wg48temp9
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meta bromination of benzaldehyde
Below is a copy of patent for the meta bromination of benzaldehyde. It claims a 89% yield. Yes it is only a patent but there is a similar method on
PrepChem which has less detail. The patent gives options for the poly chloroalkane solvent such as dichloromethane or chloroform that are more easily
obtained than 1,2-dichloroethane given by PrepChem.
Attachment: pre-mbromUS4036887.pdf (247kB)
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wg48temp9
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Below are the equations for the above bromine/chlorine method which is unusual for me. I don't know if it produces a higher yield than only using
bromine.
The above is a snip from this preparation
Attachment: continousproductionmbb.pdf (265kB)
This file has been downloaded 257 times
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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karlos³
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Well, we know that orgsyn can be trusted greatly, and they give enough details to make it repeatable.
There is this procedure, with a 59% yield for 3-bromobenzaldehyde: http://orgsyn.org/demo.aspx?prep=CV5P0117
verrückt und wissenschaftlich
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RustyShackleford
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Quote: Originally posted by wg48temp9  | Below are the equations for the above bromine/chlorine method which is unusual for me. I don't know if it produces a higher yield than only using
bromine.
The above is a snip from this preparation
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Its most likely done that way for better atom economy on the bromine, chlorine is a lot less expensive afterall.
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wg48temp9
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Thanks for that. I suspect the Br/Cl method may be designed to save bromine by using half Br and half Cl. I don't need to minimise Br usage and I
prefer not have to use Cl gas.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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wg48temp9
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Location: not so United Kingdom
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As I don't have benzaldehyde, I could make it from the toluene that I do have a few 100ml of but I decided to purchase some benzaldehyde.
So while I am waiting for the benzaldehyde to arrive I thought I would consider using NBS or the hydantoin version or Br2+Br2/Cl2. But its more
complicated than I thought.
I have to go out now and there are a lot power outs at the moment so I will post this now and add my thoughts later.
Ideally for its simplicity I would like to use NBS in a polar chlorinated solvent. Unfortunately I don't have sufficient knowledge to know if that
would work.
The obvious problem is the limited solubility of NBS in a polar chlorinated solvents. Perhaps THF could be used.
I don't understand how the reaction would get going. Apparently HBr, light or a peroxide can start the reaction. I do have HBr acid but i suspect
that can not be used due to its water content. Light initiation would be ideal if a 60W quartz tungsten halogen lamp would be sufficient. I also have
some peroxide catalyst for resin.
Also I would like to use FeBr3 perhaps made in situ,
Comments or suggestion welcome.
[Edited on 2/23/2022 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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