Sciencemadness Discussion Board - Ethanol?

Ethanol?

Acetic Acid - 11-9-2011 at 13:26

I can get denatured alcohol from the hardware store or ask a parent to get Everclear from the liquor store, but neither of these is anhydrous. Where do you get 100% ethanol?

Thanks

hkparker - 11-9-2011 at 14:12

It azeotropes with water and cannot be dried fully by distillation. Denaturents are hard (very very hard) to remove, so your best bet is to start with everclear. Distill to the highest concentration you can get. From wikipedia:

Quote:

If two solvents can form a positive azeotrope, then distillation of any mixture of those constituents will result in the distillate being closer in composition to the azeotrope than the starting mixture. For example, if a 50/50 mixture of ethanol and water is distilled once, the distillate will be 80% ethanol and 20% water (see ethanol data page), which is closer to the azeotropic mixture than the original. Distilling the 80/20% mixture produces a distillate that is 87% ethanol and 13% water. Further repeated distillations will produce mixtures that are progressively closer to the azeotropic ratio of 95.5/4.5%. No number of distillations, however, will ever result in a distillate that exceeds the azeotropic ratio.

Once you have high concentration ethanol if you really really need dry ethanol, remove the water with a drying salt (such as calcium oxide, magnesium sulfate, calcium chloride, etc).

Now denatured ethanol is still good as pure for many things, why do you want pure ethanol?

Acetic Acid - 11-9-2011 at 14:19

Everclear starts as 190 proof (95%, right before the azeotrope). So are you saying that if I just leave Everclear in a desiccator bag with calcium chloride, I can get pure ethanol?

It's just one of those things I want to have for the sake of having it.

hkparker - 11-9-2011 at 14:25

Just mix anhydrous CaCl2, MgSO4, CaO, or CaSO4 (doesn't matter) directly into the ethanol, then decant, and repeat, until the salts no longer gain mass.

[Edited on 11-9-2011 by hkparker]

Acetic Acid - 11-9-2011 at 14:26

thanks

Bot0nist - 11-9-2011 at 14:50

Here is a picture of some anhydrous ethanol. The ethanol azeotrope was obtained from distilling salted tequila. There is a little container showing copper sulfate pentahydrate that I made a while back. I just dried the copper sulfate in the oven until it was pure white. I then added it to the ~95% ethanol and shook it. The anhydrous copper sulfate gradually started to hydrate itself and turned light blue. What I am left with is a bottle with anhydrous ethanol on top of partially hydrated copper sulfate. Magnesium sulfate (Epsom salts from the pharm), or calcium chloride (DampRid) can be dehydrated in a similar manner and used as a desiccant whenever there is not a compatibility issue. Charts of different desiccants and their compatibilities can be easily found with a Google search.

Edit: Heres the link to my
<a href="http://www.sciencemadness.org/talk/viewthread.php?tid=14644&page=2#pid206362">rough Copper sulfate synth and pics</a>.
synth is two posts down.

[Edited on 11-9-2011 by Bot0nist]

redox - 11-9-2011 at 15:01

On a commercial scale, absolute ethanol is made by taking advantage of the ternary benzene, ethanol, water azeotrope that boils at 64.9C.

If 150 grams of 95% alcohol is mixed with 74 grams of benzene, 100 grams of the ternary azeotrope will distill, leaving 124 grams of pure, anhydrous ethanol.

This ethanol is unfit for drinking, due to the several ppm of benzene remaining.

In practice, a small excess of benzene is added, which is removed (after the ternary azeotrope) as a binary azeotrope boiling at 68.3C.

Acetic Acid - 11-9-2011 at 15:09

I don't have benzene

The WiZard is In - 11-9-2011 at 15:12

Quote: Originally posted by Acetic Acid

I can get denatured alcohol from the hardware store or ask a parent to get Everclear from the liquor store, but neither of these is anhydrous. Where do you get 100% ethanol?

