Sciencemadness Discussion Board - Acetic anhydride preparation

Acetic anhydride preparation

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clearly_not_atara - 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]

Elemental Phosphorus - 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.

clearly_not_atara - 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).

Waffles SS - 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 1076 times

[Edited on 8-2-2017 by Waffles SS]

clearly_not_atara - 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

BILLBUILDS - 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.

Waffles SS - 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...

theAngryLittleBunny - 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.

Waffles SS - 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.

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.

Attachment: kremann1923.pdf (355kB)
This file has been downloaded 702 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]

byko3y - 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.

clearly_not_atara - 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.

Waffles SS - 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.

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

theAngryLittleBunny - 20-5-2017 at 06:54

Quote: Originally posted by byko3y

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.

Waffles SS - 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]

theAngryLittleBunny - 20-5-2017 at 08:54

Quote: Originally posted 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.

Waffles SS - 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

theAngryLittleBunny - 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.

clearly_not_atara - 23-7-2017 at 18:06

Previous attempts at making acetic anhydride from copper acetate failed due to the difficulty of preparing anhydrous copper acetate. However it might be possible to make anhydrous copper acetate by using salt metathesis in a non-aqueous solvent. Anhydrous copper (II) chloride is soluble in ethanol (~50g / 100 mL), as is potassium acetate (16g / 100 mL according to http://chemister.ru/Database/properties-en.php?dbid=1&id... ) . Potassium chloride is basically insoluble in ethanol. So in order to make anhydrous copper acetate, add a saturated ethanolic solution of CuCl2 to a saturated ethanolic solution of potassium acetate until precipitation ceases, filter, and distill off ethanol to yield mostly copper acetate containing a little potassium chloride. Hopefully ethanol's affinity for water will help ensure the resulting solids are free of water, but all of this must be carried out while carefully avoiding atmospheric moisture, in freshly dried ethanol, it would seem.

Potassium acetate appears to be a little easier to dry than sodium acetate: the sesquihydrate converts to a semihydrate at 41 C, according to Wikipedia. I don't know when the semihydrate loses water, though.

And CuCl2 isn't too hard to dry, right?

http://www.sciencemadness.org/talk/viewthread.php?tid=15485&...

[Edited on 24-7-2017 by clearly_not_atara]

Cryolite. - 24-7-2017 at 11:42

I'm not sure about that atara: copper chloride is strong enough an oxidant to oxidize ethanol to acetaldehyde (a quick back-of-the-envelope calculation shows that the reaction is slightly favorable even without accounting for the solvation energy of HCl in ethanol). Copper acetate is probably similar, and so I'd probably expect that distilling off the ethanol would induce copper (I) contamination, or at the very least some water of hydration due to atmospheric oxidation. Maybe vacuum distillation? Still, I'd expect some reduction of the product by solvent.

clearly_not_atara - 25-7-2017 at 10:46

That's a problem for sure.

Interesting. I think vacuum distillation is probably necessary as you suggest. But if CuCl2 or Cu(OAc)2 were a good oxidant for ethanol we could take this to the acetaldehyde thread

I found the attached paper which mentions potassium acetate in acetonitrile for the ring-opening of an epoxide (page 1, example 3). However, I haven't found a ref for the solubility of KOAc in acetonitrile. I believe both copper chloride and acetate are soluble in MeCN. KCl certainly is not. This paper also mentions using "2 equivalents of anhydrous potassium acetate in acetonitrile" for something although I haven't got it:

http://pubs.acs.org/doi/abs/10.1021/jo400774u?journalCode=jo...

So if we can confirm solubility of KOAc in acetonitrile that could be a winner, although now it requires acetonitrile again, but this might be easier than going through acetyl chloride by gassing HCl and it allows you to reuse both MeCN and copper. Conveniently, acetonitrile is much less hygoroscopic than anhydrous ethanol.

Formamide (not dimethylformamide) also apparently dissolves KOAc according to Wikipedia, although I'm not familiar with formamide as a solvent (it apparently has some other uses in inorganic chemistry?). Acetamide might also work?

Paper attached.

Attachment: orellana2014.pdf (168kB)
This file has been downloaded 783 times

EDIT: according to this, CuCl (cuprous) is soluble in acetonitrile:

http://alpha.chem.umb.edu/chemistry/ch371/CH371_Information/...

this could be useful since CuOAc likely has no hygoroscopicity at all but may still provide the anhydride when heated.

[Edited on 25-7-2017 by clearly_not_atara]

clearly_not_atara - 27-7-2017 at 11:04

(Too late to edit above post)

After investigating, detailed references to anhydrous KOAc in MeCN always use 18-crown-6. It turns out this can do some cool things -- including the Lossen rearrangement, amazingly -- but it won't precipitate KCl like we want it to, and crown is expensive.

But copper (i) compounds dissolve in acetonitrile or in solvent mixtures containing acetonitrile. Furthermore they are much less likely to oxidize ethanol. So the new version is to dissolve CuCl in azeotropic acetonitrile/ethanol and add saturated KOAc in ethanol. It should still be possible to recover and reuse solvents. And the solutions can be dried over an insoluble salt like MgSO4 which helps I think.

The trouble is now we have copper (I) acetate. But as this salt is more similar to the silver salt, that doesn't seem like such a bad thing. Oxidation of the product is now unlikely. Wiley says that heating copper (II) acetate in vacuo to 220 C gives copper (I) acetate, which makes it seem like acetate gets oxidized. Copper (I) acetate might actually work better. Wiley says it decomposes at 285 C but not into what or under what conditions (O2 atmosphere?)

The last thing is you need a dry atmosphere as well for the actual distillation, because water initiates autocatalytic decomposition of the product and must be rigorously excluded. Maybe a drying tube will work but you probably want a nitrogen tank or similar.

[Edited on 27-7-2017 by clearly_not_atara]

symetrical anhydrides with sulfated Zirconium

spankyetal - 29-7-2017 at 09:51

Dawt,yes this really works,
the one thing to know is the amount of PEG-1000 to use is based on it's molwt = 62g/mol-1.
You cannot cheat and start with inexpensive Zirconium Oxide. ZrO2. The crystal lattice must be the calcined-formed tetragonal. There is a manifold increase in surface area hence greater catalytic ability. Reactions without the tetragonal form yield ZIP.

sulfated Zirconia is so easy leaves halogen Rx in the dust

spankyetal - 29-7-2017 at 09:57

Quote: Originally posted by dawt

Seems nobody has mentioned this paper before. They claim to have prepared AA from acetic acid in a 90 % yield after 2 h at 40 °C using a PTC and zirconia catalyst. Sounds too god to be true, eh? The fact that it was published in some Ethiopian journal doesn't raise my confidence, but it looks cheap enough for me to give it a shot some time next month when I have money

Quote:

Preparation of sulfated zirconia

The sulfated zirconia catalyst was prepared by equilibrium adsorption of sulfate species on the surface of hydrous zirconium oxide samples. The hydrous zirconia catalysts were prepared by precipitation method using ZrOCl₂.8 H₂O and liquid ammonia solutions. Required amount of zirconyl chloride solution was added dropwise to deionised water. The pH was maintained at 10.0 by controlled addition of ammonia solution to the reaction mixture. The precipitated solution was stirred for 16 h at 35 °C followed by filtration and washing with double distilled water until free from chlorine ions. The hydroxide precipitate were subsequently dried overnight at 100 °C and calcined at 250 °C for 24 h. To prepare sulfated ZrO₂ catalyst, a portion of the obtained hydrous zirconia sample was ground to fine powder and immersed in 1 M H₂SO₄ solution. 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.

