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EF2000
Hazard to Others
Posts: 153
Registered: 10-5-2023
Location: The Steppes
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Mood: Taste testing the Tonka fuel
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Like that: https://www.orgsyn.org/demo.aspx?prep=CV1P0199
Synthesis of diacetone alcohol. They use Soxhlet extractor with thimbles filled with Ba(OH)2.
Wroom wroom
"The practice of pouring yourself alcohol from a rocket fuel tank is to be strongly condemned encouraged"
-R-1 User's Guide
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Organikum
resurrected
Posts: 2337
Registered: 12-10-2002
Location: Europe
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Mood: frustrated
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Bisulfite did not work for anybody in a meaningful way, why do you not just follow your own advice? And try it out before repeating the old "should,
would, might" mantra?
The H2SO4 pumice works I can vouch for it. And it is much safer for having a very small actual reaction volume. Not to talk of the excellent TOF if
good quality alcohol is used.
Why is this, people always sending others on hopeless quests like this bisulfite crap?
"If in doubt, try it out!"
Absolutely.
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macckone
Dispenser of practical lab wisdom
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Mood: Electrical
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I have done the bisulfate method and produced ethyl ether.
You need DRY sodium bisulfate which is an added prep step. Out of the bag it contains more water than the monohydrate.
You do not dissolve the sodium bisulfate, you make a slush of ethanol and the powder.
Then you heat under heavy reflux until the slush is 140C.
Next you drip in additional ethanol. It is much slower than the sulfuric acid method.
I am uncertain as to the exact mechanism since this not been studied since sulfuric acid is readily available for most people outside of the EU and
that is recent.
My guess is that it is producing sulfuric acid in situ.
It is not as easy or fool proof as the sulfuric acid method.
It also builds up water quickly and the reaction ceases when it gets too 'wet'.
Doing this on a 10ml scale and expecting results is insane. I used a 1L RBF with about half filled with sodium bisulfate before adding ethanol.
I was on the verge of screaming at the number of times people said bisulfite in this thread. That is NOT what you need.
As for references, I originally got the idea from Mellor's.
It was mentioned that it produced less tar which was my primary interest in it.
The tar clean up is the worst. It requires piranha solution.
From a practical perspective, boiling down dilute acid is easier and will yield better results. Extracting the sulfuric acid from the sodium
bisulfate would be more reliable.
While this does work it is neither practical nor preferable if you have access to sulfuric acid. And given that you can extract sulfuric acid from
sodium bisulfate, you basically have access to sulfuric acid. You can also boil down 15% acid to get concentrated acid, which my understanding is
that 15% is available in the EU.
When I get time I need to do a proper write up so it is reproducible.
A few other notes about ethyl ether formation:
the diethyl sulfate decomposes to diethyl ether and sulfur trioxide when heated. So the ester formation is at least one pathway in the traditional
sulfuric acid method.
The ethyl hydrogen sulfate reacts with sodium sulfate to produce diethyl sulfate and sodium bisulfate.
oleum and ethyl ether produce significant tar when heated together.
Sodium sulfate can sequester a substantial amount of water. The commercial technical grade sodium bisulfate probably contains significant amounts of
sodium sulfate decahydrate out of the bag explaining the need to dry it.
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MrDoctor
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I attempted to produce ether again, i dont recall how much i produced from how much ethanol overall, only that i now have well over a litre and am
happy, kind of.
I made a change to the automated process and, it seems kind of stupid in hindsight. When you introduce a PID to an immovable object so to speak, if it
is integrating, it becomes not only an unstoppable force, but one that develops an unreasonable amount of momentum too. In short i cranked up the
proportional gain about 20x what it was and turned I and D to zero and everything worked almost perfectly after that since it wouldnt try harder just
because it was spending too much time below the setpoint. it was now always stable around 3-5C below the setpoint unable to ever reach it.
I have also since learned some sources state not to control this reaction based on the temperature of the acid-ethanol but rather, only by bath
temperature, and to pretty much ignore the temperature of the acid. In my opinion now, this reaction cannot, or should not be done without a bath of
some sort, or, direct heat shouldnt be used. over the course of the reaction, the boiling point of the acid will change, or in my case did change
anyway.
