Sciencemadness Discussion Board - Acetic anhydride preparation

Acetic anhydride preparation

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aliced25 - 21-4-2013 at 01:42

Yes, S.C> I figured that was what you meant. As it happens SiCl4 is rather easy to purchase, and not *too* expensive at $100 a kg. With a price like that I would not consider making it. After all I am paying a lot more for oxalyl chloride (a LOT more) and while I could make that, I don't bother.

The stoichiometry of SiCl4 in reaction with anhydrous NaOAc makes it attraactive, one mol SiCl4 plus 4 mols acetate giving theoretically 2 mols anhydride and in practice, 1.5 mols.

That helps compensate for the cost of reagent.

Si2OCl6 on the other hand seems to be unobtainium commercially.

Pity that SiCl4 is not more generally applicable to the preperation of acyl chlorides and anhydrides.

Anyway thanks for all the assistance.

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NiCoLi_BrLiNTe - 10-7-2013 at 23:58

So far I've only read the first two pages of this thread, so forgive me if I'm bringing up something thats already been dealt with. While it seems the use of sulphuric acid as a dehydrant is unlikely to work when simply mixed with glacial acetic acid, is it possible that SO3, bubbled through the acetic acid could be more effective? Potassium peroxydisulphate, when mixed with conc. H2SO4 and heated strongly, decomposes and gives of SO3.

AndersHoveland - 11-7-2013 at 01:18

I think sulfur dichloride could be used to dehydrate acetic acid.

4 AcOH + 2 SCl₂ --> 2 Ac₂O + SO₂ + S + 4 HCl

It is common knowledge that PCl3 reacts with glacial acetic acid to form acetyl chloride, so I see no reason why SCl2 could not similarly dehydrate it much more easily. Sulfur dichloride can act as a fairly strong dehydrating agent, with water it vigorously reacts and disproportionates into elemental sulfur and sulfur dioxide.

[Edited on 11-7-2013 by AndersHoveland]

NiCoLi_BrLiNTe - 17-7-2013 at 23:35

Thanks, S2Cl2 is fairly strait forward to make isn't it?

White Yeti - 13-8-2013 at 12:57

What about making acetyl chloride
from glacial acetic acid
and cyanuric chloride,
and then reacting acetyl chloride
with glacial acetic acid?

Metacelsus - 13-8-2013 at 13:59

From reading this thread, acetyl chloride is usually reacted with anhydrous sodium acetate, not acetic acid. I may be wrong, but I think this is because acetate is a better nucleophile than acetic acid, and the reaction goes by nucleophilic acyl substitution.

White Yeti - 13-8-2013 at 16:17

Yes, that's right. An added benefit is that sodium chloride is much easier to deal with than hydrogen chloride.
Sodium acetate is also much cheaper than glacial acetic acid.
You'd just have to stick the hydrate in the oven first to get the anhydrous salt.
You get the general idea though, and cyanuric chloride is pretty cheap.

One thing I'm not sure about, is if there are any restrictions on the purchase of cyanuric chloride in the United States.

kristofvagyok - 13-8-2013 at 17:04

Quote: Originally posted by AndersHoveland

I think sulfur dichloride could be used to dehydrate acetic acid.

Any references for that? Looks like a really weak idea.

Also, important to note that SO2 is really well soluble in AcOH and in Ac2O, so it would be a great task to get out the SO2 from this mixture. Another question: how would you get rid of the thioacetic acid what would form in high percent?

There is an article what describes the preparation of Ac2O from different acetate salts and thionyl chloride, but it's definitely not the same as AndersHoveland mentioned....
Patent DE275846
Fortschr. Teerfarbenfabr. Verw. Industriezweige, vol. 11, p. 1191

DrSchnufflez - 13-8-2013 at 18:10

There is a similar method to the sulfur dichloride method listed in this link.

It uses anhydrous sodium acetate and sulfur monochloride to form a sulfur linked molecule that decomposes when heated to give acetic anhydride.

In response to the question posed by white yeti, I worked with sulfur chlorides on the weekend so three days ago.
[Edited on 14-8-2013 by DrSchnufflez]

[Edited on 14-8-2013 by DrSchnufflez]

[Edited on 14-8-2013 by DrSchnufflez]

White Yeti - 13-8-2013 at 18:41

why are all of you spending so much time asking whether or not something is possible?
The real question is whether or not it's worth doing.
Hiding behind references is just as counterproductive, even if such an absurd procedure worked, when was the last time any of you worked with SCl2 or S2Cl2?
I would guess that Anders has never worked with sulfur dichloride--being the armchair synthetic chemist that he is--and none of you would look forward to handling it, that is, if you could even buy it at all.

Don't bother considering procedures that are not even within your means. A methodical scientist will work with what he has, not what he doesn't have.

Waffles SS - 13-8-2013 at 21:37

Essigsäureanhydrid
Acetic Anhydride from S₂Cl₂(Include picture)
http://www.versuchschemie.de/topic,16159,-Essigs%E4ureanhydr...

[Edited on 14-8-2013 by Waffles SS]

Mesa - 30-9-2013 at 13:50

An unabashed necro-post, but this caught my attention when researching something completely unrelated.

I believe the 'pyrosulfate + acetate salt' dry distillation method has been brought up previously in this thread, but in case it hasn't, here is a relevant patent:

http://patentimages.storage.googleapis.com/pages/US1430304-0...

I recall one of the main reasons why this was seen as impractical was due to the toll it took on glassware, and the high temperatures required for the reaction to occur.

A procedure I recently came across to produce a somewhat manipulatable gaseous hydrochloric acid uses a microwave to heat sodium bisulfate and sodium chloride:

http://mattson.creighton.edu/MicrowaveMethod/ (Near the bottom)

I can't find any information regarding the molecular dipole moment of the pyrosulfate, but I assume it would not be so different from NaHSO4. It should therefore be fairly easy to use the method from the patent, using a modified microwave, to quite easily generate assorted anhydrides from their salts.

CMOS - 3-11-2013 at 14:40

someone tried that russian patent(from acetamide)? All I got was glacial acetic acid, and acetamide left in reaction flask. I tried freezing out to check if there is even a little bit of Ac2O but all of it froze :/ (aa should stay liquid) (and there was like no fraction near 139, it just started running from 120 up, and milkish smoke appeared(probably acetamide), so I stopped distillation)

Waffles SS - 3-11-2013 at 20:44

That Russian patent is bullshit!
I tried it many times and got no Ac2O

zenosx - 14-11-2013 at 17:20

I apologize if this has been posted before, but this is a rather long thread I had to UTFSE for a bit to find surprisingly.(EDIT: first sticky in orgranic should have been obvious

)
Anyway...This was found @ http://web.mit.edu/semenko/Public/Military%20Manuals/RogueSc...
Not really the most journalistic site

(QUOTE FROM SITE)
Synthesis: Acetic anhydride is a very handy organic compound that has fallen into ill repute thanks to the drug dealers. It is technically a watched chemical, but you will only have to answer questions at gunpoint if you buy over 250 gallons. Even so, you will most likely be put on The List if you buy any, and you will have to come up with a bunch of explanations as to what you are going to do with it. Acetic anhydride is very corrosive and must be kept away from moisture, as it will decompose into acetic acid.

TLDR; Actual Syn

Into a 200-mL Florence flask, add 70 g of finely pulverized, anhydrous sodium acetate. Set the flask up for simple distillation, instead of a thermometer in the top of the flask use an addition funnel. Slowly add, by dropwise addition, 45.5 mL of acetyl chloride from the addition funnel. After half of the acetyl chloride has been added, stop the addition and stir the reaction mix with a glass stirring rod. Afterwards, continue the addition the rest of the way. If at any point during the addition some material should distill over, pour it back into the reaction flask and decrease the rate of addition to prevent this. After the addition is complete, remove the addition funnel, stop up the flask, and distill with flame or hot plate. The crude acetic anhydride thus obtained needs to be purified by distillation. Set up for a simple distillation, add 3 g of finely pulverized, anhydrous sodium acetate to the reaction flask, and then pour in the crude acetic anhydride. The sodium acetate will convert any remaining acetyl chloride into the anhydride. The receiving flask should be under a water shower for cooling. Place a large funnel (a cheap plastic one will work fine) under the flask with a tube leading to the sink, pour cold water over the top of the receiving flask. The receiving flask can also be held directly under the faucet in the sink. Commence the distillation; the yield should be about 50 g of pure acetic anhydride.
(END QUOTE)

If anyone tries this I would be curious. I don't have any acetyl chloride ATM, and I don't have time with classes to work it out theoretically, but thought I would post it in case it hadn't previously been mentioned.
If this is redundant, my apologies.

