Sciencemadness Discussion Board - 1,4-Dioxane from Ethylene Glycol and H2SO4

1,4-Dioxane from Ethylene Glycol and H2SO4

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MrMario - 12-2-2016 at 06:27

Hello,

I want to make 1,4-Dioxane from EG and Sulphuric Acid (catalyst) by Dehydrogenation. The reaction forms 1,4-Dioxane (Bp. 101), H2O (Bp. 100) and 2-methyl-1,3-dioxolane (Bp. 75) in smaller quantities. I want to use fractional distillation to separate the 2-methyl-1,3-dioxolane from the water and 1,4-Dioxane and than salt the Dioxane out of solution.

What kind of salt can I use for this? On youtube someone uses K2CO3, but does this also work with NaCl, Na2SO4 or Na2CO3 (all anhydrous ofcourse)?

Edit: corrected spelling in title

[Edited on 11-29-2023 by Texium]

PHILOU Zrealone - 18-2-2016 at 08:05

Should work, the only aim of the salting out effect is to take care of the water activity sothat it is less available for the organic molecule that is then kicked off solution...salting out effect also works by a density change favorizing the segregation of the organic phase vs the aqueous one.

UC235 - 18-2-2016 at 11:56

I've done this before. Workup is complicated by:

1) There is a fair amount of free acetaldehyde in the crude distillate.

2) 2-methyl-1,3-dioxolane is completely immune to base, including molten sodium metal.

3) 1,4-dioxane forms an azeotrope with water boiling at 88C and containing 18% water.

My suggestion is to take the crude distillate and add in solid NaOH in small portions with shaking. This salts water out and polymerizes free acetaldehyde. You're going to need a lot of it. The liquid will turn dark brown and tarry matter will settle out on standing. Decant the liquid and discard the lower layer. Allow to stand for more time over solid NaOH prills/pellets. A large column will be able to separate the two components in the absence of water but it is a very difficult fractionation.

Alternately add a portion of ~50% aq sulfuric acid and stir overnight. Carefully neutralize with conc. NaOH solution (it gets very hot. you will need to stop and let it cool). Add more solid NaOH to salt out water and polymerize the acetaldehyde you produced by destroying 2-methyl-1,3-dioxolane. Dry again over solid NaOH. I do not know if this is sufficient to destroy all the dioxolane but it will probabl make the fractionation easier.

DJF90 - 18-2-2016 at 14:52

Quote: Originally posted by UC235

I've done this before. Workup is complicated by:

1) There is a fair amount of free acetaldehyde in the crude distillate.

2) 2-methyl-1,3-dioxolane is completely immune to base, including molten sodium metal.

3) 1,4-dioxane forms an azeotrope with water boiling at 88C and containing 18% water.

My suggestion is to take the crude distillate and add in solid NaOH in small portions with shaking. This salts water out and polymerizes free acetaldehyde. You're going to need a lot of it. The liquid will turn dark brown and tarry matter will settle out on standing. Decant the liquid and discard the lower layer. Allow to stand for more time over solid NaOH prills/pellets. A large column will be able to separate the two components in the absence of water but it is a very difficult fractionation.

Alternately add a portion of ~50% aq sulfuric acid and stir overnight. Carefully neutralize with conc. NaOH solution (it gets very hot. you will need to stop and let it cool). Add more solid NaOH to salt out water and polymerize the acetaldehyde you produced by destroying 2-methyl-1,3-dioxolane. Dry again over solid NaOH. I do not know if this is sufficient to destroy all the dioxolane but it will probabl make the fractionation easier.

That second method looks much better than the first UC but I still feel it is lacking... lets think through this rationally...

In the reaction two molecules of ethylene glycol are condensed to produce one mole of dioxane and two moles of water. Acetaldehyde, 2-methyl-1,3-dioxolane and more water are formed as side products from competing reactions. Addition of concentrated sulfuric acid (theres enough water already present) to the crude mixture and arranging for distillation at e.g. 50 *C should hydrolyse the 2-methyl-1,3-dioxolane and remove acetaldehyde as an overhead product (bp 20.2 *C). With any luck any ethylene glycol formed in this hydrolysis will either form more dioxane, or undergo pinacol rearrangement to give acetaldehyde which is removed during distillation.

As such, the mixture at this point should consist only of dioxane, water and sulfuric acid. Fractionation of this mixture should give the dioxane-water azeotrope as an overhead at 87.8 *C, which has the composition of 18 %w/w (52 mol%) water, i.e. half of the water formed in the original condensation reaction (see stoichiometry) will remain as bottoms with the sulfuric acid which was added for hydrolysis of the side product 2-methyl-1,3-dioxolane.

The dioxane-water azeotrope so obtained could be further processed by salting out. Potassium carbonate is a good candidate as it has good solubility in water (52 %w/w at 20 *C). 100 g of azeotropic distillate contains 18 g water and so should be treated with ca 18 g potassium carbonate. The dioxane phase should be separated, dried over further potassium carbonate (or other dessicant) if necessary and purified by fractional distillation - any residual water passes over first as the azeotrope (saved for reprocessing with a future batch) and subsequently anhydrous dioxane should be obtained as an overhead product.

Thats how I would approach it anyway.

[Edited on 18-2-2016 by DJF90]

AvBaeyer - 18-2-2016 at 19:56

If you can get access to Elderfield's "Heterocyclic Compounds" Vol 6 there is a chapter on dioxane. Of interest is a list of references which describe solid addition complexes of dioxane which can be used for purification via crystallization. For example the complexes with sulfuric and phosphoric acids and elemental bromine are recrystalizable solids. The chapter also points out the extreme difficulty of purifying dioaxane by distillation.

AvB

DJF90 - 19-2-2016 at 03:36

Quote: Originally posted by AvBaeyer

If you can get access to Elderfield's "Heterocyclic Compounds" Vol 6 there is a chapter on dioxane. Of interest is a list of references which describe solid addition complexes of dioxane which can be used for purification via crystallization. For example the complexes with sulfuric and phosphoric acids and elemental bromine are recrystalizable solids. The chapter also points out the extreme difficulty of purifying dioaxane by distillation.
AvB

Cheers for the reference Av, I've requested it at the library and will provide photocopies of the relevant section when I get round to looking at it. I was aware of adducts with bromine and SO3, but neither are particularly efficient/useful for the purification of dioxane (as the value of the other reagents involved is quite high). The adducts with sulfuric and phosphoric acids are new to me. A quick SciFinder search revealed very little on these species, and I found two references which I have attached. I'm not sure either of the acid-adducts will be particularly useful in the purification of dioxane. I think the best method would be fractional crystallisation of the solvent but it preferably needs to be dry to avoid melting point depression (in order to facilitate good recovery).

What I suggested in my previous post was a means of obtaining dioxane from the initial crude distillate without using large quantities of other reagents. The main contaminants (acetaldehyde, 2-methyl-1,3-dioxolane, water) that make separation difficult by fractional distillation are removed first to facilitate purification. It was intended to be a suggestion/starting point for a lean process. I've attached the pages from Armarego and Perrin on what they say about 1,4-Dioxane purification.

Attachment: Crystal structure of the molecular compound 1,4-dioxane-sulfuric acid.pdf (672kB)
This file has been downloaded 663 times

Attachment: Dioxane-2H3PO4.pdf (222kB)
This file has been downloaded 654 times

Attachment: 1,4-Dioxane purification (Armarego and Perrin 6th Ed.).pdf (78kB)
This file has been downloaded 882 times

BromicAcid - 19-2-2016 at 04:32

Here's a procedure from one of my favorite members we don't see anymore.

http://web.archive.org/web/20080424022257/http://www.frogfot...

MrMario - 19-2-2016 at 08:34

I feel really sorry for all those moles who always get used in chemical reactions, kind of animal abuse

But jokes aside, many thanks for the detailed comments. This will surely will help me and other people out a lot.

DJF90 - 19-2-2016 at 13:04

Quote: Originally posted by DJF90

Cheers for the reference Av, I've requested it at the library and will provide photocopies of the relevant section when I get round to looking at it.

The book was retrieved from the stacks quicker than anticipated, so I've been down and scanned the relevant pages. Please find attached. Sorry for the large file size (not sure how to get it smaller) and wonky pages.

