Purification of denatured alcohol

Friendlycat · Mon Jun 20, 2005 5:43 am

The Denatured alcohol I use has 95% ETOH, 4.25% H2O 0.25%; MIBK, Denatonium Benzoate and Fluoroscein.

I'm told you remove the MIBK using NaOH and distilling. How exactly do you do that, and what about the rest of the junk?

Thanks,
regards FC

hAzzBEEn · Wed Jun 22, 2005 6:17 pm

I'm not sure about the "0.25%; MIBK, Denatonium Benzoate and Fluoroscein", but the water can be removed using a molecular seive. I'm glad you asked, because I wasn't familiar with molecular sieves, E85, or cars running on ethanol before I searched for the answer to your question. Someone that actually knows chemistry should enlighten us as to whether or not this process will remove the other denaturants.

riggie · Fri Jun 24, 2005 6:06 am

No, don't add water, what for?

Really it is very simple and works for me very well, just give some NaOH to the denat. alc. and distil, under vacuum or not, result is the same. I give like 10-20 g to one liter and stirr with mag. stirrer while dest.

hAzzBEEn · Fri Jul 01, 2005 6:56 pm

I stand corrected. Don't add water. Just throw in some Lye, stir, and distill.
If pure alcohol is desired, use the molecular sieve AFTER distilling.
Does the Lye remove all denaturants or just MIBK?

bio · Working Bee

......Does the Lye remove all denaturants or just MIBK?.............

Also MEK and EtOAc which are common denaturants. Me2CO would also be removed and is found in a few of the 200+ denatured alchohol formulas.

There is a US federal government document on the formulations applicable to different uses. Perhaps someone could post it as I can't seem to find it in this pile of CD's.

hahas · Sat Jul 02, 2005 11:53 pm

http://a257.g.akamaitech.net/7/257/2422/12feb20041500/edocket.access.gpo.gov/cfr_2004/aprqtr/27cfr21.141.htm

http://a257.g.akamaitech.net/7/257/2422/12feb20041500/edocket.access.gpo.gov/cfr_2004/aprqtr/27cfr21.151.htm

http://www.access.gpo.gov/nara/cfr/waisidx_04/27cfr21_04.html

bio · Working Bee

Thanks hahas, that's the one I was remembering.

It's amazing that benzene, gasoline,toluene and all manner of other shit is allowed in alcohol used in food & drug products.

The best formulas to use are the SDA 3A (5% vol MeOH) or SDA 3C (5% vol IPA).
These are readily available in tech, CP and RA grades and do not require anything except drying (if needed) for almost any purpose.

Absolute EtOH has always been a bit pricey but it's convenient, although not to Vogels "Super Dry" standard. Some RA absolute in the closet says .065% water is still in there. Until the cap is removed anyway.

Ephoton · Tue Jul 05, 2005 7:13 pm

this is probably going to be fround on by other bee's
I have always used the tast test as a way to see if denaturants
have been removed. the best way of removing denaturants I have
found was to do a ditill from caustic (lye) alcohol then acid (H2SO4)
keeping the acid in very small quantities in comparison to the alcohol
(to stop reactions happening to the alcohol in excess)
in the merk as well as some of the ketone impurities they also
state that there are bases and acids used as denaturants.
of course each brand will be different but going from base to acid
has usually done me well.
maby bisulfite might also be a good impurity remover as well (for thouse
ketones) but I have never needed to do this and I am not sure if it would
carry any new impurities after distillation

joe_aldehyde · huxleys associate

good point, ephoton. but using bisulfite for purification brings up the question of solubility - if the formed bisulfite adducts are soluble in ethanol, they could be carried over to a small extent.

i don't see how lye or acid do any good in trying to purify ethanol. does solid NaOH force the ketones to form enolate salts?

braindamage · Tue Jul 05, 2005 8:29 pm

damn lets see if i remember right-you can use azeotropic distillation,extractive distillation and of course mol. sieves...but since here they dont state what are the other denaturants,swim usually uses p.a. when he really needs it

riggie · Thu Jul 07, 2005 2:30 am

Don't put acid in the alkohol. will form esters. Pure NaOH will do the job. dest. twice. if desired. will work great, for i.e. Hg amalgam reaction

joe_aldehyde · huxleys associate

riggie, if it does the job, WHY does it do it and how did you know?

Ephoton · Thu Jul 07, 2005 5:00 pm

one would still have to distill the bisulfite solution.
not all impurities are ketones there are also acids and bases
in some denatured alcoholes. there is a section in the merk explaining
denaturents for alcohole that are comercially sutable.

Ephoton · Thu Jul 07, 2005 5:04 pm

sorry you took notice of distilling the bisulfite solution joe.
ye it might come over like a steam distill.
I dont think fractionation will remove all of the impurities I could
still tast it after using an 11 helix vigro stacked on a 7 helix vigro

Friendlycat · Sun Sep 25, 2005 12:27 pm

What about damage to the flasks? Don't know about you guy's but I love my RBF's. I get upset about the slightest scratch. So I did the 10% NaOH reflux and distillation and got apparently cleaner alcohol, orange goo and a damaged flask.

How hot does the solution have to be for the ketones to react with NaOH. I'll use vacuum but don't want more flask damage! I hate seeing those milky rings on my otherwise perfect vessels.