Sciencemadness Discussion Board - Acetic anhydride preparation

I was expecting that Cu2+ would oxidize SO2.
Fe(OAc)3 may be a somewhat stronger oxidizer, but it is much harder to dry. AgOAc is easy to dry, but expensive and probably insoluble. Pb(OAc)4 is cheaper but toxic. Perhaps Fe2(SO4)3 could be used?

I didnt find any reference for making Ac2O by this method
(i think this is time that you test your idea and publish it)

[Edited on 23-11-2018 by Waffles SS]

NZniceguy - 11-7-2019 at 01:52

Has anyone actually tried the Sodium Pyrosulphate and Sodium Acetate method from the Henry Dreyfus patent? I have seen that some people have had success with it on another forum but it looked like it was quickly dismissed in this thread without anyone actually trying it.
It is also supposed to work with Propionate salts to get Prop. Anhydride.

clearly_not_atara - 11-7-2019 at 16:36

IIRC tests by SM members showed that the method does work for propionic anhydride but does not work for acetic anhydride.

One possibility is to use pyrosulfate to make benzoic anhydride and then react this with anhydrous metal acetate to get acetic anhydride. Benzoic anhydride is probably a good case for this rxn since it is not enolizable or easily oxidized. Also sodium benzoate can bee had in bulk and IIRC is not hygroscopic.

[Edited on 12-7-2019 by clearly_not_atara]

Waffles SS - 11-7-2019 at 23:32

IIRC tests by SM members showed that the method does work for propionic anhydride but does not work for acetic anhydride.

One possibility is to use pyrosulfate to make benzoic anhydride and then react this with anhydrous metal acetate to get acetic anhydride. Benzoic anhydride is probably a good case for this rxn since it is not enolizable or easily oxidized. Also sodium benzoate can bee had in bulk and IIRC is not hygroscopic.

[Edited on 12-7-2019 by clearly_not_atara]

I tried reaction of Pyrosulfate with acetate and propionate salt without any success.I will be so happy if someone show this method is not bullshit and Henry Dreyfus is not lier !

Ac2O from Benzoic anhydride is possible and i mentioned this method on page 33

NZniceguy - 4-8-2019 at 23:27

I have seen reports that the Propionic salt and Pyrosulphate has worked for people but I just tried it and it failed. Im unsure if I managed to get Pyrosulphate from Bisulphate though which may have been the problem.

What happened when you tried the propionic salt with pyrosulphate?

Has anyone here had success with the pyrosulphate method?

[Edited on 5-8-2019 by NZniceguy]

Waffles SS - 5-8-2019 at 04:24

Quote: Originally posted by NZniceguy

What happened when you tried the propionic salt with pyrosulphate?

I just got something like propionic acid each time(I even used dry Merck pyrosulfate and propionic salt)

My advise : dont waste your time by this method

nleslie321 - 25-8-2019 at 03:22

Making acetic anhydride is very easy and straightforward if done safely using ketene. The key word here is SAFELY as ketene is on par with hydrogen cyanide. Just follow the setup that doug uses on dougs lab youtube channel or a variation of the setup. Ive had no problem using this method and if done safely it is extremely simple to achieve in a amature home lab with a fume hood. Ive also used the S2Cl2 and sodium acetate method which is also quite easy but a lot more work and messy/smelly because you have to synthesize the S2Cl2. I don't know why so many people ask about making acetic anhydride when its so simple to synthesize. I can also vouch that the pyrosulfate method is bullshit for acetic and for propionic anhydride. I had no luck with either i did however find propionic anhydride extremely simple to synth via ketene and propionic acid.

clearly_not_atara - 14-12-2019 at 09:10

Ok, I had another thought.

Suppose you gas HCl to a solution of succinic anhydride and GAA. The result should be an equilibrium between succinic monochloride and acetyl chloride (I think this leans left, but whatever):

AcOH + HOOCCH2CH2COCl <> AcCl + HOOCCH2CH2COOH

If this solution is heated, acetyl chloride should boil away first by Le Chatelier’s principle. It is dramatically more volatile than anything else in the flask.

This is particularly attractive because succinic anhydride can bee had by simply heating succinic acid to 200-250 C. See:

https://patents.google.com/patent/US3957830A/en

EDIT: this might also work for benzoyl chloride or [m]ethanesulfonyl chloride!

[Edited on 15-12-2019 by clearly_not_atara]

njl - 31-1-2020 at 07:20

2 Ideas:

Ozonolysis of acetylene

"Decomposition" of acetate salt

I know Wikipedia isn't necessarily a great source, but given the accessibility of both ozone and acetylene I think it's worth some thought. Given the fact that it would be a gaseous mixture of an explosive gas and an extremely strong oxidizer, I'm not recommending that anyone without the proper equipment and experience try.

Again from Wikipedia, heating anhydrous Zinc Acetate apparently releases Acetic anhydride in a vacuum, leaving the basic Acetate salt. A good enough vacuum might be hard to pull, but again due to the accessibility of acetate salts it may be worth a shot.

DavidJR - 31-1-2020 at 07:30

Ozone + acetylene sounds like a really terrible idea.

Tsjerk - 31-1-2020 at 07:35

Quote: Originally posted by DavidJR

Ozone + acetylene sounds like a really terrible idea.

It sounds like one of the worst ideas I have seen around here. If you want an explosion I would recommend TATP before I would recommend this one.

njl - 31-1-2020 at 10:36

Quote: Originally posted by Tsjerk

Quote: Originally posted by DavidJR

Ozone + acetylene sounds like a really terrible idea.

It sounds like one of the worst ideas I have seen around here. If you want an explosion I would recommend TATP before I would recommend this one.

Great minds think alike! So alike that I explicitly said it should not be attempted by anyone who's not equipped to deal with it. I can't tell if you actually think I want an explosion, but I'd rather sit on a nail than make TATP again. Do you have anything thoughts on the Acetate salt?

Given the fact that it would be a gaseous mixture of an explosive gas and an extremely strong oxidizer, I'm not recommending that anyone without the proper equipment and experience try.

Fulmen - 31-1-2020 at 12:04

Wasn't this combo covered in Igntition? It wouldn't be above average for those nutjobs. But yeah, that sounds like premeditated *kaboom*.

SWIM - 31-1-2020 at 13:24

2 Ideas:

Ozonolysis of acetylene

"Decomposition" of acetate salt

I know Wikipedia isn't necessarily a great source, but given the accessibility of both ozone and acetylene I think it's worth some thought. Given the fact that it would be a gaseous mixture of an explosive gas and an extremely strong oxidizer, I'm not recommending that anyone without the proper equipment and experience try.

Again from Wikipedia, heating anhydrous Zinc Acetate apparently releases Acetic anhydride in a vacuum, leaving the basic Acetate salt. A good enough vacuum might be hard to pull, but again due to the accessibility of acetate salts it may be worth a shot.

Decomposition of zinc acetate has been brought up again and again, but nobody here seems to have actually heated zinc acetate at 2 mm pressure and 250 degrees C to try it out for themselves.

