poisoninthestain
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miscible/density/ solubility issues...
If you are trying to isolate a compound that is less dense than water but it's soluable in something denser than water such as DCM...assuming all this
is done in a water solution, will that cause any problems?
Here's my situation...I have an amine solvated in DCM, and H2SO4 in water all in the same sep funnel. H2SO4 is miscible with water and is denser than
water. DCM is denser than water but less than H2SO4. The amine is less dense than all 3 but is solubable in DCM and not soluable in water.
I'm wondering though, if H2SO4 is soluable in DCM or vice-versa. I did an A/B and the amine disappeared somewhere during the workup.
Very confused.
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hissingnoise
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H2SO4 can be considered insoluble in DCM---nitric acid extracted from HNO3/H2SO4 mixtures by DCM has been found to contain only traces of H2SO4. . .
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poisoninthestain
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Awesome. Many thanks.
I still can't figure out what happened to my disappearing amine. I reduced it from a nitrostyrene with a Hg/Al amalgam, extracted with DCM, acidified,
and basified but no amine base ran to the top.
Perhaps I didn't acidify/ basify enough or something simlier. There was very clearly the formation of white crystals when the amine base was solvated
in DCM after adding a con. solution of H2SO4...the crystals eventually dissolved back into the solution quickly after forming. This left me with the
impression the reduction was successful.
However, after washing with DCM twice, I basified the H2SO4/water/amine.SO4 with con. NaOH and absolutely no phase seperation occurred. I expected the
amine base to come running to the top.
I think it's *possible* it might have something to do with not adding the DCM before basifying but after done washing...just a guess. I remember when
I extracted the amine base from the clear/slightly yellow post-amalgam solution. Before the DCM was added the whole sep. funnel was almost totally
clear with a hint of yellow.
After adding the DCM and settling to the bottom the DCM took on a golden-yellow appearance, while the top aqueous layer went from clear to a
milky-opaque white.
I thought that was kind of strange. Hopefully eventually I'll figure out what happened. I have pictures if that helps.
[Edited on 6-4-2009 by poisoninthestain]
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