Attachment: Dioxane excerpt from Elderfield's Heterocyclic Compounds volume 6.pdf (3.1MB)
This file has been downloaded 809 times

Quote: Originally posted by BromicAcid

Here's a procedure from one of my favorite members we don't see anymore.

http://web.archive.org/web/20080424022257/http://www.frogfot...

I remember seeing Frogfot's site when it was still online, but I don't think he was active on the forum when I joined up on SM. Thanks for that blast from the past Bromic. Theres some other nice syntheses on his site too.

[Edited on 19-2-2016 by DJF90]

Boffis - 19-2-2016 at 14:42

Quote: Originally posted by Magpie

Here's a video of a guy making dioxane from ethylene glycol anti-freeze. He's using NaOH for drying but does not quantify his purity.

I'm amazed that he was doing this with the garage door open for all to see. One comment addresses that.

https://www.youtube.com/watch?v=RfQGwleIA8E

At 2:53 he gives a quick shot of his large flasks sitting out on the driveway!

This was posted some time back, has anyone ever tried NaOH as the cyclitizing reagent? It looks cleaner than sulphuric acid.

MrMario - 30-3-2016 at 02:45

So I tried to make 1,4-Dioxane from EG and Sulphuric acid and got similar results to Doug's Lab.
My ethylene glycol was pre-distilled under vacuum to ensure that there were no impurities. After I obtained the mixture of 1,4-Dioxane and the side products I added some K2CO3 and NaOH (~20g for 300mls of crude yield) and let it sit for 3 days. It turned to a red mixture with two layers, but the lower layer was not extremely black like oil like in Doug's video but pretty similar. When I started the distillation of the crude separated dioxane layer most came over in the 84-88 range and only 25mls were left which I did not distill because of peroxides.

My question is, did any Dioxane even form or is it possibly destroyed by prolonged storing over NaOH or side reactions? I used a good Vigreux Column to get a decent separation.
I can re-distill it with two Vigreux columns (700mm in total) if needed. Any thoughts on this?

UC235 - 30-3-2016 at 03:48

Quote: Originally posted by MrMario

So I tried to make 1,4-Dioxane from EG and Sulphuric acid and got similar results to Doug's Lab.
My ethylene glycol was pre-distilled under vacuum to ensure that there were no impurities. After I obtained the mixture of 1,4-Dioxane and the side products I added some K2CO3 and NaOH (~20g for 300mls of crude yield) and let it sit for 3 days. It turned to a red mixture with two layers, but the lower layer was not extremely black like oil like in Doug's video but pretty similar. When I started the distillation of the crude separated dioxane layer most came over in the 84-88 range and only 25mls were left which I did not distill because of peroxides.

My question is, did any Dioxane even form or is it possibly destroyed by prolonged storing over NaOH or side reactions? I used a good Vigreux Column to get a decent separation.
I can re-distill it with two Vigreux columns (700mm in total) if needed. Any thoughts on this?

Sounds like you distilled a mixture of 1,4-dioxane-water azeotrope (b.p. 88C) and 2-methyl-1,3-dioxolane (b.p. 82-83C).

See if adding more solid NaOH forms more of an aqueous layer. 20g seems like not nearly enough for 300ml of distillate. Peroxides don't form in a couple days in the stuff so I think you're being overly-cautious in discarding the last 25ml.

I have some crude dioxane (post H2SO4 treatment as described upthread). It's sitting over NaOH for months now and freezes almost solid on cold days. It does not react.

Vigreux colums are terribly inefficient. A packed column with copper or stainless steel scrubby should be excellent here.

MrMario - 14-5-2016 at 10:37

I read the added pages and tried today to reflux 200ml of crude Dioxane (I froze it twice and decanted the remaining liquid) with 20ml H2O with 8ml HCl (32% aq.)
The freezing was anhydrous and did not have any water nor HCl.
In the paper they had it sit over Ferric Chloride and I did not. Will this have effect on the reflux (without the ferric chloride) or will refluxing with just aq. HCl be fine?
It has also stand for several weeks now over solid NaOH (minimal amount of water) and the redish colored mixture was distilled to remove the impurities.

[Edited on 14-5-2016 by MrMario]

PirateDocBrown - 10-2-2018 at 05:43

I just turned out a batch.

300 mLs of the cheapest antifreeze concentrate Wal-Mart had, with 30 mLs of Rooto, in a 1000 mL RBF in simple distillation, to get a crude product.

Next, to work up this product to a pure state.

Shout out to Doug and Nurdrage, for the videos.

[Edited on 2/10/18 by PirateDocBrown]

j_sum1 - 10-2-2018 at 13:08

Brilliant work. Including the antigravity thumbnail.

PirateDocBrown - 10-2-2018 at 13:25

Not sure why it does that. It's right side up, when you click on it.

PirateDocBrown - 13-2-2018 at 00:55

After about 200 mL of crude product came over, I added another 200 mL of antifreeze to the cooled reaction flask, and continued.

Got about 400 mL crude product.

I think I wanna do hydrolysis first, before drying. Nurdrage and Doug went with base catalysis, but Allchemystery used more acid.

I have smelled none of the sour-apple smell of acetaldehyde during any of this, so I am guessing that it all has reacted to make methyl dioxolane (or polymers left in the residuum), and came over with the product. Hydrolysis should break this up, and heat should drive off what acetaldehyde does not polymerize via aldol reaction in situ.

In short, it calls for fractional distillation, but following acid, or base catalyzed hydrolysis? Nurdrage indicates that if base is chosen, KOH is preferable to NaOH, due to higher solubility.

All questions for another day.

Chemateur80 - 23-3-2018 at 11:43

I had a go at this synthesis. For now I plan to use the dioxane to extract sodium metal Nurdrage style.

The purification steps are not completed yet.

For the synthesis I used:
Pure ethylene glycol
Pure sulfuric acid (96-98%)
Pure potassium hydroxide

I ran two batches in a 500ml RB-flask in a heating mantle. One batch with 250ml ethylene glycol and one with 200ml. I added 20-25ml sulfuric acid to each.
I then set up for simple distillation.
I had some problems with temp control in both batches, but finally got a steady drip rate of around 2 drops/sec at 102-106C.
When the foaming started I increased stirring, but finally it was too much and the heat was turned off. No black tarry foam escaped the reaction vessle.

I collected around 200-250ml of distillate after each batch. The distillate was pale yellow and had a kind of weird sweet and sharp smell, something like liquorice/vanilla. Hard to describe.

Purification
I combined the two batches and added 20ml of conc. sulfuric acid to hydrolyze 2-methyl-1,3-dioxolane.
The mixture turned orange.

I set up for fractional distillation. At first acetaldehyde came over at 20-30C, then the temp increased with a slower dripping rate.
At 84C I switched the receiver and the distillate that came over between 84C and 97C was collected.
The two fractions collected were:
47ml between 20C and 84C (mostly acetaldehyde)
ca 370-400ml between 84C and 97C

In the distillation flask I was left with around 150ml of orange liquid with some tarry pieces sticking to the magnet. I suppose this was mostly sulfuric acid and water.

To the dioxane mix I then added 40g of KOH and let it stir. The solution turned dark orange/red. When the KOH dissolved I added another 50g.
This also dissolved and when I stopped stirring I had two phases.
The bottom water phase was around 150-200ml and quite clear.
The top dioxane phase was around 200-250ml and cloudy.
I've left the two phases standing like this.

Some questions:
Any ways to improve the synthesis? Better temp control? Larger reaction vessle to control foam longer? Adding water to begin with, instead of using conc acid/glycol-mix? Better to run one big batch if possible?

I feel that the yield will be a bit low from 450ml of ethylene glycol.
Theoretical yield should be around 350ml of 1,4-dioxane and I only have maybe 200-250ml of crude product.

How fast should the drip rate be during fractional distillation? I had several drops a second. Any risk of overpowering the condensor?

Why not collect the fraction from 84 all the way up to 102C? Should all the dioxane/water-azeotrope be boiled of by around 94-97C?
If there's an excess of water I suppose so, but why not collect all the way up to 102C since pure dioxane boils at 101C?
Would I only be collecting water around 100C?

I had around 180ml left in the distillation flask after fractional distillation. It seems like a lot. Is this normal from a batch my size? Is it mostly water and/or high boiling side products?

Is the dioxane layer supposed to be cloudy after adding and stirring with KOH? Should I add more KOH when it all dissolves?