[Edited on 15-11-2013 by zenosx]

Crowfjord - 14-11-2013 at 18:50

Yes, that method (anhydride from acetate and acetyl chloride) has been discussed to death. It has also been repeatedly pointed out that unless the anhydride is needed specifically (like as a solvent or something) it is pretty pointless to make acetic anhydride from the chloride, as the latter is already a more convenient and atom efficient acetylation agent.

Apology accepted

DubaiAmateurRocketry - 17-12-2013 at 14:04

Can I just do acetic acid + P2O5 ?

I have no idea how to separate acetic anhydride and phosphoric acid though, are they miscible ?

DraconicAcid - 17-12-2013 at 14:11

Quote: Originally posted by DubaiAmateurRocketry

Can I just do acetic acid + P2O5 ?

I have no idea how to separate acetic anhydride and phosphoric acid though, are they miscible ?

I don't know if that would work, but if it did, acetic anhydride is surely a lot more volatile than phosphoric acid. It would be a high temperature distillation (about 140 C), but possible.

[Edited on 17-12-2013 by DraconicAcid]

TheChemiKid - 17-12-2013 at 17:54

This may have been asked already, but this thread is so long, I can't find it.
Can acetic anhydride be synthesized by dehydration of acetic acid with CrO₃?

Crowfjord - 17-12-2013 at 18:06

If I recall correctly, attempts failed using phosphorus pentoxide, which just gave char. Not sure if chromium trioxide was ever mentioned.

DubaiAmateurRocketry - 18-12-2013 at 02:19

Quote: Originally posted by Crowfjord

If I recall correctly, attempts failed using phosphorus pentoxide, which just gave char. Not sure if chromium trioxide was ever mentioned.

umm why did it fail using P2O5 ?

bfesser - 18-12-2013 at 05:03

Try reading through the thread.

TheChemiKid - 18-12-2013 at 05:26

If the Chromium Trioxide method works, I think the reaction would be 2 C₂H₄O₂ + CrO₃ ⇒ (C₂H₃O)₂O + H₂CrO₄
I am worried that the Chromic Acid would decompose back into Chromium Trioxide and Water and the Water could react with the Acetic Anhydride to form Acetic Acid again.
Is this a valid method?

Nicodem - 28-12-2013 at 00:27

Quote: Originally posted by TheChemiKid

If the Chromium Trioxide method works, I think the reaction would be 2 C₂H₄O₂ + CrO₃ ⇒ (C₂H₃O)₂O + H₂CrO₄
I am worried that the Chromic Acid would decompose back into Chromium Trioxide and Water and the Water could react with the Acetic Anhydride to form Acetic Acid again.
Is this a valid method?

What kind of a question is that? You ask and make claims at the same time, but give no reference. First give the reference for this preparation (which to me makes no sense chemically), so that we can read the article or patent and make sense of it.

TheChemiKid - 29-12-2013 at 04:14

I was asking whether anyone knew IF that worked, not that it did. I was speculating about the problems with it, but saying these would or would not happen. By now, I have done as much research as I have been able to, and it seems this will not work.
This is because chromium trioxide is used as an oxidant in a solution of acetic acid. Here is a link.

[Edited on 12-29-2013 by TheChemiKid]

DubaiAmateurRocketry - 9-1-2014 at 12:18

Alright,
So... what happened to the NO2 gas + Sodium acetate method ? I saw someone who tried it but did not report his result further.... on page 6-8

Also one person who used P2O5 seems to have got some acetic anhydride ? and that the crystal that form might be moist coming to the bottle that might turned few Ac2O into AcOH and therefore it precipitated ? on page 4.

DoctorZET - 25-1-2014 at 09:55

Hi there, I'm new here!
I see you have big problems related to the production of acetic anhydride (at home).
That's OK, I can help you with some new methods.
(1)First method involves Sulfuryl chloride (O2SCl2) made by the reaction between SO2 and Cl2 in the presence of a powerfull light source (I used 500 Blue LED, but it work also with sunlight). After this you just have to mix carefully (with a glass stick) 2mols of sodium acetate (fine powder) (anhydrous!!!) with 1mol of SO2Cl2(liquid at room temperature) to produce 2mols of CH3COCl (Acetyl chloride

) and 1Mol of Na2SO4. In this reaction You can use a little bit excess of SO2Cl2. Then mix the Acetyl chloride(2 mols) with another 2 mols of Na-Ac, and warm a little (45-49*C), to form the acetic anhidride (Ac-O-Ac

) and NaCl. After this you can distilate an almost pure sample of acetic anhidride. Be careful, this reactions may became hot enough to boil the SO2Cl2 or the Acetyl chloride, I recommend to add the reactants gradually.

[Edited on 25-1-2014 by DoctorZET]

TheChemiKid - 25-1-2014 at 09:57

Acetic anhydride in not Ac-Ac, it is Ac-O-Ac

DoctorZET - 25-1-2014 at 12:39

sorry about that...I mean Ac-o-Ac...However you may know that is impossible to make H3C-C(O)-C(O)-CH3 through these reactions...On the other hand H3C-C(O)-O-C(O)-CH3 is formed. (I'm wrong if I consider that the acetate radical is "H3C-C(O)O-" instead of "H3C-C(O)-" ?

)

underground - 11-2-2014 at 23:45

Quote: Originally posted by DoctorZET

Hi there, I'm new here!
I see you have big problems related to the production of acetic anhydride (at home).
That's OK, I can help you with some new methods.
(1)First method involves Sulfuryl chloride (O2SCl2) made by the reaction between SO2 and Cl2 in the presence of a powerfull light source (I used 500 Blue LED, but it work also with sunlight). After this you just have to mix carefully (with a glass stick) 2mols of sodium acetate (fine powder) (anhydrous!!!) with 1mol of SO2Cl2(liquid at room temperature) to produce 2mols of CH3COCl (Acetyl chloride

It sound interesting. Can you tell us more about the preparation of SO2Cl2 ?

Zwarts - 23-3-2014 at 03:03

Hello sciencemadness,
This is my first post here so please bear with me.
A good friend of mine works in stainless steel machine construction.
He is willing to make a setup for me in stainless steel 316.
This is how far i've gotten upto now.
<img src="http://oi59.tinypic.com/inhcox.jpg" width="800"></img>

Basically acetone being heated.
Vapours lead through copper katalyst, cooled down through a ice water heat exchanger.
Condensed acetone recuperated.
Ketene led through gaa
ch4 recuperated/ disposed off

One of my main questions is what material i could use to connect the catalyst module to the rest of the piping

Also idd like you guys your opinion of it so far

[Edited on 3-4-2015 by Polverone]

hissingnoise - 23-3-2014 at 05:36

Have a look at this before committing yourself . . . ?

Zwarts - 23-3-2014 at 07:43

myea looks similar to me , tho the stainless steel setup would be a lot less fragile, glass, high temperatures, dangerous substances
considering this one would come at the same price nearly

Oxirane - 6-11-2014 at 17:44

Seems that only special part needed for that glass apparatus is the catalytic tube. It could be substituted with something common, though, perhaps.

I would try the design I attached. You can get the basic concept very easily. Few points:

The reactor is just a small tube, about 300-500mm in length from SS tube, diameter approx 20-30mm. It is surrounded by another tube, which has diameter of appro 60mm inside, and this tube is insulated with ceramic wool or cast. Propane flame is blasted through the tube and is vented from the other end as seen in the pic. It should bring the temp high enough for acetone pyrolysis.

It goes through this setup and vapors go into stainless steel adapter with silicon plugged condenser, which in this case contains as cold liquid as possible, possibly insulated too. Unreacted acetone is condensed and led via PE/PTFE tubing back to the heating vessel to be revaporized and pyrolysed. Generated ketene and other side products will go through the column and through another tube into second column. In here a second column and flask is put if some acetone vapors shall pass, and one can use dropping funnel as well as presented in the document. The final flask contains GAA into which ketene bubbles and hopefully reacts to produce AA. Rest of the fumes are led with a tube into atmosphere.