General procedure for the preparation of symmetrical carboxylic anhydrides

To a stirred solution of carboxylic acid (10 mmol) and PEG-1000 (5 mmol) was added SO₄^2-/ZrO₂ (3 mmol) at room temperature and stirring was continued at 40 °C for the appropriate time. After completion of the reaction, as indicated by HPLC, the product was extracted with methylene chloride (3 × 5 mL). The combined organic layer was dried over anhydrous Na₂SO₄ and then filtered over a pad of flash silica gel. Removal of the solvents in vacuo furnished the corresponding pure symmetrical carboxylic anhydrides. Fresh substrates were then recharged to the recovered catalyst system and then recycled under identical reaction conditions.

Ref:
Lin Hu, Y., E Zhao, X. & Lu, M., 2011. Efficient and convenient synthesis of symmetrical carboxylic anhydrides from carboxylic acids with sulfated zirconia by phase transfer catalysis. Bull. Chem. Soc. Eth., 25(2). Available at: http://dx.doi.org/10.4314/bcse.v25i2.65900.

[Edited on 9-5-2016 by dawt]

[Edited on 9-5-2016 by dawt]

[Edited on 9-5-2016 by dawt]

hey Dawt, this does work and works well

spankyetal - 29-7-2017 at 10:02

Trying to get this posted in the right place.
Dawt, the sulfated Zirconia reactions works very well and it can be reused 5X.
you need to know what the weight of the PEG-1000 used is and that's simple.
Amazingly simple and no where near the odor or toxicity of these other idiotic halogen reaction. Did this in an apartment next to the managers unit without any problems. Amazing.

[Edited on 7/24/2017 by spankyetal]

clearly_not_atara - 29-7-2017 at 10:20

How did you separate AA from PEG-1000?

Zirconium sulfate or sulfated Zirconia ?

spankyetal - 29-7-2017 at 10:21

Quote: Originally posted by clearly_not_atara

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]

Are you possibly mixing up Zirconium sulfate with sulfated Zirconia? Two entirely different compounds. Catalytic properties of sulfated Zirconia to make symmetrical anhydrides is based upon the tetragonal form of that substance created in an oven at 600 C. Concentrated sulfuric acid does interact with Zirconia.

spankyetal - 29-7-2017 at 10:24

Quote: Originally posted by clearly_not_atara

How did you separate AA from PEG-1000?

Just like the post says, the product was extracted with methylene chloride (3 × 5 mL).

simple and sweet.

spankyetal - 29-7-2017 at 10:27

so I said to myself- self! what am I doing here? gotta run. Gotta go check the Pr. anhyd. reaction.

Waffles SS - 29-7-2017 at 19:09

Sulfated Zirconia method is bullshit,

Anhydride make ester in reaction of Alcohol or Diol even at room temperature

We discus about this method some pages ago

[Edited on 30-7-2017 by Waffles SS]

spankyetal - 1-8-2017 at 08:54

Quote: Originally posted by madscientist

I'm theorizing that concentrated acetic acid could be dehydrated to acetic anhydride by mixing with concentrated sulfuric acid; then heating, and condensing the vapors, yielding acetic anhydride. Any comments or additional ideas?

I came across a published route to symmetrical anhydrides of carboxylic acids via hot conc. H2SO4. The acid is sprayed into the hot sulfuric acid at elevated temps and the vapors (anhydrides) are condensed. Many reactions you'll find may be feasible for lab scale but due to safety and economic concerns never make it to the $$ industrial scale. Seems the future of "green chemistry" - I shudder using the words- is focused on nano sized silica or Zirconium catalysts. Remarkable non-solvent reactions yields of >94%

dehydration with hot sulfuric acid

spankyetal - 1-8-2017 at 09:08

Quote: Originally posted by Coen

I am sorry to dissapoint you, but it is not possible to dehydrate acetic acid to Ac2O.

Some time ago I was also working on the synthesis of this compound, but when I got from a friend about 1,5 L Ac2O, I stopped with that .

I strongly discourage you to do something with the route using ketene. Ketene is very dangerous. The setup is very difficult to realise. The procedure gives very low yields.
The whole process is only used in industry, and you can not always transform such syntheses to lab-scale.

I've did thought out another route using acetaldehyde which could be realised fairly easy. But you do have to make/buy acetaldehyde first for that.

Acetaldehyde can be made by leading acetylene through a solution of a Hg2+ salt and then condensing it.

pulled as repetative

[Edited on 7/24/2017 by spankyetal]

clearly_not_atara - 1-8-2017 at 11:28

Quote: Originally posted by Waffles SS

Sulfated Zirconia method is bullshit,

Anhydride make ester in reaction of Alcohol or Diol even at room temperature

We discus about this method some pages ago

This was my expectation as well, but:

* owing to the chain length of PEG-1000 (~25 ethers) it's possible that, even with solvolysis, not much of the AA was consumed
* he claims to have succeeded (!) and experiment > theory generally

[Edited on 1-8-2017 by clearly_not_atara]

Waffles SS - 2-8-2017 at 00:01

*Even if not much of the Ac2O was consumed , all reactant and product are soluble in CH2Cl2 and this mean you can not separate Ac2O by this solvent. after dissolving Ac2O in CH2Cl2 it will continue to react with remaining PEG

This is difficult to believe articles in Ethiopian journal

Quote: Originally posted by madscientist

This is possible below -5C
Gilbert, E. E.Chemical Reviews (Washington, DC, United States), 1962 , vol. 62, p. 549 - 589

[Edited on 2-8-2017 by Waffles SS]

clearly_not_atara - 2-8-2017 at 11:19

^^^Interesting. Since it relies on the volatility of Ac2O, maybe gassing the H2SO4 with HCl first would yield AcCl, and, since this has a much higher vapor pressure, it would be more practical. Something tells me that you're going to get extremely slow evaporation of Ac2O at -5 C...

Of course, HF would do even better, making acetyl fluoride (bp 21 C), but there are safety issues in dealing with fluorides.

[Edited on 2-8-2017 by clearly_not_atara]

JJay - 2-8-2017 at 16:45

Ok, so how about this plan:

1. Distill ammonium acetate through an 80-100 C column to prepare acetonitrile.
2. Gas acetonitrile with hydrogen chloride to prepare acetyl chloride.
3. React acetyl chloride with sodium acetate to prepare acetic anhydride.

The column could be a simple Liebig condenser circulating boiling water or a low temperature tube furnace in vertical position around a glass tube. It would be kept slightly above the melting point of acetamide to keep the apparatus from getting clogged.

clearly_not_atara - 2-8-2017 at 23:27

Quote:

Distill ammonium acetate through an 80-100 C column to prepare acetonitrile.

Acetonitrile is made by refluxing acetamide over acids. The decomposition of ammonium acetate proceeds through the diacetate which decomposes to acetamide + acetic acid + water. So first ammonia is lost leaving ammonium diacetate, and then this decomposes to release acetic acid and water, leaving acetamide in the condensed phase. The Orgsyn procedure for acetamide uses 50 moles of acetic acid to 23.5 moles of ammonia:

http://www.orgsyn.org/demo.aspx?prep=CV1P0003

"In a 5-l. flask is placed 3 kg. (2860 cc., 50.0 moles) of glacial acetic acid and to this is added a weight of ammonium carbonate corresponding to 400 g. (23.5 moles) of ammonia (Note 1). The flask is fitted with a one-hole stopper holding an efficient fractionating column 90 cm. long with condenser and receiver. An air condenser 150–200 cm. long may be employed. The mixture in the flask is heated to gentle boiling and the flame so regulated that the rate of distillation does not exceed 180 cc. per hour. The distillation is continued in this way for eight to ten hours, until the temperature at the head of the column reaches 110°."