Any ideas of how to remove tarry gunk from my magnets? I've tried a mix of hexane/acetone and also quite konc NaOH solution. It's still there.
Maybe heating the NaOH solution?
I'd like to avoid things like dichromates and piranha solution if possible.

Any help would be appreciated!

Vosoryx - 23-3-2018 at 12:40

I tried this, DCM works wonders for removing the tar from flasks. Don't see why it wouldn't do the same for magnets.

DraconicAcid - 23-3-2018 at 12:48

I find that boiling nitric acid cleans magnets very well.

Chemateur80 - 4-4-2018 at 13:14

A little DCM worked very well for cleaning the magnets. Thanks for the tip Vosoryx.

So I'm kind of disappointed with the experiment so far.
For details in the synthesis, see my post earlier.

After drying with KOH for a week I collected the upper dioxane layer (ca 150ml), which had an intense yellow colour.
To this I added some Na/MgO-aggregate to further dry it. This caused a lot of bubbling.
The next day I filtered the mix and added some more Na/MgO to the dioxane to see if I could isolate some sodium metal.
I set up for simple distillation, and the temp quickly reached ca 100-101C, which is the boiling point of 1,4-dioxane. The distillate was clear.

After a while I could see some tiny spheres (<1mm diam) of molten sodium dancing around on the surface. I distilled to near dryness, but the spheres never grew bigger. Probably too much Na/MgO with too little dioxane.
I used an RBF so I also think the magnet had a hard time stirring the mix to coalesce the sodium.

I collected 100ml of sweet-smelling 1,4-dioxane, which seems very low from two batches of 200/250ml ethylene glycol.

I collected some of the small spheres of sodium and put them in the dioxane to prevent peroxides from forming during storage.

Since I got so little dioxane I dumped the rest of the Na/MgO in a bucket of water. Vigorous reaction with flames, especially with the aggregate closer to the bottom of my reaction container.
With a bit more solvent I think I definitely could have isolated more sodium metal.

So, has anyone else tried the dioxane-synth with better yields?
Any improvements that I could make when I try to make more?

Maybe I could have added more KOH to the KOH/water mix to see I there was more dioxane to salt out, but I doubt that there was any.

greenlight - 4-4-2018 at 19:33

I just made some 1,4-dioxane myself using antifreeze and successfully made elemental sodium yesterday with it.
Some things I did differently:

● After the second distillation (fractional), I placed 35g KOH in and stirred for 15 mins. I only let it sit overnight and then seperated the top organic layer the next morning. A week seems a little long and adding more KOH makes the top layer darker and darker the more you add. My colour was medium dark orange.

● I added a generous amount of cooled potassium/magnesium oxide and let it stir for the whole day. When added, there was noticeable fizzing.

● I then distilled this and collected about 250ml crystal clear 1,4-dioxane from the initial 800ml antifreeze.

When you go again, use a big flask for the initial distill do you get a decent amount of product because you lose some with every distillation. I started out with 400ml from the first distillation.

The first time I tried the sodium synthesis it failed. There was a lit of fizzing and the dioxane got very warm upon addition of the aggregate prior to distillation. I got no product and I am convinced there was residual water in the dioxane still which killed the sodium.
The second time I got 8g of elemental Na from it probably due to the fact that the previous run had taken all the water out of the dioxane. Am going to run it again as I need a decent amount of sodium

[Edited on 5-4-2018 by greenlight]

Vosoryx - 4-4-2018 at 20:52

Figured i'd add in my experience to help anyone else out there.

I made 1,4-dioxane and then successfully made Sodium metal from it (though not a lot) for a science fair project a few months ago.
Everything for me worked fine on the first run. I don't have my lab journal with me right now, so I don't have the exact yields/starting amounts. However, i'm fairly sure I used, in total, 600 mLs of EG, and got about 115 mLs of dioxane. After I used it to make some sodium metal, this number was reduced even more. (Due to some being lost to the vent, dead space in the apparatus, left in the remaining slag, etc)

I just used concentrated antifreeze, and straight sulphuric acid drain cleaner - not even boiled down, and certainly not my precious 98%. I used 40 mLs for ever 300 mLs of antifreeze. For the first part of my project, I didn't have access to a magnetic stirrer. (Though I borrowed the school's for the actual sodium extraction) Thus, I couldn't use the stirring to regulate the tar produced - which ended up plaguing me intensely. The first time, I turned off heating as soon as I noticed a tar forming. However, due to the fact that my heating source was not a proper hot-plate, the reaction mixture continued to be heated lightly. The tar, fortunately, didn't reach OVER the still head (though it did reach the still head, calling for a week-long NaOH bath.) The second time however, even with me turning off the heating as soon as I saw tar, the tar ended up almost instantaneously boiling into the receiver. This proved not to be a problem, once I fractionated everything.
For each run, I placed in a bunch of NaOH. At the time, I had no KOH to use instead. I left it for a few weeks (while I was away from my lab) and decanted and fractionated the remaining liquid, to get the ethanal and other bi-products out.

From the amount of Na-MgO I had, I ended up not having enough dioxane to coalesce all the sodium, it was left in really small balls. So after I distilled off all the dioxane, I took the distillate and added it back into the boiling flask and re-distilled. This was needed in order to make the beads large enough so that i could reasonably take them out with a small pair of pliers.
Interestingly, I noticed that some of the vapour this time came off much below the dioxane BP or even the azeotrope. (It was approximately in the 60-70 degree range.) What this is I have no idea, and i'm starting to suspect it might be an error on the part of the thermometer because it is, for all tests I can run, indistinguishable from dioxane. It was dry, same freezing point, and after I tested it in these ways the boiling point had gone up to exactly that of dioxane. However, if it was a thermometer problem, I have never experienced it at any other point.

Once I had distilled down the second time, I took it off before it was completely dry (for some reason - I dunno, it was late at night) and dumped the contents onto a piece of dry paper in a plastic bin. I then spent some time with a set of jewelry pliers picking everything out. Because there was probably more sodium left in the slag, I put the slag back into a container, so that I could remove more of it at a later date should I feel so inclined, and I might do so now that I have my own hotplate.

Vosoryx - 4-4-2018 at 20:54

Quote: Originally posted by Chemateur80

A little DCM worked very well for cleaning the magnets. Thanks for the tip Vosoryx.

Glad I could help!

Chemateur80 - 9-4-2018 at 05:13

Thanks for your input greenlight and Vosoryx. Very interesting.
I will definitely use a larger flask and do one distillation the next time.

It's a messy reaction, so maybe the yields won't get better than 25-40% anyway.
My theoretical yield should have been around 350ml of dioxane, and I got 100ml, which is a 25% yield.

Would be nice to find ways to increase the yield in the starting reaction between EG and sulphuric acid. Temp control and the tarry crap seem to be the biggest problems.

I notice that neither of you used sulphuric acid to hydrolyse the 2-methyl-1,3-dioxolane formed in the initial reaction. How come?
I think I saw a thread here on SM saying that it could be as much as 10-20% of the yield.
It hydrolyses into acetaldehyde and EG when mixed with sulfuric acid, and the dioxane can then be fractionally distilled without this impurity.

The KOH was left for about a week because I didn't have time to experiment more at the time. I wonder if it makes any difference in yield.
Could the KOH and the dioxane react?

Congrats on your 8g of sodium metal greenlight! Must have been nice to see those shiny spheres.

I will make more dioxane soon.
I'm also thinking about improvements in the thermite-like reaction between NaOH and Mg, but maybe that's for another thread.
I used freshly crushed NaOH and 200um Mg-powder.

greenlight - 9-4-2018 at 05:30

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]

Synthesising 1,4 Dioxane

MöbiusMan - 15-7-2018 at 00:15

Ok, I finally did it.

I somewhat followed NurdRage’s video and Dough's but have come up with a better one.

First distill your antifreeze and collect the pure ethylene glycol; it boils at about 200ºC so i used an air condenser with a wet towel placed over it as water jacket condensers may crack due to thermal stress. Once you finish distilling the ethylene glycol, you will see a bunch of salt and corrosion inhibitors left in the flask and can wash them out with water.

You also want to distill your sulfuric acid if you are using drain cleaner; Use pieces of terracotta pot as boiling chips, they will react at first and colour the acid red but then stop reacting and make perfect boiling chips, NO BUMPING AT ALL. Once that was distilled, depending on the brand you may have some junk left in the flask.

