| Pages:
1
2 |
manimal
Hazard to Others
Posts: 180
Registered: 15-1-2008
Member Is Offline
Mood: ain't even mad
|
|
Maybe a poor man's potassium carbonate solution could be made by mixing potassium chloride with sodium carbonate.
|
|
|
papaya
National Hazard
Posts: 615
Registered: 4-4-2013
Member Is Offline
Mood: reactive
|
|
KCL may work alone, problem is we didn't really get why K2CO3 and not NaCL or Na2CO3 (from the link provided by Nicodem I only could figure out that
NaCL must be much better  )...
|
|
|
Random
International Hazard
Posts: 1120
Registered: 7-5-2010
Location: In ur closet
Member Is Offline
Mood: Energetic
|
|
I tried this with yeast&sugar alcohol solution and wood ashes but didn't encounter anything, I'll try to use food coloring next time.
|
|
|
Organikum
resurrected
Posts: 2337
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
Quote: Originally posted by Adas  | | Anhydrous CaCl2 works well for removing water. You can always heat it to make it anhydrous again. |
Just that it has a high affinity to the lower alcohols as well.
And it forms complexes with them.
Welcome to chemistry the non-intuitive home of exceptions! 
/ORG
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Random | | I tried this with yeast&sugar alcohol solution and wood ashes but didn't encounter anything, I'll try to use food coloring next time.
|
It is obvious you did not understand much about this topic. The food coloring was not added to promote the phase separation. It has nothing to do with
the "salting out" phenomena. Magpie added it only to take a more aesthetic picture. Also, I can't see how could you salt out ethanol from such a
mixture that only presumably contains ethanol and even if does it must be very diluted (I assume you are talking about some fermentation broth or wine
or something similar, because most yeast strains cannot produce ethanol of more than about a dozen % concentration). Also, you need to saturate
with K2CO3 (not some "wood ash" of undefined composition!).
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
|
|
|
Random
International Hazard
Posts: 1120
Registered: 7-5-2010
Location: In ur closet
Member Is Offline
Mood: Energetic
|
|
| Quote: Originally posted by Nicodem | | Quote: Originally posted by Random | | I tried this with yeast&sugar alcohol solution and wood ashes but didn't encounter anything, I'll try to use food coloring next time.
|
It is obvious you did not understand much about this topic. The food coloring was not added to promote the phase separation. It has nothing to do with
the "salting out" phenomena. Magpie added it only to take a more aesthetic picture. Also, I can't see how could you salt out ethanol from such a
mixture that only presumably contains ethanol and even if does it must be very diluted (I assume you are talking about some fermentation broth or wine
or something similar, because most yeast strains cannot produce ethanol of more than about a dozen % concentration). Also, you need to saturate
with K2CO3 (not some "wood ash" of undefined composition!). |
I may have written my thoughts the wrong way, I meant to say that maybe phase separation occured, but I didn't notice it. Food coloring makes them
more visible.
I used a large excess of wood ash, but still I think that concentration of yeast fermentation broth contains about 10 percent ethanol by rough
estamination. I wonder what is the minimum concentration of EtOH that can be salted out by saturating with potash.
Maybe very soluble salts ammonium nitrate would work too?
[Edited on 13-6-2013 by Random]
|
|
|
alka
Harmless
Posts: 1
Registered: 23-5-2015
Member Is Offline
Mood: No Mood
|
|
In Salting out separation of amine(weak base)-water(15% amine by weigth) by NaOH salt(18g), aqueous layer contain NaOH and some quantity of amine
.While doing titration of aqueous layer, addition of pheonphthaline indicator does not change the aqueous layer to pink, even though NaOH is strong
base and also amine is basic in nature. why its happening?? NaOH is not soluble in amine.
|
|
|
turd
National Hazard
Posts: 800
Registered: 5-3-2006
Member Is Offline
Mood: No Mood
|
|
I don't understand what you are trying to achieve, but quote Wikipedia (https://en.wikipedia.org/wiki/Phenolphthalein):
| Quote: | | In strongly basic solutions, phenolphthalein's pink color undergoes a rather slow fading reaction and becomes completely colorless above 13.0 pH.
|
Why not use standard universal pH indicator paper?
|
|
|
byko3y
National Hazard
Posts: 721
Registered: 16-3-2015
Member Is Offline
Mood: dooM
|
|
I was thinking that salting out ethanol/isopropanol might be a good way ащк separating non-polar substances from solution. I was that stupid.