Another change i implemented was using a disposable glass pipette to introduce the ethanol about half way below the surface of the acid, i just kind
of had a gut feeling and it paid off, adding ethanol below the surface resulted in an increased rate of production.
testing ether % with cold calcium chloride solution, while limiting the head temperature to that below ethanols bp, ether % went up from 35-40% to 65%
and along with it, the actual flow rate too.
I also noted the effect of simply letting the head run hotter up to 75C, more distillate came over and more ethanol was permitted to flow in, (head
temp just goes up with ethanol in anyway) but i was still seeing roughly the same amount of ether production, about 0.65ml/minute. switching to
pumping in ethanol under the acid however increased the output to 0.75ml/min for the limited time i was able to do that.
Im currently working on using activated alumina in a nice metal reactor but ill be trying sulfuric acid again because the improvements i made didnt
generate very many results, it was good but i ran out of ethanol and i want to verify exactly what impact head temperature, the use of a bath, and
adding ethanol below the surface rather than above, would have.
I also need to confirm something, i used a brand of methylated spirits called KCB, they dont disclaim what denaturants are used unlike a more
expensive MiBK based one i can get uses.
Im not huffing this ether, but i have noticed that unlike the first batch i originally made (i recorded nothing), this ether is incredibly bitter on
the tongue, i noticed this not by deliberately inhaling it but just by being in proximity. When i purified the ethanol for this i distilled once once
to produce a damn near drinkable product if not for the chemical taste from what i assume is some kind of ketone, however absolutely bitterness free.
Then i stored the distilled ethanol over KOH for a day, and distilled it again to remove ketones. no noteworthy changes. my objective though was to
eliminate anything that might produce tar. less tar did form.
Once again, the ether vapor produced was as bitter as what was made before with the previous batch. simply opening the bottle away from the hood, it
was worse than getting blowback while cleaning windows with spirits in a spray bottle. The only difference is it doesnt linger, unlike denatonium
exposure. its like whatever is doing this is volatile.
twice distilling the ether after bicarb, brine wash and drying, nothing changed, i cant imagine that its somehow got traces of denatonium in there
that it has potentiated, and is now somehow forming an azeotrope with.
The other day i made some vials with sodium carbonate, citric acid, and wet and dry activated charcoal, none had any effect either, they are control
measures i have heard some say work on the denatonium in spirits.
i dont know of any reports of other ethers regardless of whether they might co-distill, being particularly bitter, much less that they let you taste
it freely from the air just by mouth breathing in the same room as an open bottle.
Given though that whatever this is hasnt altered the boiling point, doesnt leave residue, is resistant to conc sulfuric acid and KOH, and is basically
impossible to identify or interact with at all, i wonder if at this point its safe to just ignore.
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jackchem2001
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Quote: Originally posted by MrDoctor  |
testing ether % with cold calcium chloride solution, while limiting the head temperature to that below ethanols bp, ether % went up from 35-40% to 65%
and along with it, the actual flow rate too.
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Your calcium chloride testing method sounds good. What exactly do you do? I would imagine it would be something like mixing a saturated solution of
CaCl2 in EtOH and either approximating conversion using layer size, or perhaps being a bit more precise and using the layer size of ether and its
density to deduce ether weight per weight of sample.
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MrDoctor
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| Quote: Originally posted by jackchem2001 |
Your calcium chloride testing method sounds good. What exactly do you do? I would imagine it would be something like mixing a saturated solution of
CaCl2 in EtOH and either approximating conversion using layer size, or perhaps being a bit more precise and using the layer size of ether and its
density to deduce ether weight per weight of sample. |
give that this was for tuning the process, i only needed aproximate, but relatively consistent results.
So i made a 50% solution of calcium chloride but in water. in ethanol i think it might be too miscible with the ether still. ether is not difficult
try dry most of the way. its the final 0.5% or so that gets tricky, and for my purposes i didnt need to concern myself with that. i just took 10ml of
brine, 10ml of distillate, and shook together in a 20ml cylinder to observe the change in volume of the layers.
i was seeing dramatic influences on the yield based on what i was doing, which is what i wanted.
i think the reason 50% is used is a higher concentration might boil the ether from the heat produced, at these volume ratios, and this is the lowest
conc that still works for real time testing.
