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Author Topic: Acetic Anhydride by a strange route  (Read 1014 times)

no1uno

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Acetic Anhydride by a strange route
« on: May 25, 2011, 01:09:56 AM »


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


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Acetic Anhydride is a very necessary chemical to have access to, I'm thinking up a route that bypasses the standard, impure product (from S + Cl/Br)... Dry distillation of trichloroacetic acid is supposed to give one major product, being phosgene. Now, if the dry distillation were carried out safely and the distillate passed directly into GAA/NaOAc, then it should react rapidly to give pure Ac2O.
« Last Edit: October 01, 2012, 04:57:45 AM by java »
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jon

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Re: Acetic Anhydride by a strange route
« Reply #1 on: May 25, 2011, 01:31:45 AM »
way too much hassle

Vesp

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Re: Acetic Anhydride by a strange route
« Reply #2 on: May 25, 2011, 01:45:09 AM »
"Dry distillation of trichloroacetic acid"  -- TCAA decomposes into phosgene at its "boiling" point? Or do you mean a salt of it?

So you would basically reflux that and direct the gas that doesn't condense back into GAA with anhydrous NAA added to it, to react with the HCl that forms, producing more GAA to react further with it. Correct?

TCAA is still not the easiest to get.
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lugh

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Re: Acetic Anhydride by a strange route
« Reply #3 on: May 25, 2011, 02:20:43 AM »
The easiest way for a hobby chemist to make acetic anhydride is probably by pyrolysis of acetone producing ketene:

https://the-collective.ws/forum/index.php?topic=11618.0;all

http://www.sciencemadness.org/talk/viewthread.php?tid=8148&page=8#pid99225

http://www.sciencemadness.org/talk/viewthread.php?tid=571#pid4991

Organikum states a copper tube works fine  8)

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Shake

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Re: Acetic Anhydride by a strange route
« Reply #4 on: May 25, 2011, 02:31:18 AM »
That is where it is heated to upto 1000 degrees or something? there is a bomb for everything, just bomb acetone at high temps.

"by the thermolysis of acetone at 600–700 °C in the presence of carbon disulfide as a catalyst"

wonder if carbon di sulfide can be made in situ in the vessel? adding sulf** something or other.. just a thought

From all my searches on everything upto now, if you want cleaner alternitive routes 'green chemistry' and microwave chemistry will find it..

most documents studying alternative routes to simple solvents are in the study of green chemistry. thats what i have found anyway
« Last Edit: May 25, 2011, 02:47:33 AM by Shake »

jon

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Re: Acetic Anhydride by a strange route
« Reply #5 on: May 25, 2011, 03:41:41 AM »
no the easiest way to make acetic anhydride is to react sodium pyrosulfate with sodium assatate.
i have noticed in this particular scheme the solids cake up and the reaction comes to a halt.
it's wise to wet it with a little acetic acid to solvate things a little.
basically heat it to around 100 C for an hour or so then distill the mixture.
ketene is explosive and, phosgene is poisonous not exactly kitchen friendly.

Wizard X

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Re: Acetic Anhydride by a strange route
« Reply #6 on: May 25, 2011, 04:20:34 AM »
Quantitative yields of acetic anhydride are obtained with very anhydrous sodium acetate + Acetyl chloride. http://en.wikipedia.org/wiki/Acetyl_chloride

CH3COCl + CH3COONa => (CH3CO)2O + NaCl

Glacial Acetic Acid (GAA) can be used to make Acetyl chloride & sodium acetate.
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pyramid

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Re: Acetic Anhydride by a strange route
« Reply #7 on: May 25, 2011, 04:29:37 AM »
The acetyl chloride and NaOAc method works wonderfully and is easy to do. Of course there is the issue of getting the acetyl chloride but if yu happen to have it rest assured this method works great.
The sodium acetate must be freshly fused.

hypnos

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Re: Acetic Anhydride by a strange route
« Reply #8 on: May 25, 2011, 05:04:32 AM »
 Go jon mon--this tek is the same, in principle as your PA thread yeah?

  Ketene lamps ARE not safe outside of a VERY GOOD set up...not much room for 'mistakes' with this technique,,which has already been discussed on this forum

Searching for a synth of this chem was what led me here!
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no1uno

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Re: Acetic Anhydride by a strange route
« Reply #9 on: May 26, 2011, 02:57:41 AM »
The acetyl chloride is also able to be swapped for phosgene, which reacts with acetate to give acetic anhydride, sodium chloride and carbon dioxide. Trichloroacetic acid is made from chloral, Potassium Ferrate is supposed to work wonders. I assume a salt, I'm chasing the reference now. You can survive low-level exposure to phosgene (although safety wouldn't be that hard), I'm a long way from certain you'd survive ANY exposure to Acetone that far above its flash point.
« Last Edit: May 26, 2011, 03:03:52 AM by no1uno »
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lugh

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Re: Acetic Anhydride by a strange route
« Reply #10 on: May 26, 2011, 03:38:30 AM »
In a properly designed ketene lamp the refluxing acetone displaces the oxygen so ignition is impossible  ;)  Phosgene is more dangerous than ketene, good ventilation is definitely needed  :P  Methods employing acetyl chloride are suited for small scale production, a ketene lamp is only useful when more acetic anhydride is needed  8)
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Wizard X

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Re: Acetic Anhydride by a strange route
« Reply #11 on: May 26, 2011, 05:10:25 AM »
Quote from: no1uno on May 26, 2011, 02:57:41 AM
The acetyl chloride is also able to be swapped for phosgene, which reacts with acetate to give acetic anhydride, sodium chloride and carbon dioxide. Trichloroacetic acid is made from chloral, Potassium Ferrate is supposed to work wonders. I assume a salt, I'm chasing the reference now. You can survive low-level exposure to phosgene (although safety wouldn't be that hard), I'm a long way from certain you'd survive ANY exposure to Acetone that far above its flash point.

