Sciencemadness Discussion Board

tannic acid salt

mericad193724 - 4-8-2006 at 14:49

Tannic acid can be found at a brewing and wine making supplier as pointed out by the Readily Available Chemicals page.
I cannot find any information on its sodium salt, Sodium Tannate. Simply neutralizing it with Sodium Bicarbonate should yield Sodium Tannate, CO2 gas and water.

Could someone please point me in the right direction, or does this salt not exist? I am just looking for the info, an MSDS for example (solubility, stability, toxicity).

Thanks

Mericad

12AX7 - 4-8-2006 at 15:59

Maybe, maybe not.

Tannins aren't very well defined chemicals. To make full "sodium tannate" may require a big excess of NaOH to tack a sodium on every single acidic group on every molecule.

AFAIK, tannins are usually acidic, so such a salt ought to exist as such, but again, it won't be well defined, and I doubt you'll get consistent crystals, if at all.

Tim

not_important - 4-8-2006 at 16:08

Salts of tannic acid do exist, and there is a compound 'tannic acid'. Tannins are the raw material, depending on how much trouble you go to the amount of tannic acid in 'tannic acid' will vary.

Heavy metals form precipitates with tannic acid, ferric chloride reacts as with other phenols.

Alkaline tanniates react with the O2 in air, giving a mess.

Why do you want the sodium salt? Can't see that it would be very useful.

mericad193724 - 4-8-2006 at 16:45

Thanks for the help guys.

Do you think a pharmacist would be able to order me some (less than 100g)? I have heard they have catalogs for chems, but do you think they have access to something like this? I will try to neutralize the acid and get the sodium salt crystals.

(not_important...the reason I want the sodium salt is a secret...the stuff is pretty much useless:D)

Thanks

Mericad

not_important - 4-8-2006 at 21:45

Tannic acid used to be available in the first aid section, for treating mild burns and abrasions. It tanned the exposed flesh, providing some protection agaist infection, as well as reduction in 'weeping' of the injury and decreased sensitivity. It also tanned some of the microrganisms, killing them off.

http://www.henriettesherbal.com/eclectic/kings/acidum-tann.h...

It's also used in traditional methods of dyeing fibers, a store that handles that sort of stuff might have it.

http://www.aurorasilk.com/shop/dye_tannicacid.shtml

And these guys will cheerfully sell you 25 kilos at a time.

http://www.eaco.com.cn/html/tannic%20acid/tannic%20acid.htm

Note that tannic acid(*) has little to no free CO2H groups in it, it's all phenolic OH
Making the sodium salt is a very good way to destroy it, simple adding NaOH to a solution of tannic acid and then shaking the test tube will produce noticable oxidation.

Which is to say, the reason you can't information on it is that it's pretty useless and a waste of tannic acid. If you make it aqueous solution you're likely to have little left by the time you get things dried out, just oxydized once-phenols and cross-linked gunk.

* remember that it is a mixture.

mericad193724 - 8-8-2006 at 18:59

I went to three pharmacies and they all said they are not familiar tannic acid (and malic acid) and have no means of ordering it...:(

Maybe I will order some one day just to play around with it.

Mericad

not_important - 8-8-2006 at 19:51

The pharm in my area does have it, `s bad to llive in a backwards region that lacks modern things.

http://www.itmonline.org/arts/gallnuts.htm

http://griffindyeworks.com/mordants/tannicacid.html

Tara powder is about half tannic acid
http://griffindyeworks.com/mordants/tarapowder.html



From some old source
Quote:

Malic Acid is found in most kinds of sour fruit, chiefly in unripe
apples, and in the berries of the mountain ash, and also in currants,
sour cherries, in the stalks and leaves of rhubarb, &c. Sweet cherries
contain neutral potassium malate.
The acid is readily obtained from rhubarb-stalks or from the
berries of the mountain ash at the time when they begin to ripen.
The stalks or berries are ground to a pulp and pressed out. The
juice is boiled and nearly neutralized with milk of lime. On boiling
the filtered liquid for some time calcium malate separates out as a
granular powder, which is washed with cold water and dissolved in
hot dilute nitric acid, On cooling, acid calcium malate is obtained
in large crystals, which are separated from the mother-liquid, and
dissolved in water. On adding lead acetate to this solution lead
malate is precipitated, which is washed and then decomposed by
hydrogen sulphide. Malic acid is obtained on evaporating the
aqueous solution in groups of small colourless and deliquescent
prisms, having a strong and agreeable sour taste.

mericad193724 - 29-8-2006 at 13:17

Today I got some Malic Acid from a pharmacy. 800mg Malic acid per capsule and it also contained Cellulose, Stearic Acid and Magnesium Stearate.

