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Author Topic: Grade my Ochem homework? [synthesis of DET from tryptophan]  (Read 297 times)

JustDreaming

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Grade my Ochem homework? [synthesis of DET from tryptophan]
« on: May 16, 2011, 07:46:44 PM »
Oxidation: Seems less finicky than decarboxylation.
ref - Reed A. Gray, Arch. Biochem. & Biophys. 81, 481-488 (1959)

Reduction: Raney Nickel? That sounds like a pain. How about an amalgam of some sorts? Or is this bunk?

Halogenation: of the alcohol seems like a task for serious reagents. While I'm pretty sure HI/HBr would attack the 2 position on the indole correct? Chlorination via HCl or Cl2 seems almost out of the question because it's a primary alcohol right? Obviously thionyl chloride, PCl3/PCl5/POCl3 are totally off limits. Anyone have any ideas? Or is this bunk.

Nucleophilic substitution: Any reason why this wouldn't work?

Total chem. noob here, haven't taken an o-chem course don't slam me too hard. :P
« Last Edit: June 16, 2011, 09:05:06 AM by Enkidu »
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Sedit

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Re: Grade my Ochem homework?
« Reply #1 on: May 16, 2011, 08:17:35 PM »
Reduction: NaBH3, Its pretty selective so there should be few issues. Possibly Urushibara catalyst, always seemed interesting to me and relatively simple for an amature but I never had the chance to test it.

As far as the Halogenating reagents go i'd have to get back to you. Im looking for one now to Chlorinate Tosylic acid but they all seem a pain. Talk over at Science madness of using NCl3 for chlorination but I don't know what that works on and on top of that theres also the risk of it blowing up in your face if you generate an even slightly concentrated solution of it. With any luck you may find a way to electrochemically convert the carboxylic acid directly to the halogen thru oxidative decarboxylation in the presence of a halide salt. Speculation I might add but this has been performed in the past on other substates.
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JustDreaming

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Re: Grade my Ochem homework?
« Reply #2 on: May 16, 2011, 09:05:22 PM »
Fascinating! In a simple divided cell(salt-bridge, etc)? Protonated solution? Reference for the electrochemical concept would be spectacular.

Thanks for dropping in :).

edit - yes those pesky chlorinating reagents :(. Keep fooling myself into thinking SiCl4 is a good idea.
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Sedit

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Re: Grade my Ochem homework?
« Reply #3 on: May 16, 2011, 11:00:01 PM »
Fuck. I wrote something then erased it.

Look over at science madness in the reference section you will see my thread Kolbe references wanted. I believe it was somewhere in there but I could be wrong.

Im gonna try with NaOAc and NaBr and see if it works. I would think 2.5 molar excess and up of Carboxylic acid to avoid oxidation of the halide to Br2.
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JustDreaming

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Re: Grade my Ochem homework?
« Reply #4 on: May 17, 2011, 05:06:39 AM »
Don't have access :(.

edit - nvm kolbe electrolysis, interesting :). plenty of information on this unique one!
« Last Edit: May 17, 2011, 05:25:02 AM by JustDreaming »
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antibody2

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Re: Grade my Ochem homework?
« Reply #5 on: May 17, 2011, 02:36:48 PM »
Decarboxylation in acetophenone is NOT a finicky RXN to run at all. It is a very fast, clean, high yielding RXN  and the tryptamine product usually crystallizes easily.

Ab2 worked with Urushibara catalysts several years ago (There is a RXN of his using then on Rhodium under TMA-2, if memory serves) But despite much effort the results were very difficult to reproduce, even for AB2. Catalysts formed and used under identical conditions had widely varying results with 50% or 55% yield being the best of them. Ritter also reported has some success with that RXN. Ab2 always meant to revisit Urushibara catalysts using different metal couples but never got around to it. Making the catalyst is a lot fun.

But why make it more complicated than it needs to be?  Get some acetophenone and get high yields! 8)

Sydenhams chorea

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Re: Grade my Ochem homework? [synthesis of DET from tryptophan]
« Reply #6 on: October 18, 2011, 01:56:28 PM »
The reason many failed or got low yields with Urushibara in the days of the hive is because they copied Ritter's write-up using Al foil and HCl which produces as very weak catalyst. The original catalyst using Zn dust precipitating from a NiCl2 solution in short time at 80deg C  is much more active. Also HCl is detrimental to the catalyst activity so one should avoid it.
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Sol Invictus

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Re: Grade my Ochem homework? [synthesis of DET from tryptophan]
« Reply #7 on: October 20, 2011, 09:50:54 AM »
 

  Antibody2-- Would you mind offering any tips or suggestions with regard to the crystallization of the product following acetophenone decarboxylation? Does the product typically crash out following cooling or does a salt need to be formed in order to generate a relatively pure solid product? I have seen anecdotal reports using tartaric acid to facilitate the crystallization of tryptamine, however that was a decarb utilizing different reagents.

  Thanks!


  --Sol
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