Now put however much ethylene glycol you have in a large jointed flask. You want to have a lot of headspace in you flask as it will foam up a lot (I used a 2L flask for 500ml of ethylene glycol). Then add 7% of the volume of ethylene glycol of your 98% sulfuric acid. Set up a fractional distillation with a vigreux column or others and heat up your mixture; use strong stirring. Collect everything that comes over and continue heating the reaction flask. Towards the end of the distillation the reaction flask will turn a dark brown and eventually a tarry black. It is important to keep strong stirring all the way through to stop the foaming. It is at this point most people's yield goes out the window because they stop too early due to the foam. This is why we use the oversize flask. Continue heating until the foam is super thick and fills the flask. You need good ventilation as a lot of vapours form and are toxic. Turn off heating before it all overflows and save your distillate from the oncoming foam if necessary.

I collected about 400 - 450ml of crude distillate from 500ml of ethylene glycol. To this distillate I add 5% of the distillates volume in 98% sulfuric acid. Set up another fractional distillation. Heat the flask and you will collect a bunch of impurities which boil at about 40 - 50ºC. When the still head reaches 86ºC change out the receiving flask and collect your dioxane. The temperature should then sit at 87.7ºC for a while and the rate of distillation will greatly increase. Continue collecting until 93ºC at which point the distillation is over.

With this purified dioxane, add NaCl with strong stirring and intermittently stop stirring and wait a minute. If no by-phase has formed continue adding NaCl. Continue doing this until you have a nice by-phase with a little extra pile of salt at the bottom. I left mine to stir for an hour on strong stirring.Then pour the mixture into a separatory funnel. Allow the layers to separate and drain away the lower aqueous layer. Collect your upper dioxane layer in another flask.

To this dioxane add some NaOH using the same method mentioned before (stirring then waiting for a by-phase to form). This time, make sure there is a decent amount excess NaOH sitting at the bottom. Stir this for another couple of hours. It will turn an orange colour and you may have solid bits of polymerised impurities. If you do it right the lower layer should form a semisolid thick gel layer. Add the mixture to a clean separatory funnel and allow the layers to settle. Drain away the lower orange/red layer, and collect the upper dioxane layer.

Using sodium magnesium aggregate further dry the dioxane with stirring overnight; make sure to not seal it as pressure may build up. Then distill the dioxane using a simple distillation and collect whatever boils at 100-103ºC. If there wasn't much water you may be able to create sodium spheres as you distill it but most of the time you won’t get much at all. The second time you distill the dioxane with sodium magnesium aggregate you will get alot more sodium as the dioxane is now completely dry.

Its amazing how much you can write when you enjoy what you write about.
If you have any questions write them in below.
Good Luck and Happy Carcinogening!

[Edited on 15-7-2018 by MöbiusMan]

j_sum1 - 15-7-2018 at 01:54

Thanks MM.
I have been doing the same thing the past couple of days. Again following Nurdrage pretty explicitly.

Batch 1 was about 300mL of antifreeze in a 500mL RBF using 40mL of sulfuric acid. I managed to have it foam over twice and so it got triple distilled. Then 10mL of Sulfuric acid added to the distillate and fractional distillation. Product looked clean and clear at this stage. This was followed by stirring with NaOH for several hours. I got some dark waxy-looking lumps appear quite quickly and two liquid layers. The organic layer was still very amber in colour so I responded with a large amount of additional sodium hydroxide. The result was an orange sludge of polymer gunk and a much smaller amount of discoloured dioxane. I filtered and have a measly 50mL that will still need distilling to purify.

Batch 2 was 250mL usung 60g of sodium bisulfate. Distillation was a bit slower but not unreasonably so. Distillate came over with a yellow tinge before foaming occurred so the process was halted. Volume yield seems ok at this point but I have not cleaned it up yet. Tarry mess with solidified NaHSO4 looked a real mess to clean at first. But adding some NaOH and a bit of water and leaving it over night loosened it up nicely. Washing it out left a lovely sparkling flask.

I will try the NaCl salting out. That might be a step in the right direction following my hydroxide mess.

If, as you say, the sodium synthesis needs very dry dioxane, it might be better to distil over NaOH rather than just stir and decant.

I will be doing a few runs over the next couple of weeks so I can play with the parameters a little.

[Edited on 15-7-2018 by j_sum1]

MöbiusMan - 15-7-2018 at 03:07

Yes, the NaCl salting will remove most of the water so you save on sodium hydroxide and it forms less wastage in the gelatinous stuff. What yield of distillate did you get on the first distillate because I found a lot of the distillate comes over when the foaming gets intense. This could be a one of the reasons people get such a low yield for this synthesis. Having a massive flask to allow the foam to build was the way i handled it.

j_sum1 - 15-7-2018 at 03:33

I did not measure reagents accurately so don't know the yield.
I am limited to a 500mL rbf for heating. There was quite a bit of liquid there when it began foaming. Hard to estimate volume of a foam but I would reckon equivalent of 80-100 mL of reagent from a ~300mL charge.

Maybe one of the secrets is not to be too ambitious with batch size since it will be lost anyway.

Or maybe it is worth putting an addition funnel into the process.

XeonTheMGPony - 15-7-2018 at 04:51

I'm going to give the iron sulfate method a go, I just made some from 23grams of iron turnings, it is now a nice pale green crystal structure filling the bottom of the beaker, need to dry this to anhydrous state

Attachment: 1,4-Dioxane msds.pdf (456kB)
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Attachment: Dioxane excerpt from Elderfield's Heterocyclic Compounds volume 6.pdf (3.1MB)
This file has been downloaded 618 times

j_sum1 - 15-7-2018 at 05:11

Thanks for that Xeon. I haven't read the whole thing but it is fascinating thus far. Separation of Li from other group I salts. Whodathunkit?

XeonTheMGPony - 15-7-2018 at 05:32

Quote: Originally posted by j_sum1

Thanks for that Xeon. I haven't read the whole thing but it is fascinating thus far. Separation of Li from other group I salts. Whodathunkit?

http://www.sciencemadness.org/talk/viewthread.php?tid=65311

Credit belongs to this thread! We should have a Dioxane sticky

As I suspect a great many threads will be popping up!

I'll add some pictures of my iron sulfate and eventually dioxane work up to one of these threads, probably the larger one.

I plan to use my addition funnel (250ml) and a 500ml 3 necked flask to try and do a continuous flow system

Just a tip to you guys, Seafoam containers will be ideally suited to storing Dioxane as they are a stamped aluminium seamless bottle with a fairly good sealing cap on them, and around here at least you find them around the roads due to ignorant people littering, so keep an eye out!

I use them to store my used alcohol for drying, I then dry/distill and use it in my alcohol burner.

[Edited on 15-7-2018 by XeonTheMGPony]

MöbiusMan - 15-7-2018 at 12:16

I got up early this morning at 5:30 and went up to the lab to check on things and found that my distance has frozen. Guess that's expected seen as it was 3 degrees C. Well that gives me some confidence that I actually have dioxane. Bloody climate change its nearly sub zero in Sydney! Grrrrr

Vosoryx - 15-7-2018 at 12:47

I used is 11 Celsius melting point to crystalize it before I used it in my sodium synthesis, just by heating the flask it was in and then placing it in a closed thermos in the fridge. At the end there was a tiny bit of water that I couldn't even pour off - I had to put a cool paper towel on it to remove the water.
It wasn't needed though, the Na/MgO would have removed it. I just wanted a crystal because it was my science fair project and I wanted it to look cool on the poster board. Of course, it didn't even produce a crystal, just solidified inside the flask in the thermos.

MöbiusMan - 15-7-2018 at 13:07

This raises the question if it is possible to purify dioxane by recrystallisation

Vosoryx - 15-7-2018 at 15:20

Experiments will have to be done.

I'll add it to my growing list of things to do.

MöbiusMan - 17-7-2018 at 18:07

Wohooooo

I have sodium. The dioxane i made must be good because this is what i got. I didn't have any isopropyl on hand to coaless the sodium and found that adding a few drops of the dioxane worked out and I ended up with a nice chunk of sodium. It even has those crystallisation lines that NurdRage talked about in his vid. Yieeewwww

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Boffis - 17-7-2018 at 22:43

Nice work MobiusMan!