Malic acid is supposed to be soluble in water 58g/100ml or so. When I added 200 ml of H2O the solution got really cold (14C when it was 30C in the garage). I can't dissolve the white powder, it floats on top of the crystal clear water!

This stuff is SOUR!:o

Am I missing something???

thanks

Mericad

[Edited on 29-8-2006 by mericad193724]

not_important - 29-8-2006 at 15:52

How much does one capsule weight (or 10 or 50, anything that lets you determine the average weight to better than 0.1 g) Now subtract 0.8 g from that and see about how much weight of other stuff there is.

Consider
. Cellulose - not soluble in water
. Stearic Acid - almost completely insoluble in water
. Magnesium Stearate - almost completely insoluble in water

So even if all the malic acid dissolved you'd have solid trash left over. If the strearic acid or its Mg salt coated any of the malic acid, that might be prevented from dissolving.

Reference books are your friend. CRC, Lange's, Merck, use them to check everything that's in a mix. Download those old time chem books in the board's library area, while they are out of date or completely wrong in some areas, especially structural and theoretical, preparation information can be helpful.

mericad193724 - 29-8-2006 at 16:01

The entire capsule with its constituents weighs 910 mg (my balance goes to .01g). The empty capsule weighs 100 mg. The powder from 100 tablets which I extracted weighed 86 grams. (Some stuck to the capsules when the mix was poured out.)

I am expecting very little to be insoluble as I used 100 tablets so there should be 80 grams of Malic acid. They may be coated in stearic acid or magnesium stearate, but then how would it dissolve in the body?

Does anything explain the colling to 14C?

Mericad

not_important - 29-8-2006 at 16:28

Malic acid has no proven medical applications, as such it need not dissolve to accomplish the goal of removing money from the wallet.

More seriously, you digestive tract is a bit more complex than a container of water, the fatty acid coating (if any) would be stripped off.

Dissolve, evaporate (keep dust away), weigh the result. That will tell you if much got left behind.

chemoleo - 29-8-2006 at 16:36

Eh? If the mixture became really cold, this suggests that LOTS must have dissolved. Otherwise it wouldnt go cold. Many things become cool when dissolved in water, ammonium nitrate being one of them.

How did this turn into a maleic acid thread, from totally unrelated tannic acid?

not_important - 29-8-2006 at 21:59

Yeah, I left that out - getting cool is a sign of something going into solution, and the 3 fillers aren't likely to have any effect.

They couldn't get tannic acid it appears. And all vegetable acids are the same, just that in some the carbons are in a square with the hydrogens and the oxygens outside of that while in others the carbons are in a line with the oxygens between them and the hydrogens; check any 1820s chemistry book. Or maybe it's topic drift.

Malic Acid Gel?

mericad193724 - 30-8-2006 at 10:25

Thanks for the help chemoleo and not_important,

I can't get any tannic acid without ordering it. So I just got some Malic acid as I saw it browsing the isles of my pharmacy. If you want I can make a new thread for malic acid, but I think it is unnecessary. (Eventually I will get some tannic)

I have been extracting the Malic Acid from the capsules today. I dissolved 86 grams of the stuff I got from inside the capsules, dissolved that in 200 ml water, filtered off the insoluble crap and boiled the 200 ml down to 50 ml. I stopped boiling because the thermometer went off the scale into 120C+

I have thick, clear, light green gel, EXTREMELY viscous. I thought I would get crystals? I have a gel that I am now cooling in an ice bath to see if I get crystals. The top layer is crusted VERY thinly.

Any way to get crystals from this thick syrup? I think Malic acid will boil and decompose at 140/150C, if I keep boiling it will get there.

Also, whats the difference between L-(-)-Malic Acid and DL-Malic Acid (as listed on Sciencelab.com)

thanks

Mericad

(Edited spelling errors)

[Edited on 30-8-2006 by mericad193724]

12AX7 - 30-8-2006 at 12:57

Organic stuff may supersaturate... give it some time, it may crystallize.

I would expect a syrup more than a gel, though...

