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greenlight
International Hazard
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I did use a small amount of 98% sulfuric acid in the fractional distillation, I just forgot to mention it haha. I used 60ml H2SO4 for every 500ml of
antifreeze in the first distillation and about 16-17ml in the fractional distillation to hydrolyse impurities.
I am not sure sure if the week wait would actually affect the dioxane yield but maybe next time try it the other way and see if it makes a difference.
Also I have re-weighed the sodium yield and it is only 6 grams. Something wrong with my scale and it is fines simce I replaced the batteries. Still
a decent yield though I think..
It is very exciting to see blobs of molten Na as the solvent level gets low. I plan to run the reaction quite a few more times as I need something
like 50g elemental sodium.
I wonder if the reaction can be scaled up?
[Edited on 9-4-2018 by greenlight]
The only use for an atomic bomb is to keep somebody else from using one.
George Wald
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MöbiusMan
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https://www.sciencemadness.org/whisper/viewthread.php?tid=84...
[Edited on 15-7-2018 by MöbiusMan]
If chemistry was easy it would be called biology.
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Fery
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Pitty that there are 2 threads with the same topics 1,4-dioxane, here another one:
https://www.sciencemadness.org/whisper/viewthread.php?tid=84...
I did not want to do this reaction after seeing the nasty sticky black residue foaming into condenser in youtube, but later I changed my mind. I did
some adjustments and luckily no problems with foaming from the flask into condenser, also stir bar as well glass stayed clean. I did only the
reaction, not the workup yet. My ideas and improvements:
1.
according the 3 MB attachment by DJF90 the amount of H2SO4 should be 4% (but I do not know whether it is vol% or wt%) and not 10 vol% as used
everywhere in youtube videos as well all experiments here in the forum
I performed the reaction by using third of the sulfuric acid, 11 ml 96% H2SO4 (Lach-Ner) for 300 ml of pure commercial ethylene glycol (fichema.cz)
which is 3,7 vol% of the catalyst. If the 4% should not be volume but weight then only about 6 ml would be enough for 300 ml of
ethylene glycol.
Moreover after distilling out some product, I added fresh ethylene glycol to the flask and continued.
I did 4 cycles, the remainder in the flask before adding fresh ethylene glycol was always approx 100 ml or even more. In the last round when I
distilled out more, there stayed about 50 ml of black viscous liquid in the flask which was easy to pour out.
I processed that way approx 900 grams = 800 ml of ethylene glycol in 4 cycles (distilling out 200 ml of product and then adding 200 ml of ethylene
glycol).
The H2SO4 is only catalyst, not reactant...
2.
I used large 1 L flask for the 300 ml liquid with plenty of empty space to be safe and avoid foaming into condenser (the dead volume and distance from
surface of boiling liquid to the level of condenser also reduces droplets carried into condensate by vapor).
3.
I did not distill too far during the last cycle, for the 11 ml of H2SO4 the remainder in the flask was about 50 ml and no foaming / bumping observed.
I used heater with integrated magnetic stirring.
4.
??? maybe ethylene glycol could be dripped from additional funnel during the reaction at the same drop rate as the volume of condensate ???
5.
??? could be 75% or 85% H3PO4 used too ??? as a legal and maybe more available alternative than H2SO4 for home chemistry???
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Lionel Spanner
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Something which may be of interest is this Dow Chemical patent from 1985, which involves using diethylene glycol as a starting material, and running
the reaction under reduced pressure - hence, the reaction occurs at a lower temperature, resulting in less foaming and sludge.
I've not tried it myself, so I can't comment on its feasibility.
Attachment: 1,4-dioxane (1985 patent).pdf (511kB)
This file has been downloaded 100 times
Industrial chemist rediscovering the practical pleasures of pure chemistry.
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Fery
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Hi Lionel Spanner, interesting, my friend Bedlasky brought me diethylene glycol which are they producing. But it is not so available to home chemists
as ethylene glycol.
To prevent foaming and sludge: use less H2SO4, only approx. 4 %, it is only a catalyst. Temperature during the
reaction is approx 140-150 C thanks to high boiling point of ethylene glycol and this temperature is similar as used in production of diethylether
where you drip ethanol into 140-145 C hot mixture of conc. H2SO4 and ethanol. Do not distill too far, e.g. in my case for 11 ml of
conc. H2SO4 I let about 50 ml residue in the flask and did not distill further. Use big flask and fill it to 1/4-1/3, not more, e.g.
for 11 ml of H2SO4 + 300 ml of ethylene glycol I used 1 L flask. My ethylene glycol was also pure (commercial) as well H2SO4.
Moreover I managed to perform 4 cycles with the above amount of catalyst so I processed approx. 900 g = 850 ml of ethylene glycol. I collected approx.
800 ml of condensate. Maybe the ethylene glycol could be added from dropping funnel during the distillation.
I added 10 ml of conc. H2SO4 to the 800 ml of condensate and let to stay overnight. After half a day I performed simple distillation - I collected
everything upto 98 C which gave 500 ml of distillate and later I collected 100 ml of distillate in range 99-108 C. I added excess of K2CO3 to that 100
ml fraction and 25 ml of organic upper phase separated which I tested in small flask with inserted thermometer and on boiling the thermometer read 85
C which is close to azeotrope of 1,4 dioxane with water (88 C).
