Mailinmypocket
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Separating Lidocaine from other ingredients
I have recently obtained 50ml of "Xylocaine" solution (Lidocaine HCL 2%), I am not so much interested in the Lidocaine itself but I would have many
uses for the nice bottle and septum it comes in. Before essentially throwing away the contents of the bottle, I decided that it might be neat to at
least try and extract the lidocaine in dry form and keep it just for the sake of it. Looking at the ingredients though it seems like this will be
quite difficult:
1g/50ml lidocaine
Other ingredients:
NaCl
Methylparaben (1mg/ml)
Water
NaOH and/or HCl to adjust pH to 5.0-7.0
Preservative (no description)
Obviously the water can be removed but separating the Lidocaine from other salts seems sort of difficult, and given the amount present, might not even
be worth the trouble... It was just an idea, any comments would be appreciated though 
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ScienceSquirrel
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Add a strong, weakly nucleophilic, base, I would suggest potassium carbonate, and extract with ether.
Remove the ether and dissolve the free base in ethanol, add hydrochloric acid dropwise to form the hydrochloride and crystallise.
I reckon that or something similar will sort it!
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Mailinmypocket
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Thanks for the advice! Im going to have to use sodium carbonate, as for the ether extraction... The best I have is a solvent mixture of diethyl ether
and heptane (otherwise known as starting fluid) Im assuming this would probably work OK/wouldnt affect the outcome that much, being a non-polar
solvent?
[Edited on 27-5-2011 by Mailinmypocket]
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ScienceSquirrel
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Have a look at this search, plenty of ideas there.
http://www.netscape.co.uk/aol/search?s_it=topsearchbox.webho...
I think you might have to use potassium or sodium hydroxide to liberate the base.
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entropy51
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The only constituent present in significant amounts will be NaCl, less than 1 gm per liter, or 0.05 gm in 50 mL.
I say this because normally 0.9 gm per liter of solution is used to make the solution isotonic for injection.
If you just evaporated off the H2O under vacuum you would be left with 95% pure lidocaine. Do you need it more pure than that?
Putzing around with extractions may just add more impurities than you remove.
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Mailinmypocket
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At this point that is what I am starting to consider, Ill just evaporate the liquid and call it quits from there... If the quantity was greater then I
would attempt a more elaborate extraction but if the "at best" yields would be 1g, I think I will just deal with the impurities. I really just feel
bad flushing it down the drain, Ill evaporate under a vacuum and see what happens, and post pictures once completed!
[Edited on 28-5-2011 by Mailinmypocket]
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entropy51
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Sorry, my bad. Isotonic sodium chloride is 0.9 gm per 100 mL, not per liter. So your 50 mL probably contains 0.45 gm of NaCl. If you just want to
save it for possible future use, this might still be acceptable, but not as pure as my flawed calculation above.
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Mailinmypocket
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Hey no problem! It's not like I have a real use for the minute amount of lidocaine anyways so I'm letting it evaporate as it will, and then maybe
dissolve the residue in a bit of solvent to separate the NaCl from the rest..depending if I have nothing more interesting to do lol
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The WiZard is In
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Quote: Originally posted by Mailinmypocket  | | I have recently obtained 50ml of "Xylocaine" solution (Lidocaine HCL 2%), I am not so much interested in the Lidocaine itself but I would have many
uses for the nice bottle and septum it comes in. Before essentially throwing away the contents of the bottle, I decided that it might be neat to at
least try and extract the lidocaine in dry form and keep it just for the sake of it. Looking at the ingredients though it seems like this will be
quite difficult: |
Properties: Needles from benzene or alcohol, mp 68-69°. bp4 180-182°; bp2 159-160°.
Insol in water. Sol in alcohol, ether, benzene, chloroform, oils.
Partition coefficient (octanol/water, pH 7.4): 43.
http://en.wikipedia.org/wiki/Partition_coefficient
-----
IUPAC
partition coefficient [obsolete]
This term is not recommended and should not be used as a
synonym for partition constant, partition ratio or distribution ratio.
See also: distribution constant
Source:
PAC, 1993, 65, 2373 (Nomenclature for liquid-liquid distribution
(solvent extraction) (IUPAC Recommendations 1993)) on page
2385
PAC, 1996, 68, 957 (Glossary of terms in quantities and units in
Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page
986
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The WiZard is In
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| Quote: Originally posted by Mailinmypocket | | I have recently obtained 50ml of "Xylocaine" solution (Lidocaine HCL 2%), I am not so much interested in the Lidocaine itself but I would have many
uses for the nice bottle and septum it comes in. Before essentially throwing away the contents of the bottle, I decided that it might be neat to at
least try and extract the lidocaine in dry form and keep it just for the sake of it. Looking at the ingredients though it seems like this will be
quite difficult: |
Properties: Needles from benzene or alcohol, mp 68-69°. bp4 180-182°; bp2 159-160°.
Insol in water. Sol in alcohol, ether, benzene, chloroform, oils.
Partition coefficient (octanol/water, pH 7.4): 43.
http://en.wikipedia.org/wiki/Partition_coefficient
-----
IUPAC
partition coefficient [obsolete]
This term is not recommended and should not be used as a
synonym for partition constant, partition ratio or distribution ratio.
See also: distribution constant
Source:
PAC, 1993, 65, 2373 (Nomenclature for liquid-liquid distribution
(solvent extraction) (IUPAC Recommendations 1993)) on page
2385
PAC, 1996, 68, 957 (Glossary of terms in quantities and units in
Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page
986
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