nlegaux
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Difficulty with AlCl3/Urea DES
I am trying to create an Aluminum Chloride/Urea deep eutectic solvent. This and the other type IV DESs in particular caught my eye because I do not
have access to Choline Chloride. According to wikipedia, a type IV DES can be made with aluminum chloride and urea in a 2:1 molar ratio. I have
attempted this 3 times, twice using a torch and once using a sand bath. Both times the aluminum chloride failed to melt (but my prills of Urea have)
at both 100C (the melting point of the hexahydrate) and about 200C (above the melting point of the anhydrous aluminum chloride). When I go above about
180C, the aluminum chloride begins to sublime, as expected. Both of the chemicals were ordered offline, and both of the chemicals are supposed to be
>98% pure. Anyone have any idea what may be going on or have any suggestions for making the solvent?
Thank you in advance.
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gatosgr
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You can try 1,5:1 instead, I get a clear forming DES at 80 C with 4:1 ZnCl2 + Urea molar ratio. I also can't find ChCl here, I bought some from ebay
from a guy named kevin cao and he couldn't send it after waiting a week for him to ship it to me. It's funny because all the researchers say how cheap
and available choline is 2euro/kg but they buy a 300euro/kg reagent instead.
[Edited on 28-4-2015 by gatosgr]
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gatosgr
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You should mix them really well before you heat them. I am also in the search for choline alternatives. 
[Edited on 29-4-2015 by gatosgr]
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blogfast25
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Quote: Originally posted by nlegaux  | | at both 100C (the melting point of the hexahydrate) and about 200C (above the melting point of the anhydrous aluminum chloride).
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If by "the hexahydrate", you mean the hexahydrate of aluminium chloride, that's useless for any DES.
Using anhydrous AlCl<sub>3</sub> you have no choice but to use a closed, pressure resistant vessel. Sublimation cannot be avoided any
other way.
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blogfast25
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This post by Zyklon-A:
http://www.sciencemadness.org/talk/viewthread.php?tid=29291&...
... links to a *.pdf that describes the preparation of another AlCl<sub>3</sub> based DES - KAlCl<sub>4</sub>, page 11:
| Quote: |
Equal molar amounts of aluminum chloride (AlCl3) and potassium chloride (KCl) were first weighed and then mixed into a pyrex tube under
inert nitrogen atmosphere. A polyethylene glove bag (Instruments for
Research and Industry, Cheltenham, Pennsylvania) was used for this
purpose, The tube was then evacuated overnight, as shown in Figure 5,
to below 3 mm Hg; the contents were kept thoroughly mixed by a vibrator.
The tube was then filled and continuously bled with helium while it was
immersed :i.nto an oven which was slowly heated up to 550°C. The salt in
the tube was melted and the subsequent solution was clear and colorless.
Black precipitate was observed in the bottom of the tube after about 2
hours. The salt solution was then slowly cooled. It recrystallised :in
the form of white crystals. The tube was subsequently sealed and trans~
ferred quickly into the glove box. Once inside the glove box the tube
was cracked open, The salts were ground to fine powder ready for use. |
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Metacelsus
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The vacuum step might be crucial in allowing the eutectic to form -- I imagine a thing analogous to vacuum sintering happening.
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gatosgr
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It's strange that you say that because get a clear DES at 80 C using ZnCl2.2H2O , the water becomes part of the DES.
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blogfast25
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| Quote: Originally posted by gatosgr | | It's strange that you say that because get a clear DES at 80 C using ZnCl2.2H2O , the water becomes part of the DES. |
Where did he write it was the dihydrate? Anh. ZnCl<sub>2</sub> is easily available.
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gatosgr
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you probably need anhydrous chloride then
http://www.iasj.net/iasj?func=fulltext&aId=95810
[Edited on 30-4-2015 by gatosgr]
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blogfast25
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Sure, water is the mortal enemy of most DES.
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gatosgr
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Some DES work fine with water but some others don't.
[Edited on 30-4-2015 by gatosgr]
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blogfast25
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From:
http://www.sciencemadness.org/talk/viewthread.php?tid=62315#...
| Quote: | The liquid was synthesized by slowly mixing aluminium chloride
(Fluka499%) and urea (Fisher Scientific analytical reagent grade)
together at room temperature under a dry nitrogen atmosphere.
A homogeneous straw-brown liquid was formed. |
No time-line given, though…
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nlegaux
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I have found that a 1:1 molar ratio of AlCl3/Urea heated under mineral oil forms a eutectic that seemed to be able to dissolve CuCO3 (it turned a
light green color after dissolving it). I believe the mineral oil serves the duel purpose of protecting my AlCl3 from water vapor in the air and helps
evenly heat the mix. Is anyone familiar with the mechanism by which DESs dissolve oxides and carbonates?
[Edited on 5-9-2015 by nlegaux]
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blogfast25
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| Quote: Originally posted by nlegaux | I have found that a 1:1 molar ratio of AlCl3/Urea heated under mineral oil forms a eutectic that seemed to be able to dissolve CuCO3 (it turned a
light green color after dissolving it). I believe the mineral oil serves the duel purpose of protecting my AlCl3 from water vapor in the air and helps
evenly heat the mix. Is anyone familiar with the mechanism by which DESs dissolve oxides and carbonates?
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Oh, G-d, not that again: "CuCO3".
CuCO3 doesn't exist. The only stable copper carbonate is basic copper carbonate:
Cu<sub>2</sub>CO<sub>3</sub>(OH)<sub>2</sub>, aka Malachite. A meta-stable version of it, Azurite,
Cu<sub>3</sub>(CO<sub>3</sub> <sub>2</sub>(OH)<sub>2</sub>, is a rare mineral.
I don't know anything about the mechanism of dissolution but speciation is likely to be complicated. Nothing like in 'simple' solvents like water.
[Edited on 10-5-2015 by blogfast25]
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