Triazine
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Use of n-heptane in column chromatography?
Would anyone suggest using heptane over hexanes in column chromatography? I'd like to get away from using hexanes due to its degenerative effects.
I've used n-Pentane in the past, but it can be a pain due to its low bp (disrupting the packing bed and condensing in H2O). I also use toluene and
pet ether in lieu of benzene, but I would consider these solvents only slightly less toxic nor can they fully replace hexanes in an elution.
n-Heptane, while more expensive, seems like a suitable replacement although its high bp might be a pain. I'm curious as to what kind of separation I
can expect compared to hexanes.
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Nicodem
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Quote: Originally posted by Triazine  | | n-Heptane, while more expensive, seems like a suitable replacement although its high bp might be a pain. I'm curious as to what kind of separation I
can expect compared to hexanes. |
It will not affect the separations in any significant way, if hexanes are substituted with either n-heptane or petroleum ether. The retention
factors remain more or less the same.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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phlogiston
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I was once told (by a professor in a biochemistry department) that the straight-chain alkanes and alcohols with an even-number of carbon atoms are
much less harmful than the odd-numbered ones.
Is this incorrect?
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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AndersHoveland
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| Quote: Originally posted by phlogiston | I was once told (by a professor in a biochemistry department) that the straight-chain alkanes and alcohols with an even-number of carbon atoms are
much less harmful than the odd-numbered ones.
Is this incorrect? |
I am not really sure, but I do not believe this is true. He might simply have made a false assumption because propanol and especially methanol are
poisonous, whereas ethanol is much less. Valeric acid (5 carbons) does not seem especially poisonous, and this is essentially what n-hydroxy pentane
would be metabolized to in the body, so I do not think the rule holds. Also, different alkanes would probably all be chemically similar towards the
human body
[Edited on 12-8-2012 by AndersHoveland]
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BromicAcid
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Reminds me of this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=1312
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Triazine
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Thanks Nicodem, hopefully this will help stave off dementia a few decades from now.
Thanks for the link BromicAcid. I've definitely seen other papers pointing to n-hexane's unique toxicity, although I'd be curious about other
branched alkanes such as 3-methylhexane, ect. I've also been told that exposure to acetone (or any ketone or aldehyde) concurrent with n-hexane can
worsen its effects, since acetone will compete with the 2,5-hexanedione for further oxidation.
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