I will treat also that 500 ml fraction with K2CO3 and then KOH and distill on Hempel column (packed with Raschig rings) and variable ratio
distillation head (that's why I did not yet fractionate it more precisive, I will do that as the final step, until now I hydrolyzed
2-methyl-1,3-dioxolane = acetaldehyde ethylene acetal and now I have to remove all water present).
There stayed about 200 ml residue in the distillation flask so that 10 ml of H2SO4 and the rest could be H2O and some ethylene glycol or maybe
3-hydroxybutanal from acid catalyzed aldol condensation of acetaldehyde.
[Edited on 1-9-2022 by Fery]
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Fery
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I processed the distillate with K2CO3 . 1,5 H2O and totally 130 g was necessary, only then it did not dissolve anymore (100 g should be enough if used
anhydrous K2CO3). I kept upper organic layer circa 400-450 ml and I distilled the bottom aqueous layer circa 150-200 ml from which I collected
fraction in range 85-98 C of volume 15 ml of distillate which after salting out with K2CO3 gave 9 ml of dioxane which was added to the main portion.
To the 400-450 + 9 ml ml was added 10 g freshly fused anhydrous K2CO3 (heated in nickel melting pot for 30 minutes at 300 C) which clumped immediately
so then KOH was added incrementally, totally 25 g of KOH was necessary and was let to stay for 2 days at room temperature. Then upper layer separated
(circa 350-400 ml) and bottom layer discarded (circa 50 ml). The upper layer was then let to stay with fresh solid 10 g KOH for half a day, no more
water separated, so the dioxane was then distilled, collected fraction 95-101 C which weighed 350 g and the remainders from distillation (forerun +
residuum in flask) had 20 ml.
I did not dry it with Na as I do not plane any experiment with dioxane soon. It will be dried and redistilled before possible experiment in the
future.
I processed various remainders to increase yield as much as possible. I got 350 g of 1,4 dioxane (not completely dry) from
900 g of ethylene glycol.
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Fery
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I let the bottle with the product in a fridge for few months at +4 C. Most of the 350 g solidified and there is only circa 20 ml of liquid at the top.
As temperature oscillates slightly around the +4 C the crystals of dioxane repeatedly partially dissolve in places where there are in contact with
liquid and then crystallize back. The density of solid dioxane is higher than the density of solution dioxane+water so after long time all the liquid
mixture of water+dioxane is on the top of a solid block of pure dioxane crystals and no liquid is trapped among solid dioxane so all the liquid
containing water could be easy poured out. Even that 20 ml of liquid should be mostly dioxane and only a little of water.
[Edited on 15-11-2022 by Fery]
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Fery
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After that 350 g of the product stayed in 0,5 l bottle for almost 1 year in a fridge at +4C, in the bottom part of the flask a solid block of product
was formed and the liquid moved above. This happened due to higher density of solid 1,4-dioxane and lower density of liquid phase (this also ensures
the flask does not break unlike water expanding during freezing) and hundreds (or maybe almost thousand) of partial thaw / resolidification cycles by
small temperature oscillations in the fridge.
I poured the top liquid phase (which volume increased from 20 ml into 100 ml during 1 year) into another flask and let magnetically stirred with 2 g
of 90% KOH for 1 day. Most of KOH dissolved but still some solid KOH remained. There was a reaction very likely aldol condensation (remaining of
acetaldehyde ???) because the content turned into yellow and after few hours into brownish. After turning off the stirring a dark brown mess settled
to the bottom and the upper phase was filtered through filter paper into new clean flask using gravity filtration. 1 g of calcium metal (small 5
granules forged with hammer into thin pieces to expose fresh surface) was added to the yellowish filtrate and there was very slow and tiny bubbling of
H2. I let it to magnetically stir for 1 day and then redistill.
The 250 g of solid dioxane block was let to melt at room temperature and then magnetically stirred with 2 g of KOH, but this was very likely
unnecessary, this solid phase seems to be very pure (and no liquid seems to be trapped among crystals inside the solid block): there was no reaction
with KOH and it stayed completely clear and colorless, pellets of KOH seems to be still dry and not covered with a layer of liquid. I later added 0,25
g of calcium metal forged with hammer into thin pieces with exposed fresh metal surface and there was no reaction either. So this phase seems to be
very pure and also anhydrous. I'll redistill it too. There is no need to add KOH either drying agent (Ca or Na) into this phase, either
redistillation. Just let you know what I tried and what seems to be unnecessary.
Letting the product to sit in a fridge for 1 year seems to be enough for the purification. Initially the upper liquid phase was circa 20 ml, but
during time the trapped liquid moved from the bottom solid phase to the top liquid phase and it was easy to separate it by just simply pouring it out.
It is also a good idea to let the solid dioxane in the fridge until its usage for e.g. as a solvent for a Grignard reaction. In its solid form at +4 C
fridge temperature it is pure, anhydrous, no risk of peroxide formation.
Patience is our biggest helper.
[Edited on 16-7-2023 by Fery]
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