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Author: Subject: Acetic anhydride preparation
nzlostpass
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[*] posted on 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?


Quote: Originally posted by Waffles SS  
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]
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clearly_not_atara
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[*] posted on 23-6-2020 at 20:44


Quote: Originally posted by Waffles SS  

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 112 times





[Edited on 04-20-1969 by clearly_not_atara]
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Waffles SS
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[*] posted on 24-6-2020 at 02:00


Interesting Idea.

Thanks




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Alkoholvergiftung
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[*] posted on 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
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Refinery
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[*] posted on 24-6-2020 at 12:54


Quote: Originally posted by Waffles SS  
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]
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clearly_not_atara
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[*] posted on 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]




[Edited on 04-20-1969 by clearly_not_atara]
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Waffles SS
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[*] posted on 1-7-2020 at 21:09


Quote: Originally posted by clearly_not_atara  
.

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




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[*] posted on 1-7-2020 at 23:02


Quote: Originally posted by clearly_not_atara  
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.
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Corrosive Joeseph
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[*] posted on 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




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Refinery
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[*] posted on 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.
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Eddie Current
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[*] posted on 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]
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clearly_not_atara
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[*] posted on 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.

Quote: Originally posted by Waffles SS  
Quote: Originally posted by clearly_not_atara  
.

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.




[Edited on 04-20-1969 by clearly_not_atara]
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Refinery
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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 22-10-2020 at 11:34


Where are you located? I could send you some sources on U2U.
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[*] posted on 22-10-2020 at 12:10


Quote: Originally posted by VeritasC&E  

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]
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[*] posted on 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.
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[*] posted on 22-10-2020 at 23:45


Quote: Originally posted by teodor  
Quote: Originally posted by VeritasC&E  

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]


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?
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nzlostpass
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[*] posted on 23-10-2020 at 00:43


Quote: Originally posted by VeritasC&E  
Quote: Originally posted by teodor  
Quote: Originally posted by VeritasC&E  

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]


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.
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[*] posted on 23-10-2020 at 01:26


Quote: Originally posted by nzlostpass  
Quote: Originally posted by VeritasC&E  
Quote: Originally posted by teodor  
Quote: Originally posted by VeritasC&E  

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]


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!
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[*] posted on 23-10-2020 at 02:02


Quote: Originally posted by VeritasC&E  
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]
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Corrosive Joeseph
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[*] posted on 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




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[*] posted on 23-10-2020 at 03:52


@ Corrosive Joeseph
@ Teodor

Thanks to both of you!
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clearly_not_atara
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[*] posted on 23-10-2020 at 05:44


Quote: Originally posted by VeritasC&E  

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?

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.




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 23-10-2020 at 05:50


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