Thread: anhydrous acetone via anhydrous magnesium sulphate

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    anhydrous acetone via anhydrous magnesium sulphate 
    Bluelighter f13nd's Avatar
    Join Date
    Nov 2007
    Over the stars
    Once the epsom salt is baked at 250 degrees for half an hour, what is the ratio of magnesium to acetone, and what exactly do you do once you add it to the acetone? Just let it sit? Store it somewhere? Is whats left in the container anhydrous acetone and the gunk at the bottom the leftover magnesium?

    How exactly does the Anhydrous magnesium sulphate make acetone anhydrous? What is the method in actually using this. I checked the search engine for anhydrous acetone and only found how to make An. magnesium sulfate for this or to use sodium hydroxide, but I didn't see exactly how its done once you have the two combined

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    Anhydrous magnesium sulfate is hygroscopic, i.e. will attract water. This happens due to the relative good stability of the heptahydrate-complex (7 mol water per 1 ml MgSO4).
    The amount needed to dry your acetone depends on its watercontent and, therefore, general statements can't be given.

    On the procedure: You just let the acetone sit overnight on the sulfate (some stirring at the beginning could help) in a closed (!) vessel. Then filter off your salt and store the acetone in a pre-dryed container. The magnesium sulfate can be recycled by letting evaporate remaining acetone (NOT in the oven), followed by removal of the water in the oven again.

    Be aware that MgSO4 is a very poor drying agent for acetone and that purely anhydrous acetone is quite hygroscopic, too.

    I recommend everyone interested in some basic purification techniques to obtain a copy of "Purification of Laboratory Chemicals" by Amarego.

    - Murphy

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    one liter of hardware store acetone should only need about ten grams of Mgs04(magnesium sulphate powder).

    Im skeptical this will create 100% anhydrous acetone but as the great lee junk once stated one full gram of powdered cocaine can be completely disloved (and lost) IN ONE ML of WATER! This would mean if your acetone is not 100% anhydrous you will probably be on the losing end. If im not mistaken acetone anhydrous has a tendency to suck moisture out of the air so always ALWAYS use some sort of seal even if it is just a piece of paper instead of leaving it exposed. Please let us know how it turned out fine.

    Lastly thats 2+ hours @ 400(f)degree's.
    Last edited by FrostyMcFailure; 22-12-2008 at 08:49.

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    It won't create 100% anhydrous solvent! MgSO4 is very poor for this task...

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    Neuroscience and Pharmacology Discussion
    sekio's Avatar
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    Sep 2009
    Atreides Palace
    It depends how much water is in the acetone.
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    Bluelighter alkap555's Avatar
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    Feb 2009
    New York
    A good rule of thumb is the more the better. Also, make sure that you filter the mag sulfate out after you've dried the solvent. If you leave it in there it will leach water back out into the acetone. And make sure you store your quasi-anhydrous acetone in a very airtight container as it will readily suck up atmospheric moisture.

    The ideal desiccant for acetone is CaSO4 (drierite), although CaCl2 works too. For really pure stuff you'd want to distill over CaSO4, and only use the stuff that comes over at 56-57 C.
    Last edited by alkap555; 12-06-2012 at 06:08.

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