ONLY THE TECHNICALLY EXPERIENCED SHOULD ATTEMPT THIS!!! http://en.wikipedia.org/wiki/Phosgene#Synthesis_of_acid_chlorides
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jon

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Re: Acetic Anhydride by a strange route
« Reply #12 on: May 26, 2011, 07:58:17 AM »
yes hypnos sodium pyrosulfate and freshly fused sodium assatate does the job although it cakes more that calcium propionate which brings things to a halt.
so you need to add a little acetic acid as a wetting agent.
alternately you can just mix in a little h2so4 and grind it along with the na2s2o7 or ball mill it.

hypnos

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Re: Acetic Anhydride by a strange route
« Reply #13 on: May 26, 2011, 08:21:43 PM »
 Thanx jonmon I appreciate the confirmation,,IT seemed to be, to the best of my knowledge "the same shovel doing different shit",,  and the 'pro tips' hints about dampening the dry mix with GAA, with just enough to 'miosten it-which makes good sense to me,, BUT,, is nice to KNOW--I would have "guessed this, however when I hear you make a statement like that, I KNOW,, its from ( "Experience :D

  but I've been wondering how much easier it might be to just bubble CO through GAA,,  I'm pretty sure this was a method of 'anhydrating some acids" due to the CO being happy to steal/scavenge one of the oxygen atoms--I understand this in theory only to a basic level,,but it does seem quite plausible....can anyone enlighten me as to why this tek isnt used/suggested at all?  Is it because of time factors ,,or shit yields,,or the toxicity of CO??

  This technique works on to convert SOCl2 into SOCl......Please, does anyone Know why

  It would sure be an easy "ghetto setup"....

  Please forgive me for not providing 'Refs' to this procedure, however IIRC it used to be one of the 'old commercial methods' to produce large quantities using
co produced by heating 'coke'(the Coal variety) and passed it through GAA to AA
 (early to mid 20th century) I believe

  Does anyone know why "we" dont do this--I might get achace in a few weeks to try this out,,so ANY information Re; this reaction would be greatly appreciated

  Cheers Hyppy

 P.S  I personally think jons tek for PA was/IS very clever, and EXACTLY what this Forum is about--Home synthesis using OTC chems...and thats what the lad did...and a nice bit of lateral  thinking and research... 8)

Which, No Doubt about it has caused,,shall we say,,"certain Types of Visitors" to this site and/or SM,, where this, "very successful (by all accounts) synthesis of these anhydrous acids,,are "posted"--the Damage has been done,,a Great win for 'us',,,and a "Major source of MindFuck" to "Them"...Coz there is SFA they can do to stop this synth from being done,,due to the other 'uses' of the relative precursors ;)
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jon

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Re: Acetic Anhydride by a strange route
« Reply #14 on: November 09, 2011, 03:52:45 AM »
man you don't want to work around carbon monxide are you insane?

Sedit

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Re: Acetic Anhydride by a strange route
« Reply #15 on: November 09, 2011, 04:26:33 AM »
Seriously?

I am a freak when it comes to toxic substances but to question these people who willingly play with HgCl2 about there desire to work with CO is crazy. CO is a toy compared to long term poisons. You work outside and you stay the fuck away, just like ketene, H2S, HCN...ect....

Ask me about working with Me2Hg and you will get a different reaction...
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antibody2

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Re: Acetic Anhydride by a strange route
« Reply #16 on: November 09, 2011, 06:49:04 PM »
Jon - Wow - Do you have a reference for this RXN?

« Last Edit: November 09, 2011, 06:55:39 PM by antibody2 »

Enkidu

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Re: Acetic Anhydride by a strange route
« Reply #17 on: November 09, 2011, 07:58:01 PM »
Quote from: jon on May 26, 2011, 07:58:17 AM
sodium pyrosulfate and freshly fused sodium acetate

Quote from: reckless on November 07, 2011, 03:44:27 PM
Al(OH)(CH2COO)2->AlO(OH)+(CH3CO)2O at 250-300
Al(OH)(CH2COO)2 is water insoluble.
via hyperlab.info

refs for both, please.

Vesp

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Re: Acetic Anhydride by a strange route
« Reply #18 on: November 09, 2011, 10:15:04 PM »
Quote
sodium pyrosulfate and freshly fused sodium acetate
I'm pretty sure this works and has been discussed on sciencemadness and here. Though, I have never personally done it, I think Jon has first hand experience. Not sure if it is documented in any journal/patent though, but probably.
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jon

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Re: Acetic Anhydride by a strange route
« Reply #19 on: November 09, 2011, 10:26:32 PM »
yeah i have experince with that reaction we discussed it to death in another thread.
there is a patent but it alludes me at the moment.
it's just a matter of heating sodium assatate and sodium pyrosulfate problem is the whole mess fuses up so add a little glacial acetic acid to wet it.
heat it 100 C for about an hour then distill it very easy to do.
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