Something interesting to note btw. While i cant say for sure about hydrogen and CO, ethylene is soluble in ether or ethanol. when i did this to test
the concentration of the output of my alumina reactor, since i was not properly controlling temperature well, the distillate would bubble quite a bit
as it dried, releasing ethylene. It was a cool little indicator of if overshoot had been occuring. my reactor was excessively large since i followed
something resembling hyperspacepirates ethylene converter, and could only monitor the output temp in a simple fashion. turns out it was a huge waste
of time since ethanol to ether cant convert more than 10-20% regardless of catalyst size.
[Edited on 9-9-2024 by MrDoctor]
[Edited on 10-9-2024 by MrDoctor]
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jackchem2001
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I think I may have found a way to improve the typical lab scale ether preparation. Usually, liquid ethanol is dropped onto hot sulfuric acid. Provided
the sulfuric acid is sufficiently concentrated, the boiling point of the mixture is elevated and the reaction can take place. However, I think a lot
of the ethanol flash boils over as it does not mix fast enough, so I decided to bubble the ethanol directly into the acid as a gas. A gas is both less
dense and able to be bubbled in continuously rather than added dropwise, hence minimizing the potential for flash boiling.
Check and bleed valves were used in anticipation of suck back but none occurred. If I ever have to make ether again I will definitely reuse this
procedure as reaching a steady state and managing temperature is easier.
First, 250mL of sulfuric acid was added to the reaction vessel (3). The reaction vessel was then brought to 120 degrees (measured using a thermometer
well with vasaline inside). Heat was then applied to the ethanol boiler (but heat continued to be applied to the reaction vessel). The ethanol gas
line must be very well insulated (extra foil on top of the extra silicone tubing is not shown), and there must be ample pressure release on the
ethanol boiler (in case the line clogs) and on the reaction vessel (evolution of ethylene becomes very significant above 150 degrees). Both pressure
releases separately went off as I was learning to use the apparatus, but no more after that.
The temperature is best kept between 130-145 degrees, with lower being better. During the initial warmup there will be bubbles in the gas exhaust (7).
However, if the reaction temperature is kept between 130-145 bubbling will become very slow. Distillate is still taken off very quickly (>3 drops
per second) as the bubbling reflects non-condensable gases (ethylene). Processing 3L of ethanol per day would be tedious but very reasonable. I did
1.5L over a few hours across 3 days since I don't like the ether smell.
No ether is distilled until a fair amount of ethanol is added (perhaps 100-200mL liquid), so it would probably be best to add this with the initial
250mL sulfuric acid. The ether collected initially is very pure (the head temperature is below 40 degrees). However, there comes a point where the
reaction mixture begins to foam over. At this point the sulfuric acid has become too dilute. The ethanol feed must be slowed and the fractionating
column must be insulated so water can be removed (head temperature ~60-80 degrees). This stops the foaming but the ether collected from this point is
much less pure.
The purity of the product was tested using 2.5mL of 3g CaCl2 in 10mL water solution (thanks MrDoctor and Diachrynic). I collected three fractions:
- 400mL quite pure ether (assume 100%).
- 700mL 60% ether (I think the column was insulated about half way through this run).
- 330mL 40% ether (column insulated the entire time).
Overall, this should give 70-75% yield based on the theoretical 1270mL ether. I will make another post once I distill it all to confirm. The first
fraction can probably be used as is for a lot of reactions/extractions.
Once last thing, the reaction vessel tars up pretty much immediately and it becomes impossible to see. However, the ethanol gas feed makes a lot of
noise when it is bubbling into solution. This was initially concerning, but provided there is little to no bubbling in the exhaust gas there is no
danger of an over pressure. The foaming does not represent an over pressure risk but is still a problem as it means ethanol is not being absorbed into
the acid.