MöbiusMan - 18-7-2018 at 01:07

Heheheheh I've been back in the lab. I'm addicted to the joy you get when you see those silver beauties forming.

Screenshot_2018-07-18-19-07-20-74.png - 1.2MB

monolithic - 22-5-2020 at 17:00

I filled a 1000 ml round bottom flask, set up for simple distillation, with 350 ml of purified ethylene glycol. I then added 35 ml 93% w/w H2SO4 in one portion. Heating and stirring were applied. Distillate came over at 120 C, tapering down to 105 C at the end, where foaming became too intense to continue. I haven't proceeded with the rest of the reaction so I'm not sure of yield just yet.

Videos on YouTube show distillations between 90-100 C when the H2SO4 is added to the ethylene glycol. Why is this -- why are my still head temperatures so high? Ethylene glycol boils at 197 C so it can't be unreacted ethylene glycol coming over.

[Edited on 5-23-2020 by monolithic]

[Edited on 5-23-2020 by monolithic]

draculic acid69 - 22-5-2020 at 18:12

Quote: Originally posted by j_sum1

I did not measure reagents accurately so don't know the yield.
I am limited to a 500mL rbf for heating. There was quite a bit of liquid there when it began foaming. Hard to estimate volume of a foam but I would reckon equivalent of 80-100 mL of reagent from a ~300mL charge.

Maybe one of the secrets is not to be too ambitious with batch size since it will be lost anyway.

Or maybe it is worth putting an addition funnel into the process.

Do u mean as a bulb between the neck of the flask and the distillation head?

draculic acid69 - 22-5-2020 at 18:20

Also just found this:https://m.youtube.com/watch?v=0OhWEDtIQ2M

monolithic - 23-5-2020 at 20:22

As a follow up to my last post, I tried fractionally distilling the ethylene glycol + H2SO4. This brought the distillation temperature down a bit but it was still fairly high. In total,

350 ml ethylene glycol + 35 ml 93% H2SO4, stirred 20 mins, simply distilled to yield 349 g crude distillate.
Added 35 ml 93% H2SO4 to distillate, stirred 20 mins, fractionally distilled to collect 87 - 95 C fraction total mass 205 g.
350 ml ethylene glycol + 35 ml 93% H2SO4, stirred 20 mins, fractionally distilled to yield 360 g crude distillate.
Added 35 ml 93% H2SO4 to distillate, stirred 20 mins, fractionally distilled to collect 87 - 95 C fraction total mass 211 g.
Combined both fractions, 416 g with total volume ~400 ml, and added 70 g KOH. Stirred between 1.0 and 1.5 hours.
Physical appearance: some black sludgy solids, lighter clear aqueous layer on bottom, dirty brown-red organic layer on top.
Discarded bottom aqueous layer, ~100 ml, as well as polymerized sludge.
Added another 25 g KOH, stirred for 1.5 hours. Majority of KOH did not dissolve as water was absent.
Physical appearance: undissolved KOH had some sludge on it, no aqueous layer, organic layer deeper brown-red color.
Gravity filtered solution and fractionally distilled to collect fraction 97.5 C - 102.7 C, crystal clear in appearance.
Total yield 272 g with a measured density of 1.02 g/ml @ 25 C (lit. 1.034 g/ml @ 25 C.)
Stored in an amber glass bottle with ~0.05 g BHT (~200 ppm) over 27 g activated 4A sieves (~10% w/w.)

Cleanup of the black sludge from the ethylene glycol + H2SO4 distillation was kind of shitty. Lots of acetone swirling and the stir bar had to be scraped clean with a razor blade.

[Edited on 5-24-2020 by monolithic]

Dioxane didn’t end well

TLutman - 21-4-2021 at 14:06

I was going through NurdRage vids and decided to do the dioxane from antifreeze synthesis . I used Traveller concentrated ethylene glycol antifreeze.

Using a 1000ml erlenmeyer, I used 300ml of antifreeze and 40ml Liquid Fire drain cleaner. Initial distillation brought a yellowish distillate first, followed with an overlapping clear distillate. The two were immisible, with the yellow layer staying up top.
Soon, there was perhaps 15ml of the yellow layer on top, with the clear more viscous liquid punching through like a lava lamp. This took a bit longer than planned, so I ended up shutting down heat when there wasn’t much left but tar ( no foam at all). I debated using a separatory funnel and getting rid of the yellow layer, but ultimately went to bed. After work the next day, much of the yellow was gone. I proceeded with another 10ml H₂SO₄ and fractional distillation. Small amount came over under 83C, changed flasks and 120ish ml of clear liquid from 83 to 103C was collected.
Put 40g NaOH in with stirring. It soon just turned black with clumps of dirty NaOH on the perimeter. There was no clear anything after stirring all night.

That brings me to now. I’m not sure what went south, or why. I was thinking on distilling again to see where it leads me.

Any thoughts?

clearly_not_atara - 21-4-2021 at 16:06

Quote:

This took a bit longer than planned, so I ended up shutting down heat when there wasn’t much left but tar

Don't do this. You distill all sorts of crap into the product. Anything condensing higher than 101 C is crap.

But are you sure that your antifreeze was pure ethylene glycol? The only other product I can think of is 2-methyldioxolane, which has a high water solubility; dioxane is miscible. Paraldehyde shouldn't come over until 124 C. Acetaldehyde does not form easily in these conditions, anyway. The presence of immiscible distillate suggests another organic component.

Some antifreeze may contain a mixture of ethylene and propylene glycols. If there were propylene glycol in your antifreeze, you could have obtained propanal and 2-ethyldioxolane. These are much less hydrophilic. Ethanol can be present and may form diethyl ether.

There are a lot of variants of Traveller antifreeze. I was unable to find one claiming to be pure or diluted ethylene glycol with no other organic components. What kind did you use?

It may be possible to flocculate out the tarry components with alum salts.

Alternatively, since the dioxane-water azeotrope boils at 87 C, you might collect the fraction boiling between 85-95 C and discard anything else. That could be cleaner.

Or both!

[Edited on 22-4-2021 by clearly_not_atara]

TLutman - 21-4-2021 at 16:23

Label calls ethylene glycol, diethylene glycol, water, mixed corrosion inhibitors.

As for the high temp on initial distill, I shut down at 105, which was the steady temp for the majority of time. The flask wasn’t tar, but was noticeably more viscous. After cooling, it’s more syrup, with a bit of liquid in it.

I distilled again, getting roughly 90ml, all coming over at 95c. I shut off heat when temp started dropping. Boiling flash is black with NaOH visible. Not sure if it’s thick yet, I just turned it off.

TLutman - 21-4-2021 at 17:14

I have the dioxane stirring now with NaOH. It’s looking good so far, with only some clumping of the hydroxide but no other visible reactions.

I’m sure that I will be doing this again in the near future, just trying to learn from my mistakes.

clearly_not_atara - 21-4-2021 at 17:46

Sounds like it worked out.

The other components in Liquid Fire are also corrosion inhibitors. I wonder what the hell is going on with all of these corrosion inhibitors?

XeonTheMGPony - 22-4-2021 at 03:56

Quote: Originally posted by clearly_not_atara

Sounds like it worked out.

The other components in Liquid Fire are also corrosion inhibitors. I wonder what the hell is going on with all of these corrosion inhibitors?

left in the tar usually, I distill my ethylene glycol first, and all the salts are left in the distillation flask.

draculic acid69 - 22-4-2021 at 04:55

As for propylene glycol being present (1,2 or 1,3?) Will propanal be formed and if so is it dependent on whether 1,2 or 1,3 prop glycol is present? And while 1,2 prop glycol will form 2,5dimethyl1,4dioxane will 1,3pg form a larger 1,5 dioxane variant?

clearly_not_atara - 22-4-2021 at 05:43

^the reaction of propylene glycol is different, due to the much lower energy barrier for a pinacol rearrangement. Ethylene glycol gives dioxane while propylene glycol gives propanal. This is because the carbocation forms:

CH3CHOHCH2OH + H+ >> CH3CH+CH2OH

but

CH2OHCH2OH + H+ >XX CH2+CH2OH (does not form)

The formation of a primary carbocation is forbidden, while a secondary carbocation is allowed. Propanal might undergo side reactions or just boil off. 2,5-dimethyldioxane is not a likely product.

