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Author: Subject: Acetic anhydride preparation
clearly_not_atara
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[*] posted on 14-5-2016 at 17:39


byko3y: Noted. Although I continue to insist that the differences in reactivity between SCl2 and S2Cl2 can be considered analogous to C2H4Cl2 vs CH2Cl2. SCl2 has a much smaller dipole moment because the two S-Cl bonds are in opposing directions. Likewise SOCl2 and COCl2 have large dipole moments because the C=O and S=O bonds are highly polarized.

It seems like the intent was to make anhydrous zirconium (IV) sulfate, Zr(SO4)2, which is both a dehydrating agent and a Lewis acid. Zirconium (IV) and titanium (IV) both like to form covalent-ish bonds with chlorine, nitrogen and oxygen, and TiCl4 is volatile. However, note that while it is a metal salt, it's not exactly easy:

". Excess water was evaporated on a water-bath and the resulting sample was oven-dried at 120 °C for 12 h and calcined at 500 °C for 4 h in air atmosphere and stored in vacuum desiccator."

I doubt that anhydrous zirconium sulfate can be made by an "easy" method. It's likely that simply adding zirconium to anhydrous sulfuric acid will result in passivation. In this case the half-reaction comprises 3 moles of Zr(SO4)2 reacting with 5 moles (acid / 2) of water.

http://www.sciencedirect.com/science/article/pii/00406031938...

Notably, the method as reported is consistent with this analysis of the thermodynamics of zirconium sulfate, since Zr(SO4)2 begins to decompose just above 500 C at 540 C. The half-reactions are Zr(SO4)2 + H2O >> Zr(SO4)2*H2O, Zr(SO4)2*H2O + H2O >> Zr(SO4)2*2H2O, and the one where I know the energetics, 2 AcOH + ~90 kJ/mol >> Ac2O + H2O. So the heat of hydration of Zr(SO4)2 would have to be at least 90 kJ/[mol H2O], probably higher as entropy decreases.

[Edited on 15-5-2016 by clearly_not_atara]
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[*] posted on 26-1-2017 at 15:17


What about decomposition of an acetate using dry chlorine, related to the production of nitrogen pentoxide:
2AgNO3+Cl2->2AgCl+ N2O5+O2
Enthalpy of formation:
Acetic Anhydride:-625 kJ/mol
Sodium Chloride:-411 kJ/mol
Sodium Acetate:-709 kJ/mol

Assuming we use sodium acetate, the reaction is not favored, but there may be a way to drive the reaction in favor, perhaps by using a silver salt and then recovering the silver.
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[*] posted on 7-2-2017 at 17:09


Chlorine will probably attack acetic anhydride, since the alpha-protons on anhydrides act similar to ketones, i.e. enolizability and stuff. Silver acetate can already be used to prepare acetic anhydride by simple heating as long as it's done under the right conditions. Apparently the AgOAc and surrounding atmosphere has to be completely dry to produce Ac2O because otherwise it undergoes water-catalyzed decomposition to CO2 and acetone.

There's also a method with zinc acetate that sadly has 25% theoretical yield and a possibility of using copper acetate as well although I've never seen literature on Cu(OAc)2 decomposition specifically. I'm guessing all of the dry distillation methods require exquisitely anhydrous conditions.

Another possibility if it works might be to react methylene halides with silver acetate to get the acylal (AcO)2CH2 which decomposes to Ac2O in the presence of catalytic acid. According to this page the bp of methylene diacetate is 164 C:

http://www.apolloscientific.co.uk/display_item.php?id=41521

CH2Cl2 seems much nicer to work with than Cl2, assuming it's actually reactive enough (or you'd have to use the iodide or bromide instead).
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[*] posted on 8-2-2017 at 07:53


Quote: Originally posted by clearly_not_atara  

Another possibility if it works might be to react methylene halides with silver acetate to get the acylal (AcO)2CH2 which decomposes to Ac2O in the presence of catalytic acid. According to this page the bp of methylene diacetate is 164 C:

http://www.apolloscientific.co.uk/display_item.php?id=41521

CH2Cl2 seems much nicer to work with than Cl2, assuming it's actually reactive enough (or you'd have to use the iodide or bromide instead).