It is ideal to produce acetamide and then reflux this, since the initial release of ammonia and acetic acid is likely to be obnoxious if it flows through the vessel which is meant to capture acetonitrile.

In chemplayer's synthesis of acetyl chloride I believe he used equal amounts of acetic acid and acetonitrile. Since acetic acid is much easier to produce I think it wouldn't hurt to use it in excess; this may improve the yield relative to acetonitrile.

[Edited on 3-8-2017 by clearly_not_atara]

JJay - 3-8-2017 at 01:21

Do you have a source indicating that the decomposition of ammonium acetate proceeds through the diacetate? I ran across a document that stated that recently, but it was published before the American Civil War, so I considered it apocryphal. Also, the reference that you cite (which is a good reference) directs making ammonium acetate in situ and distilling it through a long column (essentially a reflux) but doesn't mention any ammonia in the distillate even though there is only a slight excess of acetic acid.

clearly_not_atara - 3-8-2017 at 09:36

Quote:

Also, the reference that you cite (which is a good reference) directs making ammonium acetate in situ and distilling it through a long column (essentially a reflux) but doesn't mention any ammonia in the distillate even though there is only a slight excess of acetic acid.

A slight excess? There are 50 moles of acetic acid and 23.5 moles of ammonia. Not 23.5 moles of ammonium carbonate:

"a weight of ammonium carbonate corresponding to 400 g. (23.5 moles) of ammonia"

The wording's awkward, but it states a 2:1 ratio of acetic acid to ammonia.

See also the attached graph of the decomposition of NH4OAc. You can see two peaks on the differential thermal analysis (DTA) curve which shows a phase transition before complete transition indicating a sudden peak of heat capacity, but the gravimetric curve (DTG/TG) only shows the final decomposition peak. This is consistent with the loss of ammonia since only a small fraction of mass is lost but the composition of the salt changes. And while the paper (also attached) does not mention what the intermediate product is, it does state the presence of an intermediate product.

http://en.wikipedia.org/wiki/Thermal_analysis

Attachment: olszakhumienik2001.pdf (105kB)
This file has been downloaded 1085 times

[Edited on 3-8-2017 by clearly_not_atara]

JJay - 3-8-2017 at 10:05

It states a slightly larger than 2:1 ratio of acetic acid to ammonia

It does look like thermal decomposition of ammonium acetate is minimal below 50 C at atmospheric pressure.

Waffles SS - 3-8-2017 at 10:27

For making AcCl from Acetonitrile The only reference that i can find is this(i dont have access to read it)

Perrot
Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences, 1938 , vol. 206, p. 1576

This is difficult for me to believe this method,even chemplayer is not sure about final product and he didnt analysis it so far(just measure boiling point and reaction with Sodium acetate is not enough)

[Edited on 3-8-2017 by Waffles SS]

JJay - 3-8-2017 at 10:41

Here is is on Google Books: https://books.google.com/books?id=Z9RFAQAAMAAJ&pg=PA1155...

I hadn't actually read this paper until just now, but it looks as though you could chlorinate any carboxylic acid in acetonitrile with this method.

(I should clarify that they couldn't get it to work with formic acid, and obviously some functional groups could cause a problem.)

[Edited on 3-8-2017 by JJay]

clearly_not_atara - 3-8-2017 at 10:52

It doesn't seem like a particularly outlandish mechanism to me. First acetonitrile reacts with one equivalent of HCl to the imidoyl chloride. Then the imine nitrogen is protonated by a second molecule of HCl to the iminium chloride, and this attacks acetic acid to give acetic anhydride monoiminium, which reacts with the chloride ion to release acetyl chloride and acetamide.

Plus it might not have been fully characterized but how many possible products are there with that BP?

Waffles SS - 3-8-2017 at 11:13

Quote: Originally posted by clearly_not_atara

Plus it might not have been fully characterized but how many possible products are there with that BP?

This is difficult to guess about product with this BP.He should do more scientific method for analysis the product(IR-Gc-Ms,..)

Another reason that i am doubtful about this method is reaxys serach of AcCl with acetamide.(In most case N-acetylacetamide is product)

Attachment: AcCl+AcNH2.pdf (121kB)
This file has been downloaded 1061 times

[Edited on 3-8-2017 by Waffles SS]

clearly_not_atara - 3-8-2017 at 11:36

Nearly all of those reactions involve basic conditions, though (pyridine, collidine, lutidine...). And most of them are in aprotic solvents. But just look at what happens when acetic acid is the solvent: in one case you get the imino-anhydride, and in another, some kind of ketene aminal.

There is one reaction with FeCl2 in AcOH that gives an imide. But the use of a catalyst implies this product is not typical, doesn't it?

[Edited on 3-8-2017 by clearly_not_atara]

Waffles SS - 3-8-2017 at 22:05

Quote:

Acetamide (0.2 mol) was dissolved in acetic acid (40 mL)and cooled in an ice bath. Then acetyl chloride (0.1 mol) was addedwith cooling, and the formation of a crystalline byproduct was observed.
Forlani, Giuseppe; Occhipinti, Andrea; Berlicki, Lukasz; Dziedziola, Gabriela; Wieczorek, Anna; Kafarski, Pawel;Journal of Agricultural and Food Chemistry; vol. 56; nb. 9; (2008); p. 3193 - 3199

Quote:

But just look at what happens when acetic acid is the solvent: in one case you get the imino-anhydride, and in another, some kind of ketene amina

Thanks but Please provide reference?

Quote:

The primary product of the attack of an acyl chloride on an amide is the
0-acylisoamide hydrochloride 4. Since all of the amide is trapped into
a “complex” by acetyl chloride there is no “free” amide available
for the reaction with aldehyde, hence, N,N-alkylidenebisamides should not exist in the reaction mixture
Soroka, Miroslaw; Liebigs Annalen der Chemie; nb. 4; (1990); p. 331 - 334

Quote:

First acetonitrile reacts with one equivalent of HCl to the imidoyl chloride. Then the imine nitrogen is protonated by a second molecule of HCl to the iminium chloride, and this attacks acetic acid to give acetic anhydride monoiminium, which reacts with the chloride ion to release acetyl chloride and acetamide.

Imidoyl chloride can be prepared by treating a monosubstituted carboxylic acid amide with carbonyl chloride or halogenating agents.I dont think HCl is enough powerful for this.Please provide reference for your idea

Ulrich, H. The Chemistry of Imidoyl Halides; Plenum Press: New York, 1968; pp. 55–112.

[Edited on 4-8-2017 by Waffles SS]

clearly_not_atara - 4-8-2017 at 15:17

Nitriles react with HCl but the reaction does not stop at an imidoyl chloride:

https://www.researchgate.net/publication/244701085_Studies_o...

However, as the fragmentation of imidoyl chloride to nitrile + HCl is well known it is not too far gone for me to assume the reaction reverses to a small extent at equilibrium.

The requisite "dehydrating potential" comes from the energy of hydration of acetonitrile; HCl is just a catalytic acid.