Tim

not_important - 30-8-2006 at 13:34

Yes, you must give it time

Saturate suger solution + slow evaporation => rock candy

Saturate suger solution + boil down => suger syrup

This might have worked had you used one of those electric coffee cup warmers that litter second-hand stores to warm the solution, and put a loose cap over it to keep out dust.

Really cooking hydroxy-acids isn't the best thing. Alpha-hydroxy one can decarboxylate, with the right size lactones can be formed, and the shorter chains can form polymeric esters. Not likely that happened to you, but it is still something to consider when heating them.


DL is racemic, equal amounts of left and right likely handed, produced by a synthetic route, pure D likely come from biological production.

http://en.wikipedia.org/wiki/Racemic
http://en.wikipedia.org/wiki/Enantiomer

mericad193724 - 31-8-2006 at 10:05

Thanks for the in depth explanation not_important.

Yes, you guys were right, patience was the key!

I let the thick, light-green syrup sit at room temperature and when I checked back in an hour the entire thing had solidified into a white mass in my beaker. I had to pull my thermometer out of it :D. This white stuff (malic acid) looks and feels like a white bar of soap. It is difficult to scrape but comes off with elbow grease and is somewhat malleable (basically like soap). There is definitely 50+ grams in the whiter mass. The problem is getting it out of the beaker....it won't come out and drying this would take years so...I dissolved this in distilled water (still yielded a clear solution) and have it sitting on my hot plate at 80C.

Will this give me crystals if I let it evaporate at 80C to half volume and then cool?

(I got a new digital camera so I will have pictures soon);)

Mericad

not_important - 31-8-2006 at 23:42

L-Malic
Solubility:
Easily soluble in methanol.
Soluble in acetone.
Partially soluble in cold water.
Very slightly soluble in diethyl ether.
Solubility in methanol @ 20 deg.: 197.22 g/100 g solvent
Solubility in diethyl ether@ 20 deg. C: 2.70 g/100 g solvent
Solubility in ethanol @ 20 deg. C: 86.60 g/100 g solvent
Solubility in acetone @ 20 deg. C: 60.66 g/100 g solvent
Solubility in dioxane @ 20 deg. C: 74.35 g/100 g solvent
Solubility in water @ 20 deg. C: 36.35 g/100 g solvent
Practically insolubility in benzene




DL Solubility:
Soluble in cold water, methanol.
Partially soluble in acetone.
Very slightly soluble in diethyl ether.
Solubility in methanol @ 20 deg.: 82.70 g/100 g solvent
Solubility in diethyl ether@ 20 deg. C: 0.84 g/100 g solvent
Solubility in ethanol @ 20 deg. C: 45.53 g/100 g solvent
Solubility in acetone @ 20 deg. C: 17.75 g/100 g solvent
Solubility in dioxane @ 20 deg. C: 22.70 g/100 g solvent
Solubility in water @ 20 deg. C: 55. 8 g/100 g solvent
Practically insolubility in benzene

No easy to find data on solubility vs temperature, I'm sure someone has it.

Suggests that for L-malic the best bet is to evaporate slowly until crystals appear, then slowly cool to let them grow. You will lose some to the mother liquor, you could evaportate it once more to the start of crystal formation and cool again.

The slight colouring you are getting suggests there is something else in solution as well. If a dye it possible could be removed from the solution with charcoal, or if the colour stays in solution while crystallising out the malic acid you could just accept the lose of part of the acid.

If there wasn't anything else extracted along with the malic acid, you could have just evaporated slowing until crystals appeared, then poured everything onto a glass tray or wide plate or baking disk, and evaporate to as close to dryness as you can get. The wide, flat surface combined with keeping the product in a thin layer makes it easier to scrape up.

If you really wanted nice, clean crystals with little lose, you would evaporate the solution to (near) dryness, dissolve it with hot absolute ethanol, distill/evaporate enought ethanol to take the water with it as the azeotrope, get the solution near saturation at 35 C, then slowly add ether until you get crystals, cool to -10 C But if you could get absolute ethanol and ether, you could get pure malic acid to start with.

BTW - the bulb of a thermometer is pretty thin, avoid stressing it unless you like buying new ones. Likewise, therometers aren't the best stirring rods.

jimmyboy - 5-9-2006 at 12:54

what book did you get all that solubility data from? :)

nevermind - you got it off the MSDS

[Edited on 5-9-2006 by jimmyboy]