Tsjerk
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Baclofen via cinnamic acid ester
So baclofen synthesis via this method worked (overall yield ~15%).
Now I would like to try this via this way.
I can get tetrabutylammonium hydroxide as a 40% solution in water and I can get hydrogen fluoride. I'm thinking about mixing the two with a small
excess HF and drying the product over calcium chloride and sodium hydroxide. So TBAF shouldn't be a problem. I have a couple liters of THF.
I will keep you posted on the nickel/borohydride in methanol reduction. I never did that one before.
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unionised
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Quote: Originally posted by Tsjerk  | | l I'm thinking about mixing the two with a small excess HF and drying the product over calcium chloride |
Think harder.
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karlos³
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Just use another PTC agent.
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Tsjerk
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Enlighten me because I don't get it
[Edited on 10-6-2019 by Tsjerk]
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unionised
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https://www.ebay.co.uk/itm/Blue-John-Paperweight-10cm-x-7cm-...
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DraconicAcid
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Calcium fluoride is the mineral fluorite; exceedingly insoluble.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Tsjerk
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"drying over" as in drying in a exsiccator I meant.
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Tsjerk
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I will do the esterfication of cinnamic acid with ethanol, as I then can drive of the water as the azeotrope.
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karlos³
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You can likely esterify also cinnamaldehyde with ethanol under oxidative conditions using oxone.
I think then there shouldn't be any water if you use dry ethanol?
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Tsjerk
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The title of this topic is a bit wrong... as cinnamic acid esters would lead to phenibut, and not baclofen. I'm planning on making ethyl
4-chlorocinnamate via 4-chlorobenzaldehyde, acetone and bleach (url) and then esterfication with ethanol and sulfuric acid.
| Quote: Originally posted by karlos³ | You can likely esterify also cinnamaldehyde with ethanol under oxidative conditions using oxone.
I think then there shouldn't be any water if you use dry ethanol? |
The water would come from the esterfication, as a reaction product. Removing it drives the reaction to completion.
[Edited on 11-6-2019 by Tsjerk]
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DraconicAcid
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I can't comment on most of the chemistry here, but I do know that esterification of cinnamic acid works quite well (in stark contrast to flippin'
salicylates), and they can be purified by recrystallization from hexane or toluene at low temperature (methyl melts around 33 C, ethyl at 12 C). Far
easier than trying to distill the brats at 250 C.
The methyl ester smells vaguely like strawberry when heated; I can't identify the smell of the ethyl ester.
[Edited on 11-6-2019 by DraconicAcid]
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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karlos³
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| Quote: Originally posted by Tsjerk |
| Quote: Originally posted by karlos³ | You can likely esterify also cinnamaldehyde with ethanol under oxidative conditions using oxone.
I think then there shouldn't be any water if you use dry ethanol? |
The water would come from the esterfication, as a reaction product. Removing it drives the reaction to completion.
[Edited on 11-6-2019 by Tsjerk] |
Yes I know that, so I suggested this alternative path in which you go straight to the ester in anhydrous conditions where no water will be created.
I don't have the paper available right now though.
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Tsjerk
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| Quote: Originally posted by karlos³ |
Yes I know that, so I suggested this alternative path in which you go straight to the ester in anhydrous conditions where no water will be created.
I don't have the paper available right now though. |
Cool, please let me know when you find it. I planned to oxidize benzalacetone with bleach, but you might have a better solution. Benzalacetone to
cinnamic acid is done at 88% yield and the esterfication drops yield a bit further. Men, I love this forum.
Edit: bummer; I now see that benzalacetone is not the same as cinnamaldedyde.
Edit2: I could use acetaldehyde instead of acetone..
[Edited on 12-6-2019 by Tsjerk]
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karlos³
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Here it is: https://pubs.acs.org/doi/10.1021/ol0340078
A friend made ethyl benzoate successfully this way from benzaldehyde and ethanol in great yields.
Edit: it seems I have myself used "this" method, not in alcohol but DMF, to oxidise an aldehyde to its acid.
[Edited on 12-6-2019 by karlos³]
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Loptr
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Are you guys thinking about the potential for that double bond to epoxidize? I think it would get oxidized, but let's see what the literature has for
us.
EDIT: just a cursory look at Google search results list several instances with cinnamaldehyde having its double bond opened up with oxone, leading to
benzoic acid, phenylacetic acid, etc.
[Edited on 13-6-2019 by Loptr]
"Question everything generally thought to be obvious." - Dieter Rams
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