Author Topic: Newbee recrystallization question  (Read 1747 times)

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kjb1891

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Newbee recrystallization question
« on: March 09, 2004, 06:15:00 PM »
I know that recrystallization is used to ensure purity of substances, but how exactly do you go about doing this? Sorry, I'm fairly new at chemistry. I'm more of a biology guy.


place

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Will a singel Solvent (alkohol) ...
« Reply #2 on: March 09, 2004, 07:34:00 PM »
Will a singel Solvent (alkohol) recrystalizering be enough make the product 100% pure?

SWIM has acetone to a dual solvent recrystal., but SWIM does not know if its "dry" and still don't know how to drye it. (Have read on Rhodium).


Rhodium

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recrystallization basics
« Reply #3 on: March 09, 2004, 10:23:00 PM »
Will a singel Solvent (alkohol) recrystalizering be enough make the product 100% pure?

Definitely not, such a purity is not possible to attain. You usually need to recrystallize several times to achieve purities exceeding even 99.5%, and the number of solvents used in the recrystallization does not determine purity. Every crystal is unique, and needs its own unique treatment for the best and most efficient purification. A lot of solvents and solvent systems will work okay, but may either cause loss of product or give an inferior purification - or both. If you do not have a pre-determined solvent system you have to go by trial & error.

If you cannot find out how to dry solvents after reading the documents at rhodium.ws > Chemistry > Equipment & Lab Technique > Solvents then you really need to re-read those documents and use the search engine here to learn more about practical chemistry.


ApprenticeCook

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important parts skipped
« Reply #4 on: March 09, 2004, 10:31:00 PM »
You need to dry your solvents before recrystallization otherwise when doing something like mdma.hcl some will dissolve in the hot water portion and you will lose it...

Sadly, there is no such thing as 100% purity ever... sad facto of chemistry, however you can get to things like 99.998% (Alfa Aesar Puratronic) so the portion of impurity is so small it can be negated in this case.