Or should I roto it first and separate the eth out first?
Can you do 5 gallons of 99% iso?
We definitely can. Normally thats an order we would push to a retailer but if you email Sales@Carbon-Chemistry.com we can see what we can do for you.
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So just add 5%ro water to the 95/5 denatured stuff
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You cannot distill (roto) it to separate it. Thatās what defines an azeotrope. As @square_root_pharms said, you just add 5% water to 95% of the mixture.
So for every 100ml, you want it to be 5% water, 5% heptane, and 90% ethanol. This takes iterative math to calculate.
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At what portion of water does the heptane start separating out?
Well I got about a dozen jars with 200g and 2l of this solution in the deep freezerā¦ going to funnel it and rotovap it then short path itā¦ fingers crossedā¦?
Downtown said theyāre selling a lot of this to avoid the tax on buying etoh for winterizing
You can Winterize it as is, but it works better with that little bit of water. If the container is not sealed, it will likely pick up water from the air to make the ethanol portion 190 proof, anyway. I am pretty sure thatās how the stuff works for people in the first placeā¦ they just donāt realize it is happening.
@Alchemist , the short answer is I donāt know if it even does that, but if it does, the amount of water is probably too much to leave the ethanol useful, since heptane and ethanol form an azeotrope up to 51% heptane in ethanol.
Naturally, I have a long answer, too. First, you must understand that the point of denaturing ethanol is to make it into an inseparable mixture, so that it cannot be made drinkable by easy methods. Partitioning is really easy. Distillation is easy. In order to separate denatured ethanol from its denaturants, it usually takes something that more strongly azeotropes with the denaturant, then subsequent distillation.
Water forms a hydrogen bond based azeotrope with ethanol, which is quite strongā¦ strong enough to make the ethanol more dense than it is without the water. However, ethanol only needs about 5% water (actually a little over 4.4% water to ethanol by mass), so during distillation, any water in excess will stay behind after the 95:5 azeotropic mixture has all boiled off, because water has such a high boiling point relative to the azeotrope and to ethanol, itself.
Now, the ethanol azeotrope with heptane is likely a strong van der Waals interactionā¦ so it is a more evenly distributed azeotrope, almost half and half, although the actual molecular bonds are weaker. The thing is, in chemistry, the interactions generally follow a logarithmic pattern, so the first stuff that happens is composed of āstrongerā events than the subsequent stuff. A good example is the way a triprotic acid (like citric) has 3 different pKa valuesā¦ a (relatively) strong protic dissociation first, then a significantly weaker moderate one, then one that is so weak that it cannot even happen without a base present in the water with it. The p in pH and pKa signify the logarithmic nature of hydric and hydroxyl dissociation. Logarithms are basically exponents in powers of 10ā¦ so log 1 is way smaller than log 2, which is hella more smaller than log 3, etc.
As usual, I digress. The practical upshot is that although 5% water has a stronger ethanol azeotrope than that between heptane and ethanol, its small percentage is not sufficient to break the initial (first 5% heptane) bond with ethanol on its own. Instead, a ternary (3 part) azeotrope is formed, which all boils together at a specific b.p., just like any binary azeotrope.
The only way to break that strongly bound 5% heptane away from the ethanol with water (and this is just a hypothesis) is likely to overwhelm it with so much water that the solution is almost completely water. This may coax the heptane to separate out because there is enough water to overcome the bond strength between all the 19:1 EtOH:heptane bonds and partition the heptane outā¦ or it may just make a very watery ternary mixture.
That said, assuming the 5% heptane bonds are equally as strong as the 5% water bonds with ethanol, my guess would be that partitioning starts with about 19 parts water to 1 part 5% heptane:EtOH. Unfortunately, all bets are off if the heptane is composed of mixed C7 isomers, because they each have different bond strengths with the ethanol. It may be easier or harder to partition each individual isomer from the aqueous ethanol, depending on their various bond energies in the azeotrope. Hell, that might be a great way to isolate isomers in general, for all I know. Interestingā¦
Iām glad we broached this subject here as an intellectual exercise, but if you do find the magic numbers, please do not broadcast themā¦ because we do NOT want the powers that be to ban heptane-denatured ethanol, since it is the safest (re: health) denatured (i.e. less expensive) ethanol for us to use in our processes. Thank you! 
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thanks for that in depth response!
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Going to roto here in a bit Iāll post some photos
Well rotoing it now looks to have maby let more thru than normal sop I do. Will see tomorrow when distilling if there is an issue. It didnāt seem to cake up as much as normal when funneling which I take it is the heptane like you mentioned being more lipophilic @Photon_noir
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Iām not sure I understand. āThe roto looks to have let more throughā. Let what through?
āIt didnāt cake up as much when funnelingā do you think this is a function of the danatured solvent not freezing out waxes as efficiently as straight etoh?
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Ya it looks like a dirty solution but roto all the way down n itās kinda ok. Il see how it goes today in the dilly
Did you add the 4.4% water by weight or any water at all prior to freezing and filtering, or is this just straight heptane-denatured ethanol? Thanks for the report!
I didnāt add any I figured capping with wrap would allow some moisture. It went pretty smooth Iām waiting tell tomorrow to distill about 4 liters so hopefully the return is well and everything is ok.
Yeah, the return should be fine. The potency will just be a little lower from the lipids and wax in there. You can always re-Winterize.
Doin the first pass now and Iāve had to significantly raise my mantel to get the first fraction
Check your vacuum lines, especially around the cold trap, to make sure they are not clogged. That is usually the culprit, if not an apparent vacuum leak.
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Iāve got a great -30 vac I use a Welch 1400 itās super deep
Iām thinking also residual solvent evaporating was cooling the system as well making me increase temp