These the parameters quoted in old sources for this decomposition reaction.

Abromination - 31-1-2020 at 23:13

Quote: Originally posted by SWIM

If i have nothing going on, I might try it this weekend just for the fun of it. People like to suggest things, not read the thread and then not try it.

G-Coupled - 1-2-2020 at 21:55

Quote: Originally posted by Abromination

If i have nothing going on, I might try it this weekend just for the fun of it. People like to suggest things, not read the thread and then not try it.

I feel that would be a most valuable contribution to the sum of knowledge on this fine forum. I eagerly await your results, should you perform this experiment. :cool:

Abromination - 2-2-2020 at 15:54

Quote: Originally posted by G-Coupled

Quote: Originally posted by Abromination

If i have nothing going on, I might try it this weekend just for the fun of it. People like to suggest things, not read the thread and then not try it.

I feel that would be a most valuable contribution to the sum of knowledge on this fine forum. I eagerly await your results, should you perform this experiment. :cool:

I will soon, but weekend was spent fumehood building. Ill read through the whole thread and do some more research first. I dont think it will work, but why not try

Waffles SS - 7-2-2020 at 13:00

Quote: Originally posted by byko3y

I want to put an end to the discussion of distilling acetate for preparation for acetic anhydride.
https://www.sciencemadness.org/whisper/viewthread.php?tid=9&... - link to the original article on Zinc Acetate.
https://www.sciencemadness.org/whisper/viewthread.php?tid=9&... - report about results by very same Waffles SS.
Now let's look inside the article - at the mass spectrum graph they recorded:

Here I made a spectrum for 260°C :

Now let's take a look at the reference mass spectrum of acetic anhydride from NIST:

Do you see the similarity? Because I don't. How the hell could those douchebags find acetic anhydride in their spectrum - god only knows. Some more spectrums of possible reaction products for reference (major ions in orded of decreasing intensity):
http://webbook.nist.gov/cgi/cbook.cgi?ID=C108247&Mask=20... - Acetic anhydride: 43 (faint 42)
http://webbook.nist.gov/cgi/cbook.cgi?ID=C64197&Mask=200... - Acetic acid: 43, 45, 60 (15, 42)
http://webbook.nist.gov/cgi/cbook.cgi?ID=C67641&Mask=200... - Acetone: 43, small 58 (42, 15)
http://webbook.nist.gov/cgi/cbook.cgi?ID=C123422&Mask=20... - Diacetone alcohol: 43, small 58, 59 (101)
http://webbook.nist.gov/cgi/cbook.cgi?ID=C141797&Mask=20... - Mesityl oxide: 83, 55, 98, 43, small 29, 39 (a lot of faints)
http://webbook.nist.gov/cgi/cbook.cgi?ID=C630080&Mask=20... - Carbon monooxide: 28
http://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Mask=20... - Carbon dioxide: 44 (28, 16, 12)
http://webbook.nist.gov/cgi/cbook.cgi?ID=C7732185&Mask=2... - Water: 18, small 17
http://webbook.nist.gov/cgi/cbook.cgi?ID=C74828&Mask=200... - Methane: 16, 15, small 14, 13
http://webbook.nist.gov/cgi/cbook.cgi?ID=C74840&Mask=200... - Ethane: 28, small 27, 30, 26, 29
http://webbook.nist.gov/cgi/cbook.cgi?ID=C75070&Mask=200... - Acetaldehyde: 29, 44, 43, 15, small 42, 14
(there're similar spectrums on restek website, e.g.
http://www.restek.com/compound/view/67-64-1/Acetone - Acetone
http://www.restek.com/compound/view/123-42-2/Diacetone%20alc... - Diacetone alcohol )

Now let's try to analize the spectrum of gaseous products at 260°C: 15, 43, 16, 44, 45.
15 m/z is a methyl ion CH3+.
16 m/z is not oxygen but methane ion CH4+. Prevalence of it together with 15 m/z means methane is a major product. The fact that intensity at 15 is higher than 16 means there are other methyl-producing substances.
44 m/z is a carbon dioxide ion CO2+. CO2 is another major product of the reaction.
There's no 18 ion meaning no water detected. That could be explained by the fact decarboxylative ketonization does not generate water but carbon dioxide is produced instead.
45 m/z is an unknown ion. It could be acetaldehyde, but this substance has a very distinctive 29 ion which was not detected by authors. Acetic acid has smaller ion 45, but it also has a smaller definite 60 ion, which was not detected too. My guess: 60 m/z ion was ignored for some reason (small relative intensity?) and acetic acid is formed in substantial amounts.
43 m/z is acetyl CH3CO+. Could be derrived from any molecule with acetyl fragment. Probably that's acetone and diacetone alcohol which both have much smaller other ions.
I'd guess the detected products were methane, CO2, acetone, diacetone alcohol, small amount of acetic acid. There's also a lot of solid products, formed by polymerization of acetone, but those were not volatile enough to be detected.
Update: corrected ion number for acetaldehyde. Now acetic acid is the only option for 45 m/z.

[Edited on 28-2-2018 by byko3y]

Dont try unsuccessful methods !.

[Edited on 7-2-2020 by Waffles SS]

clearly_not_atara - 7-2-2020 at 13:30

Waffles is right, I’m still not sure why we get so many people wanting to try stuff we know doesn’t work.

But nobody wants to work on the methods that do or might work. S2Cl2 is too hard, let’s build a ketene lamp. I don’t get it. Because ketene is safer than chlorine, somebody thinks.

I admit I’m just mad because I posted a kind of unlikely idea and everyone ignored me and then went for these obviously terrible ideas. Obviously I’m wasting my time

Abromination - 7-2-2020 at 15:28

Hope I don't sound hostile, but I read through the entire thread and determined the same. Someone mentioned an idea, and the same idea had been mentioned several times by others who had not read the full thread. I looked into it, found the idea to be futile and did not bother with saying so assuming anyone else who wanted to would do the same. It was simply an accessible idea, and even though I have no use for acetic anhydride I still found it worth looking into.
If you have an idea, test it yourself and report back. No one is stopping you.

[Edited on 2-8-20 by Abromination]

Tamerlane - 3-5-2020 at 11:03

I had an idea for forming acetic anhydride by transacylation with a more easily prepared cyclic anhydride. For example, maleic anhydride is freely soluble in aromatic solvents, whereas maleic acid is almost completely insoluble, on the order of tens of milligrams per liter of toluene. If there is any sort of equilibrium formation between maleic and acetic acids and anhydrides in toluene, the disproportionation would be driven forward by the extreme insolubility of maleic acid in the solvent.