I think this same device could be used for making acetaldehyde, formaldehyde and ether by packing the reactor tube with proper silica gel supported catalyst and using a digital hot air gun to control the heat, which is significantly lower in these reactions. In these cases, for formaldehyde you could use very cool condenser coolrant, but in case of acetaldehyde, you would use coolrant at 20-30C and in case of ether, you would do it at 40C. Also the first receiver flask would be put into controlled water bath to evaporate all ether/acetaldehyde but rest the ethanol down there.

There is also a close view of the reactor. It is presented in here as a quartz tube, but cheaper and much less fragile 316 will subside as well. The ends are 1" stubs of SS tube filled with ceramic material and the flanges are steel.

[Edited on 7-11-2014 by Oxirane]

clearly_not_atara - 7-2-2015 at 15:08

The major problem in this route seems to be the preparation of anhydrous sodium acetate, after that everything is "easy" (known)... The interesting thing is the existence of sodium diacetate, which appears to be non-hygoroscopic, and in any case is generally prepared with water as a solvent:

http://www.scientific.net/AMM.508.79

A study of its crystal structure does not mention any hygoroscopicity or water of crystallization:

http://pubs.rsc.org/en/Content/ArticleLanding/1975/P2/p29750...

It appears the preparation of NaOAc*AcOH is much easier than the dehydration of the trihydrate of NaOAc.

Maybe you could use the dry EtOH/NaOEt solutions prepared here to neutralize and rextalize anhydrous NaOAc. I have a feeling that heating NaOAc*AcOH just gives acetone and NaHCO3, though. If you're really lucky, NaOAc*AcOH might react with S2Br2 directly; it is dry, after all...

franklyn - 28-2-2015 at 01:18

If this hasn't been cited before it's worth a look.
NaHSO4 is heated to obtain Na2S2O7 and that then is heated with CH3COONa
http://chemistry.mdma.ch/hiveboard/novel/000462958.html

.

clearly_not_atara - 28-2-2015 at 11:52

I'm afraid that reaction has been revisited dozens of times over the years, and it doesn't work at all. Similar reactions have been attempted with P4O10, SO3, and NaPO3, among similar reagents (Al(OAc)2OH etc) which all fail to produce any anhydride.

I have however wondered if pyrosulfate could be used to dehydrate methanesulfonic acid to mesyl anhydride. While on the surface it sounds like it would be even worse, sulfonic acids turn out to dehydrate more easily than carboxylic acids, and MsOH dehydrates to Ms2O with P4O10. Plus MsOH can probably protonate S2O7(2-) which should make it more reactive. If even a little Ms2O is present at equilibrium you might be able to distill it off with a little coaxing; the anhydride is significantly more volatile than the acid.

Or maybe it's all wishful thinking, but it would be pretty cool if it worked.

morganbw - 28-2-2015 at 19:04

I do not now and will maybe never, need the anhydride, but before I
would ever say that it clearly does not work I would have to design many experiments ( and test them to be sure ).
I have witnessed many things not possible for some but very doable for others. Just saying

To be sure, I have failed many synthesis.

[Edited on 1-3-2015 by morganbw]

franklyn - 1-3-2015 at 19:02

• Dry distillation of Calcium Acetate by itself leaves Calcium Carbonate and Acetone
. Ca(CH3COO)2 => CaCO3 + CH3COCH3

• Reacting Calcium Acetate with Sulfuric acid yields Calcium Sulfate and Acetic acid
. Ca(CH3COO)2 + H2SO4 => CaSO4 + 2 CH3COOH

• Reacting Calcium Acetate with the acid anhydride Sulfur Trioxide must make Acetic Anhydride. What else ?
. Ca(CH3COO)2 + SO3 => CaSO4 + (CH3CO)2O

• Skipping a step for a one pot synthesis :
. CaS2O7 + Ca(CH3COO)2 => 2 CaSO4 + (CH3CO)2O

Since Calcium Acetate discomposes at just 160 ºC, and Calcium PyroSulfate not until 720 ºC
that presents a problem. However Sodium Acetate melts at 324 °C boils at 882 ºC without
decomposition. Sodium PyroSulfate melts at 401 °C boils at 460 ºC without decomposition.

As it is detailed here _
Attachment: Acetic Anhydride Manuf US1430304.pdf (193kB)
This file has been downloaded 840 times

http://books.google.com/books?id=yZ786vEild0C&lpg=PA161&...

SO3
http://www.sciencemadness.org/talk/viewthread.php?tid=5495
The Thermal Decomposition of Potassium and Sodium Pyrosulfate
http://doc.utwente.nl/68103/1/Vries69thermal.pdf

Closely related, previous post
http://www.sciencemadness.org/talk/viewthread.php?tid=9&...

.

clearly_not_atara - 1-3-2015 at 23:46

Energy, people.

CaSO4: -1434 kJ/mol
Ca(OAc)2: -1479 kJ/mol
SO3: -395.7 kJ/mol
Ac2O: -625 kJ/mol

-1479 + -395 > -625 + -1434

I think we might in fact have ourselves a winner. Unfortunately, this route is even worse than the last one... :p

franklyn - 2-3-2015 at 12:25

Am I the only one with imagination here. Mind you I'm not the chemist so how am I the one that conjures these things.

Pyrolyze Potassium Bisulfate to produce Potassium PyroSulfate
2 KHSO4 => H2O + K2S2O7
Potassium Bisulfate decomposes at ~ 214 ºC
www.ilo.org/dyn/icsc/showcard.display?p_card_id=1585

Heat Potassium PyroSulfate and Sodium Acetate to distill Acetic Anhydride
K2S2O7+ 2 NaCH3COO => K2SO4 + Na2SO4 + (CH3CO)2O

Initially the precursors will melt and Acetic Anhydride will boil out leaving dry solid Sulfates. What can go wrong ?

Sodium Acetate NaCH3COO melts at 324 °C
Potassium PyroSulfate K2S2O7 melts at 325 °C
www.caslab.com/Potassium_pyrosulfate_CAS_7790-62-7

Sodium Sulfate Na2SO4 melts at 884 °C
Potassium Sulfate K2SO4 melts at 1069 °C

.

clearly_not_atara - 3-3-2015 at 23:49

Quote:

What can go wrong ?

You know, I'm really glad you asked, because if nobody had asked I wouldn't have thought about it anymore. Anywho, the definition of insanity is to try the same thing over and over expecting different results. And now, may I introduce you to Mr. Clay S. Encondensation.

Step 1 is the evolution of SO3. It might be P2O5 in some other synthesis, but, like, who cares? We start with SO3; that one's easiest.

NaOAc + SO3 >> NaO(SO2)OAc, "sodium acetyl sulfate" -- a known compound (though to be fair I don't actually know if it forms in this reaction -- I was just thinking about possible pathways that the combination would follow)

Anywho, sodium acetyl sulfate has an active methylene on the "acetyl", and since NaOAc is capable of deprotonating Ac2O you bet it's capable of deprotonating acetyl sulfate. On the other side, acetyl sulfate is itself a pretty powerful acylating agent. Thus:

2 NaO(SO2)OAc >> NaSO4H + NaO(SO2)OAcAc

NaO(SO2)OAcAc >> CO2 + Me2CO + NaSO4H

A drastically more energetically favorable reaction than the production of Ac2O, and we already know that acylative decarboxylation occurs by heating some acetate salts all by their lonesome. I figure the self-condensation of acetyl sulfate (and probably acetyl phosphate) explains all the mess -- and possibly the overheating, charring, etc...

[Edited on 4-3-2015 by clearly_not_atara]

[Edited on 4-3-2015 by clearly_not_atara]

learningChem - 12-4-2015 at 15:23

So, if there's any reaction between sodium acetate and sodium pyrosulfate, it doesn't yield acetic anhydride anyway?

If that's the case, then I've got a couple of questions :

Why do people bother to fill fake patents like US 1430304?

What kind of dumb joke is a patent system that allows outright lies to be 'patented'?

UC235 - 13-4-2015 at 18:05

Quote: Originally posted by learningChem

What kind of dumb joke is a patent system that allows outright lies to be 'patented'?