1,3-propylene glycol may give 1,5-dioxocane or oxetane, possibly a mixture of both. However, it is not used in antifreeze.

draculic acid69 - 22-4-2021 at 06:01

Quote: Originally posted by clearly_not_atara

^the reaction of propylene glycol is different, due to the much lower energy barrier for a pinacol rearrangement. Ethylene glycol gives dioxane while propylene glycol gives propanal. This is because the carbocation forms:

CH3CHOHCH2OH + H+ >> CH3CH+CH2OH

but

CH2OHCH2OH + H+ >XX CH2+CH2OH (does not form)

The formation of a primary carbocation is forbidden, while a secondary carbocation is allowed. Propanal might undergo side reactions or just boil off. 2,5-dimethyldioxane is not a likely product.

1,3-propylene glycol may give 1,5-dioxocane or oxetane, possibly a mixture of both. However, it is not used in antifreeze.

Nurdrage did a video on 2,5dimethyl1,4dioxane from 1,2pg so it works.
Just for clarity are U saying 1,3pg won't form propanal but 1,2pg will due
to the OH's being next to each other?

clearly_not_atara - 22-4-2021 at 06:19

No, it's because the carbocation is secondary. 1,3-propylene glycol cannot form a secondary carbocation because both of the alcohols are primary. See:

https://twitter.com/dasingleton/status/1115120772132016129

draculic acid69 - 22-4-2021 at 06:52

Quote: Originally posted by clearly_not_atara

No, it's because the carbocation is secondary. 1,3-propylene glycol cannot form a secondary carbocation because both of the alcohols are primary. See:

https://twitter.com/dasingleton/status/1115120772132016129

Your above sentence is a bit too technical for me
Thats why I asked for clarification.could U simplify it

clearly_not_atara - 22-4-2021 at 07:49

Read the twitter thread. Prof. Singleton explains it better than I ever could. With pictures. See also:

https://en.wikipedia.org/wiki/Carbocation#/media/File:CarboC...

TLutman - 22-4-2021 at 13:30

Quote: Originally posted by clearly_not_atara

Sounds like it worked out.

The other components in Liquid Fire are also corrosion inhibitors. I wonder what the hell is going on with all of these corrosion inhibitors?

Tricky question. If these manufacturers would put them in the msds, people like yourself could figure any reactions. Don’t look at me, I only had a semester of chemistry as a freshman in high school in the early 80s.

TLutman - 3-5-2021 at 18:21

Tried this again, paying mind to what was said.
First thing, it wasn’t Traveller brand, it is Pride 1000.
I first distilled the ethylene glycol, not trying to squeeze every drop. I discarded all below 195c, and stopped before it was even done.
I used concentrated H₂SO₄, and did a simple distillation. First distillate came over around 92c, and was yellow in color. At 96c, a clear distillate came over. I proceeded until 104c and stopped.

I poured that into a separatory funnel and pulled the yellow out, around 10ml. I took it outside and put on a paper towel and held a lighter to it, and it immediately and rapidly lit on fire, similar to what gasoline would.

I then took the clear distillate and proceeded with the NaOH, and just like the last time, it turned a dark red brown, with almost a suspension in it. I let it stir for a few hours and tried to gravity filter through a couple coffee filters. It removed nothing, but left the filter stained brown except the last 13mm of the perimeter, which was clear wet. I took it outside and again held a lighter to it. The perimeter lit up as I would expect, but the brown stained paper wouldn’t burn.

This is basically the same thing that happened my first go with it. I’m going to grab a different brand and try again, not so much that I need more dioxane, but because I want this to go the way it’s supposed to.

S.C. Wack - 3-5-2021 at 19:12

Sounds like the yellow is what you want and the clear is full of aldehyde/acetal...might want to go with HCl instead (Vogel) after salting out with not-base and extracting.

XeonTheMGPony - 4-5-2021 at 03:07

Sounds like you skipped the second sulfuric acid wash after distillation

ErgoloidMesylate - 27-8-2022 at 10:13

Quote: Originally posted by monolithic

As a follow up to my last post, I tried fractionally distilling the ethylene glycol + H2SO4. This brought the distillation temperature down a bit but it was still fairly high. In total,

350 ml ethylene glycol + 35 ml 93% H2SO4, stirred 20 mins, simply distilled to yield 349 g crude distillate.
Added 35 ml 93% H2SO4 to distillate, stirred 20 mins, fractionally distilled to collect 87 - 95 C fraction total mass 205 g.
350 ml ethylene glycol + 35 ml 93% H2SO4, stirred 20 mins, fractionally distilled to yield 360 g crude distillate.
Added 35 ml 93% H2SO4 to distillate, stirred 20 mins, fractionally distilled to collect 87 - 95 C fraction total mass 211 g.
Combined both fractions, 416 g with total volume ~400 ml, and added 70 g KOH. Stirred between 1.0 and 1.5 hours.
Physical appearance: some black sludgy solids, lighter clear aqueous layer on bottom, dirty brown-red organic layer on top.
Discarded bottom aqueous layer, ~100 ml, as well as polymerized sludge.
Added another 25 g KOH, stirred for 1.5 hours. Majority of KOH did not dissolve as water was absent.
Physical appearance: undissolved KOH had some sludge on it, no aqueous layer, organic layer deeper brown-red color.
Gravity filtered solution and fractionally distilled to collect fraction 97.5 C - 102.7 C, crystal clear in appearance.
Total yield 272 g with a measured density of 1.02 g/ml @ 25 C (lit. 1.034 g/ml @ 25 C.)
Stored in an amber glass bottle with ~0.05 g BHT (~200 ppm) over 27 g activated 4A sieves (~10% w/w.)

Cleanup of the black sludge from the ethylene glycol + H2SO4 distillation was kind of shitty. Lots of acetone swirling and the stir bar had to be scraped clean with a razor blade.

[Edited on 5-24-2020 by monolithic]

Good to see a small cyclic ether can be made quite easily.

Fery - 31-8-2022 at 06:14

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???

Lionel Spanner - 31-8-2022 at 07:07

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 314 times

Fery - 1-9-2022 at 07:53

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]

Fery - 5-9-2022 at 04:34

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.

TLutman - 14-11-2022 at 15:39

After little hiatus with other projects, I’m back to this

I tried running the same antifreeze to finish off the gallon to tidy up some shelf space, but tried paying more mind to what was going on.

Last night I distilled the E.G. from the antifreeze (simple distillation). I got my first drips around 100C. No surprises there. It does say it has added water, but it is concentrated and not premix.

@100C, distillate was cloudy, but uncolored.
@ 150C a slight yellow color was observed, and collection was continued in same flask
Discarded below 170C, approx 150ml
170-180C collected in test tube. Increasing yellow tint- approx 5ml
180C -190C collected in test tube. Yellow tint most noticeable approx 10ml
190-197C new test tube, tint decreasing approx 8ml
Started collecting at 197.1C a pretty clear product at fair rate- 400ml

Interesting was the flask I discarded had a yellow powdery film on the glass when it dried.
I intend to distill crude 1,4 dioxane tonight and believe the yellow layer I initially had will be there. I intend to sep funnel as soon as I finish, but am thinking about taking different fractions to see when it is coming over.

I’m not seeing others having this issue, and most look like they are collecting right off the bat and yet still have a clear distillate. I don’t particularly think I’m going to get an answer from anyone because it might be the dye or inhibitors creating the problem and they don’t divulge those compounds. This is mostly for anyone else who might run into this.

Rainwater - 14-11-2022 at 18:37

From my lab notes a year ago.
https://www.autozone.com/antifreeze-radiator-additives-and-w...
Sds sheet

https://www.autozone.com/batteries-starting-and-charging/bat...
%30 sulfuric acid

In a 3-necked 2 liter rbf roughly 500ml 95% ethylene glycol was added along with 200ml 30% battery grade sulfuric acid.
A stir bar, 5 boiling stones(2mm), 6in thermowell, an addition funnel, and a fractional column were added. The column was insulated with foam.
Atop the column a 3 way distillation adapter with a thermowell w/thermocouple, liebig condenser and 2L receiving flask chilled with ice water

Cooling water was maintained at 25c 2L per minute.

A heating mantle was placed under the boiling flask and a thermometer into its well.

