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Author: Subject: Acetic anhydride preparation
hissingnoise
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Teflon begins to decompose @ 260*C and melts @ ~327*C; you'll find you'll have teflon flu symptoms from the decomposition products. . .

Jimmymajesty
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Thanx for the info, I once tried to decompose teflon to its monomer, but even at red heat temps I could not succeeded. Next time I am going to attach a pt100 temp sensor to the lamp head, I am also interested to know its temp during operation.

[Edited on 6-7-2010 by Jimmymajesty]
peach
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Teflon is an idea. I was just wondering about DIY'ing my own HF distillation setup using some.

I would worry about using PTFE around such a hot element however. It would need to be a decent distance from the walls to avoid melting them.

I just did some quick searching and found one place doing 1.5" OD, 1" ID extruded virgin teflon tubing, it's $47.43 per foot ($284.58 for 6). The molded virgin teflon tubing of 1.5"OD has an ID of 1.25" and is $34.08 a foot ($204.48).

The extruded tubes go up to 3" OD

...OD......ID......code......per foot
1.500 1.250 KM-1116 $34.08 1.750 1.375 KM-1117$55.42
1.875 1.500 KM-1118 $59.30 2.000 1.500 KM-1119$81.80
2.250 1.500 KM-1120 $125.74 2.500 2.000 KM-1121$107.24
3.000 2.000 KM-1122 $234.40 They also do a recycled version of teflon tubing. For a 1.5" OD 1.25" ID tube it's$21.76 per foot ($130.56 for 6). However, a foot length rod of 1.5" virgin rod is$25.40 (\$152.40 for six). Which actually makes it almost as cheap as the recycled, molded stuff, and you have the option of leaving ends intact, varying the wall thickness and such. Teflon also cuts like butter, so machining it out is not a problem. You could clamp the rods and use a spade bit to make you own closed end vessels for less than the tubing.

Having read the threads on the ketene furnaces, I'm also not use how productive the lamp is going to be. It might be a better idea to work on producing a mini, high temperature, cheap furnace.

I was thinking something much smaller than those linear tube furnaces could be make by spiraling some quartz tubing into a coil - rather than having it as a long rod. I've already found silicon carbide elements that are small and coiled, so they've fit a decent OD tubing inside without being long. The quartz could sit inside there and be replaceable with different sizes of tube. Or a cup sized crucible for high temperature solid work. Plus aerogel for insulation.

[Edited on 6-7-2010 by peach]
Jimmymajesty
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Having read the thread on ketene furnaces was the main cause why I chose the lamp instead of a leaking makeshift furnace

If you can spiral a quartz tubing, then to make a decent ketene lamp would be a joke for ya!

The quartz tube with grounded joints that magpie posted would be my holy grail, it is definitely sg that I cannot afford, to a 1m long tube like that with ns29/32 grounded joints I would give the ketene lamp and my stock of platinum electrodes too! sorry for being off topic but quartz tubes are my wet dreams ever since I took up GP catalytic reactions

Literature suggests that with copper tubing the conversion to ketene is almost 100%, cataytic effect is not mentioned IIR, maybe it can be heated more evenly than any other metal tubes, unfortunately at those high temps, your copper tube turns into black flakes very soon unless you are using reducing atmosphere.

I can see many flaws with tube furnaces (apart from the lower efficiency, yield, purity and lack of reflux) the main problem is leaking, you cannot make a reliable connection between metal and glass, even if you can, it will leak after a couple of disassembling.
watson.fawkes
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 Quote: Originally posted by Jimmymajesty you cannot make a reliable connection between metal and glass, even if you can, it will leak after a couple of disassembling.
Well, you can. They're called Housekeeper seals, after the fellow who invented them. They're easiest with copper, as they rely upon the flexibility of copper to absorb the difference in thermal expansion rates. They're also not really for beginners, and they usually require a lathe to turn a fine tapered edge.
Jimmymajesty
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The head of the lamp can be made of teflon. I seal all the glass joints of the lamp, and every glassware with grounded glass joints with teflon tape, in case of the lamp after 5 runs, the tape was still tape, not a decomposed holed mass.. you can quote me on this

I also distilled H2SO4 at atmospheric pressure at the weekend, and the teflon tape remained teflon tape.. again