What does it matter if the patented thing is useless to the patent holder and they paid the fee? Patents aren't meant to be a how-to guide for third parties, but a legal protection for an inventor so they can (for a limited time) capitalize on their work without being immediately ripped off by competition. In order to have that legal protection they have to elaborate on what they invented so they can point a finger in court when another corporation/entity starts doing it.

If the patent is garbage, it is worthless to the inventor. In order to keep garbage patents out of the system, the patent office would have to have experts on everything on staff and test every single patent.

byko3y - 19-4-2015 at 04:03

Okay, so the Na acetate + pyrosulfate method doesnt work, right? But the sulfuryl chloride + sodium acetate works. Or maybe it needs some catalyst? And what is the mechanism of formation of acetyl chloride via sulfuryl chloride? For some reason there's almost no references for this reacton in the modern literature: there's one patent that leads to monochloracetic acid, and there's nice article in the thorpe dictionary of applied chemistry about acetic anhydride using SO2+Cl2+NaOAc in glacial acetic acid (SO2 forms adduct with acetic acid).
And does anyone finally found the mechanism of acetic anhydride(AA) formation from NaOAc+S+Cl2/Br2? Because the Ac-O-S-S-O-Ac most likely is a bullshit. And we know that the reactian actually does not starts easily for some reasons, so there's no scientific research on this mechanism. But sodium benzoate + S + Cl2 readily gives benzoic anhydride. I'd say sodium benzoate would be a nice catalyst for the reaction, though I never tested it.
I think the actually catalyst for the old industrial preparation (NaOAc+S+Cl2) was a carbon obtained from fusing of the sodium acetate. But what happens in the process? Stochimetry of the yield says that 2/3 of it can be made via sulfur oxidation product SO2 by converting it into sulfuryl chloride SO2Cl2 and then reacting with sodium acetate as usual. But 1/3 of the yield is a mistery. Can it be a thionyl chloride? Maybe some Ac-O-(S=O)-O-Ac intermediate.
We know that after the reaction finished, on heating to AA boiling point (140°C) the SO2 gas comes off. Also, we know that sulfuryl chloride decomposes to SO2 and Cl2 above 100°C. Also, we know evolution of SO2 during the AA distillation from the final mixture leads to lower yields (Thorpe says so), this is why vacuum distillation is used.
And did anyone try the Al2(SO3) + NaOAc method?

clearly_not_atara - 21-4-2015 at 23:49

I guess it makes a little more sense to assume that the adduct between S2Cl2 and NaOAc has a form like a thio-thionyl dihalide, or S=S(OAc)2, producing an Ac-O-S(=S)-O-Ac. Maybe AcOSSCl rearranges to AcOS(=S)Cl, which looks vaguely reasonable. Or even AcSS(=O)Cl, which is lower energy -- and the resulting hemithio-dianhydride AcSS(=O)OAc has a sort of reasonable degradation pathway.

In any case the degradation byproduct is a known compound, providing a rationale for the process:

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

I think the real question is whether someone can find a reasonable way to produce pure S2Br2. All of this in situ bullshit hurts yields and makes everything smell bad.

byko3y - 22-4-2015 at 03:24

You don't need the S2Br2, you need a SBr2 if you want to make anhydride.
What would drive the reaction towards yielding Ac-O-S(=S)-O-Ac ?
I've found some answers in the article "Dialkoxy disulfides and their branch-bonded thionosulfite isomers"
DOI: 10.1080/1741599342000202176
"12a–12c synthesized by Wang [46] in excellent yield (>90%) are included for completeness (ROAg + S2Cl2, under vacuum). These compounds are thermally unstable and decompose readily to form the anhydride, SO2 and sulfur [47].

[46] Wang, C. S., Pullen, K. E. and Shreeve, J. N. M., 1970, Inorg. Chem., 9, 90.
[47] Denham,W. S. and Woodhouse, H., 1913, J. Chem. Soc., 1861."
They say the -O-S-S-O- isomer is the most stable one.
And here's a pic from that doc, though it describes slightly different compounds.

I was unable to find the 46 reference ( Wang, C. S., Pullen, K. E. and Shreeve, J. N. M., 1970, Inorg. Chem., 9, 90 ), but the 47 is available - https://www.thevespiary.org/rhodium/Rhodium/Vespiary/talk/fi...
And also this, written by one of the authors of the previous article https://www.thevespiary.org/rhodium/Rhodium/Vespiary/talk/fi...
Although those are way too old.

clearly_not_atara - 22-4-2015 at 09:33

SBr2 doesn't exist! I'd be surprised if it were an intermediate, and no source (including yours) has suggested this. Besides, the reaction obviously works with S2Cl2, and apparently by simple scission. The mechanism isn't really hard to understand -- what people forget is that sulfur has a really large covalent radius, which allows sulfur compounds to undergo reactions that ordinary compounds don't. For instance, cyclizations of sulfur compounds can violate Baldwin's rules:

http://pubs.rsc.org/en/Content/ArticleLanding/1976/C3/c39760...

In this case one of the acetyl groups attacks the oxygen on the other one, and gives off S2O, or at least that's my guess. The analogous reaction with SBr2 seems if anything less favorable.

byko3y - 23-4-2015 at 07:17

Truly, my sources still don't answer the question about maximum yield stochiometry of
8NaOAc + SCl2 + 2Cl2 = 4AcOAc + 6NaCl + Na2SO4
which is based on practical observations (thorphe 1921, vol. 1, p.28)
As far as I understand, the SBr2 is relatively unstable and is gaseous - the latter one is a more important problem. Just like SOBr2 is unstable compared to SOCl2, and SCl4 is unstable. I'd suggest using chlorine instead of bromine.
Speaking about sulfur large size, I can mention sulfur mustard and willgerodt-kindler reaction with 3-membered rings.
Nevertheless, disulfur dichloride is not reactive enough to be successfully attacked by carboxylate, and, as you could see, researchers were forced to use a silver salt, because they failed with sodium. I thought the mechsnism of NaOAc+SO2Cl2 reaction would help me to answer the question, though I still don't have the mechanism.

clearly_not_atara - 23-4-2015 at 23:25

There is one serious problem with your hypothesis: silver makes carboxylate salts less nucleophilic, not more nucleophilic, which is why silver acetate reacts with bromine: Br+ won't react with AcO- (even in solution), but silver's electronegativity of 1.93 (compare Na 0.93) means that the Ag-O bond has covalent character whereas the Na-O bond is decidedly ionic (oxygen's electronegativity is 3.44; the rule of thumb for ionic bonding is a difference of 2, which is seen by considering how AgF is soluble but Ag2O is not). Instead silver allows the salt to undergo other complex sorts of reactions, which is why the Hunsdiecker reaction occurs in nonpolar solvents where AgOAc reacts with molecular Br2. Another example is the Kolbe reaction in ether which produces isonitriles because the carbon atom is essentially covalently bonded to Ag and so the nitrogen is alkylated instead.

This might be why diacyloxydisulfides are not formed:

S2Cl2 + NaOAc >> NaCl + AcOSSCl

AcOSSCl + NaOAc >> Ac2O + S2O + NaCl

where in the second reaction AcOSSCl behaves as an acyl pseudohalide and acylates AcO-, and the electron in [O-]SSCl is transferred to chlorine to leave S2O. Using silver salts prevents acetate from being acylated directly, possibly due to steric hindrance, or due to silver's (soft acid) affinity for Cl- (soft-ish base) outcompeting AcOSSCl's affinity for acetate.

Sulfur-halogen bonds are very weak in general. It would be surprising if any of them don't add to acetate; they add to, for example, benzene in the presence of AlCl3, or with aniline uncatalyzed, and we can reasonably assume AcO- reacts about 60 times slower than aniline (which reacts essentially instantaneously, and not only that, it reacts twice!. You'll notice that on Rhodium's Archive the yield is more than 90% based on S2Cl2, which makes a mechanism dependent on oxidation seem pretty unlikely.