I get to use that dirty word again book.

How a chemist would dehydrate ethanol is described in —
Brauer - Handbook of Preparative Inorganic Chemistry.
You can DL a copy from the library where science is often
most mad.

I suffer from doubts - many as too the utility of some of the
methods described here @ Science Madness.

djh
----
Science is a collection
of successful recipes.

Paul Valéry
French poet-essayist
(1871-1945)

[Edited on 11-9-2011 by The WiZard is In]

redox - 11-9-2011 at 15:22

Quote: Originally posted by Acetic Acid

I don't have benzene

Supposedly it works with cyclohexane, too. But with different boiling points obviously.

The WiZard is In - 11-9-2011 at 15:49

Quote: Originally posted by The WiZard is In

I am falling way behind my studies in gynecology via
The picture study method answering this question.

Ye old Vogel - Practical Organic Chemistry also details the
the same method as recommended by Brauer and a
procedure to produce super dry ethanol.

Vogel's book dobe in the forms library.

djh
----
FM5-34 Engineer Field Data

Raptor Intelligent Combat Outpost

Raptor introduces an entirely new concept to the combined
-arms team. A combined system involving the hand emplaced-
wide area munition product improvement plan (HE-WAM PIP)
also known as "Hornet-PIP", advanced acoustic sensors,
electronic gateways for Hornet coordination, and an overall
electronic control station.

The Raptor detects, classifies, and engages heavy and light
tracked and wheeled vehicles (see Figure 7-19). It is capable of
being ordered or programmed to develop coordinated attacks
with other minefields and/or direct and indirect fire weapons.
Once activated, the Raptor can be inactivated, allowing freedom
of maneuver through the munitions while still providing
near-real-time intelligence and situational awareness.

A hand-emplaced, top attack system, the Raptor can be used as
a stand-alone tactical obstacle or integrated with other
conventional or situational obstacles. It can communicate with
its employing unit for remote on/off/on programming
and reporting of battle-space intelligence. Intelligence data may
include target descriptions, numbers, and the direction and rate
of movement.

Because a soldier can arm the Hornet-PIP, a planning
consideration should be that the soldier moves to a safe
separation distance (500 meters) within 5 minutes of arming
this prevents the Hornet-PIP from accidentally engaging the
emplacing unit during obstacle construction.

Prudent - Proper - Planing - Prevents - Piss Poor - Performance,
and a the loss of a lot of blood!

DJH
-----
Friendly fire ..... isn't!!

Murphy's Law of Combat

Chordate - 11-9-2011 at 15:50

Distill everclear over 3A molecular seives: Absolute ethanol and no benzene. They're cheap and no one will look at you cross-eyed for ordering them.

uchiacon - 11-9-2011 at 15:55

take the everclear, then get a basic molecular sieve that'll abosorb water and not ethanol. Chuck the sieve in there, leave it to sit, then decant off the ethanol and dry the molecular sieve beads in an oven at 150C ish. Real basic bro. Or use anhydrous CaCl2 or something, and do the same process. You'll be pissed in no time mate!

Man I wish we had everclear here, I'll need to make my own ethanol if I need pure stuff/want to get abominably drunk, or work on fractional distillation and test for methanol levels.

I must say too, this forum is notorious for people offering loads of different paths of doing this, but never really putting the emphasis on the method that will actually be practical..

The WiZard is In - 11-9-2011 at 17:32

Quote: Originally posted by uchiacon

I must say too, this forum is notorious for people offering loads of different paths of doing this, but never really putting the emphasis on the method that will actually be practical..

Actually be practical is dimensionless...
being a function of what you have at hand at the moment.

I have suggested two standard references... if their methods
are not actually practical it is not a failure of the
method... the failure is the experiments lack of
reagents-equipment-experience-training-&c.

Nowhere do-it-be written down that chemistry has to be
simple. Syntheses easy to perform — with common chemicals
and simple apparatus.

djh
----
I would like to have seen Marckwald's beaker!