In fact you cannot salt out a bare isopropanol with Na2CO3 or NaCl solution - it will just form another homogenous solution. Maybe
this solution will have a top part with slightly higher alcohol content and bottom one with lower alcohol content, but there will be no layers. What
you really need is anhydrous Na2CO3 or NaCl. And truly, when I add anydrous NaCl to isopropanol solution, I can see the bottom layer which ends right
above the solid salt layer. Still the upper layer contains the salt, dissolved in isopropanol-water solution, and you can't remove all the water from
it using NaCl.
I just watched the video https://www.youtube.com/watch?v=9kV0bmLVoeo which is actually misguiding and the author has no idea what he talks about. Well, you can get
separate layers using NaCl completely dissolved. For that you need another compound, non-polar, which will draw the isopropanol from salt, making it
possible for the layers to appear. But still a lot of isopropanol will be dissolved in water, and a lot of water will be present in the alcohol.
So, the dissolved salt actually just shifts the equilibrium, but it will shift nothing if you have a homogenous mixture.
There's such thing as https://en.wikipedia.org/wiki/Hofmeister_series . It describes observation that some salts lead hydrophobic substances to separation, while others
may cause them to mix with water. Chlorides lay somewhere in the middle of the series, while both potassium and carbonates favor separation of
hydrophobic molecules.
As you might already know (at the first page of the thread), K2CO3 seems to be the only one capable of separation of MeOH from water. I think that
probably ammonium carbonate can remove water from ethanol. Hovewer, I have no ammonium carbonate to verify my theory.
Anyway, salting out hydrophobic substances might be a viable alternative to diethyl ether extraction, because diethyl ether is a controlled substance
in most countries, but for some reason the theory of alcoholic salting out seems to be poorly known. AFAIK, acetone used to be a good substrate for
salting out, but guess what? It's also on the goddamn list.
[Edited on 7-8-2015 by byko3y]
|
|
|
clearly_not_atara
International Hazard
Posts: 2789
Registered: 3-11-2013
Member Is Offline
Mood: Big
|
|
The reason NaCO3 doesn't work is the same reason you've never heard of NaOtBu, always KOtBu: alkoxides are sort of covalent, and the more substituted
the alcohol, the more covalent the bond. NaOiPr is pretty covalent, but it can still be used as a base. However it's certainly covalent enough that
iPrOH readily dissolves Na+. Potassium has much weaker covalent interactions and so does not dissolve as easily.
Ammonium carbonate or ammonium sulfate has a pretty good chance of salting out alcohols, methinks. You can prepare KHCO3 by passing CO2 over KOH,
possibly prepared by thermal decomposition of KNO3, which itself is very soluble at high temperatures but nearly insoluble near 0 C. K2CO3 forms by
pyrolysis of KHCO3.
[Edited on 8-8-2015 by clearly_not_atara]
|
|
|
byko3y
National Hazard
Posts: 721
Registered: 16-3-2015
Member Is Offline
Mood: dooM
|
|
The reason why potassium is used for t-Bu bases is because it interacts with DMSO and HMPA much better than sodium, e.g. solubility of Na2CO3 in DMSO
is 1.4g/100ml while it is 4.3 for K2CO3. Although, still I have no idea why there's not reports on NaOtBu-DMSO adduct. Cesium is even better than
potassium, but it is more expensive.