[Edited on 24-4-2015 by clearly_not_atara]

byko3y - 24-4-2015 at 20:57

S in halides is a weak electrophile (+1, +2, +4 oxidation state)
S+ + Cl- + OH- + H+ -> SOH + HCl ... + Cl- -> SO + 2HCl
Countrary, it is really stable while in -2 oxidation state.
Acyl group in acyl halide is electrophilic too, this is why it attacks amines. Acyl halides and sulfur halides need a lewis acid to attack non-activates aromatics. But Cl-S-S-N- is a strong electrophile, this is why it easily attacks activated aromatics. Just like acyl halides can attack the activated aromatics without a lewis acid, although they prefer to attack O or N group.
Btw, as you may know, there exists a R2N-S-S-NR2 compound and well known R-O-S-S-O-R compounds having sulfur clearly in +1 oxidation state which seems to be the most stable one.
The idea of a weak electrophile means that sulfur can bind to nucleophiles capable of giving electrons, like alcohols or alkenes do, but not the carboxylic acids. For this reason you can't make H2S just by pouring a sulfur into acid.
So the Ac-O-S-S-Cl can be barely called pseudohalide. In a regular sulfoxide (R-S(=O)-R) the S-O bound is strongly polarized, and then Ac group is bound to the oxygen, totaly dividing the molecule into [AcO]- and [S-S-Cl]+.
Let's look at the benzoic acid salt. Unlike the aliphatic acid, this one can relatively easy give away oxygen, providing a [Ar-C=O]+ ion. Or... accept electrophiles like H+ or S+. Alkenes are also nucleophilic. as you can see in the picture I've posted above (the mechanism of rearrangement of substituted vinyl alcohol to sulfoxide). And sulfur halides love nucleophiles like alkene (our good old sulfur mustard).
Obviously, acyl group in the sodium acetate is a bad nucleophile, while AcO- is a perfect nucleophile, but! Acyl group of silver acetate is more nucleophilic! Just like in that of Al(AcO)2OH (acetic anhydride via aluminium acetate proven to work, not by me though and yield is like 30%).
This is the reason why I wanted to read some fresh reasearches on the subject (like that 1970 article) - because in 1913 there were no X-ray diffractometers, IR, NMR spectrometers, and researches on mass spectrometers were actively conducted.
I really think the active intermediate is not a Ac-O-S-S-O-Ac, but a Ac-SO-S-OAc or even Ac-SO-SO-Ac (the later will probably rearrange to Ac-SO2-S-Ac). The reason why sodium acetate + sulfur chloride is so hard to perform could be:
- bad nucleophility of acyl group and unability to form a stable sulfoxide, while dithionite is unstable ( [AcO-S(Cl)-S-Cl]- decomposes back to [AcO]- and S2Cl2, because sulfur is more affine to the chloride then to AcO);
- a need for acetic anhydride either as a catalyst or as a solvent;
- or just a bad solubility of sodium acetate in sulfur halide ^_^ .
Btw, Ph-SO2-S-Ph is a relatively unfavorable product (obtained from (PhSO2)O + PhSH) compared to Me-Ph-SO2-S-Ph-Me (tolyl toluenethiosulfonate) (38% yield former, 71% yield latter), according to a article "Aromatic Sulfonic Acid Anhydrides" by Lamar Field. Although I don't know which side brings more stability to the system - both sulfurs have positive oxidation state, so probably both activated aromatics make the product more favorable.
My theory is that decomposition of Ac2O2S2 compound follows intermolecular pathway (some other acyl group is responsible for the formation of acetic anhydride), as opposed to a high temperature decomposition leading to regeneration of acetate. I doubt that the intermediate could be a Ac-SO-S-Cl, though this way is possible and thiosulfinates are stable compounds ( https://en.wikipedia.org/wiki/Thiosulfinate ), but the terminal chlorine doesn't look good.
Transition states might be close to Pummerer rearrangement's ones with something like a CH3-C(=S-R)-O-Ac compound.

Quote: Originally posted by clearly_not_atara

Well, he's only half wrong. It's generally agreed that S2Br2 converts sulfonic acids to their anhydrides by an unknown mechanism; presumably the disulfonyloxydisulfide intermediate is too unstable to isolate

I was not able to find any information on reaction of sulfonates with sulfur halides. Maybe I could try to read some book on the subject? But there is so few researches of these compounds. And the products of the reaction are unstable, as you and me confirmed, so it might need a catalyst or strong heating to form them.

Quote: Originally posted by clearly_not_atara

However of course other reagents exist; cyanuric halides come to mind, as does antimony pentachloride.
What's more interesting to me is I'm still pretty sure the pyrosulfate route will work with methanesulfonic acid (possibly toluenesulfonic acid)

US8222450 tells about preparing of sulfonic anhdyrides via chlorinated acyl chlorides.
In fact you can mix acetic anhydride with MsHO to get the Ms2O, beacuse this compound can be easily removed from the reaction mixture by distillation, so there are a plenty of different methods to do this conversion.

[Edited on 25-4-2015 by byko3y]

[Edited on 25-4-2015 by byko3y]

byko3y - 25-4-2015 at 10:15

Okay, I finally found a modern article about dicarboxy disulfide.
Here's a quote of things that seem important to me:
"Thermal Decomposition of Bis(trifluoroacetate) Disulfide.
When (CF3COOS)2 (90.1 mg) was held at 40°C for 12 hr, SO2 (9.8 mg), (CF3CO)2O (65.6 mg), and S (14.7 mg) were obtained after trap-to-trap separation. Experimental (calculated) percentages of products are: SO2, 10.89 (11.03); S, 16.42 (16.55); (CF3CO)2, 72.59 (71.42), based on the equation
2(CF3COOS)2 ----> 2(CF2CO)2O + SO2 + 3S
Hydrolysis of Bis(trifluoroacetate) Disulfide.
An excess of H2O was condensed onto (CF3COOS)2 (86.3 mg). The hydrolysis products formed [SO2 (9.6 mg), CF3COOH (67.6 mg), and S(14.5 mg)] support the equation
(CF3COOS)2 + 2H2O ---> 4CF3COOH + SO2 + 3S
.....
Sulfur dichloride with CF3COOAg, C2F5COOAg, C8F7COOAg, or CF3COOH failed to yield the monosulfide analogs, (RfCOO)2S. When these silver salts were treated with SCl2 in a 2:1 ratio under the same conditions that have been described for the preparation of disulfides (which are not described in the papar in fact), only SO2, anhydrides, and sometimes traces of perfluoroacyl chlorides were obtained after trap-to-trap or gas chromatographic (Kel-F no. 3 oil on Chromosorb P) separations. A very exothermic reaction occurred when a 1 : 1 ratio of CF3CO2Ag to SCl2 was tried. After 30 min, separation yielded CF3COCl (60%) and a trace of (CF3CO)2O, SO2, and SOCl2, as well as an unidentified yellow liquid. The ir spectrum of the yellow liquid is similar to trifluoroacetic anhydride except for an additional strong peak at 934 cm-l. Work is continuing on this reaction,
Attempts to break the S-S bond by chlorination of bis(trifluoroacetato) disulfide with chlorine were made. Bis(trifluoroacetato) disulfide and C1, in the ratios 1.2:1, 1:1.6, and 1:5 were used. After separation of the reaction mixture, the presence of CF3OCl, (CF3CO)2O, SO2, and a trace of CF3Cl was shown by ir analysis. Unreacted chlorine which remained in all but the first reaction was identified also."
There's another research "Bis(trifluoroaceto) Disulfide (CF3C(O)OSSOC(O)CF3): A HeI Photoelectron Spectroscopy
and Theoretical Study" J. Phys. Chem. A 2006, 110, 5685-5691 but I was not able to retrieve from it any information that would explain more about chemical properties of the compound.

Metacelsus - 25-4-2015 at 10:59

The attempt to remove an atom from a disulfide bond described in that paper sounds a bit like a procedure I saw in a university lab to convert an alkyl xanthic disulfide into a thioanhydride. The procedure used triphenylphosphine, I believe.

clearly_not_atara - 26-4-2015 at 19:59

Quote: Originally posted by byko3y

S in halides is a weak electrophile (+1, +2, +4 oxidation state)
S+ + Cl- + OH- + H+ -> SOH + HCl ... + Cl- -> SO + 2HCl
Countrary, it is really stable while in -2 oxidation state.
Acyl group in acyl halide is electrophilic too, this is why it attacks amines. Acyl halides and sulfur halides need a lewis acid to attack non-activates aromatics. But Cl-S-S-N- is a strong electrophile, this is why it easily attacks activated aromatics. Just like acyl halides can attack the activated aromatics without a lewis acid, although they prefer to attack O or N group.
Btw, as you may know, there exists a R2N-S-S-NR2 compound and well known R-O-S-S-O-R compounds having sulfur clearly in +1 oxidation state which seems to be the most stable one.
The idea of a weak electrophile means that sulfur can bind to nucleophiles capable of giving electrons, like alcohols or alkenes do, but not the carboxylic acids. For this reason you can't make H2S just by pouring a sulfur into acid.
So the Ac-O-S-S-Cl can be barely called pseudohalide. In a regular sulfoxide (R-S(=O)-R) the S-O bound is strongly polarized, and then Ac group is bound to the oxygen, totaly dividing the molecule into [AcO]- and [S-S-Cl]+.