To my dismay, according to Solvolytic Reactions of Cyclic Anhydrides in Anhydrous Acetic Acid (J. Pharm. Sci.), there is no appreciable equilibrium reaction between maleic or phthalic anhydrides and acetic acid. However, the equilibrium reactions between saturated cyclic anhydrides such as succinic anhydride, glutaric anhydride, and trans-1,2-cyclohexanedicarboxylic anhydride with acetic acid DO take place. But the solubility characteristics of those anhydrides in aromatic solvents are much less favorable! :mad:

From what little information I've found, succinic anhydride doesn't seem to be too soluble in aromatics, and the free acid is possible somewhat soluble as well. Glutaric anhydride/acid could perhaps be more favorable but I haven't found much in the way of solubility data. Perhaps if appropriate solvents could be found, the reaction could be made to work. Or perhaps in the case of maleic anhydride, a sufficiently long period of time could coax the sluggish equilibrium forward. It really seemed like I was on to something!

clearly_not_atara - 3-5-2020 at 11:29

Tamerlane: I had considered the same with Le Chatelier's principle applied through volatility:

RR=(C2O3) + HCl <> HO2CRRCOCl
HO2CRRCOCl + AcOH <> AcCl + HO2CRRCOCl

AcCl is much more volatile than any of the other rxn components and should distill out. In this case GAA is the ideal solvent.

However, while the preparation of succinic anhydride by thermolysis of succinic acid is commonly talked about, it is difficult to obtain a pure product in decent yield. I wonder if sodium pyrosulfate or metaphosphoric acid could be used to make succinic anhydride?

[Edited on 3-5-2020 by clearly_not_atara]

Refinery - 14-6-2020 at 11:34

On the ketene lamp concept, could ketene be formed by just distilling acetone trough SS tube that is drawn through ceramic wool furnace heated with propane burner?

It could be more feasible to produce this than operating with nichrome wire. Put acetone vapor through bottom inlet, heat the inside of furnace to 800C and out comes ketene, which is cooled with reflux condenser with receiver for any side reactants and the final gas ketene led into GAA.

This type should be easily scalable due to tube length being the factor of pyrolysis capacity. The temp of 800C would be very easy to maintain with ordinary high pressure propane torch.

The joint between steel and glass between the pyrolysis tube end and the condenser would be an issue though. The gas would be very hot leaving the furnace and it would quickly melt any plastic joint. Making a larger tube ending and turning a graphite adapter would be an option.

[Edited on 14-6-2020 by Refinery]

Waffles SS - 17-6-2020 at 00:10

As you know ketene(Ethenone) is very toxic and working with this compound is really dangerous.

I wonder why someone here didnt try any other possible method?

I didnt see someone to try reaction of DCC(N,N'-Dicyclohexylcarbodiimide) with acetic acid ? (I tried it before and this is very easy to get Ac2O from DCC)

Or why someone didnt try NaPO3(Sodium Metaphosphate) with AcOH/AcONa according to GB299342 ?

Or Cleavage of Acetoxysilanes to Ac2O ? (I tried it before and that is very easy and high yield)
MECHANISM OF REVERSIBLE CLEAVAGE OF ACETOXYSILANES TO SILOXANES AND ACETANHYDRIDEJ.POLA, M.JAKOUBKOVA and V. CHVALOVSKYInstitute of Chemical Process Fundamentals,Czechoslovak Academy of Sciences, 165 02 Prague- Suchdol

Or Isopropenyl acetate or Vinyl acetate method (i tried those too)?Or...
Reactions of Isopropenyl AcetateHUGH J. HAGEMEYER, JR., AND DAVID C. HULLTennessee Eastman Corporation, Kingsport, Tenn.

Why dont try or research easier and safer methods?Why?

[Edited on 17-6-2020 by Waffles SS]

monolithic - 23-6-2020 at 18:07

Or why someone didnt try NaPO3(Sodium Metaphosphate) with AcOH/AcONa according to GB299342

Where can I find a copy of this patent? Google is not showing anything.

nzlostpass - 23-6-2020 at 20:19

Maybe because we cant pop down to the hardware store and pick up some N,N'-Dicyclohexylcarbodiimide or some Acetoxysilanes .....but can easily get acetone and glacial acetic acid.
To be honest, this is the first i have heard either of those two synthesis mentioned......can you elaborate more on what the process was and where one might obtain such chemicals?

As you know ketene(Ethenone) is very toxic and working with this compound is really dangerous.

I wonder why someone here didnt try any other possible method?

I didnt see someone to try reaction of DCC(N,N'-Dicyclohexylcarbodiimide) with acetic acid ? (I tried it before and this is very easy to get Ac2O from DCC)

Or why someone didnt try NaPO3(Sodium Metaphosphate) with AcOH/AcONa according to GB299342 ?

Or Cleavage of Acetoxysilanes to Ac2O ? (I tried it before and that is very easy and high yield)
MECHANISM OF REVERSIBLE CLEAVAGE OF ACETOXYSILANES TO SILOXANES AND ACETANHYDRIDEJ.POLA, M.JAKOUBKOVA and V. CHVALOVSKYInstitute of Chemical Process Fundamentals,Czechoslovak Academy of Sciences, 165 02 Prague- Suchdol

Or Isopropenyl acetate or Vinyl acetate method (i tried those too)?Or...
Reactions of Isopropenyl AcetateHUGH J. HAGEMEYER, JR., AND DAVID C. HULLTennessee Eastman Corporation, Kingsport, Tenn.

Why dont try or research easier and safer methods?Why?

[Edited on 17-6-2020 by Waffles SS]

clearly_not_atara - 23-6-2020 at 20:44

Or Isopropenyl acetate or Vinyl acetate method (i tried those too)?Or...
Reactions of Isopropenyl AcetateHUGH J. HAGEMEYER, JR., AND DAVID C. HULLTennessee Eastman Corporation, Kingsport, Tenn.

With regard to isopropenyl acetate, a while ago I found an article that describes the efficient preparation of 1-bromo-2-acetoxypropane by the reaction of propylene glycol with a solution of hydrogen bromide in anhydrous acetic acid. This solution is not the easiest thing to prepare, but HBr is still much less dangerous than Cl2.

A simple Sn2 dehydrohalogenation of the product gives isopropenyl acetate. Circuitous, but this provides both acetic anhydride and acetoacetone by different rearrangements, using relatively "safe" and cheap methods.

Attachment: golding1973.pdf (923kB)
This file has been downloaded 654 times

Waffles SS - 24-6-2020 at 02:00

Interesting Idea.

Thanks

Alkoholvergiftung - 24-6-2020 at 02:22

Why not over the rout of benzotrichlorid.
2mol concentratet acetic Acid few percent of zinkacetat and 1 mol benzotrichlorid.You get HCL gas and Acetylchlorid and benzoeacid remains.If you want to get acetic Acid Anhydrid directly dont use acetic Acid instad only zinkacetat.
Here is the link if some one knows german.
http://dingler.culture.hu-berlin.de/article/pj239/ar239071

Refinery - 24-6-2020 at 12:54

As you know ketene(Ethenone) is very toxic and working with this compound is really dangerous.

I wonder why someone here didnt try any other possible method?

I think there are two methods to produce compounds:

1) The easy/safe/convenient/etc method
2) The economically viable method

These two do not usually mix well.

