Sciencemadness Discussion Board

Vinegar purification

chucknorris - 25-1-2013 at 22:08

I vaporized some vinegar and found out it contains 0.5-2% of impurities that will leave brown-blackish residue when distilled dry.

I just though that what kind of impurities those could be, and would there be any easy ways to get rid of them? Boiling isn't, since vinegar concentration is so low I'd need to distill whole container of that stuff.

And, would these impurities cause trouble in some processes other than decreasing the possible yield by a percent or two, since this definintely doesn't matter.

hissingnoise - 26-1-2013 at 03:04

Glacial AA is easily bought almost anywhere!
And I know that some vinegars contain caramel in solution but that may be the amber variety ─ most vinegars would have flavorings or spices of various sorts!
Google it?

K12Chemistry - 9-2-2013 at 11:48

It is really dependant upon the type of vinegar. I'm guessing it is malt vinegar, if it is then the residue is barley malt. I wouldn't use it as a source of acetic acid because it is really weak and impure. At the supermarket you can get malt vinegar for 45p (500ml) or distilled vinegar for 30p (500ml).

Distilled vinegar is a great source for acetic acid and you can fractional crystallize it to get stronger concentrations.

:)

Pyro - 9-2-2013 at 12:24

mix with NaHCO3 untill no more CO2 forms. then distill with conc. H2SO4

vmelkon - 9-2-2013 at 14:11

Quote: Originally posted by hissingnoise  
Glacial AA is easily bought almost anywhere!


Your local supermarket sells it?

wireshark - 9-2-2013 at 16:51

Actually I heard some oriental grocery stores carry glacial acetic. Analog photography is dead, so there went that source (stop bath). Best thing to do is to just order GAA and pay the hazmat fee. It'll still be cheaper than buying dozens of gallons of vinegar.

sbbspartan - 9-2-2013 at 18:37

You can get Acetic Anhydride at Elemental Scientific very cheaply, at about $1 an ounce or $15 for 16 ounces. Their glacial acetic acid is also only about $9 for 16 ounces. There is no hazmat fee for Elemental either... That would probably be easier than trying to purify regular vinegar or making your own concentrated stuff. You would have to wait a while to receive your order though...

elementcollector1 - 9-2-2013 at 19:23

Quote: Originally posted by sbbspartan  
You can get Acetic Anhydride at Elemental Scientific very cheaply, at about $1 an ounce or $15 for 16 ounces. Their glacial acetic acid is also only about $9 for 16 ounces. There is no hazmat fee for Elemental either... That would probably be easier than trying to purify regular vinegar or making your own concentrated stuff. You would have to wait a while to receive your order though...

To clarify, Elemental-Scientific doesn't have hazmat on this particular chemical. Oh, would that I could order anything I wanted and not pay the extra $11-25 for various hazmat fees...

wireshark - 9-2-2013 at 19:34

See attachment. It's possible to electrolytically oxidize ethanol to ethanoic acid. There's also the possibility of the thermolysis of acetone to ethenone, and quenching it produce ethanoic acid.

The ambitious chemist only needs earth, fire, water, and air. :cool:

Attachment: acetic.acid.from.ethanol.pdf (288kB)
This file has been downloaded 1066 times

Sedit - 10-2-2013 at 01:08

Add a fuck load of salt to distilled vinegar then extract 3x with DCM. Combine the DCM extracts and dry with MgSO4. Distill the DCM to recover Glacial acetic acid. If your starting with 5% AcOH dont expect alot of GAA from the process but its tried and true. IIRC Potassium Sulfate is one of the best salts to use to force AcOH into the non-polar layer but NaCl is rather cheep so I would go with that.

The stronger the starting concentration the higher the yields.


Electrolysis of EtOH with NaCl and Copper electrodes produced awesome crystals of Copper acetate and some polymer gunk as well. Just a rough and dirty test.