Watson there must be a reason that I cannot see home chemists running around with house keeper seals
franklyn
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franklyn
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Attached image excerpted from
A Dictionary of Applied Chemistry Vol 1 - T.E. Thorpe
Sidebar reference cited , 4 th entry down here _
1111384; Patent; Hoechster Farbw.; DE 210805;
Farbwerke Hoechst Aktiengesellschaft (Formerly) Vormals Meister Lucius Bruning
Patent in German available here _
http://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&a...
Click Cancel in the file download window then click - [ Volldokument laden ] - at the upper right
wait a moment , type in requested text ( case sensitive ) click - [ G O ] - to download the full document

[Edited on 5-8-2010 by franklyn]

Attachment: DE000000210805A_all_pages.pdf (112kB)

JohnWW
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Thanks, Franklyn, but that German patent DE 210805 appears to be restricted, requiring secure log-in by subscribers to gain access. Please post it here.
Jimmymajesty
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Franklyn thanx for the info on acetyl sulphuric acid! I made some by leading ketene into sulphuric acid with continuous cooling. It is indeed very viscous, I poured it into a test tube and it did not even flow out of it when I turned the tube upside down for a moment, it was of honey consistence.

Could one make nitromethane with sulphoacetic acid by sodium nitrite? sorry to be offtopic

[Edited on 4-8-2010 by Jimmymajesty]
Panache
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Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein

an alternate design requiring one joint, this is more effective imho, hey jimmy whats the second photo in your 'lamp running' doc, of?

Jimmymajesty
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Hey Panache!

A grounded glass joint to the head of the lamp is necessary to let off the remained air/oxygen before the startup (during reflux), prolonged reflux of acetone will surely flush all the air off from the head of the lamp, but I would not trust in that. I usually get rid of the remained air by pulling one electrode off till a condensate starting to wet the grounded glass joint (of the electrode).

The second picture was taken of the cooling element of the ice cube maker after about 4 hours. At normal operation, a small pump fills the tray from a reservoir, when the small tray is full of water the electronics swith the pump off and the compressor of the cooling circle starts up, but in this case the small pump and the compressor of the cooling circle runs continously, the small holes on the bottom of tray was made in order to increase the efficiency of heat exchange.

BTW how did you make the small clamps that holds the filaments apart? I could not really make it out of your pictures could you take some HD photo and post it in a word doc like I did?

Thx!

P.S I have been thinking for a long time what uses it could have other than generating ketene. I mean, what other usefull chemical could be churn out by means of this stuff.

I tried to make acetonitrile by boiling ethyl acetate and led dry ammonia into that, then reflux this mixture over standard filament deposited with fine Al2O3 (sprinkled triethyl aluminium onto the filament) but no luck, the forming acetonitrile clogging the small reflux tubing.

I also tried to deposit SiO2 onto the filament by decomposition of silicium tetraacetate but I failed to deposit a useable SiO2 layer so far.
un0me2
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Hmmm, glycine, on chlorination in aqueous solution (pH dependent), gives theoretical yields of Cyanogen Chloride (useful bit of information, no?, more here & here, but it is all over the web if you look).

Cyanogen Bromide, in conjunction with pyridine & acetic acid in benzene (as a diluent/solvent) gives good yields of acetic anhydride (see the other paper attached).

Anyone got any ideas on how to utilize this without having to isolate the fucking cyanogen chloride? I don't want to breathe it, touch it, or even stare lovingly at it, I just want from the first to the second flask

Attachment: Ho.Wong.A.Rapid.Method.for.Anhydride.Formation.pdf (150kB)

Attachment: Na.Olsen.Mechanism.and.Kinetics.of.Cyanogen.Chloride.Formation.from.the.Chlorination.of.Glycine.pdf (343kB)

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bbartlog
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The figure on p 1471 of the second pdf you linked does not lead to unbridled optimism about this as a preparative technique. Starting with 10 micromolar glycine they get a concentration of CNCl that tops out around 3 micromolar after 4 minutes, then drops due to ongoing hydrolysis. Seems like you'd have to remove the CNCl from the reaction somehow, or see whether this reaction can be done under non-aqueous conditions. I think the 13th reference in this paper (Sawamura, Sakurai &c) might have useful additional information, but I would bet against this as a useful path to acetic anhydride. Or even cyanogen chloride.

un0me2
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As oxidation with chlorine is the accepted process for converting cyanide to cyanate that hydrolysis occurs really isn't a suprise. How to get the CNCl out of the solution (BP ~12C) and, more to the point (providing the proceeding is viable) dried...

Work that out and there is a chance it could be useful.