If you only produce a compound for the academic interest of it, it may not matter if you need to use 400$ worth of reagents you can't even write without copy-pasting them from Sigma site to make a hundred mL of desired compound. But if you're gonna use it for anything, the cost becomes determining factor. Second to that, many amateurs simply cannot afford the buck nor get the exotic reagents anywhere.

I've always been fascinated by the concept of making stuff dirt cheap out of thin air. It also fascinates that with quite minor lead in costs you could actually build a generator that can put out a kg order of ketene per hour and be run almost indefinitely. Dangerous? Most likely. Where do you need kg's of ketene/AA? That's a different matter.

[Edited on 24-6-2020 by Refinery]

clearly_not_atara - 24-6-2020 at 16:59

The idea of building a ketene generator with "minor lead-in costs" strikes me as a suicide mission. Perhaps you don't mind the risks, but your neighbors do. Safety equipment is the wrong place to cut costs.

The cheapest method is probably the nitrogen dioxide method. NO2 is toxic, but compared to ketene it's just another brown gas.

The method I suggested requires more steps, but the reagents (sodium bromide, sodium bisulfate, acetic acid, propylene glycol, potassium hydroxide, ethanol) are all cheap.

[Edited on 25-6-2020 by clearly_not_atara]

Waffles SS - 1-7-2020 at 21:09

.

A simple Sn2 dehydrohalogenation of the product gives isopropenyl acetate.

I checked this part of your reaction again

I think another products are possible to form,like aldol product ,hydrolysis of acetate, intermolecular product,..

This is difficult to suggest major product

Refinery - 1-7-2020 at 23:02

The idea of building a ketene generator with "minor lead-in costs" strikes me as a suicide mission. Perhaps you don't mind the risks, but your neighbors do. Safety equipment is the wrong place to cut costs.

I was not attempting to cut costs from safety, but when the concept is to distill acetone through seamless copper/steel tube which ends to GAA and finally to a scrubber, it does not strike as a complicated to me. I see a point if someone attempts this with paint cans and caulk, but I have access to a lathe and a tig welder if it comes to that.

Corrosive Joeseph - 1-7-2020 at 23:15

I remember reading a post on a forum years ago where somebody stated that a ketene generator would probably smell like vinegar and death... If I was even considering that, I would put all my effort into just obtaining acetic anhydride by any means necessary, surely it must be easier.

/CJ

Refinery - 2-7-2020 at 09:08

It's no more toxic than phosgene. Doing it outdoors in remote(read=big yard) in a closed system that is scrubbed properly should really be no hazardous at all. You dont need to monitor the process constantly once you adjust it, and normal abek is enough to protect from any traces. It's not bioaccumulative. I would be more scared with long half life solible metal salts, even lead is a bit eh to me due to this.

I would never do it indoors or with substandard apparatus. But i trust in seamless tubing.

Eddie Current - 2-7-2020 at 22:29

Quote: Originally posted by Refinery

It's no more toxic than phosgene.

Now there's a sentence you don't read every day.

It's insidiously dangerous, and not for the hobby chemist.

https://www.cdc.gov/niosh/idlh/463514.html
https://www.pnas.org/content/117/12/6349

[Edited on 3-7-2020 by Eddie Current]

[Edited on 3-7-2020 by Eddie Current]

clearly_not_atara - 3-7-2020 at 08:23

Refinery: You are obviously more interested in defending your previously stated opinions than considering the actual costs of your plan. For one thing, most of us don't have a machine shop at our disposal. For another, you need a substantial excess of GAA to disperse the heat both from the 500 C pyrolysis and the exothermic ketene-carboxylate Michael reaction. That already drives up costs. Then you have to recover Ac2O (bp 140) from a dilute solution in AcOH (bp 119), which adds another step.

You can also make nitrogen dioxide by a flow process and work at low temperatures rather than hot. You can make S2Cl2 by a flow process and the cost of sulfur is definitely not that high. You can also make trichlorotoluene in pretty large quantities if you're willing to build an apparatus.

None of these are the safe lab-scale methods that Waffles and I are interested in, but they're still way less dumb than ethenone at scale. I don't know if you're imagining that you won't have to clean the equipment or that there won't be byproducts, but your device isn't going to be as optimized as the industry's; you'll get ketene polymer crap and diketene derivatives. Acetone reacts with ketene to isopropenyl acetate which can lead to other condensation products. The Orgsyn procedure reports a <30% yield of acetanilide with their ketene lamp and it's fucking Orgsyn, they're not stupid. The yield is given based on acetone decomposed, which is only about half of what passes through the apparatus.

.

A simple Sn2 dehydrohalogenation of the product gives isopropenyl acetate.

I checked this part of your reaction again

I think another products are possible to form,like aldol product ,hydrolysis of acetate, intermolecular product,..

I agree that byproducts are possible. However, I can't conclude that it will or won't work without testing. It makes no sense to try some complicated method without at least giving potassium hydroxide a chance. If that doesn't work you can try pyridine, triethylamine, etc.

Refinery - 6-7-2020 at 09:59

I don't think there's an issue with using condenser unit to cool down the gas, and also use cooling bath with the GAA.

If you don't have resources available, it doesn't necessitate other wouldn't. And if they have the resources and the planning, they could actually manufacture a working pilot plant for ketene. If one is dedicated enough, the device gets complicated quickly, including condensate recovery for unreacted acetone/high bp side products, a plug valve for purging/decontaminating the system without opening it. All this would, of course, necessitate the need for a larger quantity of anhydride, and could probably be easily designed at once to be converted into making something else as well, as gas catalysis bed, etc. I highly believe that somewhere, some folks do, probably in the region between eastern Europe and western China, but enough for that.

For the record, I was not gonna build a ketene generator of any sort, because I don't need it, I need my time and space for more important stuff, and the device would need much more delicate designing and reading through various articles, patents and other documents to fully understand the mechanisms.

VeritasC&E - 22-10-2020 at 11:27

Would anyone who has gone through the pain of reading the 38 pages of this topic tell me if it contains ANY method for preparing fair amounts of acetic anhydride in a small lab at an affordable cost from readily available reagents?

I'd like to use it to make some aspirin but for some reason I can't find a source at reasonable price in Europe.

Antigua - 22-10-2020 at 11:34

Where are you located? I could send you some sources on U2U.

teodor - 22-10-2020 at 12:10

Would anyone who has gone through the pain of reading the 38 pages of this topic tell me if it contains ANY method for preparing fair amounts of acetic anhydride in a small lab at an affordable cost from readily available reagents?

I think the route from acetyl chloride is the most affordable one. I was able to order some acetyl chloride as private individual in EU few days ago. I really don't know which sources Antigua means, even became curious.

[Edited on 22-10-2020 by teodor]

Antigua - 22-10-2020 at 14:56

I have a friend who can get some acetic anhydride locally and would be willing to ship it to someone if they needed. I can give you the contact info on U2U if you'd be interested.