600 The mantle was set to 102c. Stirring was started.

640 After the boiling flask reached 100c, distillation began. Distillate 100c 6 drops/minute

700 boiling flask reached 100c. Distillate 100c
distillation rate increased to the point of overloading the condenser. constant drip & steam

710 Boiling flask reached 102c. distillate is coming over very slowly. 3 drops / minute
Heating set to 130c, first fraction recovered.

730 boiling flask reached 130c. Distillate 103c 30 drops / minute

1100 addition funnel is filled with about 500ml %95 ethylene glycol and slowly dripped into the boiling flask.

1500 addition funnel is filled with about 200ml %95 ethylene glycol and slowly dripped into the boiling flask.

1900 distillation rate has slowed. Distillate 105c 10drops / minute. Tar has began to form in the boiling flask. About 1100ml of distillate has collected and is placed into the freezer.
The apparatus is turned off for the day.

TLutman - 14-11-2022 at 19:42

It may very well be this antifreeze brand.
Distilling the E.G. from the antifreeze left varying amounts of a uniform yellow tint all the way to 195C, and probably traces after that.
I had two major fractions in the end from two separate runs. The lower from 180-195 and the 195 up.
I put the lower one of 425ml and 50ml of drain cleaner in a 1000 ml rbf and ran a simple distillation. At 100C I was getting drops in the condenser, cloudy at first and then started two layers. I could see the drips flowing down the condenser looking odd. I believe the 2 immiscible layers were coming on the same drop.
I put a test tube under the vac adapter at 100, 114, and 120C and had a denser layer of clear liquid on bottom and a layer of yellow on top. Shaking showed a quick separation. The yellow was more intense, and is opaque, almost as if all the color in the original EG was pushed out of the crude dioxane to form a separate layer.
I ran the distillate through a sep funnel a few times through the distillation the rid it of the yellow. I might see if my uv light will light it up,but it may be the wrong wavelength. I was thinking maybe some sort of uv dye, but this is the cheap antifreeze from the country store up the road. Not sure if this brand would go so far as to add one.
Maybe tomorrow. Right now is getting everything corked up because that stuff stinks and I don’t want to leave my fumehood run until tomorrow night.

Rainwater, sounds like you kept some good notes. I could improve on mine a bit. I like your temp and flow on cooling,and that is on my to do list I wrote up yesterday. Adding a vac guage and means of adjusting is as well.

Fery - 14-11-2022 at 21:38

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]

Fery - 14-11-2022 at 22:16

Well done guys!
TLutman good that you distilled and purified your ethylene glycol, >150 ml of forerun and 400 ml of main fraction is a lot. Bottles with antifreeze should have a table which tells temperatures at which antifreeze could be used and also its various mixtures with water. A mixture water:glycol 1:3 should have worse temperature usage than concentrated glycol - the dilution of antifreeze could be perhaps guessed from this worse temperature when reading the table from bottle in a shop.
TLutman and Rainwater - why do you use such amount of H2SO4? It is only a catalyst. I used <4 vol % and the etherification reaction ran well. I repeatedly added fresh ethylene glycol into the remainder (4 distillation cycles) and still not overrun at all unlike seen in videos on youtube, remainder darkened in color into black but was easy to pour out after the last cycle and clean the flask with just water.
https://www.sciencemadness.org/whisper/viewthread.php?tid=65...
Rainwater you used stirbar with boiling stones - did it bring some advantages? By my experience the stirring is necessary but not boiling stones then. You put all 1100 ml of distillate into freezer - what was the result? Wasn't it contaminated with acetaldehyde? Anyway you cooling water temperature was above its b.p. but b.p. of another sideproduct 2-methyl 1,3-dioxolane is 83 C. I guess your distillate contains still this sideproduct and also a lot of water as it should be an azeotrope dioxane:water. I got rid of 2-methyl 1,3-dioxolane by a hydrolysis using a little of H2SO4, there was enough water in the azeotrope to hydrolyze it. Then I distilled it and obtained azeotrope dioxane:water but now without 2-methyl 1,3-dioxolane. Then I dried it using K2CO3 and KOH and distilled it again. This product was then placed into fridge at + 4 C for few months. Putting into freezer (-18 C) would freeze not only dioxane but also the water remained after drying the product. So I used only fridge +4 C and not freezer -18 C.

Rainwater - 15-11-2022 at 00:39

Quote:

why do you use such amount of H2SO4?

My acid was very diluted. All the readings on this procedure suggested 40~60ml of 99% Sulfuric acid
the molar equivalent is 133~200ml of 30% consentrated.

Quote:

Rainwater you used stirbar with boiling stones - did it bring some advantages?

The stir bar slings the stones around the flask and i think that helps stop bumping, but my heating mantle loves to decouple from the stirbar and when its not spinning properly the stones help me hear there is a problem. They are quite loud when everything is just right.

Quote:

You put all 1100 ml of distillate into freezer - what was the result?

A yellow semi-solid mass. It stopped most of the reactions and allowed me to store the crude product safely stoppered until i could work on it again. I should note that the flask still build up pressure

Quote:

Wasn't it contaminated with acetaldehyde?

yep.
I purified it a few days later. Fractional distillation in acidified conditions, koh soaking, decant. Then used it to clean crude sodium metal which also served to further purify the dioxane.
Waste disposal i dont remember how much i got below 80c during the second distilation, something l8ke 150~200ml i think. I suck at keeping track of yields.

Quote:

Putting into freezer (-18 C) would freeze not only dioxane but also the water remained after drying the product. So I used only fridge +4 C and not freezer -18 C.

Very true, I figured that my rbf was almost half way full, so if the water did freeze solid it wouldnt break my flask, and my freezer is set to -5c but from the readings i didnt expect it to freeze solid
( digging. Please wait )
https://www.journal.csj.jp/doi/abs/10.1246/bcsj.46.2965
Attachment: bcsj.46.2965.pdf (692kB)
This file has been downloaded 276 times

1,4 dioxane + water melting points

Fery - 15-11-2022 at 09:30

Rainwater - well done. Luckily dioxane on solidification does NOT expand in volume unlike water. It is possible to remove most of the water still present after KOH drying and then distillation - by solidifying the almost dry dioxane in a fridge at +4 C for (few months better than only few days) and pouring out small amount of liquid on top of solid mass of dioxane. Then you need only tiny amount of hard to get sodium metal to dry it completely.
Guys I like you are doing experiments. The more experiments, the better!

TLutman - 16-11-2022 at 15:52

After some additional digging I found this is formulated for gas and Diesel engines. It has a few more components not on the bottle.
Boron >200ppm
Nitrite/moly >1600ppm
Inhibitors>2%
Glycol 95-97%

Not sure if the inhibitors add anything different than normal for the diesel application other than low silicates.

I ran the second distillation with an additional 10ml H2SO4, collecting from 84-94C using a fractional column. I don’t have a total on the distillate yet as it’s stirring with some KOH, but it is depressing in both amount and that it is a uniform red with no separation yet.

Rainwater - 16-11-2022 at 16:52

If you are not getting separation, add more Koh. Keep adding in small amounts until some of the hydroxide does not dissolve.

TLutman - 16-11-2022 at 19:19

I added more koh earlier, and it went from red to black. All koh dissolved, but the returns on the effort and amount of koh used has me ready to set aside this brand antifreeze and try another to see if it’s me or the antifreeze. I’m estimating out of 350ml of crude product, I got under 100ml from 84-94C, and with the losses from the koh , yield will be truly horrible.

I am happy I never got a sludge volcano, but I do have some black slime/tar that is going to be fun.

Rainwater - 17-11-2022 at 01:02

May i suggest testing/purifying your H₂SO₄
Lots of videos out there about this subject. Your initial distillate should smell sweet, don't go sniff it. It's a powerful smell that will fill an outside area if it's not too windy

TLutman - 17-11-2022 at 14:54

I have about 500ml of distilled H₂SO₄ left and a couple liters of liquid fire drain cleaner. I am hoping to stretch the distilled until another warm spell hits, as I would prefer to do it outdoors away from all my machine tools and it is looking like cold and snow for … who knows?
I originally did this with the distilled with the same results, even though I used NaOH at the time. I did grab some Prestone concentrated while in town today. I’m going to try it here tonight and see which way it goes. I really want to get all the glassware cleaned up because it smells. Yes there is some sweet smell in the last flask, but the yield is very minimal.

alexrandomkat - 23-2-2023 at 20:58

Just tried out my own attempt at dioxane, and I got what I wanted, although it was stopped not by prudent choice but by me yeeting the receiver before a sludge volcano came over (luckily all contained in glassware).