Dude, you can't use poor grammar and abuse of formal oxidation states to argue against numbers. AcO- clearly attacks S2Cl2 in the absence of other ingredients and in nearly quantitative yield. The fact that you, personally, do not like the way the molecule looks does not in any way constitute scientific evidence.

Sulfur's preference to bonding with oxygen is a result of the existence of a low covalently-bonded molecular orbital between sulfur and oxygen with bond order 2. This causes the C-O bond in Ac-O-S to be weaker than in other bond systems. It has nothing to do with the oxidation state of sulfur in a formal sense.

The reaction must be due to a reaction between S2Cl2 and NaOAc. This either involves formation of the dimer or at least a heterodisulfide intermediate. And the nucleophilicity data of acetate resp. aniline clearly indicate this is possible.

EDIT: Oh, the other reason silver salts are preferred to isolate the intermediate is that, as before, they dissolve in nonpolar solvents, and so does S2Cl2.

[Edited on 27-4-2015 by clearly_not_atara]

Meri - 15-7-2015 at 09:36

by heating potassium acetate with benzoyl chloride,yields?synthesis mechanism?can anyone give me some info?

lochatron - 19-7-2015 at 01:39

Simple,mix all ingredients 1:1 distill and vuolia,in good yields

byko3y - 19-7-2015 at 05:33

Meri, it's well known that you can exchange the chloride group of benzoic and aliphatic acids, shifting the equilibrium by distillation. This way you can distill off the acetyl chloride (b.p. 52 °C), leaving benzoic acid.
I don't think that mixed anhydride is capable of doing the same, until you target compounds is a mixed benzoic-acetic anhydride. In the latter case the reaction is a regular anhydride synthesis procedure via acyl chloride and carboxylate salt.
UPD: okay, actually sodium acetate is capable of exchanging with benzoyl chloride, this way acetyl chloride is distilled from the reaction mixture.
http://onlinelibrary.wiley.com/doi/10.1002/recl.19891080203/...
"A distillation set up was first thoroughly dried. In a 25-ml round-bottomed flask, 1.9g (23 mol; 1 eq) of sodium acetate and 13.8 g (99 mmol; 4.2 eq) of benzoyl chloride were heated in an oil bath and then using a naked flame until no further acetyl chloride distilled from the mixture (b.p. 51-53°C). Yield 1.35 g (75%). 1H NMR (100 MHz): 6 2.6 (CH3, s)."

[Edited on 19-7-2015 by byko3y]

Meri - 19-7-2015 at 07:01

Nice one, thank you Byko3y.

Meri - 19-7-2015 at 07:31

you get (acetyl chloride),as well,so way this mechanism is not efficient,nobody talks about this method,becose is low tempetures takes ages or what?
S2Cl2 or other methods is realy not nice for you health.

2talltman - 24-7-2015 at 13:07

I hate to be 'that guy' and not read the entire thread before posting, but I stumbled across this and thought it wouldn't hurt to post it here for now. I searched the name of the process and nothing came up, so I figure there's a decent chance it hasn't been posted, but that surprises me considering that it's an industrial route to AA.

It's the Eastman Chemical Company Acetic Anhydride Process.

Attachment: 10.1016@0920-5861(92)80188-s.pdf (980kB)
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byko3y - 25-7-2015 at 12:51

2talltman, this one is really close to https://en.wikipedia.org/wiki/Monsanto_process , having the same CH3I -> CH3COI intermediate and the same rhodium-iodide catalyst at 50 atm CO pressure.
The reason why it was not mentioned is because nobody on this board can perform such reactions.

2talltman - 13-8-2015 at 14:29

A few days ago, while delving into the madness that is Wikipedia hyperlinks, I stumbled across something interesting: zinc oxyacetate. Apparently during its production from zinc acetate, acetic anhydride is formed (albeit in low yields).

I was quite curious.

50 American pennies were dissolved (partially) in 5% white distilled vinegar (a painstakingly long process) and crystallized, then recrystallized into a white powder, likely zinc acetate dihydrate. 65 grams of this powder were heated under vacuum as the water was driven off, and an unknown liquid was distilled. The white crystals seemed to burn at first, so the RBF was removed and the crystals stirred, then placed back under vacuum. The crystals partially melted and released a large amount of vapor, assumed to be H₂O. After this, the crystals darkened slightly to a yellowish color and began to fume. Throughout the process an odor reminiscent of caramel or heated marshmallows was present, along with the occasional acetate scent. ~10mL of distillate was collected. The liquid had a density of ~1.00g/mL, was clear, yellowish, and smelled of acetate. It had a pH of 2. It did not combust readily.

However, (and this excites this chemist greatly

) a portion of the distillate still in the condenser which had not reached the RBF was found to be much more viscous and greatly irritating to smell, as well as smelling strongly of acetate and something else which this chemist cannot identify, but not acetone. It did combust readily. When added to water, distortions similar to those above the road on a hot day appeared (this chemist has forgotten their name). There was not enough liquid to find its density.

To be quite honest, my setup is extremely ghetto. My vacuum source is from an inflatable bed motor, and I'm using an alcohol lamp as a flame source since I don't have access to the gas lines for a Bunsen burner. I also did not use anhydrous zinc acetate or dry out the condenser after the water was driven off. If someone were to do this a tad more professionally, then I'm nearly certain good yields of acetic anhydride could be had. I do not know if the zinc oxyacetate can be regenerated into zinc acetate dihydrate through the addition of acetic acid, but if it cannot, then the zinc oxyacetate can be combusted to yield ZnO which could then be reacted with the acetic acid to yield the zinc acetate. I also haven't yet found the mass of the solids left in the RBF, since I know it'll be a bitch to get them out of it.

Attachment: Crystal Structure of Zinc Oxyacetate and Thermal Studies of its Precursor, Zinc Acetate Dihydrate.pdf (671kB)
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Attachment: The Crystal Structure of Zinc Oxyacetate.pdf (3.9MB)
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Bad quality picture of the fumes resized.jpg - 2.1MB

Bad quality picture of the distillate resized.jpg - 1.9MB

Edit:

Quote: Originally posted by byko3y

2talltman, this one is really close to https://en.wikipedia.org/wiki/Monsanto_process , having the same CH3I -> CH3COI intermediate and the same rhodium-iodide catalyst at 50 atm CO pressure.
The reason why it was not mentioned is because nobody on this board can perform such reactions.

Thanks for that, I wasn't really thinking, I guess.

On an unrelated note, I wasn't even attempting to find acetic anhydride syntheses when I stumbled across these two. Wikipedia is just amazing like that.

[Edited on 13-8-2015 by 2talltman]

Update: The alcohol left a whole bunch of carbon on the bottom of the RBF, which I got on my hands as I was about to clean it. I removed the thermometer from my distillation setup and smelled a bit of the condensation on it. It burned my nose absolutely terribly, making me even more confident that this is a viable route to acetic anhydride. But, carbon on hands + burning nose --> one funny looking guy. On the bright side, the mass was quite easily removed from the RBF with a little bit of 91% isopropanol. I could vacuum dry it and find its mass if anyone is interested.

[Edited on 13-8-2015 by 2talltman]

Edit #3:
Welp, editing for the third time I see that this synthesis was posted earlier in the thread. Sorry, I promise I searched for it!

It just didn't come up for me. Oh well, experimental evidence never hurt anybody.