Hf 298 (an unreliable estimator, but if one side is way bigger the reaction favors that sie)
Acetonitrile: -40 kJ/mol
HCl: -92 kJ/mol
Acetamide: -310 kJ/mol
Acetic acid: -486 kJ/mol
Acetyl chloride: -274 kJ/mol

40 + 92 + 486 = 618
310 + 274 = 584

The left side wins very slightly, but when you take into account that acetamide (pKa of conjugate acid = -0.5) is much more basic than acetonitrile (conjugate acid is strong in water), acetyl chloride formation looks preferable. I don't have the Hf values for acetamidium and acetonitrilium in acetic acid, though :p

Quote:

Most nitriles having α-hydrogen react with HCl to give N-(α-chloroalkenyl)alkylamidine hydrochlorides (3).

This is consistent with formation and subsequent dimerization of imidoyl chlorides (attached). The possibility of such dimerization supports my hypothesis that using an excess of acetic acid will improve yields, IMO.

diacetimidoylchloride.png - 6kB

[Edited on 4-8-2017 by clearly_not_atara]

JJay - 4-8-2017 at 18:37

Is the dimerization reversible?

clearly_not_atara - 11-8-2017 at 17:00

I think probably not. However, upon further consideration, it's possible the dimer is actually the active chlorinating agent. If you add HCl to the dimer, you get 1,1-dichloro-N-(ethylimino)ethylamine, which is structurally very similar to dichloromethyl methyl ether and also to dichloroacetic acid, both of which are known chlorinating reagents for the AcOH -> AcCl transformation.

I can't tell what pathway it is, although the dimer seems a somewhat more plausible chlorinating agent on energetic grounds. One way to know would be to try reacting GAA with pre-formed N-(1-chlorovinyl)acetamidine and HCl and compare the acetyl chloride yield to that obtained with acetonitrile.

dichloroamidine.png - 3kB

[Edited on 12-8-2017 by clearly_not_atara]

spankyetal - 10-9-2017 at 20:09

Quote: Originally posted by clearly_not_atara

Quote: Originally posted by Waffles SS

Sulfated Zirconia method is bullshit,

Anhydride make ester in reaction of Alcohol or Diol even at room temperature

We discus about this method some pages ago

Hate to burst your bubble but I have gobs of anhydrides created from their corresponding acids. Sulfated Zirconia is NOT Zirconium Sulfate.
i.e. - precipitated Zirconium hydroxide is dried, sulfated with 0.1 M solution of conc. sulfuric acid, calcined 4 hrs at 550 Centigrade. 2 moles of the acid yield 1 mole of the anhydride. Bada-bing bada-boom! Room Temp.
Nothing happens without the correct molar amount of PEG-1000. More P. Anhydride than ever imagined- etc. - disclaimer, I have violated no laws within the jurisdiction or Territories of the United States.

SWIM - 10-9-2017 at 20:25

@spankyetal

I understand WHY you're concerned, but disclaimers just make people wonder what you're talking about and draw attention to you.

[Edited on 11-9-2017 by SWIM]

Babs - 21-10-2017 at 04:09

I haven't read all the proposers in this thread, quite a few, but I want to somewhat awkward look at what would potentially happen if one added GAA, dry if possible, to a flask, say 100ml, and to that, one adds say, fifty ml of dry toluene, and also 10ml of 80% sulphuric acid, and DS conditions, and very importantly prevent the moisture from entering via the condenser sitting on the DS trap.
So the way it looks to me is one molecule would react with a secondary molecule via some nucleophilic addition, 1,2 addition, then followed by a 1,2 elimination, which creates the bad guy as H2O that is a good nucleophile, thus causing the anhydride to hydrolyse, I think is the word, but in short, being reverted back to the two acetic adds, so what about the azeotrope beginning to be formed by the release of these water molecules, and with DS trap, would theoretically result in toluene water azeotrope, bp at 84.1C, but as we know when that chills post hitting the condenser, the water makes its way to the bottom of the toluene layer. So the other players are
acetic acid b.p.118-119C
The anhydride 139.8C
Toluene and water azeotrope being 84.1C

This bunny wont play with list one anythings, well most things, but this thing, nope, but people know people, and its been stated to work. After refluxing where no more increase of water is created, then the trap empties, then gets filled up again with the expected, as well as toluene, as toluene is so like benzene, so if benzene is clearly known to be in solution together with the anhydride formed, so toluene would also. The person who spoke up said that he'd worked out the theoretical amount of water eliminated and when that was obtained, although now being generated much more slowly, he factored it into the solvents must have got water, especially the only species left are the supposed to be Tol, and the anhydride, then he realised he hadn't plugged up the condenser, with a dry dry salt, a few more mls after doing so, then nada, for a good 40minute rate. Please don't jump on me to hard, Im only a passing wind, potentially dreaming of such ease, but its experiment worthy, and of course this has been thrashed to pieces, my apologies etc.
One could pretty simply reduce the needed amount of toluene to bind somewhat with the H2O from this addition reaction, but given if toluene is in the pot, and water is being formed, then its dancing shoes till not. Anyway, its all a learning curb for here, and I feel it may well have merit.

Cheers folks

[Edited on 21-10-2017 by Babs]

SWIM - 21-10-2017 at 07:43

If the Dean Stark is pulling the water out you're going to start getting sulfonation of the toluene at some point as the acid concentration goes up.
I suspect sooner rather than later.

This ought to be able to happen before it gets dry enough for Acetic anhydride formation as you can sulfonate toluene without an especially dry environment (no drying tube, no need for 100% sulfuric acid).

I Have no idea if mixed toluenesulfonate isomers would be worse or better than sulfuric acid for trying to make acetic anhydride(I suspect worse), but I'm pretty sure they would be generated in your reaction mixture.

[Edited on 21-10-2017 by SWIM]

Comment on below post: Yeah I totally missed that, but I get it now, thanks.

[Edited on 22-10-2017 by SWIM]

clearly_not_atara - 21-10-2017 at 16:59

You can't dry acetic acid with sulfuric acid. Even ignoring sulfonation, the bp of water increases when it's mixed with H2SO4, so the toluene/water azeotrope will not form.

Babs - 21-10-2017 at 17:55

I trust the source, so Im saying it does. I also see that 10ml of 80%, is excessive, as it only requires one proton to promote what does occur, but quickly gets reversed due to the nucleophilic eliminated H20. IF that gets mopped up, over a long function of time, then surely one would have the cream. Sulfonation, I am not sure.
Whether the azeotrope can also include H30+ and anions, albeit ever so minimally, I am not sure, my guess is yes.

Google searching- can an azeotropic mixture ever include anions and protons. The answer is yes. Hydronium nitrate found in an azeotropic mixture between water and nitric acids. So if this is indeed so, the more acidic it gets, the more these ions are forced into bonding amidst the azeotropic. Im stating this, as Im not interested in being right, but it appears this could be. I cannot link, and the URL is to long to just copy paste, but its an interesting read. Re-Google books.

"Biophysical and Structural Aspects of Bioenergetics"

[Edited on 22-10-2017 by Babs]

clearly_not_atara - 22-10-2017 at 00:01

The constant boiling mixture of nitric acid and water is a negative azeotrope, i.e. it has a higher boiling point than either of its components. This is the reverse of a typical azeotrope but because it has a certain useful property (it can be distilled) we call it "azeotropic". A mixture of water and HCl has a higher boiling point than either and yet HCl does not intersect water at all in their liquid ranges.

Point is, your source is wrong. The presence of acids lowers the vapor pressure of H2O. Azeotropes form because the lower cohesion in a mixture vs the pure substance leads to higher vapor pressures; acids cause higher cohesive forces because of ionization. Thus constant boiling mixtures of HCl, HBr, HNO3 with H2O all boil above 100. This is the opposite of what happens with toluene. You are being misled by the flexibility of the word "azeotrope": the nitric acid/water azeotrope is the OPPOSITE of the toluene/water azeotrope.

