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tom haggen
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[*] posted on 14-1-2004 at 08:03
glycerin


I found these suppositories that contained glycerin usp . does anyone know how to extract glycerin from glycerin usp?

[Edited on 14-1-2004 by tom haggen]




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AngelEyes
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[*] posted on 14-1-2004 at 09:31


Glycerin USP is just glycerin that has been manufactured to a specific standard, yes? In this case the USP standard. I can't remember what the acronym stands for though...

Just found it: USP = United States Pharmacoepia

Can you not just buy glycerin OTC in the US? If you get it from a pharmacy it will be the pure stuff. You seem to be able to buy most other stuff in the US...

[Edited on 14-1-2004 by AngelEyes]
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tom haggen
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[*] posted on 14-1-2004 at 11:30
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ok it stands for united states pharmacopeial convention. I guess my real question is how do I extract glycerin from a glycerin and sodium hydroxide mixture. If glycerin is insoluable in water than i can just mix with water and filter out the glycerin right? sorry about not putting this in the general chemistry section



[Edited on 14-1-2004 by tom haggen]




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[*] posted on 14-1-2004 at 11:31


Glycerin can be found in pharmacies in little bottles (not as laxatives)... I don't remember its specific purpose, but I found them in the first aid section in Rite Aid, near the Ipecac (is that the spelling?) Syrup.

As a laxative, it is only 80%... I believe most of the rest is water, and probably some binder. One way to purify it may be to heat it to a liquid, and then add a suitable desiccator. It shouldn't be too strong, as it would then react with the Glycerin, but strong enough to absorb the water.
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[*] posted on 14-1-2004 at 12:07
Glycerine, uses and sources


Extracting pure glycerine from suppositories might be a difficult enterprise, from what I have read. Dope fiends have great difficulty extracting the components of such mixtures, drugs and glycerine form very intimate and tenacious mixtures.

Glycerine is a byproduct of biodiesel production, there are pilot plants all over the country and at various universities, you might simply be able to procure a cake for the asking. If not you could buy some glycerine soap base from one of many soaperies (that cater to bored and crafty housewives)

One might consider a specialty soap as a more ecomically logical OTC feedstock for Glycerine. Glycerine is a component of glycerine soap, which is made from denatured alcohol, glycerine, sodium castorate (from castor), sodium cocoate, sodium tallowate, sucrose, water and parfum (fragance). Sometimes one adds sodium laureth sulfate. Someone might consider this almost a classic case scenario for fractional distillation.

Or, if your need was immediate and you wanted the peace of mind of extraordinairily high purity, a common and completely innocent use for pure pharmacuetical grade glycerine is to preserve leaves. You could simply go to a chemical supply house and ask for it,

To preserve leaves,Use a mixture of one part glycerin to two parts water. Place the mixture in a flat pan, and totally submerge the leaves in a single layer in the liquid. You'll have to weight them down to keep them submerged. In two to six days, they should have absorbed the liquid and be soft and pliable. Remove them from the pan and wipe off all the liquid with a soft cloth. Done correctly, the leaves will remain soft and pliable indefinitely.

Good luck.




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guaguanco
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[*] posted on 14-1-2004 at 13:42


Quote:
Originally posted by tom haggen
ok it stands for united states pharmacopeial convention. I guess my real question is how do I extract glycerin from a glycerin and sodium hydroxide mixture. If glycerin is insoluable in water than i can just mix with water and filter out the glycerin right? sorry about not putting this in the general chemistry section
[Edited on 14-1-2004 by tom haggen]

Why do you need to separate glycerin from an NaOH solution? Pure glycerin is freely available in the US.

Glycerin is miscible with water, so you'll have to look for another purification method. Vacuum distallation comes to mind...
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[*] posted on 14-1-2004 at 13:48


You can buy small containers of glycerine (100 ml or so) in larger chain stores in the health sections. It is used "As an emollient or skin softener." (apply locally)



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[*] posted on 14-1-2004 at 18:11
Or...


