Organic reagents starting place

Quote: Originally posted by Etaoin Shrdlu

Hydrolyze the tannic acid and purify the resulting gallic acid. [x] [x] Decarboxylate the gallic acid to make pyrogallol. [x] Luminescence! [x]

Gallic acid isn't very soluble in cold water, and sulfuric acid is miscible with water, so I think if the solution was evaporated to saturation while warm, then cooled, gallic acid should precipitate out and then it could be washed with ice water to get rid of the last of the sulfuric acid. I can't speak for how the sulfuric acid will affect solubility but I don't think it will be much. (Someone yell at me if this isn't the case.) You might even get gallic acid precipitating out during the entire reaction without doing any evaporation since tannic acid is far more soluble in water.

I love the old chemistry books. They use methods that are more accessible to amateurs than a lot of modern scientific papers, and they usually have tests to help characterize products other than "we stuck it in the IR." Plus there's this air of meticulousness underlaid with sheer fascination.

If you don't know the purity of your tannic acid I'd make a close-to-saturated solution and filter off any gunk first. I've had samples that ranged everywhere from near-perfect dissolution to something that must have been barely processed because it left brown foamy junk sticking to everything.

EDIT: Missed a crucial word.

[Edited on 4-17-2014 by Etaoin Shrdlu]

Quote: Originally posted by Etaoin Shrdlu

Gallic acid isn't very soluble in cold water, and sulfuric acid is miscible with water, so I think if the solution was evaporated to saturation while warm, then cooled, gallic acid should precipitate out and then it could be washed with ice water to get rid of the last of the sulfuric acid. I can't speak for how the sulfuric acid will affect solubility but I don't think it will be much. (Someone yell at me if this isn't the case.) You might even get gallic acid precipitating out during the entire reaction without doing any evaporation since tannic acid is far more soluble in water. I love the old chemistry books. They use methods that are more accessible to amateurs than a lot of modern scientific papers, and they usually have tests to help characterize products other than "we stuck it in the IR." Plus there's this air of meticulousness underlaid with sheer fascination. If you don't know the purity of your tannic acid I'd make a close-to-saturated solution and filter off any gunk first. I've had samples that ranged everywhere from near-perfect dissolution to something that must have been barely processed because it left brown foamy junk sticking to everything. EDIT: Missed a crucial word. [Edited on 4-17-2014 by Etaoin Shrdlu]

Thank you so much! Now I have to get some sulfuric acid... Sad, I know, that I don't have it. I'll get some 16 Molar stuff soon, parents are slightly restrictive and slow to decide.

On solubility, all I can say is I accidentally dumped my entire supply into like 15 mL of water (which was the same volume as my supply of tannic acid!). It is now being stored at an unknown strength in a 20 mL dropper bottle, because my only use used to be for Iron testing.

I like the old chemistry books to. If I recall, I do have an old Chemcraft manual, but I think that's the oldest chemistry book I have.

And on purity Did we get the same batch? Mine is SO dirty. But I'm a little upset because I don't want to loose any in the filtering process, do you think I would at such high concentrations as what I described?

[Edited on 4-17-2014 by The Volatile Chemist]

Quote: Originally posted by Etaoin Shrdlu

You can get something like 2x tannic acid into water by weight, so it's probably dissolved if the volumes were equal. If you're worried it isn't, you could always add a little more water before you filter it, or wash the gunk left on the filter and see if any more dissolves. I always have a bunch of light-colored putty-like stuff left over that doesn't seem to go into solution to any appreciable extent. We probably did get similar batches. It's extracted from plants so a lot of it that gets sold is still contaminated with a bunch of other stuff. Google Books is a fantastic place to find old chemistry texts. You can even download them to read offline. The pharmaceutical ones often have some nice info too. I'm personally amazed by how well the text recognition worked.