It's mildly annoying to watch people spend time on things that obviously won't work. But only mildly. Ho hum.

Sulfuric acid will never dehydrate acetic acid. The equilibrium:

2 [AcOH] <> [H2O] + [Ac2O]

leans so far to the left that the concentration ratio of [H2O]/[AcOH] will always overpower the greater volatility of H2O vs AcOH. As such AcOH boils away faster when the mixture is heated.

If something so trivial worked, this thread would be entirely unnecessary.

[Edited on 22-10-2017 by clearly_not_atara]

Babs - 22-10-2017 at 01:12

quote,

“Examples of this geometry for hydrogen bonds of water and hydronium ions are to be found in azeotropic mixtures of “WATER WITH ALCOHOL’ which has a lower bp, I believe. it goes on to include water with strong(mineral) acids, and used the one that, is positive, or has a higher bp, as you have implied, as one example. The point I see it makes is azeotropic mixtures appear to, or can, include hydronium ions, and anions. Which is a big point, IMO

As far as Le Chatelierl's principals deal goes, yes its so far over to the left, but you are adamant that anything on the right could ever be moved, and Im not buying it. I fully believe an azeotropic mixture gets formed and that my knuckle headed friend who wrote me this, aint lying
I wont go on and I know this is flying in the face of years of questing this, and I can sense frustration, and i definitely don't want to waste peoples time.
Whenever I see something that appears to be so ridiculously challenged, my head goes to the Helicopter virus, the actual cause of stomach ulcers, but hey, this is inquiry, exploring, daring to state what I doubt would be taken as plausible, but Im not backing down. Sorry to be an annoying noob.

I am not sure what you mean by boils away faster, as the lowest bp would be the water toluene azeotropic mixture, that you wont consider, and Im painfully stating otherwise. My tone is brotherly, but sometimes, with things that appear huge hurdles, a simple method isn't going to be considered. Hiding in plain sight. Now Ive probably pissed you of even more by stating that, but I believe their is some truth to that, and see it app here.

Cheers mate.

[Edited on 22-10-2017 by Babs]

hissingnoise - 22-10-2017 at 03:00

Quote:

It's mildly annoying to watch people spend time on things that obviously won't work. But only mildly. Ho hum

This vale of minor irritations... LOL!

Waffles SS - 22-10-2017 at 07:29

Quote: Originally posted by hissingnoise

Quote:

It's mildly annoying to watch people spend time on things that obviously won't work. But only mildly. Ho hum

This vale of minor irritations... LOL!

Exactly,
We are going backward in chemistry basics every day in this topic

[Edited on 22-10-2017 by Waffles SS]

CaptainMolo - 22-10-2017 at 08:23

Quote: Originally posted by Babs

I cannot link, and the URL is to long to just copy paste, but its an interesting read. Re-Google books.

"Biophysical and Structural Aspects of Bioenergetics"

I tried to find this on google books to no avail, is there an author or an ISBN number I can use to find this? It sounded like an interesting read. Also < / lurk> :p

[Edited on 22-10-2017 by CaptainMolo]

clearly_not_atara - 22-10-2017 at 18:46

Quote:

I fully believe an azeotropic mixture gets formed and that my knuckle headed friend who wrote me this, aint lying

Vapor pressure is continuous. The lower bp component only leaves faster if its vapor pressure is higher. And the vapor pressure of a component decreases with lower concentration.

http://en.wikipedia.org/wiki/Vapor_pressure

Your "friend" generalized from an inaccurate understanding of how chemical equilibriums work. At any given time, in a mixture of liquids, all of the liquids are evaporating. Which liquid forms a larger component in the vapor depends on both concentration and volatility of the component: the evaporate from a mixture of 99.99% AcOH and 0.01% H2O is primarily composed of AcOH.

Quote:

My tone is brotherly, but sometimes, with things that appear huge hurdles, a simple method isn't going to be considered. Hiding in plain sight

You know what else is hiding in plain sight? The reports from other people who have tried such methods that don't work, 35 pages of them in fact. They're in this thread, which you have not read. Dehydration of acetic acid with acids wasn't "not considered", it was the first thing anyone tried. And it doesn't work. Fancy that. You want to know just how much it was considered? It was the very first post in the thread!

https://www.sciencemadness.org/whisper/viewthread.php?tid=9#...

How could you know what was and wasn't tried if you don't look? SO3 doesn't work, Na2S2O7 doesn't work, P2O5 barely works, HPO3 doesn't work, and H2SO4 obviously doesn't work. Toluene is a joke.

https://www.sciencemadness.org/whisper/viewthread.php?tid=9&...

Quote:

Whenever I see something that appears to be so ridiculously challenged, my head goes to the Helicopter virus, the actual cause of stomach ulcers, but hey, this is inquiry, exploring, daring to state what I doubt would be taken as plausible, but Im not backing down. Sorry to be an annoying noob.

Backing down is a sign that you're the sort of person who is capable of learning, "not backing down" is the sign of someone who will never listen to criticism and slowly develop from an annoying noob to an incessant gadfly who everyone has learned to tune out. Sorry to be a condescending prick, but your "brotherly tone" is not actually helping to move the discussion forward, it's just a shield so that you can play the victim when people call you out on your crap.

[Edited on 23-10-2017 by clearly_not_atara]

Babs - 22-10-2017 at 22:23

I haven't a problem being wrong, i used to think I knew a fair bit of chemistry, but in time, the thing I learnt was how huge this Art is and how little I did know. I don't mind at all appearing foolish but that said, I still won't backdown. I could, can, but at the risk of looking even more retarded, can't. That said, I can't present a spectral analysis of what knucklehead sorted, only the fact we are closer than close and as such he won't lie. I'll have a look at the posts you presented, but maybe this needed excess H+, but that said. If the moderators here believe I am deliberately being obstanant, and what I have presented is so obviously daft, including my responses that present a degree of argument to the initial responses as to why this is bs, etc, then I'll gladly delete the first post hence gone. I am assuming that's how it works, if not maybe the moderators can wipe my so called bs findings.

Tsjerk - 23-10-2017 at 00:02

The moderators could, but won't do what you suggest, and you know that . Again you use something to hide behind, putting your shit in someone else's hand because that is how you try to look "right". Nice try but won't work

Babs - 23-10-2017 at 00:47

Well I don't in fact, I think Ive seen or heard of posts being moved to beginners or something but you call it hiding, I merely mentioned it as an option. See I don't see what Im suggesting as anything but an interesting manner, in the context of this thread, and when checking out the first post, I do not see that this deal has been explored at all. Adding acid to acetic, reflux and distill, is all I saw, but that aside, Im done, and thsnkyou for the critiques, suggestions etc.

Cheers.

JJay - 23-10-2017 at 01:08

@Babs: People are telling you it won't work. If you don't believe them, feel free to try to prove them wrong with actual experimentation. I can't say that reputation doesn't matter at all on ScienceMadness, but it doesn't matter that much; if you are discussing things scientifically with a solid factual background, people will notice and respect that.

clearly_not_atara - 23-10-2017 at 01:28

With regard to the claim that "anything can happen" - in chemistry, my friend, that is certainly true. Just on the last page Waffles SS and I were arguing about the plausibility of the claimed synthesis of acetyl chloride using acetonitrile and hydrogen chloride as the combined chlorinating agent. Neither of us could have predicted the eventual discovery of a dimer of acetonitrile formed by HCl, N-(alpha-chlorovinyl)acetamidine. The existence of this dimer threw off all of our previous arguments about the reactivity of the compounds.