Separation of glycerin from NaOH is also possible if you have no Distillation apparatus or aspirator.But you do have a knowledge of chemistry!:D

One could titrate an equimolar quantity of sulfuric acid into the glycerine/NaOH sol'n. The hydroxide would be neutralized and sodium sulfate formed which is unfortunately fairly soluble in water.

However, glycerine is also miscible in alchohol while sodium sulfate is not, so if you dry the glycerine and then mix the dry glycerine/sodium sulphate in alchohol the sodium sulphate will precipitate out and then pure glycerin could be decanted off or filtered.:D
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[*] posted on 14-1-2004 at 19:27


Or one could buy 99.5% Glycerin USP for $1.50 per 118 mL at any pharmacy or large grocery store in the United States. CVS, Eckerds, and Walgreens all have it labeled pure glycering the grocery store has it labeled 99.5% from a company called humco, check out there website at www.humco.com . Still that's a damn good method Hermes.



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tom haggen
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[*] posted on 14-1-2004 at 20:11


emolient (sweet oil)sold at the stores near me it says the ingredients are olive oil. hermes, I had though about adding an acid and testing with a ph tester untill my solution was neutral. I just wasn't sure what to do afterwards. You sure cleared that up. however, when the glycerine/sodium sulphate is added to alcohol, the sodium sulphate is what should be filtered out an then the left over alcohol evaporated leaving pure glycerine?

[Edited on 15-1-2004 by tom haggen]




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[*] posted on 15-1-2004 at 09:49


Tom,Hi!
Try a tack store or saddlery.Horse people use it for a variety of reasons.Specifically as a "sweat" to reduce edema in horses legs.You should be able to buy it by the gallon.




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Hermes_Trismegistus
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smile.gif posted on 15-1-2004 at 11:20
in response to Mr. Haggen.


Yes, the sodium sulphate is what will precipitate out, however...realistically, you have to take into account the practical difficulties, the glycerine must be completely dried before the alchohol is added, and that might take awhile(days and perhaps you might have to place the glycerine in a sealed container with a powerful dessicant like sulphuric acid or calcium chloride).

Also, the alchohol would have to be practically anhydrous (unless the glycerine molecules had a greater affinity for the water molecules than the sodium sulphate molecules had for the water). If not, then quantity of sodium sulphate removed from the glycerine would be a direct function of the amount of water in your alchohol.

and as for filtering, it would be difficult to filter a thick glycerine sol'n (you'd wanna minimize the water in sol'n so you'd put just enough alchohol/water azeptrope in the sol'n to make it fluidic).

You could calculate the maximum possible amount of sulphate contaminant by calculating the maximum solubility of the sodium sulphate in water and the total water present in your glycerine/alchohol/water mix.

This method would present a challenge, but it's not impossible, nor expensive, just time consuming.

All things considered, I feel that purchasing commercial glycerine is the way to go from a procurement standpoint, but I have attempted to answer the question you actually asked.

Besides.....You didn't post this in the "Reagents and Apparatus Aquisition" topic!!!

:D




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tom haggen
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[*] posted on 15-1-2004 at 17:39


hey wrench buddy ol pal. sorry about that nitromethane thread. I needed to be put in my place. well it turns out I found a source of 100% glycerine. But what the hell, extracting glycerine from a glycerine NaOH solution made for a good chat. I might even try a lab like this some day. and I just got my 3rd star with this post. Rock on! Also Hermes, I thought that information on preserving leaves was fucking cool! I guess i consider myself somewhat of a naturalist I just need to travel more. Anyway I will definitely be trying that method of preserving leaves.





[Edited on 16-1-2004 by tom haggen]




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[*] posted on 16-1-2004 at 13:23


Hermes, how did you plan to remove the alcohol from the glycerin (after ppting th Na2SO4)?
I guess you could do it in a desiccator over CaCl2
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