There's no need in preparing K2CO3 - most people can easily buy it.
|
|
|
byko3y
National Hazard
Posts: 721
Registered: 16-3-2015
Member Is Offline
Mood: dooM
|
|
I've found that acutally sodium alkoxides are more soluble in low polar/nonpolar solvents, e.g. 2% for KOtBu, 7% for NaOtBu, and 25% for NaO-t-pentyl,
13% for NaOtBu in hexane, 38% NaO-t-pentyl in hexane. But, as I've already mentioned, the things go opposite direction when we use a strongly polar
solvent polar solvents (DMSO).
|
|
|
clearly_not_atara
International Hazard
Posts: 2789
Registered: 3-11-2013
Member Is Offline
Mood: Big
|
|
Yeah, that's because NaOtBu is basically a covalent molecule, thus dissolves preferentially in the nonpolar phase. Some is explained in this patent I
found a long time ago when I was wondering why I couldn't just use Mg(OtBu)2 -- short answer, that just doesn't work.
http://www.google.com/patents/US6544446
KOtBu on the other hand is totally ionic. Mg(OMe)2 might be a good base if you need a strong anhydrous base, but I don't know if anyone here has ever
successfully isolated it -- the famous procedure is all in situ.
|
|
|
Fyndium
International Hazard
Posts: 1192
Registered: 12-7-2020
Location: Not in USA
Member Is Offline
|
|
According to https://doi.org/10.1021/ac60333a023 CaCl2 at 31.8g per 100g of solution or 4.2M should result in almost total recovery of acetone with 0.6%
residual moisture with 2h equilibriation. This extraction could be dried with standard procedure of 25g/L of CaSO4 and distilled pure over 10g/L for
pretty anydrous product.
Considering CaCl2 is available as road salt for 50c a kg, it would be an economical method for recovering acetone.
http://revues.univ-biskra.dz/index.php/jaest/article/view/38...
This article also demonstrates the pushing of solvate into an immiscible layer, eg. Extracting acetic acid from water solution with salting. It could
provide easier to extract a substance into low boiling phase than distilling the water base directly.
[Edited on 1-9-2020 by Fyndium]
|
|
|
Fyndium
International Hazard
Posts: 1192
Registered: 12-7-2020
Location: Not in USA
Member Is Offline
|
|
A test to confirm NaCl salting out.
47mL of store grade acetone was added into a cylinder with 46mL of water, resulting in a homogenous mixture. 16g of NaCl was added and stirred. A
layer started to form slowly on top, and reaches 27mL in 15 minutes, and after 12 hours of sitting, the layer volume was 28mL. The upper layer
consists of acetone with unknown amount of water content. Part of the NaCl remains undissolved at the bottom of the cylinder.
59.5% of acetone is therefore separated with NaCl.
I'll do a test with CaCl2 as soon as I get my hands on some.
I also recovered some toluene from a paint thinner, which is stated to contain 50-75% of toluene. 56% of volume remained undissolved after water wash,
and the turbid liquid was washed with brine to result in a clear solution. It will be dried with CaSO4 and fractionated later. The water washing was
treated with NaCl up to saturation, but no phase separation occured.
|
|
|
VancouverBackyardChemist
Harmless
Posts: 6
Registered: 10-8-2020
Location: Canada
Member Is Offline
|
|
Has anyone tried salting out acetic acid from vinegar?
I tried this questionable method here: https://chemistry.mdma.ch/hiveboard/acquisition/000478316.ht...
multiple times, testing different salts and solvents, but none of my attempts managed to produce a phase separation. I tried using NaCl and CaCl2 as
my salts, and Acetone and Isopropanol as my solvents, but none of these attempts worked. I even added water based food coloring to help me see the
organic phase separating out easier, but the mixture's been sitting for 3 months now and there hasn't ever been any separation.
|
|
|
Fyndium
International Hazard
Posts: 1192
Registered: 12-7-2020
Location: Not in USA
Member Is Offline
|
|
Afaik acetic acid per se cannot be salted out, at least with any economical means.
But it can be made less hydrophilic, meaning that it can be extracted with non-water-miscible solvent in a much larger portion as it migrates more
readily out from water.
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
