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beta-asarone to alpha-asarone izomerization
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Chainik

Joined: 17 Apr 2005
Posts: 3
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View Single Post4078
beta-asarone to alpha-asarone izomerization

 Mon Apr 25, 2005 10:23 am		 Reply with quote
Hello everyone,

Could someone please post a working and tested procedure for converting a mixture of beta/alpha/gamma-asarones to alpha-asarone together with the subsequent workup (since alpha-asarone is a solid).

There are snippets of information floating around, but no complete procedure to my knowledge.

Microwave assisted base catalysed isomerization of asarone with KOH would be ideal, however if someone successfully done a ATM or vacuum isomerization that would also be good...

Reason for the question is because someone told me, that after 30 minutes in the MW oven at LOW-MED a mixture of 5.2g of asarones, 8.8g of KOH in 50mL of EtOH gave a dark brown/orange oil, which after removal of EtOH solidified to a dark brown/orange sludge, which dissolved in IPA to form a dark top layer and a lighter bottom layer. No crystals formed in the freezer.

Thank you.
Chainik.
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Pemulwuy

Joined: 31 Mar 2005
Posts: 6
193.56 Points
View Single Post4079

 Mon Apr 25, 2005 10:27 am		 Reply with quote
Why would you isomerise alpha/beta or gamma asarone?
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Chainik

Joined: 17 Apr 2005
Posts: 3
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View Single Post4081

 Mon Apr 25, 2005 11:01 am		 Reply with quote
In order to convert it into the corresponding benzaldehyde.

See, https://www.synthetikal.com/Rhodiums_pdfs/chemistry/asarone.html:

Quote:

It was recorded (Kelkar and Rao, J. Indian Inst. Sci., 1934, 17, A, 26) that the main constituent of the oil from the roots of Acorus Calamus, Linn. was a liquid phenolic ether, which gave asaronic acid on oxidation with potassium permanganate and polymerised to par-asarone on treatment with arsenious acid. The ether, which differed from asarone, C6H2(OMe)3CH=CHMe, in that it could not be obtained crystalline, was at first regarded as the allyl isomer (Current Sci., 1935, 552), but asarone and this liquid ether, β-asarone, are now shown to be cis/trans-isomerides.



So beta-asarone on oxidation with KMnO4 supposedly gives asaronic acid, not the benzaldehyde, hence the izomerization question.

But is there a better way?

Thanks.
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Pemulwuy

Joined: 31 Mar 2005
Posts: 6
193.56 Points
View Single Post4087

 Mon Apr 25, 2005 1:15 pm		 Reply with quote
http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/piperonal.isosafrole.html

https://www.synthetikal.com/Rhodiums_pdfs/chemistry/epox-iso.iodide-dmso.html

https://www.synthetikal.com/Rhodiums_pdfs/chemistry/isosafrole.electro.html
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Chainik

Joined: 17 Apr 2005
Posts: 3
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View Single Post4245

 Thu Apr 28, 2005 11:50 am		 Reply with quote
Does anyone know if beta-asarone is interchangeable with apha-asarone in an electrochemical oxidation or would it give a different product? What about the nitrosite route?

Apparently it is not, in the KMnO4 oxidation, which i suppose means that acorus calamus oil needs to be repeatedly fractionated to obtain alpha-asarone. But given the beta/aplha asarone boiling points are so close, is that really plausable? What have thge other bees done, Uumera, Chromic, etc if you are reading this?

There is a patent for converting beta into alpha using expensive reagents, not kitchen chemistry (US 6,544,390) as well as one utilising 10% Pd/C (US 6,528,041). There is also commentary on the Hive about using a standard KOH isomerization on beta-asarone.

Any suggestions what to try? Perhaps straight KOH isomerization on crude oil and then vacuum distillation to get all the isomerized asarone out?

Thank you.
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anime

Joined: 13 Apr 2005
Posts: 131
Location: Planet Earth
3517.62 Points
View Single Post4647
re: beta-asarone to alpha-asarone izomerization

 Wed May 11, 2005 1:02 am		 Reply with quote
Vanadium Pentoxide could be used to oxidize the alkene (beta) to an aldehyde.
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