VeritasC&E - 22-10-2020 at 23:45

What is the route from acetyl chloride? I've found a source at which 98% acetyl chloride is priced at 48€/L (which seems a bit expensive to me). How much did you pay for yours?

nzlostpass - 23-10-2020 at 00:43

What is the route from acetyl chloride? I've found a source at which 98% acetyl chloride is priced at 48€/L (which seems a bit expensive to me). How much did you pay for yours?

it's in this thread repeatedly.....add the Acetyl Chloride dropwise to Sodium Acetate and then distill.

VeritasC&E - 23-10-2020 at 01:26

Quote: Originally posted by nzlostpass

What is the route from acetyl chloride? I've found a source at which 98% acetyl chloride is priced at 48€/L (which seems a bit expensive to me). How much did you pay for yours?

it's in this thread repeatedly.....add the Acetyl Chloride dropwise to Sodium Acetate and then distill.

Thanks a lot!

teodor - 23-10-2020 at 02:02

I've found a source at which 98% acetyl chloride is priced at 48€/L (which seems a bit expensive to me). How much did you pay for yours?

Yes, something like that. I think half a year ago I saw also acetyc anhydride there priced half as that, so even more cheap, but now there is no in the list anymore. Or may be I don't remember it correctly.
Anyway, that was a legal business with fast predictable delivery, good packing skills and option to sell wide range of chemicals to private individual and I always supports companies like that even if they sell chemicals twice as expensive, so I just decided to support them.

! Doing the preparation don't forget that the acetate must be anhydrous !

[Edited on 23-10-2020 by teodor]

Corrosive Joeseph - 23-10-2020 at 03:04

Taken from somewhere else...

Quote:

Quantitative yields of acetic anhydride are obtained with very anhydrous sodium acetate + Acetyl chloride.
CH3COCl + CH3COONa => (CH3CO)2O + NaCl

The acetyl chloride and NaOAc method works wonderfully and is easy to do. Of course there is the issue of getting the acetyl chloride but if you happen to have it rest assured this method works great.
The sodium acetate must be freshly fused.

/CJ

VeritasC&E - 23-10-2020 at 03:52

@ Corrosive Joeseph
@ Teodor

Thanks to both of you!

clearly_not_atara - 23-10-2020 at 05:44

Bluntly, no. All of the methods require either:

- a fume hood (liquid bromine)
- gassing chlorine
- gassing HCl
- gassing SO2 (basically a guess on my part, though)
- specialty chemicals (acetyl chloride, cyanuric chloride, oxalyl chloride, carbonyldiimidazole, et cetera)
- a sizeable investment and excellent technique (silver acetate)

Of the methods gassing HCl is by far the most "accessible" but also requires the most setup since you have to make or buy acetonitrile.

teodor - 23-10-2020 at 05:50

@clearly_not_atara Why you didn't mention the ketene route which is also should be effective ?

Antigua - 23-10-2020 at 05:52

Even if it is, it's based on producing an awfully toxic substance - definietly not something you'd like to do on your balcony, and I believe that would qualify as "needing fumehood".

teodor - 23-10-2020 at 05:57

I think it is probably something more irritating than toxic, but yes, it requires some well-tested setup, may be the same or next level after chlorine. So, that's why I proposed acetyl chloride.

njl - 23-10-2020 at 06:00

I think it is probably something more irritating than toxic, but yes, it requires some well-tested setup, may be the same or next level after chlorine. So, that's why I proposed acetyl chloride.

Are you talking about ketene or acetyl chloride? Because ketene would probably kill you before it irritated you.

[Edited on 10-23-2020 by njl]

teodor - 23-10-2020 at 06:10

Are you talking about ketene or acetyl chloride? Because ketene would probably kill you before it irritated you.
[Edited on 10-23-2020 by njl]

I have no experience with ketene, but wikipedia says:
"Exposure to concentrated levels causes humans to experience irritation of body parts such as the eye, nose, throat and lungs. Extended toxicity testing on mice, rats, guinea pigs and rabbits showed that ten-minute exposures to concentrations of freshly generated ethenone as low as 0.2 mg/liter (116 ppm) may produce a high percentage of deaths in small animals.
...
An IDLH limit is set at 5 ppm, as this is the lowest concentration productive of a clinically relevant physiologic response in humans.
"

IDLH as 5 ppm is identical to such substances as H2SO4 / SO3 fumes, ozone . For bromine which most of us distil we have 3 ppm.

Comparison with phosgene is not correct because phosgene action is different and delayed.

So, yes, I don't know but it seams no at the same level.

[Edited on 23-10-2020 by teodor]

clearly_not_atara - 23-10-2020 at 06:12

@clearly_not_atara Why you didn't mention the ketene route which is also should be effective ?

Because it requires even more equipment? I also left out the nitrogen dioxide route, because it's basically the chlorine/bromine route but with NO2 instead and no sulfur.

Also the ketene route is flypaper for reckless idiots so I prefer to avoid talking about it as much as possible.

[Edited on 23-10-2020 by clearly_not_atara]

Antigua - 23-10-2020 at 06:13

Ketene is said to be 8 times more toxict than the all-frightening phosgene.
Ask yourself if you'd be willing to work with 10g of liquid phosgene (that'd be around 0.1 mol, so 2.24dm³? That's almost 2.5 liters of a deadly gas. Now do the same, but either counting it that the gas is 8 times deadlier or there's 8 times more of it (the second option being actually more forgiving, as it's easier to notice a leak). Just an analogy that presents how awful ketene is for an inexperienced chemist.

Edit: as a follow up, as I can see some more posts emerged while I was writing this:
https://www.ncbi.nlm.nih.gov/books/NBK224928/
Take a look at this, ketene really IS awful and any underappreciation of it's toxicity comes from, I believe, the scarcity of it's uses. Considering how much press carbon monoxide or cyanides get, comparing them would be unfair, even though our main hero is much worse.

[Edited on 23-10-2020 by Antigua]

teodor - 23-10-2020 at 06:18

Quote: Originally posted by Antigua

Ketene is said to be 8 times more toxict than the all-frightening phosgene.

I will not force anybody to use this substance, just want to point that the link in wikipedia which can proof that is broken, so we don't know.

clearly_not_atara - 23-10-2020 at 06:22

I will not force anybody to use this substance, just want to point that the link in wikipedia which can proof that is broken, so we don't know.

You've been posting here for more than a year, you've doubtless seen the stupid ketene dance in this thread before, so you should not need me to traipse through the literature pulling out all of the reasons why underequipped labs should not attempt the prep of ketene. But fine, here:

https://pubs.acs.org/doi/abs/10.1021/ja01216a526

I didn't mention the ketene route because I was responding to a question about small labs using readily accessible chemicals. Ketene is not appropriate and for that matter it's worse than the others. At least when you gas chlorine you don't do it at 600 C.

teodor - 23-10-2020 at 06:51

At least when you gas chlorine you don't do it at 600 C.

