Triazine
Harmless
Posts: 6
Registered: 11-8-2012
Member Is Offline
Mood: No Mood
|
|
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.
|
|
Nicodem
Super Moderator
![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif)
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by Triazine ![](images/xpblue/lastpost.gif) | 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)
Read the The ScienceMadness Guidelines!
|
|
phlogiston
International Hazard
![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif)
Posts: 1378
Registered: 26-4-2008
Location: Neon Thorium Erbium Lanthanum Neodymium Sulphur
Member Is Offline
Mood: pyrophoric
|
|
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?
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer
|
|
AndersHoveland
Hazard to Other Members, due to repeated speculation and posting of untested highly dangerous procedures!
![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif)
Posts: 1986
Registered: 2-3-2011
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by phlogiston ![](images/xpblue/lastpost.gif) | 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]
|
|
BromicAcid
International Hazard
![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif)
Posts: 3237
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
Reminds me of this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=1312
|
|
Triazine
Harmless
Posts: 6
Registered: 11-8-2012
Member Is Offline
Mood: No Mood
|
|
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.
|
|