Sulaiman
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Diethyl ether synthesis, maximum allowed water?
I want to make diethyl ether from ethanol and sulfuric acid,
Is there a maximum ratio of water that can be present?
e. g. Would 90%ABV ethanol and 68% sulfuric acid work?
(the diethyl ether article in prepublications by len1 would indicate not, but I hope someone can make a useful suggestion)
P. S. I can use 3A sieves or KOH so wet ether is OK.
[Edited on 30-5-2020 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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Ubya
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as water is produced during the reaction, the less the water you have in the reagents the better the yield. even if you don't distill the sulphuric
acid, you can still heat it until white fumes appear, so it should be close to 98%, surely better than 68%.
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wg48temp9
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68% sulphuric acid is 72% water on a mole basis !!!
and that's not counting the extra water in the alcohol.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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mackolol
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I did the ether synthesis with 95% ethanol and 92% sulfuric and getting water outta it without fractional distillation by salting it out was true pain
in the ass. I didn't manage to get all of the water even though I treated it with anhydrous Na2SO4 few times. And don't try to dry it with CaCl2 if
you're not going to distill it later, because it will contaminate your product with calcium ions which are precipitating later during extractions with
H2SO4 and so...
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draculic acid69
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No point in doing this with diluted h2so4 as it's not hard to concentrate it.u have to heat it up anyway.
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Sulaiman
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OK, I'll leave this one for now as the only heating facility that I have at the moment is a 5 litre rbf in a heating mantle,
I'll wait until I've got my other equipment available.
Thanks.
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Panache
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im sorry there is no sensible way with those limitations. I find it particularly frustrating that one cannot simply manifest ether out of the ether.
Is there anything they didn't lie about.
It is the supposed 'king of Inhalants', like durian is the king of fruits and any anyone using the Microsoft search engine is the king of bing
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SWIM
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Do you have access to NaHSO4 ?
Could be a way around the problem.
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Sulaiman
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yes, I can buy 'pool grade' (91.5% to 95.2%),
please enlighten me.
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SWIM
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Sodium acid sulfate hydrolyzes in ethanol to sulfuric acid and sodium sulfate.
The reaction is slow at room temperature, but much faster with heat, and has been used to do reactions which would otherwise require sulfuric acid in
ethanol.
I just checked and failed to find references here for this, but I'm sure they exist.
A post about making hydrogen ethyl sulfate this way, and a report of the resulting solution producing ether when boiled.
I'll look around today for a reference to making ether this way. I believe I have seen one before.
If not, I'll give it a try here on a small scale.
I'm thinking of boiling a slurry of equimolar amounts of ethanol (90%) and the acid sulfate and adding more of the ethanol through an addition funnel
as the ether distills off.
Maybe more ethanol will be needed initially to keep the slurry mobile enough for smooth boiling.
No fractionating column so the distillate can carry off as much water as possible.
Increasing water content is what will eventually kill the reaction, so I'm thinking getting a more impure ether with
water/ethanol/ethylsulfate(maybe?) in it would be worth the trouble if the total yield is larger.
Distilling ether is not really a big deal, but I'd still rather get the most out of each batch.
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SWIM
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Well, I've been unable to find any posted procedures for this.
I was also out of non-denatured ethanol so I'm running a batch for testing it out.
250mm of glass coils and a 6:1 reflux ratio. Seems to be doing the job.
Half way through and so far the thermometer is stuck just over 78C and not budging.
Vertical stills sure save a lot on counter space.
EDIT: Well, its more vertical than it looks in the picture.
And yes, the thermometer was too short. Replaced it with a 100 mm immersion one soon after things got to temperature.
[Edited on 5-6-2020 by SWIM]
[Edited on 5-6-2020 by SWIM]
[Edited on 5-6-2020 by SWIM]
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j_sum1
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SWIM, not many of us have a lav with a stained glass window.
Just for clarity, that setup is for distilling ethanol is it not? It is unclear from your post.
I am watching this space -- I need some ether myself and I am low on high concentration H2SO4. So this looks like it could be a good way to go. Let
me know how you get on.
J.
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S.C. Wack
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From JACS 35, 794 (1913): "a mixture of 25 cc. each alcohol and sulfuric acid and 100 cc. of water were placed in the generating flask, the
temperature raised to 140C, considerable liquid distilling over, and then alcohol admitted as usual. The distillates gave on fractionation the
following results, the first 93 cc. being that obtained before the temperature reached 140°, and evidently consisting largely of water...The normal
progress of this preparation when highly diluted sulfuric acid was used shows that the water formed in the reaction does not accumulate at the
temperature employed so as to interfere with its usual degree of completeness."
See Can J Chem Eng 79, 54 (2001) on using sodium sulfate to absorb water from ethylsulfuric acid. They claim that it works.
Concentrated battery acid was suitable for me for years.
[Edited on 6-6-2020 by S.C. Wack]
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SWIM
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@ S.C. Wack: Thanks for the references.
And the advice.
I've used concentrated battery acid too, but lately I've noticed the trouble a lot of our members from other parts of the world have in getting acids
and have become interested in finding some practical alternatives.
There are a few Ideas for making Sulfuric acid I'd like to try out as well.
If I have any luck, or learn anything useful I may do a thread on alternatives to sulfuric acid and alternative sources for it.
@j-sum1:
I didn't have any non-denatured ethanol left so I'm distilling some cheap vodka with salt to get some for the test.
Also testing out these 4 x 12 mm glass coils as packing. So Far they seem to be pretty good.
The stained glass is because I don't mind distilling alcohol in the kitchen. (Observe the towel racks behind the still)
The real lab is a garage with a low ceiling, but for taller projects (and smellier ones) there's a sort of greenhouse about 14 feet high that's also
stained glass. The thread, big old still, has some pictures from out there.
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
All this glass came out of a demolished church and was installed here by the previous owner. (I suspect he had a personal interest in alkaloids, even
though he was clearly no chemist.)
[Edited on 6-6-2020 by SWIM]
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SWIM
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I think I made ethylene by mistake last night, but will give it some thought and another go.
Ethylene and considerable ether smell.
Also, I missed the point of S.C. Wack's post above in relation to Sulamain's immediate problem:
That it should work fine to just use the dilute H2SO4 and the water should boil off to allow the reaction to proceed.
That is, if I'm not missing something.
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S.C. Wack
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Yes. Some care is taken in many preparations of ethylsulfuric acid, but on the whole it seems resistant to change until the higher temperatures are
reached. One could skip acid if that was a problem, with alumina at 250C.
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