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phenylpropanolamine from benzaldehyde and alanine
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Author Topic: phenylpropanolamine from benzaldehyde and alanine
drone 342
Member posted 10-15-98 09:18 AM
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Reactant BRN 471223 benzaldehyde
1720250 DL-alanine
Product BRN 3196917 (1RS,2RS)-2-amino-1-phenyl-propan-1-ol
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Reaction Details
Reaction Classification Preparation
Temperature 140 øC
Other conditions Erwaermen des Reaktionsprodukts mit wss.-aethanol. HCl
Ref. 1 2262852; Journal; Takagi et al.; YKKZAJ; Yakugaku Zasshi; 73; 1953; 1086; Chem.Abstr.; 1954; 12021;
This informative post was brought to you by drone(tm) #342, who reminds you: euphoria -- its what's for dinner.
-drone #342
Rhenium
Member posted 10-15-98 10:20 AM
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Drone,
I have a similar paper here, it's in Japanese and was published around 1942. I can't read it, but the pictures suggest that they reflux the two and get the PPA and CO2 produced. They have a little picture of piperonal as well, but I can't figure out what they're trying to do with it.
Take care,
Rhenium
beagle boy
unregistered posted 10-15-98 10:50 AM
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Shwing! I like what I hear. But I only hear the basic outline. Can anyone (please) fill in the details. Like what solvent? How long a reaction time? Japanese writing looks cool, but thats about all I get out of it.
Labrat
Member posted 10-15-98 10:51 AM
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This is great and shit at the same time, great because it's one beautiful method of making PPA from simple reagents, shit because the article is in Japanese!
There are professional translators on the Net. How about paying one to translate the experimental section of the two Yakugaku Zasshi articles we have? If we share the costs, it won't be that expensive. Lr/
drone 342
Member posted 10-15-98 03:38 PM
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I have a friend who's a Japanese native. The problem is she knows nothing of chemistry. I sat down with her, and we went through the Yakugaku Zasshi article from a while back, but they really didn't say anything too intersting that I hadn't read elsewhere.
I could talk to her about translating the the two papers, but you'll have to send me the second one, Rhenium. Hope you have a scanner.
-drone #342
Cherrie Baby
Member posted 10-15-98 04:48 PM
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US patent 4501919 describes the reaction of glycine with p-nitrobenzaldehyde (in a two phases: H2O-DCM with MeBu3NCl as a PTC and concn. NaOH as a base, at 5-7°C) to give b-hydroxy,p-nitro-tyrosine.
What would happen if alanine were used in place of glycine? The a-methyl analog?, which could be decarboxylated to p-nitro-norephedrine? Your guess is as good as mine. This looks like an interesting patent to explore as all the reagents are OTC.
It would work with other ring-substituents apart from nitro-, but I only discovered the Chem. Abstract tonite [CA:102, 204296] and I've not yet read the patent!
beagle boy
unregistered posted 10-15-98 08:48 PM
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Just checked that patent and saw that they were getting 70+% yield of the ß-hydroxy phenylalanine derivative from this easy procedure. And makes sense that alanine gives the alpha-methyl derivative, which should be more readily decarboxylated, no?
So if just refluxing these cpds. in say, xylene, will decarboxylate in good yields, this is one dandy scheme. Easy access to both ethanolamines and propanolamines for that comprehensive aminorex study.
Rhenium
Member posted 10-16-98 10:22 AM
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Drone : My friend with the scanner will be back in a couple of days. I will try sending it to you after that. This could be a very interesting procedure, hopefully the yields will be nice...
Take care,
Rhenium
Cherrie Baby
Member posted 10-16-98 05:56 PM
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beagle boy
In one of my references that quotes this they said that it was an Aldol condensation between the aldehyde and the amine forming an imine - which was subsequently hydroysised back to an amine, after condensation with a further 1 mol of glycine. So it looks like a different reaction mechanism to the one Drone's talking about - theres only a slight possibility that it might work with alanine. [I don't think so - I'm almost sorry I posted it - but it looked good to me when I first saw it.
[no don't ask me I never thought that amines underwent Aldol condensations either!]
beagle boy
unregistered posted 10-16-98 10:12 PM
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Cherrie:
I believe the patent you gave claims alanine could be used. Checkitout:
http://www.patents.ibm.com/cgi-bin/viewpat.cmd/US04501919__
Wierd amine aldol condensation, different from what I was thinking. The question about decarboxylation remains, but I think these serine derivatives should decarboxylate quite a bit easier than tryptophan.
One downside to the above condesation is that the benzaldehyde would have to be in twofold XS. The extra benzaldehyde is claimed to be recovered for recycling after the reaction, but I'm not so keen about letting precious aldehydes stir around in aq. NaOH and then trying to recover them. Maybe the other route will turn out better.
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