[Edited on 14-8-2015 by 2talltman]

byko3y - 13-8-2015 at 18:09

2talltman, I can't understand what are your products, because you give not temperatures. Most common way to determine whether you've got anhydride or not is to react it with amine to form amide. No other product at r.t can do the same. Ammonia is not liquid and usually stored as solution in water, so aniline is the most common reagent for the purpose. Acetanilide has m.p. of 114.3 °C
Aluminium acetate is also known to decompose into acetic anhydride. Yield is declared to be 30% (although you can use only 2 of 3 acetate molecules, so it's 45%). I'm pretty sure the mechanism is ketene formation, obviously, the yield is low because of poor balance and different side reactions comparing to industrial ketene process with dedicated acetic acid -> ketene reactor operating at 700-750◦C.

[Edited on 14-8-2015 by byko3y]

2talltman - 14-8-2015 at 05:24

Most of the liquid distilled over at ~90°C under vacuum, but the temperature went up to 97°. I have such a limited lab that I basically don't have one, so I can't test the distillate with acetanilide. I would love for someone else to do so, though.

If it does in fact go through ketene, wouldn't that be exceptionally dangerous? The idea of it really freaked me out last night, so I quenched everything with water and sprayed water into the air, as well. Here's hoping I wasn't exposed to anything. From the data I read, death usually occurred within 12 hours, so I'm thinking I'll be okay.

Meri - 15-8-2015 at 10:47

yes

[Edited on 16-8-2015 by Meri]

clearly_not_atara - 18-8-2015 at 22:48

It's probably a concerted mechanism, but even if ketene were an intermediate I wouldn't worry that much. Ketene has to be produced in some quantity for there to be a concern; it should immediately react with acetate. It's much more unstable than cyanide or phosgene or even SOCl2 for that matter.

After all if a significant amount of ketene were produced, 2tallman would already be dead...

clearly_not_atara - 20-8-2015 at 15:54

Can't edit ^^ anymore, but I found a ref that says that anhydride is produced from Zn(OAc)2, but the acetate and oxyacetate are molecular (hence volatile) and will also vaporize under vacuum. Ideal conditions were a low heating rate in a nitrogen atmosphere.

So 2tallman's route is not just some Wikipedia citogenesis.

Attachment: actaznoacanhydride.pdf (1.8MB)
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Waffles SS - 20-8-2015 at 20:52

Anhydride from acetates mentioned some pages ago.

I got anhydride from silver acetate by this route and this is possible for aluminium ,zinc and copper too.(you can find my post about it)

There is no need to use aniline for testing anhydrid,A single drop placed in cold water did not dissolve, but sank to the bottom as an oily blob

Read page 28

[Edited on 21-8-2015 by Waffles SS]

CuReUS - 21-8-2015 at 03:32

it seems ethylidene diacetate on heating decomposes to give acetaldehyde and acetic anhydride. Although the diacetate is quite expensive,it can be made from acetylene and acetic acid in the presence of mercuric sulphate catalyst.

Waffles SS - 21-8-2015 at 08:04

Ethylidenediacetate method is my suggested method.this method is cheap and easy.just require acetic acid,acetylene and small amount of mercuric catalyst.recommended catalysts are mercury(II( salt of disulfonic acids like methandisulfonic acid(methionic acid),benzenedisulfonic acid and other disulfonic acids.By using this type of catalysts tar formation decrease and yield increase.

I usually make my Ac₂O by this method(just vinyl acetate instead of acetylene)

More information about this method on page 28.

I attach useful review about making ethyidenediacetate and vinyl acetate

Attachment: morrison1933.pdf (1MB)
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[Edited on 21-8-2015 by Waffles SS]

clearly_not_atara - 21-8-2015 at 18:15

Quote: Originally posted by Waffles SS

Read page 28

With all due respect, there doesn't seem to have been a mention of Zn(OAc)2 on 28; Ctrl+F "zinc" and "zn" both find nothing. In any case hopefully the paper is useful.

[Edited on 22-8-2015 by clearly_not_atara]

[Edited on 22-8-2015 by clearly_not_atara]

[Edited on 22-8-2015 by clearly_not_atara]

[Edited on 22-8-2015 by clearly_not_atara]

Waffles SS - 22-8-2015 at 07:42

on page 28 you can read about pyrolysis of silver acetate and copper acetate

Waffles SS - 3-10-2015 at 11:00

Reaxys search of all possible way for synthesis Acetic anhydride

Attachment: Acetic anhydride.pdf (2MB)
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brew - 20-11-2015 at 06:59

I'm pretty sure that if the following was possible, it would be in the literature. Yet I cannot help wonder because if the inclusion of a dehydration reagent can work for eg, acetic acid to go on to form the anhydride, well its clear that a 1,2, addition has occurred, and water being eliminated, and soaked up with say phosphorous pentoxide, hence I'm wondering if a small amount of acid catalyst (98% H2SO4) was added to say, acetic acid, and utilizing toluene, under DS trap conditions, as no azetrope forms between acetic acid and water I think, but does very well with toluene and water. b.p, around 80 odd C, and when it cools down in the trap, they are obviously are going to separate. Perhaps with the inclusion of another reagent that mops up water would quicken this up. As said, Im sure that if this was a given, it would be known, but its had me wondering, and hopefully I have some facts correct, and of course experiment is king.

If this is utter nonsense, and Ive not got my facts straight, then my apologies, but thought an amateur chem forum is the sort of forum that ideas, albeit nonsense ones, can at least be expressed.

Im also not interested in the product, but its more about novel ways to get to these reagents that I find the challenge.

clearly_not_atara - 21-11-2015 at 20:04

The energetics of the reaction: Ac2O + H2O >> 2AcOH are such that it might as well be considered irreversible. As such trying to use Le Chàtelier's principle probably won't work. Effective methods all rely on generating some low-energy byproduct, be it SO2, Ag2O, Zn4O(OAc)6, etc.

chemplayer.. - 6-3-2016 at 02:30

We'll post this as it might be interesting; there has been some speculation in the past on this but to our knowledge no one has actually tried it. Not that we can recommend it as a way to produce acetic anhydride though as the yield is low and the process is potentially very dangerous (toxic fumes + explosion risk).

Nitrogen dioxide was produced in a 500ml 2-neck flask (cooled in a cold water bath) containing 68% nitric acid, by adding cupro-nickel coins (about 60g of coins in total, although some didn't react completely).

The evolved brown fumes of NO2 were dried using aan anhydrous CaCl2 drying tube and then condensed in a liebig condenser using ice cold water. The resulting liquid NO2 was dripped onto 30g of anhydrous sodium acetate contained in a receiving flask which was cooled in an ice-salt bath. During the generation of liquid NO2 the receiving flask was rotated to ensure even distribution of the NO2 in the sodium acetate.

The resulting blue-green mixture in the receiving flask was allowed to warm to room temperature. A fair bit of NO2 came off (unreacted). Distillation of the mixture was carefully attempted, with more NO2 being evolved and a clear unknown liquid starting to boil with a vapour temperature of 50-55C.

At this point distillation was stopped, the mixture cooled, and then extracted using 25+15ml of dichloromethane. After filtering off the solids, the DCM extracts were evaporated down to give 1.6g of slightly yellow liquid. Nothing else evaporated off on heating to ~100C.

Smells like acetic anhydride, catches fire like it, sinks in cold water with that characteristic 'round blob' and tiny bubble on top. Not enough to distill and test the bp though, so purity unknown.

So amazingly it looks like this does actually work. Probably a curiosity rather than a practical method though.

The full video of the process is here on the ChemPlayer YT channel:
https://www.youtube.com/watch?v=r1tgmgG8VIY

hissingnoise - 6-3-2016 at 04:46

Quote:

Smells like acetic anhydride, catches fire like it, sinks in cold water with that characteristic 'round blob' and tiny bubble on top.

Have you discounted the real probability that what you have may well be peracetic acid?

chemplayer.. - 6-3-2016 at 08:04

Peracetic acid? What's the water miscibility and boiling point (assuming it exists as a pure substance) of that?

aga - 6-3-2016 at 08:59

Today some 50g of zinc acetate almost got made, intended for use in a try at acetic anhydride by vac decomposition/distillation.

250ml beaker, GAA and Zn powder + water in stoichiometric amounts.

After watching bubbles bursting and dropping fine zinc particles for a while (which is wonderful to watch) the heat and stirrer were turned on to speed up the reaction.

Shortly after that a neighbour arrived with some sad news.
... time passes ... heated beaker forgotten about ...

