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Harmless
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post tosylation purification
Hi
to create this molecule: N-benzyloxycarbonyl-ethanolamine tosylate, I'm planning to tosylate this molecule:
http://www.sigmaaldrich.com/catalog/product/aldrich/407909?lang=de®ion=AT
with tosyl chloride: http://www.sigmaaldrich.com/catalog/product/fluka/89730?lang=de®ion=AT
I intend to do it in pyridine as the base. But I need to know is how to purify it afterwards to get the substance pure.
I was thinking about using the melting points to precipitate it and then re-crystallize it later on (I'd still need to know which salutes to
recrystallize later on). Since I don't know it's melting point, as it seems to be a rare compound/combination, I was thinking I just look into all the
expected compounds in the end solution, and if anything precipitates at a temperature which rules without being any of the expected compounds, then
I'd know it's quite likely the desired compound/product.
Or would anyone have a better idea, like using a liquid liquid extraction, and which strategies/solutions should I use there?
[Edited on 2-6-2014 by discard]
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Harmless
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the rest of the post
I've seen online that someone added 10 times more 2N HCl than pyridine after the reaction. Was that a purification step?
Because the tosylate alchohol precipitates due to lack of a basic environment
I'd like to post more but this forum is quite buggy (no offence :))
[Edited on 2-6-2014 by discard]
[Edited on 2-6-2014 by discard]
[Edited on 2-6-2014 by discard]
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Harmless
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I've understood that the 2N HCl causes the pyridine to form pyridine hydrochloride. Decant the fluid out and evaporate the remaining HCl ?
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Nicodem
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Quote: Originally posted by discard  | | I was thinking about using the melting points to precipitate it and then re-crystallize it later on (I'd still need to know which salutes to
recrystallize later on). |
Judging from what you say, this must be your first synthesis ever. In such case it is pointless to reinvent the wheel. Follow a published procedure
for the synthesis of TsOCH2CH2NHCbz. I'm not going to search the literature instead of you, but I'm sure the compound is well
known and this synthesis reported. In the unlikely event it isn't, follow the synthesis of a similarly protected aminoethanol (e.g., N-Boc or other
carbamates). It is all fine to start ambitiously, but one needs to know his limitations. Not even a synthetic chemist with years of expertise would
bother developing the synthesis of such a simple product unless unsatisfied with the published procedure. Well perhaps a lazy chemist with plenty of
O-tosylation reactions experience would thought it clever to just set an experiment and only check the literature later (but such attitude does not
yield well on a longer run).
PS: Threads without references belong in the Beginnings section only. Please read the forum guidelines for more information. Also, please do not make
unwarranted publicity to chemical sellers. You can upload a reaction scheme when you want to show the structures. It is way more practical.
…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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Nicodem
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Thread Moved
2-6-2014 at 22:29 |
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Harmless
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Thanks, that turned out to be useful. I found a synthesis for N-Boc ethanolamine. http://www.rsc.org/suppdata/ob/c2/c2ob25258a/c2ob25258a.pdf page 4
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