Good point, clearly_not_atara. But also the apparatus will never contain much of ketene, in Vogel preparation III,90 the rate of ketene production with a Ketene lamp was calculated as 0.45 mol/hour. So, probably you can construct it such a way to have only small percentage of internal space be filled with ketene and make this space really small. Anyway, I don't want to proceed with this. Just pointed that we have no reliable test of toxicity.

I don't remember really all the dances but now I noticed you mentioned route from S2Cl2 somewere. I have plan to put my hands on this compound. Is there some route I can check to acetic anhydride from S2Cl2?

(I also don't want to study real toxicity of ketene on humans)

Edit: the good point that ketene route is not as clear and simple as 1,2,3 and it can create also many byproducts.

[Edited on 23-10-2020 by teodor]

njl - 23-10-2020 at 07:00

S2Cl2 can be disproportionated with elemental sulfur to form SCl2, which reacts with SO3 to form thionyl chloride, SOCl2. That can be used to chlorinate acetic acid which can then react with sodium acetate to form acetic anhydride. I believe more direct routes have been mentioned in this thread which are almost certainly less work.

Acetic Anhydride

Triflic Acid - 4-11-2020 at 15:54

A random thought, but would ozonolysis of 2-butyne create acetic anhydride?
https://en.wikipedia.org/wiki/Ozonolysis#Ozonolysis_of_alkyn...
Ozone generators are already made, so only the 2-butyene is a problem. Anyone know how to make 2-butyene?

Triflic Acid - 4-11-2020 at 19:53

Maybe taking 2,3 dibromo butane and putting it in Na+NH3 (Makes NaNH2 in-situ) would work?

njl - 5-11-2020 at 04:36

That or the similar synthesis of phenylacetylene via 1,2 dibromoethylbenzene. UC235 has a youtube video following that procedure.

Link: http://orgsyn.org/demo.aspx?prep=CV4P0763

[Edited on 11-5-2020 by njl]

Triflic Acid - 5-11-2020 at 08:01

Can you put a link to the procedure that UC235 followed?

clearly_not_atara - 5-11-2020 at 10:08

It would have to be 1-phenylpropyne in order for cleavage to generate an acetyl anhydride. Phenylacetylene gives you benzoic-formic anhydride.

Probably not practical as alkynes are typically quite hard to make. Unless you can adapt this rxn to OTC:
https://www.organic-chemistry.org/abstracts/lit6/936.shtm

njl - 5-11-2020 at 11:06

Could there conceivably be a route to 2-butyne from 2-butanone? In the interest of OTCness.

Triflic Acid - 5-11-2020 at 12:11

Exactly how would the 1-phenylpropyne work? A rnx diagram would be helpful. I came up with an idea to make the 2-butyne. Starting with methyl ethyl ketone, its reduced to 2-butanol. After that, thats dehydrated to 2-butene. This reacts with bromine to make 2,3-dibromobutane. Reaction with Na in anhydrous liquid NH3 to give 2-butyne. That reacts with ozone to make acetic anhydride. Any problems with this? Also, can I get 2-butanol without needing to do an expensive NaBH4 reduction?

clearly_not_atara - 5-11-2020 at 14:35

You actually need to do the double dehydrohalogenation in two steps because otherwise you'll probably get a diamine when the 2,3-dibromobutane immediately reacts with the NH3 solvent. First remove one bromine with pyridine, then the other with NaNH2. But the other problem is that the preferred product is the allene, IIRC.

For phenylpropyne the ozonolysis product should be this:

acetylbenzoyloxide.png - 5kB

[Edited on 5-11-2020 by clearly_not_atara]

Triflic Acid - 5-11-2020 at 15:19

So how do I convert benzyl-acetic anhydride to acetic anhydride?

Fluorite - 5-11-2020 at 22:13

Why everyone keeps trying to find a way for acetic anhydride? Just reaction between sodium acetate and disulfur dichloride should make acetic anhydride ITS SO SIMPLE

clearly_not_atara - 6-11-2020 at 05:24

Quote: Originally posted by Triflic Acid

So how do I convert benzyl-acetic anhydride to acetic anhydride?

It reacts with (anhydrous) potassium acetate -- the more volatile anhydride distills out. Sodium acetate also works fine but is slightly harder to dry.

Triflic Acid - 6-11-2020 at 09:15

@Fluorite, a new method can't hurt. The thing I like about this is that there is no need for messy/stinky/hard-to-clean sulfur chlorides.
@clearly_not_atra, do you think that you can try that, my lab is down for the next couple months.

Waffles SS - 6-11-2020 at 11:32

Sodium acetate also works fine but is slightly harder to dry.

Anhydrous Potassium Acetate is more hygroscopic than dry Sodium Acetate.

vano - 4-12-2020 at 10:36

Does anyone tried the following reaction?
2Ch3COOH + SbCl3 → (CH3CO)2O + SbOCl + 2HCl

clearly_not_atara - 15-12-2020 at 15:29

A variation on the succinic anhydride method, which was cool, but succinic acid isn't quite as easy to find as... citric acid:

https://en.wikipedia.org/wiki/Itaconic_anhydride

Now, these cyclic anhydrides are obviously more stable than the acyclic ones, so the real idea here is to gas HCl into a solution of the cyclic anhydride in GAA, which will hopefully open the ring and in this case could hopefully also add to the double bond, destabilizing the ring geometry. In fact, if HCl won't do it, give HBr a shot, it's a million times stronger.

Once you generate the open-chain acyl halides, you should get a reasonable equilibrium with the acetyl halide. Then AcCl (bp 52 C) or AcBr (bp 76 C) should be able to distill out. (This method really makes AcCl or AcBr, but it is not too hard to obtain Ac2O, and anyway you can often use any of the three with slightly altered methodology.)

____________________________________________________

Mind has been on anhydride lately for some reason. Anyway, Orgsyn mentions that diphenyldichloromethane can be used to dehydrate sodium benzoate to benzoic anhydride:
http://orgsyn.org/demo.aspx?prep=cv1p0091
http://en.wikipedia.org/wiki/Diphenyldichloromethane

This can be regenerated from the benzophenone byproduct by:

- reduction to the alcohol (Zn/NaOH)
- HCl Sn2
- free-radical chlorination with TCCA in benzene or similar

This is all very tedious, but it's also the first OTC method not involving gassing that seems to have any chance of working, which is mildly interesting.

[Edited on 16-12-2020 by clearly_not_atara]

vano - 2-1-2021 at 10:39

Quote: Originally posted by vano.kavt

Does anyone tried the following reaction?
2Ch3COOH + SbCl3 → (CH3CO)2O + SbOCl + 2HCl

I wrote a reaction to the mistake. Acyl chloride should be prescribed instead of anhydride.

dicyanin - 27-1-2021 at 03:44

Working with ketene is madness in a home lab.

GB299342 looks interesting as sodium metaphosphates are commercially available OTC. Sodium hexametaphosphate is a common food additive (E452i) and water softener, and sodium trimetaphosphate is used in construction. Calgon according to some sources is sodium polymetaphosphate Na₂[Na₄PO₃]₆ but polycarboxylate to others. Still I've seen 1lb bags of pure sodium hexametaphosphate offered for under 10 euros as a water softener.