On disposing of the neighbour and returning to the lab, the beaker had boiled over and there was a mess of zinc powder on the hotplate, and a New (to me) smell in the fume hood - distinct from acetic acid, yet somehow related.

Whatever it was, it appears as if something can be obtained via the zinc acetate decomposition approach.

UC235 - 6-3-2016 at 12:35

Quote: Originally posted by hissingnoise

Quote:

Smells like acetic anhydride, catches fire like it, sinks in cold water with that characteristic 'round blob' and tiny bubble on top.

Have you discounted the real probability that what you have may well be peracetic acid?

I'm pretty sure peracetic acid is miscible with water. Also, I have no idea where the peroxy group would have come from.

A more realistic possibility is acetyl nitrate, but given that when pure, it seems to be a fuming explosive liquid that is rapidly decomposed by water, I would tend to believe that acetic anhydride was indeed made. I suspect AcONO2 as an intermediate however.

The whole prep seems particularly unpleasant, but addition of some pre-formed Ac2O may improve yield as is the case with the bromine-sulfur route.

[Edited on 6-3-2016 by UC235]

hissingnoise - 6-3-2016 at 13:10

Quote:

A more realistic possibility is acetyl nitrate.

It occurred to me but for it to go that far would require much more NO₂ than was apparently used!

It's presence is much more likely than AC₂O, however . . . ?

chemplayer.. - 6-3-2016 at 21:21

Yeah definitely not recommended as a preparatory technique. The interesting thing is the colourless liquid boiling at 50-55C from the reaction mixture. After extracting with DCM this seems to be gone, but it's definitely present shortly after the reaction completed. No idea what it is, but at the time I remember having that intuitive "this doesn't look very friendly" feeling...

Waffles SS - 6-3-2016 at 21:37

@chemplayer,

I watched your video on Youtube and i am sure your final product is Ac2O.(I have experience on making Ac2O and working with it)

Also i watched another videos and in fact all of them are not true and logical(like Hydroxy mandelic acid)

[Edited on 7-3-2016 by Waffles SS]

chemplayer.. - 7-3-2016 at 00:08

Yes the hydroxymandelic acid looks to be a failure. We tried again and got the same result. The prep was actually from a very old textbook (which are usually more reliable than say Tetrahedron letters, but not this time it would seem!).

As we point out in the video we couldn't find much info on the product and so we couldn't confirm what we got in the end.

clearly_not_atara - 9-3-2016 at 14:19

If I had to guess I'd assume the reaction of NO2 with NaOAc is just like other reactions with dinitrogen tetroxide, which usually reacts as though it were nitrosyl nitrate, (NO)NO3. So initially:

NONO3 + AcONa >> AcONO + NaNO3

The acetyl nitrite is oxidized by NO2 -- the monomer this time -- to acetyl nitrate, giving off nitric oxide:

ACONO + NO2 (l) >> AcONO2 + NO (g)

Acetyl nitrate will acetylate sodium acetate:

AcONO2 + AcONa >> Ac2O + NaNO3

In the background, the equilibrium 2NO2 >><< NONO3 allows both reactions to occur. The driving force is thus not dehydration, but redox, which explains why the reaction is favorable.

Rynoaus - 18-3-2016 at 04:50

After reading pages and pages I still can't find a definitive yes or no for AA via sodium acetate and disulphur dichloride. Has anyone experienced performed this I've seen a couple of one time posters saying that it had worked but looking for a bit more confirmation and insights Into the reaction if any cheers.

clearly_not_atara - 18-3-2016 at 11:21

I honestly think the bigger question is how are you going to produce S2Cl2?

There's a reason methods like this tend to show up and hang around the discussion for years and years without solid confirmation: they're hard to do. The method has been reported on Rhodium's Archive with 90% yield, but the production of S2Cl2 requires Cl2 gas, which most people don't have the equipment to handle, and those that can usually are also able to make acetic anhydride some other way. Plus there's the possibility of generating SCl2 and SOCl2 byproducts which are quite toxic.

https://www.erowid.org/archive/rhodium/chemistry/anhydrides....

You might be able to do 2 CuCl2 + 2S >> 2 CuCl + S2Cl2 by reacting sulfur with anhydrous (brown) cupric chloride, by analogy to the well-known reaction:

2Cu2+ (aq) + SO2 (aq) + 2OH- + 2 Cl- >> 2CuCl (s) + H2SO4 (aq)

https://en.wikipedia.org/wiki/Copper%28II%29_chloride#Redox

[Edited on 18-3-2016 by clearly_not_atara]

aga - 18-3-2016 at 12:29

S₂Cl₂ is simply a matter of passing chlorine over sulphur.

Molten sulphur is more efficient, yet normal powdered sulphur works fine.

Well, it did for me on two occasions.

Plenty of threads on SM regarding the production of this.

Here was my second successful attempt.

http://www.sciencemadness.org/talk/viewthread.php?tid=62254

It is nasty stuff to store.

Jammed up the glass stopper making it necessary to use a hammer on glass to get it out).

[Edited on 18-3-2016 by aga]

clearly_not_atara - 18-3-2016 at 14:26

Quote:

the production of S2Cl2 requires Cl2 gas, which most people don't have the equipment to handle, and those that can usually are also able to make acetic anhydride some other way.

aga: does my dilemma apply to you? ^,~

aga - 18-3-2016 at 14:36

No, sorry.

I just thought that the closed-system approach might be useful.

Rynoaus - 28-3-2016 at 19:02

In regards to the SCI2 or and SOCI2 could one just leave it air for a period until one notices the sulphur start to come out of solution the biproducts if any should have been reconverted back. And I can't see that a little sulphur is going to cause problems with AA synth as this method is pretty much the same as using the sulphur sodium acetate and chlorine in situ to produce AA so a tiny amount of sulphur shouldn't worry anything should it?

hissingnoise - 29-3-2016 at 11:44

Thionyl chloride is most convenient as the byproducts are SO₂ and HCl!

Rynoaus - 31-3-2016 at 15:47

Quote: Originally posted by aga

No, sorry.

I just thought that the closed-system approach might be useful.

Indeed aga has shown u could do this at room temp and if one had a way to add an amount of chlorine gas to closed vessel with sulphur and allow to react then replenish gas and go again until full reaction occurs then distill as recommended I know it would take time but the reaction would surely proceed wouldn't it?its just very OTC and as such appealing though out of my reach until I get a decent distillation set. Thionyl chloride I'll have to research that.

hissingnoise - 1-4-2016 at 00:32

Thionyl chloride is SOCl₂ . . .

Rynoaus - 1-4-2016 at 01:29

Quote: Originally posted by hissingnoise

Thionyl chloride is SOCl₂ . . .

Ah I've been reading wiki too much and looking at the formula not names and because that didn't interest me that much I hadn't looked at it just that it will regress but thanks also I hav'nt seen the route for using that though I was reading through trying to see if the method on rhodium erowid had been tried and was possible so I'll go back to the start and reread

100PercentChemistry - 1-4-2016 at 07:07

NIle Red made a video on the ketone process. I may try it.

hissingnoise - 1-4-2016 at 07:41

Did you mean the ketene process?

Loptr - 1-4-2016 at 11:37

Be careful with ketene. By the time you have smelled it you are already over the exposure threshold, and not to mention, it's pretty poisonous for humans.

It's formal name is ethenone, so many that's where you got the -one from?

dawt - 9-5-2016 at 05:15

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]

byko3y - 9-5-2016 at 06:29

Rynoaus, sodium aetate + sulfur halide definitely works, but is tricky to perform and leads to different yields dependingon conditions, which is even more complicated because the reaction mechanism is poorly known, despite the fact dibenzoyl-disulfide and bis(trifluoroaceto) disulfide have been prepared and shown to lead to the anhydride production via thermal decomposition.

clearly_not_atara, i see no problem with preparation of Cl2 or Br2. Toxic concentrations of halogens are almost unbearable. You can use any of SCl2, S2Cl2, S2Br2, or their mixture with each other and any other crap.

dawt, this article looks like a gorrible bullshit. I see no dehydration agents there at all.

PS: once again want to ask you that I'm looking for some book about sulfur inorganic/simple organic coumpounds, especially about sulfur chlorides, every author seems to be afraid of writing about sulfur chlorides.

[Edited on 10-5-2016 by byko3y]

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