[Edited on 22-9-2024 by jackchem2001]
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MrDoctor
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very elaborate, and nice, although i cant help but wonder if you couldnt at this point just totally substitute the acid for alumina in that flask
haha.
I saw improved efficiency when i was squirting ethanol well under the acid using a needle-type glass pipette, due to the extended contact time,
although this does get me to thinking, the normal reaction for which the standards of how much ether x amount of acid can produce, is essentially
based on ethanol dripping into and boiling on the surface of the sulfuric acid where it possibly draws out and vaporizes ethyl sulfate, through
solvent-extraction. when it boils, this might be what carries ethyl sulfate so hard.
With a properly water controlled reaction, it would be interesting to see just how far this can go with a given amount of acid. I have a feeling that
with the ethanol constantly in the gas-phase, aside from what refluxes, it shouldnt have the opportunity to steam distill the ethyl sulfate quite so
much. But i base this on absolutely nothing but gut feeling from watching my own reaction and, how tweaking it changed things.
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Fery
International Hazard
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Great finding! Ethanol could be also added to the bottom of the reaction flask by long stem dropping funnel. It will very likely completely boil from
liquid into gas in the glass tube much earlier than leaving the tube when reaching the bottom of the reaction flask (b.p. ethanol 78 C, T of the
mixture in the reaction flask 140 C). Also a separating funnel with long stem could be assembled into a stopper with a hole or into thermometer
adapter. Or long glass tube assembled into stopper / thermometer adapter and connect a separatory funnel to the glass tube with short piece of plastic
tubing (glass tube so long that the plastic tubing is in outside of the reaction flask so it does not melt at 140 C inside). Now to invent how to
return back the unreacted ethanol from fractionating column (to the bottom of the reaction flask) and the setup will be complete.
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jackchem2001
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I realized my original post doesn't make this very clear but I am bubbling the ethanol into the mixture using a glass stem below the joint (as in your
picture Fery but just as a gas).
I would keep going to find the limit of ether production but I am sick of my bedroom smelling like ether. The idea of using a very thin end stem below
the acid surface with liquid ethanol is interesting. It probably has the same effect as bubbling the ethanol as a gas (reduces flash boiling).
I imagine if you wanted to use alumina as a catalyst you would probably need a different apparatus as the one I used doesn't superheat the ethanol
vapor.
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MrDoctor
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I did the math, even if you bubble the alumina catalyst tube vapor directly into the ethanol reflux vessel and got 100% absorbtion of the heat, it
would only boil maybe, 20% or so as much ethanol as what originally comprised the liquid that became that vapor.
Also other downside is, for whatever reason, possibly dilution, only 10% or so ether can form in a single pass through alumina. higher % is possible
with fancy dopants but also, must be alongside ethylene, which is not great if you dont need ethylene and like me, you need to pre-process your
ethanol quite a bit due to the denaturants so wasting 2/3rds in exchange for quicker returns, doesnt quite math out.
Another thing to note is, much like the delightful past time of dumping cola into the deep fryer to make chicken-coke-nuggets, adding liquid too deep
has ill effects here too. heat creeps up the pipette and boils the ethanol, its constantly ejecting drops of ethanol then sucking up acid from the
vacuum that formed, and a little reciprocation occurs. as a result, you cant put the stem in too low, at least, not unless you can keep the bulk of
the ethanol well away from where it can be boiled. otherwise the bubbling and knocking gets pretty bad. I only added it maybe mid-way at most.
Recently i realized i might want to start collecting ethyl sulfate for another reaction, and it doesnt look like theres any reasonable way to dry and
de-tar the leftover mixture even if all the sulfate is recovered, however, now its a useful side product i almost considered making directly anyway.
So, its suddenly more economical to flesh out and automate this reaction more.
One immediate change that can be made is using a fresh new longer unbroken pipette, and bending the stem so much more is under the acid, for possibly
a nicer flash boil, but, also ill keep the area the bulk of the ethanol is, much further away so that none of that dangerous sputtering occurs.
