Jackson
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Gallic acid extraction
hi, i was looking into gallic acid extraction, and i found a paper that seemed to suggest that gallic acid was extracted to a relatively pure sample
from pomegranate rinds using either ethanol. the procedure was to extract a dry powder of the rinds with 60% ethanol (not specified as to what this
percentage is, it was given as a ratio of 60:40 ethanol to water) which was then filtered and reduced to 1/3 its volume. it was then left at room
tempature overnight, resulting in a precipitate of gallic acid. is this a good way to get relatively pure gallic acid? thanks in advance.
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UC235
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Pomegranate extract contains almost no gallic acid. Most of its polyphenolics are found as punicalagin A and B. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4927587/
You may see total phenolic content elsewhere expressed as gallic acid equivalents, as gallic acid is a typical standard. That does not mean what they
are measuring is gallic acid.
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Jackson
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thanks for the response. what plant material would be good as a starting point? also, could i hydrolize tannins to get gallic acid? if i could, how
would i go about purifying the gallic acid from that mixture?
edit: i also have access to acorns and oak galls. would they be a good source of tannins/gallic acid?
[Edited on 3/30/2019 by Jackson]
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nezza
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I too have been looking for a source of gallic acid. For some reason it seems difficult to get hold of.
If you're not part of the solution, you're part of the precipitate.
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draculic acid69
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eBay has many listings.expect variation between them.i think it was here on scimadness someone had a picture of multiple samples side by side and all
were different.
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Boffis
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I posted a comparison of different types of "tannin" and "tannic acid" see this thread about halfway down for simple tests that allow you to determine
what type of tannin you have.
http://www.sciencemadness.org/talk/viewthread.php?tid=20487#...
There are basically three types:
Gallotannins, these give gallic acid and sugars on hydrolysis
Catechutannins, these give pyrocatechuic acid, phloroglucinol, catechol and sugars on hydrolysis
Third type (I don't have a name of this type) give a hard to hydrolyse gallic acid dimer sugar etc
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UC235
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So apparently, sumac leaves contain huge amounts of gallotannins and are readily extractable. Best harvest time is apparently June-August. American
weed tree species like Staghorn Sumac are easily accessible by most US members, I would think. Something to try out in the next few months, I think.
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S.C. Wack
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Unfortunately sumac is on the decline here, in or near town it's been replaced by the ultra invasive imported much taller lookalike the wrongly-named
Tree of Heaven. I can only find sumac in isolated rural areas now. There is a bushy ornamental variety but I can't find anyone selling it. AFAIK sumac
was never actually used as a commercial source of gallotannin, and if you don't have tara the preferred material is still the same as it has been for
some hundreds of years.
The lowest cost for a kilo or less of galls from the internet whole or otherwise when I last checked a few months ago was for Bixa Botanicals Galnuts
Powder. That was also the only product physically located in North America. It's surely the best packaged source, and each jar contains 200.0 g of
finely ground old school Aleppo oak galls.
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