However, you have not claimed any new chemical transformation. You have, instead, talked only about the thermodynamic properties of the substances you are describing. Such as azeotrope formation and so on. But thermodynamics is not chemistry: it does not teem with surprises. You cannot cheat at thermodynamics with catalysts. So H2SO4 does not shift the equilibrium, and to the extent that it does, it adheres to water molecules and prevents them from boiling away. If you heat dilute sulfuric acid to 250 C, it will still contain water. And toluene lowers the bp of water but crucially does not reduce the vapor pressure (!!) any more than it does that of AcOH. And generally solvents which would have such a large differential effect on vapor pressure do not exist and have never been described. The vapor pressure of water is too low to effect this transformation by several orders of magnitude so a 15 C azeotrope is pissing into a canyon.

This is why I can know that you are wrong. Also, if you read the thread, you will learn that treating AcOH with strong acids can cause dimerization and also that your rxn system may lead to Friedel-Crafts rxns between AcOH and BnH. This may account for any observed water production or unexpected smells. Happy wasting reagents day! (It's every day!)

Babs - 23-10-2017 at 06:40

Quote: Originally posted by CaptainMolo

Quote: Originally posted by Babs

I cannot link, and the URL is to long to just copy paste, but its an interesting read. Re-Google books.

"Biophysical and Structural Aspects of Bioenergetics"

https://books.google.com.au/books?id=5G0oDwAAQBAJ&pg=PA2...

Babs - 23-10-2017 at 21:12

With respect to the comment that toluene lowers the boiling point, well If a mixture has a high vapour pressure it means that it will have a low boiling point. To isolate water, and state that its vapour pressure hasn't changed, well yes, but in the context of a mixture, if the boiling point has been lowered, then its vapour pressure surely has increased, Im probably of base, but the vapour pressure is also dependant on the mole fractions, and that isn't just the 10ml of 80%, its overtime acetic acids carbonyl gets protenated and reacts with one that hasn't been, as in a nucleophilic 1,2 addition then elimination, and the eliminating specie is water. Sure much of it going to act itself as a nucleophile, but some surely could get caught in the azeotropic mixture, that being toluene and water, and perhaps knucklehead needs to present the actual molar amount of H+ in the context of the molar amount of acetic acid, be it potential to be an electrophile, or a nucleophile, which I feel is a given that this isnt a problem about forming acetic anhydride, but suppressing the role water has in breaking this given.
Now I will shut up, and I apologise if Ive been NON Scientific, and immature by defending it so hard, without more evidentiary material.
Clearly_Not_Atari, I can understand what you are stating, and feel I get that the hold between a concentration of acid, and water perse, can indeed have, an azeotrope, where the boiling liquid and the vapour phase there and then, cannot, not remain constant, at a particular concentration or mass percent/fraction.
The other thing I wanted to state is, How hard have I really looked at the system I have been defending. Truth of the matter is, probably not half as much as I would need to be, to remain so obstinate, so my bad for presenting as such. One would surely have to know that its repeatable, use what one can, as far as evidence of what is what, and i have not done that, so I have taken some comments on board, and appreciate it. Cheers.

[Edited on 24-10-2017 by Babs]

[Edited on 24-10-2017 by Babs]

SWIM - 24-10-2017 at 01:47

Not sure if I missed this.

Has anybody actually tried the route where acetylene is bubbled into hot (90C) acetic acid with mercuric sulfate and the reaction temp rises to, and is maintained at, 130-140C to form ethylidine diacetate and immediately decompose it to acetic anhydride? (US425500)

[ EDIT: as pointed out below, I meant 1425500. ( I MUST learn to write things down!)]

I mean sure it's just a patent, but WafflesSS says he's done something very similar, and this does look like a nearly OTC approach other than the mercury.

Hell, all you need is the oxide, as they form the mercuric sulfate in situ in the patent.

[Edited on 24-10-2017 by SWIM]

[Edited on 24-10-2017 by SWIM]

hissingnoise - 24-10-2017 at 04:15

FWIW, and it's not much, the correct patent is US 1680760 A ─ the words "straws", "clutching" and "at" readily come to mind.

hissingnoise - 24-10-2017 at 05:02

Of the various syntheses of the anhydride, the ketene process and the reaction (POCl₃+NaOAc) would appear most accessible...

Red phosphorus can be used for PCl₃ which is itself oxidised by chlorate.

More here!

SWIM - 24-10-2017 at 09:55

Quote: Originally posted by hissingnoise

FWIW, and it's not much, the correct patent is US 1680760 A ─ the words "straws", "clutching" and "at" readily come to mind.

Sorry, I did screw up the patent number. I was referring to the patent numbered 1425500 granted August 8 1922.

I'm not saying your assessment is wrong because of this, but I just wanted to point out that I'm not quite that bad at remembering numbers.

There are a few differences in these patents as this one is for making acetic anhydride in one pot without acetic anhydride being called for in the initial reaction mix. It does call for more mercuric sulfate, but they were using acetic acid at concentrations as low as 96%.

If this is a blind alley it seems several chemical engineers wandered down it in the early 20th century. (Yeah, I know, some patents are total crap

)

Edit: It was worth posting this to get your reference on PCl3 and route to the oxychloride. Thanks for being helpful to a novice.

[Edited on 24-10-2017 by SWIM]

clearly_not_atara - 24-10-2017 at 11:29

hissingnoise: if you have to chlorinate something, it makes far more sense to chlorinate sulfur than phosphorus! Sulfur is cheap, phosphorus is illegal. And S2Cl2 works just fine. But these are both inferior to the sulfur/bromine method in practice. Or the nitrogen dioxide method, because while NO2 is dangerous it's less dangerous than chlorine.

Also, it's worth pointing out, that S2Cl2 can be made in large quantities without having to deal with a lot of molten sulfur, and therefore, without having to deal with a lot of hot chlorine. Once you've produced a small amount of S2Cl2, this will react readily with Cl2 gas to make SCl2, which will react with solid sulfur to re-form more S2Cl2, which can then absorb more Cl2, etc, and friends of mine have done this in order to make lots of S2Cl2. Additionally, sulfur is soluble in S2Cl2, so you can more than double the S2Cl2 on each iteration. This is much easier than e.g. trying to chlorinate 200 g of molten sulfur -- you can chlorinate 3g molten sulfur, and then use this to make 500g S2Cl2.

This thread really hasn't gotten anywhere since we discovered the sulfur/bromine method. The only new methods in the last ten pages or so are the acetonitrile method and the copper/silver acetate method, but the last one is extremely unreliable. And it's frigging impossible to get people to talk about the one method that might actually be a new, OTC, "safe" procedure for making AcCl because they all insist on retreading things that have been posted thirty times already.

Babs: "Sure much of it going to act itself as a nucleophile, but some surely could get caught in the azeotropic mixture" -- for the last time, there is absolutely no such thing as "getting caught" in an azeotropic mixture. Your post is attempting to justify a procedure that does not work based on a phenomenon which does not exist. The only thing which is implied by the word "azeotrope" is that the relative vapor pressures of two components of a mixture have the same ratio as their concentrations. The remainder of your post is not only bad chemistry, it's atrocious English. Go to bed for fuck's sake. There is no reason for anyone to ever believe such a reaction could work; your friend is a moron.