Working with a large quantity of crude tellurium, obtained from about 15 tons of
Joachimsthal pitchblende, the author-succeeding in preparing about 3 mgrms. of
radiotellurium, many times more active than the product prepared confirming the
view that radiotellurium is an individual radio-active substance, not identical with
Curie’s polonium. Doubtless, the latter product, like Geisel’s polonium, contains
radiotellurium, but is a mixture, not an individual substance.

[Shortly thereafter his cleaning lady inadvertently trashed da 3 mgrms.!!]

Radiotellurium. W[illy] Marckwald.
Ber., 1905, 38, 591-594.
(See this J., 1903, 49, 1146)

In:— The Journal of The Society of Chemical Industry.
5 [24] 252. March 15,
1905.

[More – Willey got an F on this lab as “radiotellurium” is in truth polonium
previously discovered by the Curie’s.]

smuv - 11-9-2011 at 19:50

CaCl2 cannot be used to dry ethanol...it simply dissolves in it...and for alcohols it is insoluble in, it absorbs the alcohol similar to the way it interacts with water.

Also MgSO4 is never indicated in literature to dry ethanol. I have my doubts of its utility here...

CaO (as mentioned), CuSO4, ternary azeotropes, Molecular sieves (all mentioned) and distillation in vacuo are reasonable methods of drying ethanol. Additionally fairly dry samples may be made quite anhydrous with Mg.

[Edited on 9-12-2011 by smuv]

kryss - 12-9-2011 at 14:07

Freezing works as well. Certainly to concentrate anyway, not sure about to get abs though.

[Edited on 12-9-2011 by kryss]

hkparker - 12-9-2011 at 14:12

Quote: Originally posted by smuv

CaCl2 cannot be used to dry ethanol...it simply dissolves in it...and for alcohols it is insoluble in, it absorbs the alcohol similar to the way it interacts with water.

Also MgSO4 is never indicated in literature to dry ethanol. I have my doubts of its utility here...

My mistake, thank you. CuSO4 came to mind, though I read somewhere its pretty exothermic with water, so I wasn't sure if it was the best option. Bot seems to have done pretty well with it so looks like it works well. Color change is nice too.

Bot0nist - 12-9-2011 at 16:05

Yeah, we conversed via u2u on this. I imagine that it probably doesn't dry it completely. But, when adding the white copper sulfate, at one point it stops turning blue. If I drip some of the alcohol from that bottle onto a little pile of anhydrous copper sulfate, it stays white. Maybe it dries it some, but can't fully break the azeotrope.

franklyn - 9-10-2012 at 15:32

Lab methods for absolute ethanol outlined
www.sciencemadness.org/talk/files.php?pid=29459&aid=379

www.sciencemadness.org/talk/viewthread.php?tid=7174&page...

Quotations from very old past postings on drying ethanol _
If you can get hold of some molecular sieve ( A4 will take water and methanol
out , A3 will dry methanol , A4 will dry ether ( batch wise)). If you can heat it
upto 250-300 ºC, you can reactivate it. Test, put some on your hand and add
one drop of water. 3A sieves rule supreme for drying ethanol. On Ebay you can
get 5 pounds capable of absorbing 15 % + of their weight in water for around $30.
Anhydrous CuS04 will also work, but I'm uncertain of solubility of Cu++ in
ethanol so distilling afterward might be prudent. It is easily prepared by heating
the pentahydrate to 200 ºC until all the blue color is gone, and you are left with
grey-white ashlike powder.

How is this for a solution ( no pun ) to the problem of ethanol drying
www.separationprocesses.com/Distillation/DT_Chp06c08.htm

.

ScienceSquirrel - 9-10-2012 at 17:24

I have just trimmed this thread.
Someone quoted a previous post and it became very messy.
It might b a fault in the software.
It looks OK now, please repost any remark I have inadvertantly removed.