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zed
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I suggested some time ago, that isopropenyl acetate, if given the opportunity, would actually prefer being transmogrified, into acetic anhydride and acetone (given the right reaction conditions, and some acetic acid to react with!).

Clay Catalysis: A Convenient and Rapid Formation of Anhydride from Carboxylic Acid and Isopropenyl Acetate Under Microwave Irradiation. Synthetic Communications, Volume 23, Issue 4 February 1993 , pages 419 - 424

http://www.informaworld.com/smpp/content~db=jour~content=a75...

[Edited on 26-8-2010 by zed]

[Edited on 26-8-2010 by zed]
un0me2
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IMHO One of the only, truly realistic approaches to (Ac)2O for the amateur chemist remains that of the silica tetraacetates.

Attachment: Zanetti.Note.on.the.Action.of.Oxychlorides.of.Silicon.on.Sodium.Salts.of.Fatty.Acids.pdf (220kB)

Attachment: Lanning.Preparation.of.Silicon.Tetrapropionate.pdf (154kB)

Attachment: Lanning.Silicon.Tetrabenzoate.pdf (470kB)

Attachment: Montonna.SiCl4.as.a.Reagent.for.the.Preparation.of.Acid.Chlorides.pdf (181kB)

Attachment: Quig.Wilkinson.Preparation.of.Disilicon.Hexachloride.pdf (303kB)

Attachment: Schuyten.Weaver.Reid.Preparation.of.Substituted.Acetoxy.Silanes.pdf (381kB)

Attachment: Voronkov.etal.Reaction.of.Carboxylic.Acids.with.Tetrachlorosilane.pdf (154kB)

Attachment: Witucki.A.Silane.Primer.Chemistry.and.Applications.of.Alkoxy.Silanes.pdf (113kB)

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hector2000
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Better way for making Silicon Tetraacetate

SiO2(s) + 4HF(l) --->SiF4(g) + 2H2O(l)(this reaction need heat)
SiF4(g) + 4NaOAc(s) --->Si(OAc)4(l) + 4NaF(s)(Solvent is anhydrous benzene )

* SiO2 is available every where

[Edited on 12-9-2010 by hector2000]

Chemistry=Chem+ is+ Try
maxidastier
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Thank you Franklyn for that awesome GERMAN! patent.
This method is so fu***** awesome, why are you guys still looking for other methods?

btw: Franklyn, did you try it?
franklyn
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Regarding this post on Ac2O formation.

@ Jimmymajesty

@ maxidastier

and also from whom I received this U2U _

" hi , I have tried your method for acetic anhydride, via sodium acetate and chlorine
and sulphur. it works pretty well, the only problem was the drying complete of sodium
acetate , ie turning tri hydrate to anhydrous form was a lengthy and messy job. and
then the chlorine leakages are nasty. could you sketch out a nice apparatus from
stainless steel, as glass seems to be difficult for larger quantities. thanks."

- - - - - - - - - - - -

I am not a chemist !
In the course of researching references , when I see a method or procedure which
is of interest to the forum members I post that information faithfully just as I find it.
Polverone said it best " lab work isn't as simple and easy as paper work ! "

I speculated in an earlier thread post that similarly Ca(CH3COO)2 + SO3 might yield Ac2O
but that is just me wondering out loud.

.
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maxidastier: have you tried using a solid chlorinating agent, such as TCCA? Be careful if you do: the rate of gas and heat evolution could be considerably greater. If this is workable it'd be a lot easier than dealing with gasses.

I believe what's going on here is the formation of S2Cl2, which reacts with 2 mol of sodium acetate to form sodium chloride and a compound of the form CH3COO-S-S-OOCCH3, which decomposes on heating to yield acetic anhydride, sulfur, and sulfur dioxide. Should be generalizable to other acid anhydrides as well. You're supposed to use acetic anhydride as a solvent to start the reaction, but it seems that's unnecessary.

I weep at the sight of flaming acetic anhydride.
Luton
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Is it possible to use Ethyl Acetate CH3COOCH2CH3 instead of Acetyl Chloride to make Ac20
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Nope.

Also, I should revise my previous idea to carry a harsher warning: it might explode.

I weep at the sight of flaming acetic anhydride.
Luton
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Has anyone successfully tried using Acetyl Chloride with Sodium Acetate to make Ac2O, if you could you please take me step wise
hissingnoise
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This simple reaction is very well documented - try googling it!

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 Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Acetic anhydride preparation Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Test Forum