All possible way for synthesis of methylene diacetate by reaxys

(item 4/36 and 19/36 and is interesting):

Quote:

Methylene Diacetate Stock Solution:
Bu4NOAc (11.4 g, 37.8 mmol) and anhyd benzene (60 mL) wereplaced in a round-bottomed flask equipped with a Dean–Stark apparatus. This solution was refluxed under an argon atmosphere with continuous removal of the azeotrope over a period of 1 h. Then the flask was connected to a vacuum line to remove the rest of the benzene. Finally, anhyd CH2Cl2 (37 mL) was added to the flask containing Bu4NOAc (11.2 g, 37.1 mmol) under an argon atmosphere.
This stock solution was allowed to stand at r.t. for 3 d before use and then kept at 4 °C
Boron Trifluoride Mediated Prins Reaction of Methylene Diacetate with Styrenes. One-Pot Synthesis of 3-Chloro-3-arylpropanolsAlper Isleyen, Özdemir Dogan*Department of Chemistry, Middle East Technical University, 06531 Ankara, Turkey
item 19/36




Attachment: Methylene Diacetate.pdf (309kB)
This file has been downloaded 50 times



[Edited on 8-2-2017 by Waffles SS]
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[*] posted on 8-2-2017 at 10:02


Well now I'm not sure if silver acetate would work or not. Apparently acetate ion will eventually react with CH2Cl2, so the counterion shouldn't matter *too* much, right?

Tetrabutylammonium acetate would of course be preferable. I wonder if you can get away with tetraethylammonium acetate? But take precautions in handling tetraethylammonium (full body covering) as its salts are highly neurotoxic and you don't want it on you
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[*] posted on 18-5-2017 at 19:06



from wikipedia


Quote:

Basic zinc acetate
Heating Zn(CH3CO2)2 in a vacuum results in a loss of acetic anhydride, leaving a residue of basic zinc acetate, with the formula Zn4O(CH3CO2)6.


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[*] posted on 18-5-2017 at 21:50


Quote: Originally posted by BILLBUILDS  

from wikipedia


Quote:

Basic zinc acetate
Heating Zn(CH3CO2)2 in a vacuum results in a loss of acetic anhydride, leaving a residue of basic zinc acetate, with the formula Zn4O(CH3CO2)6.




read page 21

also below article:

Evidence for the formation of anhydrous zinc acetate and acetic anhydride during the thermal degradation of zinc hydroxy acetate, Zn5(OH)8(CH3CO2)2·4H2O to ZnO
Timothy Biswicka, , William Jonesa, Aleksandra Pacułab, Ewa Serwickab, Jerzy Podobinskib
http://www.sciencedirect.com/science/article/pii/S1293255808...
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[*] posted on 19-5-2017 at 17:16


Befor I do it, I just wanna ask if anyone tried this:
Succinic acid can be dehydrsted at about 230°C to succinic anhydride, and unlike the acid, the anhydride is liquid 230°C. So my idea is to just mix the succinic anyhdride in a 1:2 mol ratio with sodium acetat and melt this whole mix. And then you might be able to distill off acetic anhydride. The succinic acid can then be recycled by dissolving the sodium succinate in the distilling flask and acidify it, to precipitate the succinic acid out. That can then be dehydrated again by heating it.
As I said, I have no idea if that would work, but I'am planning on trying that out.
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[*] posted on 19-5-2017 at 19:10


I tried Zinc acetate method and even your idea method by Succinic anhydride,Phthalic anhydride and another anhydride like benzoic anhydride.
According to my experiment reaction of cyclic anhydride with acetic acid will not lead to Ac2O.I dont know what exactly happen but i think in this case formation of 5 membered ring is main route and Ac2O will not produce.

untitled.jpg - 15kB


About benzoic anhydride and another linear anhydride we have equilibrium between formation of Ac2O and benzoic anhydride and you can make Ac2O if you can push reaction to it side.

2.jpg - 17kB

Attachment: kremann1923.pdf (355kB)
This file has been downloaded 3 times

There are many articles about pyrolysis of Zinc acetate and most of them scale are Micromole.I tried it but i was unsuccessful.You have to heat powder to about 300C,at this temp huge amount of smoke produce and then yellow liquid start to come that has acetic odor but is not Ac2O.



[Edited on 20-5-2017 by Waffles SS]
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[*] posted on 19-5-2017 at 21:14


Succinic anhydride dehydrates more readily than acetic acid, while acetic acid is more volatile than acetic anhydride. Even benzoic anhydride-acetic acid pair will give a solution of acetic anhydride in acetic acid.
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[*] posted on 20-5-2017 at 00:57


If you want to do that, consider gassing the AcOH/(RO)2O with HCl to distill out AcCl. This can be recombined with sodium acetate which is particularly preferable if the product is to be stored or it may be used immediately.
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[*] posted on 20-5-2017 at 01:22


Quote: Originally posted by byko3y  
Succinic anhydride dehydrates more readily than acetic acid, while acetic acid is more volatile than acetic anhydride. Even benzoic anhydride-acetic acid pair will give a solution of acetic anhydride in acetic acid.


You are right.This is why acetyl chloride Produce in reaction of benzoyl chloride and acetic acid.Because acetyl chloride is more volatile than another materials and the equilibrium move to acetyl chloride side.


