theAngryLittleBunny
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Registered: 7-3-2017
Location: Austria
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Weird property of indium
Most of you are probably aware that anhydrous aluminium chloride, which is used as a friedel craft catalysist, can't be obtained by boiling down an
aqueous aluminium chloride solution, as it would decompose in aluminium oxide and HCl gas. The same is true for all the other halides of Boron,
Gallium and Thallium, but appearently not Indium. The book "Lehrbuch für anorganische Chemie" by Holleman Wiberg states on page 1191 that anhydrous
Indium halides can be obtained from aqueous solutions by simply boiling them down, sounds insane, doesn't it? O.o Well, I tested it today by
dissolving 10g of indium in hydrobromic acid. The theoretical yield is 30.9g of InBr3, I got 28.8g, which is a 93% yield. I assume that the missing 7%
are mechanical losses, so I'am pretty sure, that what I got is InBr3. Because if it would be In2O3, the yield would be only 12.1g, if OInBr would have
been formed (I know lanthanides form these compounds), then the yield would still only be 18.4g. One interesting thing to note is that this stuff is
extremly hygroscopic, I had some InBr3 on a piece of paper, and within a few minutes, it turned into a liquid drop. Anyway, what I would love to know
is if it would work is a friedel craft catalysist. Well, I suspect it wouldn't, because the fact that you can obtain it from aqueous solutions means
that it's probably not a very stong lewis acid, but I'am gonna try it anyway. If it doesn't work, I wanna use it to make triethyl indium, which can be
made by simply reacting the InBr3 with 3 mol equivalent CH3CH2MgX.
Anyway, I found almost nothing about indium on this forum, so I hope someone is interested in that .-.
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violet sin
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Posts: 1475
Registered: 2-9-2012
Location: Daydreaming of uraninite...
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Properties of Concentrated Solutionsof Indium Chloride
ALANN. CAMPBEL
https://www.google.com/url?sa=t&source=web&rct=j&...
""...a solid prepared in the following way. Metallic indium was refluxed with excess of concen- trated hydrochloric acid until all the indium had dis-
solved, a process requiring about 12 h. The product was evaporated on the water bath to syrupy consistency; on cooling, it solidified.
Analysis at this point showed that the product contained slightly less chlorine (about 2%) than corresponded to InCI3.3H20, i.e., the product was
slightly damp, but contained no free HCI. The salt was then dissolved in water and the crystallization repeated. Provided excess of concentrated
hydrochloric acid is used in the preparation, the sole product is the trichlo- ride, uncontaminated by the mono- or dichloride.
Anhydrous indium chloride cannot be otained by heating the trihydrate in a drying oven at 11O 0, because of the occurrence of the hydrolysis reaction
followed, no doubt, by dehydration to the oxide. The product of the above treatment is not more than 50% anhydrous chloride.
====The anhydrous chloride can, how- ever, be obtained by heating in high vacuum at 70". ===== ""
So it would seem you can get it pure of mono- do-chlorides, and drive off most moisture, but it's still a hydrate unless high vacuum and low heat are
used. Not bad for an mp of 586'c (wiki).
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