How are people dealing with the waste from this, given throwing dioxane down the drain is not the best of ideas? Is absorbing it into something, sealing in bags, and using the trash acceptable?

Was on my mind since I'll have more clean-up than expected...

Fery - 23-2-2023 at 21:38

alexrandomkat - no tar, no volcano: https://www.sciencemadness.org/whisper/viewthread.php?tid=65...

alexrandomkat - 23-2-2023 at 21:48

Thanks, should have read that thread before I started...

Just stopping a tad earlier would have saved me a lot of hassle now.

Fery - 24-2-2023 at 04:36

Use less acid and bigger flask or put smaller volume into your flask. You can repeatedly add fresh ethylene glycol and resume synthesis. I used 1 L flask and filled 300 ml into it, distilled out 200 ml so remainder in flask 100 ml... then added fresh 200 ml of glycol and repeated (4 cycles totally). Finally I distilled the content from flask a little more so only 50 ml remained inside (from that 11 ml should be H2SO4). Could be done using dropping funnel instead adding glycol on cycles. When I saw the disastrous situations on youtube I postponed this synthesis for more than 1 year. Meanwhile I luckily found better sources like using 3 times less of catalyst and bigger flask filled less. I wonder whether H3PO4 could be used instead of H2SO4 but I usually do not repeat experiments as I have long list of new experiments to do. Meanwhile I also bought a lot of 1,4-dioxane from es-drei.de

TLutman - 5-3-2023 at 16:13

Interesting update. I finally got around to cleaning up all the different fractions I collected from both the ethylene glycol distill and dioxane. There was perhaps 30-40mL total. I put them all in a gallon jug (empty distilled water). All those test tubes were capped, since I really don’t care for the smell of it.
There was one last tube in that rack, unmarked and open with a mL or so of a clear liquid. It couldn’t be to volatile, and being from the same time I just put it in the same jug.
A few seconds later, all the vapors ignited in a single woof. I felt the jug, but no heat was noticed.
I wish I knew what was in the open tube, and why it reacted the way it did.
Also regret assuming it was fine to just throw in with the dioxane/EG/ mystery yellow liquid.

Rainwater - 5-3-2023 at 17:30

If this stuff has been sitting, waiting for 3 months, it likely formed peroxides

Fery - 16-7-2023 at 01:42

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]

B(a)P - 7-9-2023 at 20:59

I am in need of some 1,4-dioxane for an an experiment that I intend to do once I have sourced the required regents and solvents. I intend to make the 1,4-dioxane via dehydration of ethylene glycol with sulfuric acid. I recently purchased some impure ethylene glycol (anti freeze) for this purpose. What I have unfortunately realised since purchasing the ethylene glycol is that it is 50% water.
Is it worth distilling the ethylene glycol to remove the water before I attempt the dehydration reaction with sulfuric acid?

j_sum1 - 7-9-2023 at 21:04

I would.

That said, I have never been very successful at dioxane synthesis. I have used ~100% ethylene glycol and also the same stuff pre-distilled. I think I have lost a lot in the work-up with NaOH or KOH and made a lot of tarry goop. Which is to say, my advice might not count for a whole lot.

B(a)P - 7-9-2023 at 21:44

Thanks, I have never tried the synthesis, so any advice is most welcome. I was concerned my crude product would be too dilute and the dioxane I produced would get mostly lost when I was trying to pull the water out. I will get rid of the water first.

Fery - 8-9-2023 at 05:04

Certainly remove the water as much as you can. During the reaction use only less of the catalyst, not 10%. 4% was enough in my case. You can add fresh ethylene glycol then and repeat few cycles. Do not overfill the flask. Filling for only 1/3 is better than filling 1/2 of the flask.

Runaway polymerization during dioxane synthesis?

Sir_Gawain - 27-11-2023 at 13:11

While making dioxane yesterday for the first time, I noticed something strange. I was using unpurified antifreeze (300 mL) and purified drain cleaner acid. The distillation went pretty smoothly for the first two hours, with none of the tar people talk about. It did slowly grow darker until it was almost black, but there was no foaming. The vapor temperature had been fairly stable at around 110*C, but when around 100 mL was left in the boiling flask the temperature suddenly spiked. It climbed to over 120*C and a lot of distillate came over very rapidly, maxing out my condenser. Even though I immediately turned off the heat it continued to keep going. About 50 mL came over in just a few minutes. Tar also started to form, and foamed up almost to the condenser.

Could the rapid polymerization reaction cause the heating? The exothermic reaction that forms Bakelite comes to mind. Usually, it seems the tar forms over a couple minutes. Mine, however, formed all at once. I did add a little less sulfuric acid than most people(30 mL).

End result.

[Edited on 11-27-2023 by Sir_Gawain]

Fery - 28-11-2023 at 01:15

what was your ratio of ethylene glycol : H2SO4
volume of your flask and volume of reactants?

Sir_Gawain - 28-11-2023 at 06:56

300 mL antifreeze, 30 mL sulfuric acid, 500 mL flask.

Texium - 28-11-2023 at 08:05

Oof. I don’t envy the task you have ahead of you with cleaning that flask.

I can’t explain what happened, but I recommend carefully re-distilling your product, because who knows what all came over when the temperature spiked.

Sir_Gawain - 28-11-2023 at 08:50

Quote: Originally posted by Texium

Oof. I don’t envy the task you have ahead of you with cleaning that flask.

It actually wasn’t that bad. Hot water got most of it out, a little acetone removed the rest.
I’m going to fractionally distill it, dry over sodium hydroxide, and distill again.

Fery - 28-11-2023 at 11:11

Quote: Originally posted by Sir_Gawain

300 mL antifreeze, 30 mL sulfuric acid, 500 mL flask.

for 300 ml glycol you should use 1 L flask and 11 ml of H2SO4
distill out 200 ml of product and then add fresh 200 ml of glykol into the flask and repeat few times

Sir_Gawain - 28-11-2023 at 12:29

Only 11 mL of sulfuric acid for 400+ mL of glycol? I reasoned less sulfuric acid would cause less tar, but that seems like a lot less.

Dr.Bob - 28-11-2023 at 18:41

Likely you made some polyethylene glycol in the process, that might happen if mostly glycol and not enough acid. The acid might help stop the polymerization and make dioxane rather than chain elongation.

Fery - 28-11-2023 at 21:40

Everyone repeats the mistakes of former home lab experimenters although everyone sees the consequences. I postponed this synthesis for few years only due these nasty looking experiences - black tar and messing apparatus with it. If at least one had did the experiment properly I did it few years earlier.
Here the method to avoid nasty experiences:
https://www.sciencemadness.org/whisper/viewthread.php?tid=65...
Use 1/3 of the H2SO4 amount the unhappy experimenters used and use twofold volume flask compared to them. Distill off only 2/3 of the content from the flask. Then you can add the consumed glycol amount and resume. You can perform few such cycles.
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

monolithic - 29-11-2023 at 05:00

It's been a few years since I've made any but I remember having to carefully control the power output on my heating mantle. Toward the end of the distillation it will go crazy and foam out of control, so you have to babysit it and taper down the power and play with the stirring speed, and there will be a point where you have to call it quits. You can push the distillation pretty far, however.

I used a 1L round bottom flask + 350 ml ethylene glycol (distilled from antifreeze concentrate) + 35 ml unbuffered drain cleaner straight from the bottle (tested as 93% w/w concentration.) http://www.sciencemadness.org/talk/viewthread.php?tid=84819&...

[Edited on 11-29-2023 by monolithic]

Texium - 29-11-2023 at 09:11

Here you go: the dioxane sticky thread that people have been wanting for years but was never made!

[Edited on 11-29-2023 by Texium]

Sir_Gawain - 2-12-2023 at 12:54

Thanks, Texium!

Fery, I’ll try your method next time.

Another improvement I discovered is, when drying the impure dioxane azeotrope over sodium hydroxide, to add about 30 grams of sodium hydroxide per 150 mL of dioxane and let it dissolve. At this point, Nurdrage added more sodium hydroxide and it all gummed up and solidified. Instead, drain off the bottom aqueous sodium hydroxide layer and add another 30 grams of sodium hydroxide to the dioxane. You lose a lot less dioxane this way. It’s also probably drier.

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