3.jpg - 13kB


[Edited on 20-5-2017 by Waffles SS]
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[*] posted on 20-5-2017 at 06:54


Quote: Originally posted by byko3y  
Succinic anhydride dehydrates more readily than acetic acid, while acetic acid is more volatile than acetic anhydride. Even benzoic anhydride-acetic acid pair will give a solution of acetic anhydride in acetic acid.


That might be true, but luckly, succinic anhydride melts at about 230°C, and I imagine that if you put sodium acetat into molten succinic anhydride, you'll get acetic anhydride distilling out.

Quote: Originally posted by Waffles SS  
I tried Zinc acetate method and even your idea method by Succinic anhydride,Phthalic anhydride and another anhydride like benzoic anhydride.
According to my experiment reaction of cyclic anhydride with acetic acid will not lead to Ac2O.I dont know what exactly happen but i think in this case formation of 5 membered ring is main route and Ac2O will not produce.

About benzoic anhydride and another linear anhydride we have equilibrium between formation of Ac2O and benzoic anhydride and you can make Ac2O if you can push reaction to it side.


[Edited on 20-5-2017 by Waffles SS]


I honestly still don't know why people make acetic anhydride though benzoic anhydride, I mean isn't benzoic anhydride as least as hard to get as acetic anhydride? And for making only one molecule of acetic anhydride, benzoic anhydride is quite a big molecule, so you also need quite a lof of it for little acetic anhydride.

Quote: Originally posted by clearly_not_atara  
If you want to do that, consider gassing the AcOH/(RO)2O with HCl to distill out AcCl. This can be recombined with sodium acetate which is particularly preferable if the product is to be stored or it may be used immediately.


You brought me to a quite interesting idea, maybe it's possible to mix acetic acid with succinic anhydride, and then bubble HCl gas into this solution, which then should react with the succinic anhydride to make succinyl monochlorid, which then makes acetyl chlorid which you can distill out. And seeing that acetyl chloride is way cooler than acetic anhydride, I'am really eager to try that out.
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[*] posted on 20-5-2017 at 07:21


Quote: Originally posted by theAngryLittleBunny  


That might be true, but luckly, succinic anhydride melts at about 230°C, and I imagine that if you put sodium acetat into molten succinic anhydride, you'll get acetic anhydride distilling out.


According to what mechanism or reference Sodium acetate will react with molten succinic anhydride and make Ac2O?Did you invent new reaction?

Bigger or smaller molecule is not problem because we dont want to run a plan of Ac2O from benzoic anhydride.We are not looking for economic way for synthesis AC2O.We are talking about possibility in organic chemistry,Possibility of making Ac2O from Benzoic anhydride or another anhydride.



[Edited on 20-5-2017 by Waffles SS]
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[*] posted on 20-5-2017 at 08:54


Quote: Originally posted by Waffles SS  

According to what mechanism or reference Sodium acetate will react with molten succinic anhydride and make Ac2O?Did you invent new reaction?

Bigger or smaller molecule is not problem because we dont want to run a plan of Ac2O from benzoic anhydride.We are not looking for economic way for synthesis AC2O.We are talking about possibility in organic chemistry,Possibility of making Ac2O from Benzoic anhydride or another anhydride.



[Edited on 20-5-2017 by Waffles SS]


What? I thought the whole point of this thread was to find a way of making acetic anhydride for people who don't havee access to it, people like me .-.

And I don't have a reference, I don't even know if it would work, it's just an idea of mine I wanna try out, since it would be a very economical way of making acetic anhydride in theory.
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[*] posted on 20-5-2017 at 10:36


Theory should be true according to chemistry laws and should be logical.This thread based on logical ways for synthesis Ac2O not our wishes.I promise there are no way for synthesis Ac2O by reaction of Succinic anhydride with sodium acetate because is not logical according to chemistry laws.
This is basic Organic Chemistry
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[*] posted on 20-5-2017 at 11:31


Quote: Originally posted by Waffles SS  
Theory should be true according to chemistry laws and should be logical.This thread based on logical ways for synthesis Ac2O not our wishes.I promise there are no way for synthesis Ac2O by reaction of Succinic anhydride with sodium acetate because is not logical according to chemistry laws.
This is basic Organic Chemistry


Seeing that you're 13 years older then me, you probably know that stuff better then I do. I mean seeing that benzoic anhydride could dehydrate acetic acid, I honestly don't see a reason why succinic anhydride could not react with sodium acetat. I also thought about a methode of recluxing succinic anhydride dissolved in acetone with calcium acetate, my idea is that it would make calcium succinate and acetic anhydride. But as I said, I still have to try it. I still would love to know the mechanism in which an carboxylic anhydide dehydrates an carboxylic acid, I'am sure you know it, because I can't really find anything about it on the internet. I imagine that that is starts with the negative oxygen on the caroboxylate attacking the carbon in the acid group, since that should be somewhat electrophilic. Because if that's the case, I see no reason why it shouldn't work with an carboxylate salt.
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