careysub
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Syringol and Liquid Smoke
There has been very little discussion of the subject of the possibly useful compound "syringol" (2,6-dimethoxyphenol) on SM over the years. Googling
reveals only a few.
This simply notes syringol's scarcity:
https://www.sciencemadness.org/whisper/viewthread.php?tid=70...
This mentions distilling from wood as described in a paper (no experiment):
http://www.sciencemadness.org/talk/viewthread.php?tid=19433
Nothing on 2,6-Dimethoxyphenol either.
"Liquid smoke" also brings up nothing but a couple of screening composition posts.
But I find by Googling that:
Lignin (not cellulose) pyrolysis evidently produces lots of methoxylated phenols.
http://www.leffingwell.com/smoke.htm
and
https://books.google.com/books?id=PO4DhgFWIuQC&printsec=...
which shows up in hardwood liquid smoke flavorings.
Something like up to 30% of the smoke residue, showing up as "liquid smoke" are phenols, with syringol making up by far the largest portion of this
mass.
This analysis of a commercial liquid smoke product ("commercial full-strength liquid smoke") finds it containing syringol making up 12.4% of the total
mass, 34% of which consists of phenols. However they also analyzed "refined liquid smoke" products that had the phenol fraction stripped out.
http://onlinelibrary.wiley.com/doi/10.1002/fsn3.9/full
Here is a challenge I post to SM's membership who have access to GC or other suitable analysis instruments:
Can you find a commerical liquid smoke product available for retail sale containing significant amounts of syringol?
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careysub
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An additional source of information:
http://krex.k-state.edu/dspace/bitstream/handle/2097/3947/Al...
According to this dissertation (focused on developing low phenol smoke products):
"Base liquid smoke has an approximate phenolic content of 17 mg/ml."
and
"Liquid smokes used in conventional meat applications have a phenol range of approximately 6-20 mg/ml"
2,6-dimethoxyphenol (syringol) is such a dominant component of the phenolic fraction of liquid smoke that this paper uses it as a proxy for the entire
phenolic content.
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AlchemistMage
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I would look into the pyrolysis of lignin. It's cheap and highly available. Like literally, everywhere. These compounds help form the characteristic
aroma associated with burning wood.
You should be able to obtain guaiacol and syringol in this manner. Of course, these can potentially be used to obtain catechol and pyrogallol via
de-methylation, if those are desired (though, there are more practical methods to obtain those).
Purification might be a challenge, but it's better than spending a fortune trying to separate a tiny quantity from an expensive bottle of liquid
smoke..
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aga
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I still have a bottle of the heavier fractions derived from wood pyrolysis a while ago.
Most things OC are beyond my ken, so would this be a useful base material to begin with ?
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AlchemistMage
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I would think it'd be a good place to start. Could try fractional distillation to separate some of the compounds.
Guaiacol boils at 204-206C
Syringol boils at 261C
That should be enough difference to separate those two compounds. Obviously anything that distills over at a lower temperature, or stays in the
reaction flask after reaching 261C is likely to be an impurity.
From there, if necessary, more specific purification methods would have to be used to separate the compounds from any other impurities found.
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aga
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I don't have a GC handy, so it'd be hard to know what i had.
Hmm.
Would some sort of GC column work to separate the (doubtless) huge number of components ?
Edit:
The stuff in the bottle is many months old, and is a brown tar with a watery component.
[Edited on 1-9-2015 by aga]
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careysub
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Quote: Originally posted by AlchemistMage  | I would think it'd be a good place to start. Could try fractional distillation to separate some of the compounds.
Guaiacol boils at 204-206C
Syringol boils at 261C
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I think you would start by extracting the phenol fraction with NaOH/water solution, Then acidify to convert water soluble phenolates back to their
basic form. Perhaps extracting the aqueous phenolate solution with a non-polar solvent also to remove impurities?
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careysub
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| Quote: Originally posted by AlchemistMage | | ...Of course, these can potentially be used to obtain catechol and pyrogallol via de-methylation, if those are desired (though, there are more
practical methods to obtain those). |
This article:
http://www.orgsyn.org/demo.aspx?prep=CV3P0759
refers to preparing pyrogallol monomethyl ether (methylating only one of the two flanking hydroxy positions) using methyl iodide or dimethyl sulfate.
Refs cited are:
Graebe and Hess, Ann., 340, 232 (1905);
Herzig and Pollak, Monatsh., 25, 811 (1904).
Any references on how to methylate the other (but not the central hydroxy) to form syringol?
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aga
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Groovy.
Plenty of other people's Doings, but no suggestions about what to actually Do.
There's a lot of this these days.
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Crowfjord
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Here's a good reference:
JACS 39, 1431 (1917)
"The Preparation of Halogen Derivatives of Catechol, Homo-Catechol and Pyrogallol Methyl Ethers and Sulfonic Acids"
See under "Pyrogallol Dimethyl Ether sulfonic Acid." They use methyl bromide and methanolic sodium methoxide. I would bet that methanolic sodium or
potassium hydroxide would work fine.
This reference is also discussed in this old discussion.
Attachment: ja02252a016.pdf (320kB)
This file has been downloaded 461 times
[Edited on 1-9-2015 by Crowfjord]
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S.C. Wack
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Pearl mentions that article in JACS and his patent US2516412 as a good method.
Fixed:
| Quote: Originally posted by careysub | | This analysis of a commercial liquid smoke product ("commercial full-strength liquid smoke") finds it containing syringol making up
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12.3% of the peak area of the DCM extract.
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