solo
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Need suggestions on method to remove water from the ionic soluton ......
Aside from distillation any suggestions or method to remove water from the ionic soluton of 1-methylimidazole and HCl.........solo
Note: addendum, ....also would there be any reaction with the amine group in a primary amino alcohol while attempting to halogenate
this alcohol?
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HX is immobilized by reaction of halogen acid with methylimidazole, and the formed ionic liquid [Hmim]X was used as halogenating agent, catalyst as
well as medium for conversion of alcohols to alkyl halides. Excellent yields were obtained. The halides produced could be easily separated from the
reaction mixture via simple decantation, and the ionic liquid [Hmim]X could be regenerated conveniently by adding equivalent of halogen acids followed
by removal of water. Hence, for the whole process, the reaction consumed equivalent of halogen acid and alcohol to produce halide and water.
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................source,
Immobilization of HX: [Hmim]X as Halogenating Agent,
Recyclable Catalyst and Medium for Conversion of
Alcohols to Alkyl Halides
WU, Hai-Hong( ) SUN, Jing( ) YANG, Fan( )
TANG, Jie*( ) HE, Ming-Yuan( )
Chinese Journal of Chemistry, 2004, 22, 619-621
[Edited on 31-5-2006 by solo]
Attachment: HX- [Hmim]X Conversion of Alcohols to Alkyl Halides copy.pdf (47kB)
This file has been downloaded 1076 times
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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solo
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I guess I'll try adding dryrite pellets and see if the water is removed ............it seems like it's the simpler thing to do, as the pellets can be
placed in the oven and dried for reuse or not? I guess if they're cheap enough to just use a fresh supply......as for the reactivity with the amine
since the 1-methylimidazole is an amine and it releases the Cl to be bonded with the vacated OH site by the reaction with H to make H2O hence I don't
forcee any activity at the amine site.. ...will try and see as this seems like an excellent method for halogenation of primary
alcohols................solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Nicodem
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But what exactly is the problem? Could you elaborate at which step and where exactly you have troubles?
I know somebody who used that method and he simply followed the indications from the paper. That is, to neutralize 1-methylimidazole with conc. HCl
and strip off the water in a rotavapor in a boiling bath. I went to ask him again and he said the hydrochloride solidified but it was so hygroscopic
that if left for a few minutes on air it would liquefy. He reported no special troubles other than hygroscopicity.
Solo, I was unable to follow your arguments on the interference of the amine group with the substitution reaction and why would the forming water
prevent such a thing. But anyway, off course the amino group would interfere. It is more basic than 1-methylimidazole and thus it would neutralize one
equivalent of [Hmim]Cl. This can be avoided by using the hydrochloride or sulfate salt of the amine in the first place. Then you still have the
question if the neighboring protonated amino groups interferes with the reaction. Obviously a charge nearby will have a very large influence, but I
don’t know if favorable or unfavorable. I vote for the unfavorable, but you can’t be sure before you do the experiment.
…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!
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jack-sparrow
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I agree with Nicodem, these imidazolium are so hygroscopic that the chinese researcher probably confused real ionic liquid such as
N-butyl-N'-methylimidazolium salts and the hygroscopic N-methylimidazolium chloride which is a solid and not a liquid.
Furthermore, I would suspect that your amino-halogeno compound would undergo (intra or intermolecular ?) coupling with elimination of HX captured by
the imidazole moiety. Remember the alkylation of amines with RX in presence of a base.
For drying solutions, I suggest calcium chloride, or sulfates (Na, Mg) nothing that can interfere with imidazole or HCl.
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Nicodem
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Studur, aziridine formation should not be a problem since, like I already said, the amine will be protected by protonation due to more than 100-fold
difference in acidity with [Hmim]Cl. I don't think the formed equivalent of 1-methylimidazole would be enough basic/nucleophilic to drive the
cyclisation, especially since it is buffered to neutrality by the excess of [Hmim]Cl.
But anyway, I wouldn't be so sure the substitution would work on a primary alcohol with a neighbouring amino group in the first place.
Solo, I suggest you reread another thread that you initiated: https://sciencemadness.org/talk/viewthread.php?tid=4654#pid5...
The simplest possible solution to your continuous question has already been presented to you, but you obviously missed it. I even uploaded you the
required paper. And it does not require any fancy methods, only proved ones…
…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!
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