Brain&Force - 26-6-2014 at 20:35
It's trivial to get white vinegar, it's easily available at any grocery store. But one of the major problems with this OTC source is the presence of
organics other than acetic acid, which can interfere with things like hot ice, producing metal acetates, and other projects.
What is the best way to remove these organics from white vinegar without distilling with sulfuric acid? I don't need the acid to be stronger, I just
need to remove the organics. One of the more interesting things I have noted is that I don't detect any contamination after producing copper acetate
from household vinegar. I don't know if the color of the copper complex is just masking the impurity, or if it's catalyzing a decomposition.
gdflp - 27-6-2014 at 04:32
That's funny, the exact same thing happened to me, I could crystallize copper acetate just fine. With some other compounds I actually had a hard time
crystallizing using the same vinegar so I'm not sure what's happening. Distilling without sulfuric acid should still yield the same concentration
without organics but if you're looking to avoid distillation, it might be easier to buy a liter of glacial acetic acid. It's not that expensive,
around $10.
blogfast25 - 27-6-2014 at 08:36
White vinegar is sold here as 'distilled vinegar', which has always led me to believe it's relatively pure. Do you have any solid evidence for any
specific impurities?
gdflp - 27-6-2014 at 08:40
It's sold as the same where I am, but there are still issues. No evidence of impurities, but it says diluted to 5% acidity with water so it may be
impurities in that water.
Brain&Force - 27-6-2014 at 08:46
This post suggests it's caused by impurities from production - the vinegar itself isn't distilled; the ingredients used to make the vinegar,
however, are, so there are way too many organics in the vinegar. Glucose seems to be the main culprit - perhaps some sort of enzymatic browning is
occurring in the presence of hydrolyzed proteins and amino acids?
I don't have any lab equipment at this point, so I may not be able to do anything unless there's a better OTC source I'm missing out on.
Texium - 27-6-2014 at 10:45
Household vinegar can also commonly contain the acetobacter used to metabolize the alcohol which is just even more unwanted organic sludge. I've found
colonies of the stuff living quite happily in older samples before, showing that they were already present in the vinegar along with plenty of
undigested alcohol for them to consume. It is definitely not guaranteed pure.
I guess there's always the possibility of making your own? That's something I've considered trying before. While it's not a given that you will be
able to produce any purer of a substance, it might be easier to do on a smaller lab scale, plus you know exactly how it was made and what the possible
problems could be.
violet sin - 27-6-2014 at 11:35
I noticed that when crystallizing calcium acetate from hydrated gardening lime and distilled vinegar, the crystals grew up away from the increasingly
brown solution. leave a semi-porous object in the middle of a thin puddle of crude solution as you let it evaporate. the odd kinda feathery
"crystals" grew off it out of sol. when redissolved, there was a light straw color to the sol.
if your just trying to get various acetates, calcium is pretty easy to drop out. also never tried it, but bubbling CO2 through it may even leave you
with a fairly clean acetic acid.
alternately there is this: http://www.vyse.com/applications_gelatin_clarifying_aid.html "..., and vinegar are natural media for the settling effect of Type B Gelatin,
because the haze causing materials, such as yeast particles, tannins and resins have a negative charge. These haze causing materials have the tendency
to stay in suspension. The addition of gelatin can help speed up precipitation and settling. The positively charged gelatin and the negatively charged
haze are attracted and combine to form an agglomerate that settles to the bottom of the tank...." worth a shot
Brain&Force - 27-6-2014 at 17:18
I was considering the CO2 method - I can get dry ice easily, and just drop it in a copper acetate solution. Hopefully that'll induce
precipitation.