berry1
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How To Recrystallise ?
Im looking to recrystallise a testosterone powder to remove impurities from my current research i think i would need to dissolve steroid powder in
methanol - add cold water to saturate the solution and this should cause the solution to form crystals of the steroid powder that should remove
impurities.
Could someone tell me if this procedure is correct?
What amounts of each to add? powder? methanol? water?
Is there any more efficient way to remove impurities from testosterone powder to verify the purity?
Thanks guys
[Edited on 24-9-2014 by berry1]
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chemrox
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Look up the solubility of your compound in common solvents and try one in which your substance is slightly soluble and see if it is more soluble in
hot solvent. Try that before trying binary solvent systems
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Artemus Gordon
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Chemrox is right, you need to know how your substance performs in different solvents and temperatures. Some substances are LESS soluble in hot water
than they are in cold water, for example.
Re the methanol/water situation you describe: if you substance is soluble in water, then adding cold water to your methanol mixture probably won't
cause a precipitation. If you are sure that your substance is less soluble in cold methanol, you could put the whole flask in your freezer, or in an
ice bath to lower the temperature without adding water to the mixture.
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Dan Vizine
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If the material is just testosterone...
Despite the fact that the material is an alcohol, you may find that boiling hexanes or petroleum ether dissolution of the material, filtration &
cooling works nicely and with good returns.
Long ago I needed to prepare highly pure cholesterol (testosterone's biological precursor) for a client. This was very simple, it consisted of
repeated recrystallizations from HPLC grade hexanes, if my memory is correct.
The relatively large carbon backbone is more determinant of solubility than the presence of a polar alcohol group with many of these large saturated
ring systems. I don't think the additional alpha, beta unsat. ketone will change anything, but...
If testosterone is slightly different (i.e., less soluble), try very small additions of ethanol to the boiling alkane. Or, just look it up. This just
has to be somewhere on the net.
Generally speaking, if it's meant to go into you, use recrystallization solvents of low toxicity. For example always think "ethanol" before you think
"methanol". Many materials retain solvents of recrystallization in their crystalline lattices, although I don't think this material is likely to do
that and doses are low. Still, it's a good practice...
[Edited on 25-9-2014 by Dan Vizine]
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Chemosynthesis
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CAS Number 58-22-0 recrystallizes from methanol and water, yes. It can also be recrystallized from aq. acetone, hexane, or isoPrOH. It differs for
salts. The propionate recrystallizes from aq. EtOH, and the acetate from MeOH.
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