The patent from 1927 claims "the production of acetic anhydride from a mixture of sodium metaphosphate, anhydrous sodium acetate, and infusorial earth moistened with glacial acetic acid, the reaction being effected at 150-180°C". Sounds too good to be true, but it could work, and yield wouldn't really be an issue considering the requirements. I've heard mixed results from a similar low-yielding process, heating sodium pyrosulfate with sodium acetate.

dicyanin - 27-1-2021 at 04:39

Quote: Originally posted by monolithic

Or why someone didnt try NaPO3(Sodium Metaphosphate) with AcOH/AcONa according to GB299342

Where can I find a copy of this patent? Google is not showing anything.

non-US patents can be found on espacenet

https://worldwide.espacenet.com/
https://worldwide.espacenet.com/patent/search?q=GB299342
https://worldwide.espacenet.com/patent/search/family/0017418...
go to "original document"

The patents says to take the mixture of Ac₂O and GAA and use it as solvent for a fresh NaPO₃/NaOAc batch, increasing the yield of Ac₂O recovered every time.

[Edited on 27-1-2021 by dicyanin]

Interesting procedure

LeLaborantin - 30-1-2021 at 15:29

Hello,

I'm sorry if this has already been discussed. But isn't it possible to proceed in this way to produce Acetic anhydride?

It sounds like a pretty interesting procedure.

UV LED lamps are not expensive and TCCA is easy to obtain.

What do you think about it?

(Sorry for my English, I'm French-speaking Belgian. )

Attachment: MICF_Leonor_Pereira.pdf (1.5MB)
This file has been downloaded 606 times

Screenshot_20210131-002151_Drive.jpg - 130kB

[Edited on 30-1-2021 by LeLaborantin]

clearly_not_atara - 31-1-2021 at 13:02

This method using TCCA and benzyl alcohol or benzaldehyde has been discussed, a few times in fact. It is probably the most OTC and easiest way to benzoyl chloride.

However, caution is advised because one SM member reported an explosion when working up this rxn! The partially reduced DCCA and MCCA byproducts can decompose to CO+N2+HCl.

A few alternatives might work better:

- Use AgBr or KICl4 as the halogenating agent instead.

- Add sodium benzoate upon rxn completion and extract benzoic anhydride with a nonpolar solvent. This way you convert cyanuric halo-acids to the salts and they are retained in the polar phase, while Bz2O can be distilled or used in situ. Not easy because you can't use water to force a separation.

- Do the above, but with an N-halo monoimide, like succinimide or diformylimide. This means that only one salt will form, increasing the chance of precipitation. In particular, since diformylimide has a small anion, it should have less soluble salts.

- Add excess acetic acid to the rxn mixture and try to remove AcCl by vacuum distillation at room temperature, so no heating is involved. Definitely the best option if it works; probably need a good condenser.

- Do the above but distill AcCl at atmospheric pressure, around 80 C. The explosion reported by Johnny_Windchimes occurred at 180 C, which is a decent margin of safety. Small scale only.

EDIT: Here is the post about why you should not try to distill BzCl from TCCA+BzH at atmospheric pressure ("boom!"):

https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

[Edited on 1-2-2021 by clearly_not_atara]

[Edited on 1-2-2021 by clearly_not_atara]

Corrosive Joeseph - 10-2-2021 at 17:38

Continuation of this locked thread - "Acetic Anhydride from Zinc Acetate?"
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

Here is the paper linked by pip.... Dunno what to make of it but my first thought is that it does come out of India. (big eye roll)

/CJ

Attachment: Synthesis of Acetic Anhydride by using Phosphorous Pentoxide, Sodium Acetate and Calcium Chloride as a Catalyst.pdf (1.5MB)
This file has been downloaded 552 times

zed - 11-2-2021 at 02:06

Yes! We have no bananas!

Phosphorus Pentoxide? No problem for me. Seemingly, I can buy as much as I want. For $20/LB. US Dollars. The problem is its high molecular WT. of ~280, and the limited amount of bang, you get for your buck.

Meaning the problem is the cost. Our fellow poster Len1, published a nice little procedure for producing POCl3 via Phosphorus Pentoxide.

POCl3 is a handy reagent, and hard to come by. And, so I suppose, worth it.

Using Phosphorus Pentoxide to make Acetic Anhydride, seems less than parsimonious.

It takes a significant amount of Phosphorus Pentoxide, to make a small amount of Ac2O.

Though I suppose, the spent Phosphorus Pentoxide can be utilized for some other purpose.

It cannot be easily regenerated. It's a one way street.

I did see a failed procedure on YouTube utilizing Phosphorus Pentoxide, but the experiment didn't have a robust design. They simply dripped Glacial Acetic Acid onto Phosphorus Pentoxide solid, and produced some charred stuff.

Acetic Anhydride acquisition was not formerly a problem in the USA. There was a restriction on sales, but it only applied to very large amounts, being transacted in international trade. A regular guy like me, could just walk into a supply company, and buy as much as I wanted.

A side note: Some of the Acetylations performed by Acetic Anhydride, might be performed by Isopropenyl Acetate. We have discussed this before, but it has been a while.

To the best of my knowledge, Isopropenyl Acetate is unrestricted. So.... You might be able to just buy some.

Also, to the best of my knowledge, Isopropenyl Acetate isn't wildly toxic. But, that's just my knowledge. Does anybody have personal experience working with it?

https://pubs.rsc.org/en/content/articlelanding/2012/gc/c2gc3...

https://www.sciencedirect.com/science/article/abs/pii/S00404...

[Edited on 11-2-2021 by zed]

[Edited on 11-2-2021 by zed]

njl - 11-2-2021 at 05:51

Can't remember where but I think I remember a prep for isopropenyl acetate that involved bubbling MAP gas through glacial acetic acid.

zed, how are you getting P2O5 at that price? I don't think there are many brick and mortar stores that sell it.

[Edited on 2-11-2021 by njl]

Acetic acid and calcium Chloride

LeLaborantin - 13-2-2021 at 13:33

Good evening,

While looking a little bit on the internet, I came across this.

Has anyone ever tried it?

I'm putting the publication as an attachment.

I'll try this reaction soon

Edit : Oops it's already been put in a message before mine.

Screenshot_20210213-214915_Acrobat for Samsung.jpg - 185kB

Attachment: doc.pdf (1.5MB)
This file has been downloaded 580 times

[Edited on 14-2-2021 by LeLaborantin]

xSJF1414 - 13-2-2021 at 14:33

So I was just reading over acetic anhydride preparation on this came up; it seams way too good to be true but can someone verify this for me?

[Edited on 13-2-2021 by xSJF1414]

Possible Acetic Anhydride Preperation.png - 44kB

Waffles SS - 17-2-2021 at 14:03

Quote: Originally posted by zed

Also, to the best of my knowledge, Isopropenyl Acetate isn't wildly toxic. But, that's just my knowledge. Does anybody have personal experience working with it?