Quote:

If [acetylene] is a blind alley it seems several chemical engineers wandered down it in the early 20th century.

It's just a really stupid alley, anything that involves the words "acetylene" and "140 C" in the same sentence should be enough to send you running in the other direction, of course you can do that if you're a chemical ENGINEER, because you're going to spend all of your time building a huge factory in which such conditions are actually achievable. Otherwise, you're going to burn down your house. Do you want to burn down your house?

It is possible IIRC to make vinyl acetate from acetylene and Hg(OAc)2. Vinyl acetate is useful for all sorts of other things (Heck rxn, precursor to acetaldehyde) and IIRC it can be used to make acetic anhydride by rxn with acids. And this happens at achievable non-house-destroying temperatures and pressures. A safe two-step method beats an explosive one-step method every day of the week.

Also I'm pretty sure acetylene has come up in this thread several times.

[Edited on 24-10-2017 by clearly_not_atara]

hissingnoise - 24-10-2017 at 11:46

You're welcome. The PCl₃ synthesis from red P, unfortunately, requires PCl₃ for initiation so you would need yellow P to start.

The ketene process requires only acetone, water and some, er, high temp. plumbing...

[Edited on 25-10-2017 by hissingnoise]

hissingnoise - 25-10-2017 at 07:35

Quote:

hissingnoise: if you have to chlorinate something, it makes far more sense to chlorinate sulfur than phosphorus! Sulfur is cheap, phosphorus is illegal. And S2Cl2 works just fine. But these are both inferior to the sulfur/bromine method in practice. Or the nitrogen dioxide method, because while NO2 is dangerous it's less dangerous than chlorine

Indeed c-n-a, being caught with PCl3 wouldn't be funny, but they all have pitfalls ─ and the S2Cl2 route comes with filtration headaches...

Acetaldehyde (an excuse to fuck around with acetylene hydration) oxidation has possibilities but ketene turning water to Ac2O has a biblical look to it?

byko3y - 28-2-2018 at 10:35

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]

Waffles SS - 28-2-2018 at 11:08

Thanks byko3y.that is great information

clearly_not_atara - 29-6-2018 at 13:26

Quote: Originally posted by clearly_not_atara

Nitriles react with HCl but the reaction does not stop at an imidoyl chloride:

https://www.researchgate.net/publication/244701085_Studies_o...

This study, which describes the formation of a compound I suspect chlorinates acids, is attached. However, the 2:3 adduct, which contains the crucial alpha,alpha-dichloro moiety, appears to be unstable. It may form transiently during the acetonitrile method, but it may not be feasible to isolate it.

Attachment: phpkMmtNR (1.1MB)
This file has been downloaded 653 times

CuReUS - 11-8-2018 at 01:48

why not do a baeyer-villiger on diacetyl to get AA ? -https://books.google.co.in/books?id=AcpPyv0HWRsC&lpg=PP1...
diacetyl is available as butter flavour

anyways,if you want AA only for acetylation ,you can do it using acetic acid/TCT instead

Waffles SS - 11-8-2018 at 07:38

Quote: Originally posted by CuReUS

why not do a baeyer-villiger on diacetyl to get AA ? -https://books.google.co.in/books?id=AcpPyv0HWRsC&lpg=PP1...
diacetyl is available as butter flavour

anyways,if you want AA only for acetylation ,you can do it using acetic acid/TCT instead

Quote:

5,4 g Diacetyl (63 Millimole) wurden in 500 cm3 Ather gegossen, die 14,1 g Perphtalsaure(77,5 Millimole) gelost enthielten. Nach wenigen Stunden war die einem Mol. entsprechende Menge Perphtalsaure verbraucht. Unter Ruhren haben wir hierauf wahrend
einer Stunde trockenes NH3-Gas eingeleitet, hierauf die Flussigkeit von dem entstandenen Niederschlag abdekantiert und sie auf 20 cm3 eingeengt. Uber Nacht krystallisierte daraus Acetamid aus, das nach Umkrystallisieren aus Benzol bei 81 schmolz und mit Acetamid keine Schmelzpunktsdepression zeigte. Ausbeute 0,87 g, d. h. 24% der Theorie.

Zur Oxydation von α‐Diketonen und einigen Derivaten von solchen mit Phtalpersäurev
Karrer; Hohl - Helvetica Chimica Acta, 1949, vol. 32, p. 1933

[Edited on 11-8-2018 by Waffles SS]

GrayGhost- - 11-8-2018 at 13:21

sincerely I dont read the 36 page of this thread.

In the patent of 1933 number 42573 preparate acetic anhydride with sodium pirosulfate ( from SO4HNa calcinated ) and ammonium acetate.

[Edited on 11-8-2018 by GrayGhost-]

Waffles SS - 11-8-2018 at 21:02

Quote: Originally posted by GrayGhost-

sincerely I dont read the 36 page of this thread.

In the patent of 1933 number 42573 preparate acetic anhydride with sodium pirosulfate ( from SO4HNa calcinated ) and ammonium acetate.

[Edited on 11-8-2018 by GrayGhost-]

Maybe you have to read or search some pages of this topic.this method and similar method tested many times without any success.

CuReUS - 12-8-2018 at 01:20

Quote: Originally posted by Waffles SS

5,4 g Diacetyl (63 Millimole) wurden in 500 cm3 Ather gegossen, die 14,1 g Perphtalsaure...

Oxone would be a better,cheaper and more OTC choice than perpthalic acid -https://www.organic-chemistry.org/abstracts/lit4/052.shtm

Waffles SS - 12-8-2018 at 05:04

Quote: Originally posted by CuReUS

Oxone would be a better,cheaper and more OTC choice than perpthalic acid

Of course

[Edited on 12-8-2018 by Waffles SS]

clearly_not_atara - 12-8-2018 at 06:39

It appears that in the BV oxidation of diacetyl, the AA needs to be trapped in situ, because it reacts with nucleophiles which are present. But maybe the trapping reagent could be something which gives an activated acetyl, such as imidazole or N-hydroxysuccinimide.

GrayGhost- - 12-8-2018 at 08:03

Quote: Originally posted by Waffles SS

Quote: Originally posted by GrayGhost-

Maybe you have to read or search some pages of this topic.this method and similar method tested many times without any success.

I dont tempt make , but i sure what this reaction should be in strictly anhydrous conditions like Grignard and Friedel-Craft.

Waffles SS - 12-8-2018 at 21:02

Quote: Originally posted by GrayGhost-

I dont tempt make , but i sure what this reaction should be in strictly anhydrous conditions like Grignard and Friedel-Craft.

Please read more pages !

CuReUS - 13-8-2018 at 03:05

Quote: Originally posted by clearly_not_atara

It appears that in the BV oxidation of diacetyl, the AA needs to be trapped in situ, because it reacts with nucleophiles which are present.

I don't see any potential nucleophiles in the oxone paper I linked above

Quote:

But maybe the trapping reagent could be something which gives an activated acetyl, such as imidazole or N-hydroxysuccinimide.

won't imidazole or NHS themselves get oxidised under BV conditions ?

