vmelkon
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Aluminium isopropoxide - reaction with water
Hello,
I imagine that Aluminium isopropoxide reacts with water and forms 2-propanol + Al(OH)3.
If I were to prepare Aluminium isopropoxide (I think written Al(iso-Pr)3), how do you clean the glassware?
The bp for Al(iso-Pr)3 is around 140 C?
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DavidJR
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Yes, alkoxides do indeed readily hydrolyse.
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myr
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Wash with a little dry solvent miscible with water that has a decently high vapor pressure- acetone, ethanol, methanol all work well enough- and heat
to dry, preferably while pulling a vacuum.
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DavidJR
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Quote: Originally posted by myr  | | Wash with a little dry solvent miscible with water that has a decently high vapor pressure- acetone, ethanol, methanol all work well enough- and heat
to dry, preferably while pulling a vacuum. |
Or.... just rinse with isopropanol, which seems the most logical if you're going to be making isopropoxide.
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Amos
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Are you trying to clean the glassware before or after the prep? Afterward there shouldn't be anything wrong with cold water followed by some HCl to
remove aluminium oxides that might be adhering to the glass.
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Tsjerk
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Before you shouldn't have to clean it, maybe bake it a bit in an oven if you want to be sure. But that depends on how dry your IPA is to begin with,
if that is not rigorously anhydrous it doesn't make sense to bake your glass. Also, does a bit of aluminium hydroxide interfere with your reaction?
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vmelkon
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| Quote: Originally posted by Amos | | Are you trying to clean the glassware before or after the prep? Afterward there shouldn't be anything wrong with cold water followed by some HCl to
remove aluminium oxides that might be adhering to the glass. |
I am concerned with the after part.
If the insides of your glassware get coated with Al(OH)3, does conc HCl easily react with it?
Another issue is that I might need to boil the Al(iso-Pr)3 in order to separate it from bit of Al. Is a vacuum necessary?
Can't I just heat to 140 C at 1 atm?
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Amos
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Any aluminium oxides/hydroxides produced by wet chemistry that I've encountered aren't particularly fussy about dissolving; you can use either dilute
acid or solutions of alkali metal hydroxides.
The problem with the boiling point you just suggested is that it was obtained under vacuum. I don't see anything online that points to a distillation
being done at atmospheric pressure.
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unionised
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You may be able to avoid any precipitation in the first place if you add a solution of potassium sodium tartrate, rather than water.
That stuff can also be used during some work-ups.
It holds the aluminium in aqueous solution, but it has a near neutral pH.
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