I also feel compelled to see what will happen if i load the flask up with inert glass/ceramics, so ill try refluxing some of the nasty older batch
leftovers with some fresh alcohol. if they dont amplify foaming or bumping, i feel like it might be a good way to eliminate water from the liquid, as
well as keeping ethanol under the acid for longer. it will probably need to sit above the fluid level so evaporation can occur as well, so filling
with that much perlite is probably a no go. pummice in large chunks might do the job though.
Lastly, if you add a dean stark trap, the hydrostatic pressure from the height of the condensed fluid, will resist any back pressure from a boiling
chamber. as long as the fluid height is significantly greater than the depth of the fluid vapor ultimately gets pushed through, plus the stopcock also
adds a huge amount of resistance meaning a disproportionate amount of pressure is required. This means you can either, link the output from that dean
stark to the feed line so all condensed ethanol goes under the acid (imo probs not a smart idea, great for alumina method tho), or, you send it to
your boiling chamber/flask where it can be boiled out. This is how i plan on supplying ethanol to my alumina reactor, since it lets me avoid using a
pump (ether is not compatible with most kinds of low volume pumps), but, suckback isnt a concern there. in this however, it might be.
[Edited on 23-9-2024 by MrDoctor]
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jackchem2001
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The ethylene byproduct and low conversion per pass with alumina is a bit unfortunate. Having multiple passes with a dean stark trap like you say would
definitely help.
There is a thread in Prepublications by Magpie on diethyl sulfate preparation (https://www.sciencemadness.org/whisper/viewthread.php?tid=78...). It seems there is difficulty in distilling the material as it is high boiling
but also a bit heat sensitive. I'm not sure how practical it would be to extract from the left over ether reaction mixture.
Some inert materials in the reaction flask might help with flash boiling (better mixing due to baffles). I think flash boiling and foaming would get
worse with a recycle stream as ether has no affinity for sulfuric acid (foaming is observed when ethanol is bubbled into too dilute an acid - I think
ether would behave like this). If I ever repeat this procedure I would take the product stream and add it to the ethanol boiler to see what would
happen anyways.
[Edited on 26-9-2024 by jackchem2001]
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MrDoctor
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Oh i meant just, ethyl sulfate, not diethyl sulfate. I need to read up more but as far as i can tell, you can just neutralize it with calcium to form
the easily seperated calcium salt. Whats not clear is if it rapidly hydrolyzes in those conditions or something.
As for foaming, did you observe it before any tar had formed? i wouldnt think that bubbling ether through the acid should be an issue anyway.
from what i observed, foaming is just a problem when tar thickens then solution, but also, the water forms as extremely small bubbles, being more
readily caught and forming bubbles/foam as a result.
without either water, or tar, no foaming should occur.
Ive seen this in a patent for producing ethoxide without an alkali metal, but if you load a dean stark with a compatible dessicant, you can control
water formation. i just needs to be able to absorb water at those temps at the rate of formation. i think silica gel might work, given some ethyl
sulfate will condense over, making activated alumina or 3A unsuitable, without an acid-filter at least.
When using the alumina reactor, i noticed a lot of fog was produced when the temp spiked, which i suspect was water forming as it would steam up the
glass and coat it with droplets rather than form a nice clean solvent-film, i believe its possible to extract water from the ethanol stream by turning
the temperature down, and cycling ethanol through a few times, then cranking the heat up and collecting the new distillate seperately, as alumina can
remove water from the vapor stream, i think.
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jackchem2001
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Surprisingly methyl bisulfate salts (salts of methyl hydrogen sulfate) are used as counterions in drugs (I guess they are only efficacious as
alkylating agents under very acidic conditions so it's safe). Perhaps there may be more information on preparing it. That is the only comment I can
add about alkyl sulfates.
I observed tar formation pretty much immediately after bubbling ethanol into the hot acid. Foaming occurred much later on because I had a
fractionating column and wasn't removing water. Once insulated and allowing the head temperature to rise, foaming stopped.
My best guess for the fog is this: https://youtu.be/gyND4M2WrlI?t=360 The fog is condensable as I observed it even when there was little to no bubbling in the exhaust bubbler (which
comes from non-condensable gases so ethylene in this synthesis). I also didn't see any fog past the graham condensor.
[Edited on 30-9-2024 by jackchem2001]
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