I have experience in this method.

I even made Ac2O by this method,That is really easy

Just add AcOH and 2-3 drop Sulfuric acid and then distill it,first you get acetone and then Ac2O.

I even did this reaction with vinyl acetate and got same result but with less yield and with nasty acetaldehyde instead of acetone

[Edited on 17-2-2021 by Waffles SS]

njl - 17-2-2021 at 17:44

Please elaborate...

zed - 19-2-2021 at 11:18

Ketene is a deadly gas. Bad stuff.

Acetic Anhydride can be readily prepared via bubbling Ketene through Glacial Acetic Acid.

The procedure is pretty simple, though decidedly deadly if screwed up.

Acetic Anhydride, is a very basic and useful reagent, that for no particularly relevant reason, is quite difficult to purchase now-a-days.

Anyway.... Some folks may be able to acquire Iso-Propenyl Acetate. To the best of my knowledge, it is fairly uncommon, but it is unrestricted to purchase.

Iso-Propenyl Acetate, is manufactured by the action of Ketene on Acetone. It might be considered an analog of Acetic Anhydride. Wherein unwilling acetone, has been subjugated by powerful, super reactive, Ketene. Acetone thereby, being locked into it's Enol configuration.

Well, Acetone is a Ketone, and it doesn't like being locked up in an Enol configuration. Uncomfortable, and unstable. So.... Given a chance, it will free itself from bondage, and send that Acetyl group, somewhere else.

This makes Isopropenyl Acetate, both an acetylating agent, and a potential source of Acetic Anhydride.

https://en.wikipedia.org/wiki/Isopropenyl_acetate

Thank you Waffles. I attempted this discussion about a decade ago, with Sauron present. The idea was not well received.

But, time has gone on, and Acetic Anhydride has become progressively more difficult to obtain.

Times change.

[Edited on 19-2-2021 by zed]

Waffles SS - 19-2-2021 at 14:56

Please elaborate...

Read page 2923
REACTION WITH ACIDS AND ANHYDRIDE FORMATION

Attachment: Isopropenyl Acetate.pdf (703kB)
This file has been downloaded 668 times

From Vinyl acetate try DE503131 example 7

[Edited on 19-2-2021 by Waffles SS]

zed - 20-2-2021 at 14:31

Thank you, Waffles! I knew something about the possibilities, in a theoretical way. Educated guessing.

But, you provided quite an expose'. Many more facts, than I had easy access to. :cool:

SWIM - 20-2-2021 at 14:34

Wish I could find that old paper.

They were dehydrating acetic acid in a tube furnace.
It was over porous ceramic chips at 800 or 900 degrees. They got the reaction at lower temperatures by doping the chips with various chemicals, (calcium phosphate?? some phosphate they prepared and cooked onto the ceramic at 800 or 900 degrees). the reaction started as low as 650 degrees.

The problem was the reaction gives you a very hot mixture of water, acetic acid, and acetic anhydride. Not a very stable concoction.

They cooled it fast in a quartz condenser in some cases. In others they used an inert carrier gas like ligroin to limit decomposition. The ligroin (or whatever) was fed into the tube furnace along with the acetic acid in a large excess, and on condensation the anhydride wound up in the ligroin from which the water could be separated. The solvent was then dried with some drying agent and distilled to get the anhydride.

It was an interesting paper but I neglected to copy it and the link I used is dead now.

Too bad, because I just picked up a 100 year old household appliance that will probably function as a tube furnace with some modification. It hits 760 degrees C inside the tube as it was built, and has hit 920 C with some insulation, but the insulation got fried. (Sone cheap Chinese stuff that was supposed to be good to 1000 C. It came out looking like an overdone cannoli and part of it fused to the heating tube.)

Maybe the lack of a rheostat is making it harder on the insulation. Plug it in and it heats on full, and keeps doing so until you pull the plug. It doesn't even have an on/off switch.

It's also one of the least safe appliances I've ever seen. Just putting your hand on it in the wrong place can give a shock with full house current. Fortunately, it gets so damned hot in operation that you wouldn't want to touch it anyway.

https://www.picclickimg.com/d/l400/pict/173744823542_/Vintag...

Jenks - 14-4-2021 at 12:24

Quote: Originally posted by LeLaborantin

Good evening,

While looking a little bit on the internet, I came across this.

Has anyone ever tried it?

I'm putting the publication as an attachment.

I'll try this reaction soon

Edit : Oops it's already been put in a message before mine.

[Edited on 14-2-2021 by LeLaborantin]

I notice that every time they get a good yield they use the least catalyst (e.g., CaCl2). It seems the secret to their success is to use the least possible amount of "catalyst". I think the reason this is working is that they chill the acetic acid/sulfuric acid for 30 minutes before refluxing it. Heating right away leads to charring right? But in theory, the hydrolysis of acetic anhydride is reversible - at room temperature, acetic anhydride reacts with water to produce heat and acetic acid. The reverse of this, at room temperature, should absorb heat and produce acetic anhydride as water is scrupulously absorbed. The problem is finding a sufficiently efficient drying agent. Assuming sulfuric acid will suffice, then equilibrating acetic acid with sulfuric acid (or any other drying agent) at room temperature will produce acetic anhydride.

symboom - 26-4-2021 at 14:39

see what you All were talking about how the ketene process is dangerous here is a guy doing the synthesis at 5ppm it's deadly compared to hydrogen cyinide at 50 ppm.

https://youtu.be/g9sPlMkYEIw

Acetic anhydride using acetyl iodide
https://youtu.be/SGQ35JWq0eg

Acetic anhydride by nitrogen dioxide
https://youtu.be/gsVDuPjE9zY

Acetic anhydride by acetic acid and phosphorus pentoxide in DCM
https://youtu.be/Spd1RnRZbvk

clearly_not_atara - 28-4-2021 at 15:30

Recently a number of people on a sister forum have reported success with the acetonitrile/HCl method. It seems that the news has not yet reached ScienceMadness, but I think it definitely seems like a major step forward in this quest. Scarecrow claims that the HCl gassing should continue until the reaction mixture has nearly solidified (for a 1:1 AcOH/MeCN).

The product acetyl chloride is a bit nastier to handle than Ac2O, though.

symboom - 28-4-2021 at 17:43

That's great to hear do share the process and link also what sister fourm?

S.C. Wack - 28-4-2021 at 19:05

It's not posted in this thread because the title is acetic anhydride. We hardly need posts and videos from anywhere.

njl - 29-4-2021 at 02:57

Atara is referring to a thread on the vespiary by user Scarecrow called "Reliable OTC Acyl chloride synthesis (All C#)". I'm not sure what the policy is for linking to the vespiary so I will edit in the link if asked.

S.C. Wack - 29-4-2021 at 19:49

BTW the original reference was posted by lugh and translated by Klute, in 07 here.

Texium - 29-4-2021 at 20:01