Isn't there any other way of isolating the AA,either by using a biphasic medium or nucleophile scavengers ?

professsormuddyhutty - 10-10-2018 at 10:04

Can distilling zinc acetate and condensing the vapors manufacture AA?

clearly_not_atara - 10-10-2018 at 11:21

One thing I am kind of curious about is the reaction (if any) of anhydrous copper (II) acetate with SO2. It seems like SO2 might be oxidized under this condition. If so, the net reaction should look like:

2Cu(OAc)2 + SO2 >> Cu2SO4 + 2 Ac2O

Since SO2 has a high solubility in acetic acid, the reaction might be performed effectively in acetic acid as solvent. There are a lot of methods that try to produce acetic anhydride by oxidation, but this is the first one that uses reduction, to my knowledge. Ensuring all reagents are anhydrous will be a challenge. If Cu2SO4 is produced, it is light green. Possibly, dithionate will be formed instead:

2 Cu(OAc)2 + 2 SO2 >> Cu2S2O6 + 2 Ac2O

http://en.wikipedia.org/wiki/Dithionate

Quote: Originally posted by professsormuddyhutty

Can distilling zinc acetate and condensing the vapors manufacture AA?

The paper which claimed Ac2O release from Zn(OAc)2 was criticized by byok3y for inferring the presence of Ac2O using an NMR spectrum that didn't actually seem to show any Ac2O present.

In a related method, which is known to work, silver acetate does decompose to release acetic anhydride. However, if there is any water present, it catalyzes the decomposition of acetic anhydride like this:

Ac2O >> Me2CO + CO2

In order to achieve a reasonable yield of acetic anhydride, the AgOAc had to be dried carefully and carried out under an inert atmosphere. Therefore, even if silver is available, the reaction may not be very practical.

The short answer is that distilling acetates is a dead end for all practical purposes.

[Edited on 10-10-2018 by clearly_not_atara]

Waffles SS - 10-10-2018 at 13:25

Quote: Originally posted by clearly_not_atara

One thing I am kind of curious about is the reaction (if any) of anhydrous copper (II) acetate with SO2. It seems like SO2 might be oxidized under this condition. If so, the net reaction should look like:

2Cu(OAc)2 + SO2 >> Cu2SO4 + 2 Ac2O

Possible but you will get copper sulfite instead of sulfate
(below reaction of ammonium acetate with SO2)

[Edited on 11-10-2018 by Waffles SS]

Jackson - 30-10-2018 at 07:49

https://patents.google.com/patent/US3281462A/en

This patent uses oxalic acid and boric acid as catalysists for formation of Ac2O under pressure of 10 to 70 PSIG at 20° to 80° C

Because it is not to much pressure, it could probably be carried out relatively easily at the labratory scale.

NZniceguy - 8-11-2018 at 01:27

I was recently given the following and was curious as to what you guys thoughts were......
take some GAA fill a “pipe bomb” ie threaded and capped pipe, add an excess amount of ground up dry ceramic wrench that cap on like it’s never coming off (though it is) and through in a hot fire like a brick oven with good O2 flow ie accordion type thing and cook the fuck out of it for a few hours. If tight enough and anywhere near hot enough lots of wiggle room it won’t pop and the brick oven would protect shrapnel anyway the ceramic will absorb water as it is removed and cools (water produced from the condensation) pour off the crude as fuck AA fractionally distill off anything boiling at 100 or less and collect only that coming over above 135-140 IIRC. That’s your clear clean highly pure AA. I’m not gonna describe fractional distillation if one is to undertake this is will work but for safety and other reasons one needs dedication and some basic lab knowledge ie what bps are and what a fractional distillation is. If not one shouldn’t even bother. The pressures generated in that pipe will be very high numerous atmospheres as you are going way above it normal bp in a static volume. For thermodynamic reasons with the absorption of water produced and the decrease in molar amounts of free substance in the product direction it becomes favorable for it to go to completion. Do not even bother thinking this will ever work at normal pressure or normal temp. You need the energy of heat and the pressure effects. Pressure will nearly always drive a rxn in closed volume towards whatever produces the least gases (or at least with the higher bps) and in direction where there is overall less molecules. Part of the idea is that it is somewhat driving the whole system into a supercritical semiliquid semigas phase which is impossible to label as one or the other. It is the oldest low tech way to make anhydrides for over 130 years I believe.

froot - 8-11-2018 at 02:16

Crude method crudely written.

" the ceramic will absorb water as it is removed and cools (water produced from the condensation)"

Will it? Don't hydrated ceramics lose their water at high temps?

clearly_not_atara - 8-11-2018 at 11:32

Sounds pretty made-up to me. Author doesn't even know what the composition of the "catalyst" is supposed to be.

NZniceguy - 9-11-2018 at 00:41

Quote: Originally posted by clearly_not_atara

Sounds pretty made-up to me. Author doesn't even know what the composition of the "catalyst" is supposed to be.

I dont see a catalyst mentioned....or are you referring to the ceramic pieces?

hissingnoise - 9-11-2018 at 07:54

Quote: Originally posted by NZniceguy

Quote: Originally posted by clearly_not_atara

Sounds pretty made-up to me. Author doesn't even know what the composition of the "catalyst" is supposed to be.

I dont see a catalyst mentioned....or are you referring to the ceramic pieces?

What you were 'given' sounds like some idiot ineptly trying to describe the cracking of acetic acid to produce ketene?

Waffles SS - 9-11-2018 at 08:51

Quote: Originally posted by hissingnoise

What you were 'given' sounds like some idiot ineptly trying to describe the cracking of acetic acid to produce ketene?

I think yes,
There are so many patents and articles about making Ac2O by this method with different catalyst

US2045718(silica gel and Al2O3 at 700-750c)
US2006787(CuCl and CuCO3 at ~700c)
US1915572(calcium tungstate at 550-650c)
Compardou; Seon - [Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences, 1928, vol. 186, p. 592] (TiO2 at 300c)
DE410363( α-Al2O3*H2O; phosphoric acid; pumice stone at 600c)
DE475885( phosphoric acid at 680℃ , I think this happen with different route and not with ketene)
DE408715(with NaCl at 550c and with pumice stone at 650c)
and so many ...

[Edited on 9-11-2018 by Waffles SS]

BakingBrownies - 14-11-2018 at 11:49

the best way to get it is to pass acetone vapor over a hot coil and then pass the gas through a condenser and then through the water. do it until the water is saturated.

hissingnoise - 15-11-2018 at 11:13

Quote:

the best way to get it is to pass acetone vapor over a hot coil and then pass the gas through a condenser and then through the water. do it until the water is saturated.

It worked well for you, then?

Tell us more?

clearly_not_atara - 15-11-2018 at 11:59

All these shitty makeshift ketene generators scare me. It's a toxic, flammable, explosive gas; it's one thing if you're following a known procedure, but just generating shitloads of ketene "over a hot coil" sounds like a recipe for disaster.

Quote:

Possible but you will get copper sulfite instead of sulfate

I'm not sure you correctly interpreted? I was expecting that Cu2+ would oxidize SO2. In particular I had considered a mechanism like this:

AcOSO2- (acetyl sulfite) + Cu²⁺ >> AcOSO2* (radical)

2 AcOSO2* >> (AcO)2S2O4 (diacetyl dithionate)

(AcO)2S2O4 + 2 OAc- >> 2 Ac2O + S2O5^2-

http://en.wikipedia.org/wiki/Dithionate

So that would give you copper (I) dithionate, at least in theory. The compound acetyl sulfite, AcOSO2H, is known in the solid phase:

https://pubs.acs.org/doi/abs/10.1021/ja01233a507

(Note: there is no need to access the article; the preview contains the whole thing!)

However, the potential for Cu²⁺ to oxidize this compound is unclear. Cu²⁺ has a similar redox potential to bisulfate in aqueous solution, but it may be a stronger oxidizer without aqua ligands.

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?

[Edited on 15-11-2018 by clearly_not_atara]

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