decarbed. They're definitely producing freebases, can't clean the bastards off nothing, and they have that strange smell...

Question is: purity. How much can be done.

And second question is: what does it mean when acetone is 'critical' Is that what I am thinking? equal vapour/liquid pressure? I saw somewhere someone saying that 800K makes acetone decompose, but I'm only talking about 523K, 250C. I've done it twice in a standard .068mm thick galvanised house pipe 3" long and I raised the temp to 250 and then turned it off. I first tested the temp thing slowly, first at 100 in boiling water (hey, my water boils at 101, does that mean it's heavy water... nah think my thermo's a bit wrong. I am virtually sea level here though) Then at 150 in the oven. Then 200. Then 250. When it peaks at 250 I freak and switch the whole damn thing off and let it cool slowlike. Nobody's told me whether critical acetone is dangerous, contained in a pipe. I want to emphasise that nobody should fool around with flammable stuff near flames. Banish thine gas stove from thine mind. Do not use gas stove. Bad. [spank] [dammit] very bad kiddies

Test your pipe, at 100, make sure it don't leak. At 150 - make sure it don't leak. At 200, make sure it don't leak. at 250 make sure it don't leak. I don't think leaking acetone is good at 250, methinks it could flash. I've seen hexane/pentane/heptane/octane go boom inside oven at 150. Bee Veeeerry Careful. Must not leak. Get super duper high-grade multigrips of monkey wrenches to tighten the pipe with. It's gotta be hermetic, or there could be trouble. With sufficent tension, and adequate PTFE tape, it should be all good.

I thinks that 250C acetone is supercritical. It will break off those COO's quick smart. Including cooldown, and assuming pressure test passing, this process with high-pressure (maybe even supercritical) acetone is over in about half an hour. As long as you've got pure aminos, it's a good 90% yield at least.

Dammit, would someone with better equipment and equivalent brains check out the high pressure acetone idea? If only someone could give a definitive pressure figure on a 2/3 full pipe sealed with acetone. Dwarfer says 1000psi, which is really stretching it on the pipe, I says 100psi.

I WANT AN ANSWER GODDAMMIT! you guys, cmon, take up the challenge, if you're so sure this bee's trippin, put the figures on the table. And if he's not trippin, put the figures on the table. This is worth proving. DMT synthesis without needing a reflux to make tryptamine. That is a good thing. IS IT SAFE? I want some definitive answers.

Next is to see if a non-reflux method can make it into dimethyl... then we are really talkin. Catalytic hydogenation? electrolytic hydrogenation? doable? or not?
I know naaaathing.