Sciencemadness Discussion Board

Acetic anhydride preparation

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Jimmymajesty - 3-6-2010 at 10:33

The smell of AA is etheral in the first 2-3 second then the pleasant light smell turns into strongly acetic, and irritates the eyes and all your mucous membrane like hell.. I really fucked up the first time I smelled it:)

If you pour a little water(cold) + AA into a test tube then shook it, the mix quickly separates, my experiance is that the AA will be the upper layer in spite of the fact that its density is higher than that of water.

Also you can light it with a flame, while glacial acetic does not burn.

Another test is to boil it with ethyl alcohol, but do not forget to add a few drops of H2SO4 or you will get nothig.

If you ask me, the kete method beat the shit outta all the other methods mentioned here.. I mean.. It is nice to filter extract heat chlorinate fractionate etc.. to get a few ml of AA and get closer to chemistry, but if you want a decent quantity, ketene is the way to go.

I made pure/colourless ~95% AA by the ketene method several times ~250ml/run. One run takes me about 6 hours. and the yield was always more than 80%.

Magpie - 3-6-2010 at 12:35

Quote: Originally posted by Jimmymajesty  

I made pure/colourless ~95% AA by the ketene method several times ~250ml/run. One run takes me about 6 hours. and the yield was always more than 80%.


Jimmy could you please provide the particulars for the procedure you used to do this. I have tried this several times without success. My tube furnace was either run wo/packing or with broken pieces of porcelain. I followed the procedure in OrgSyn.

http://www.orgsyn.org/orgsyn/default.asp?formgroup=basenpe_f...
up&dataaction=db&dbname=orgsyn

[Edited on 3-6-2010 by Magpie]

Jimmymajesty - 3-6-2010 at 14:50

I will take a photo from the ketene generator when I got back my cam.. I am going to put a spline or something next to it for you to be able to take its measures by the picture. But easier to say that I followed the organic reactions vol 3 that is in the public library.

I could not follow all the instructions for obvious reasons, for example I cannot afford platinum wire.. But the lamp works well, and thats the point.

The main issue with the tube furnace method is the reflux, I use a two litre RBFL as a reboiler, and during the 6 hours, if I had to make a guess, I reflux the 1 litre acetone a hundred times. This cannot be done in case of tube furnaces.. I think.. but I never tried tube furnaces.

BTW carbonisation is not that big of an issue, after two runs the kanthal wire was still ok, and the reboiled acetone had only a yellow tint, also it can be reboiled to get rid of conjugated olefines which I think the main impurities in acetone after a couple of runs.

If you are seriously planning to bulid a lamp, I can advice you how to improve you filament and also plastic materials which are resist to ketene, but a lot of plastics resist to it.. actually all of the plastics I used till now resisted to ketene:)

Jimmymajesty - 5-6-2010 at 04:57

See attachment for photos.

The tungsten rods were purchased from welding shop, their diamater=1mm

It was difficult make the upper part of the device for even an experienced glass blower.

And when I showed to him the original drawing, he said at first that theres no way that he could make it, so we discussed the possibilies, again, it works well and only costed me about 30 dollars not counting the tungsten rods which costed about 1 dollar each.

I can highly recommend to anyone who wants to make ketene or acetic anhydride to make this device, it was a first run success type synthesis, while with acetaldehyde I sucked alot.

P.S. Magpie seeing the apparatus you have, you should really give the lamp a try! I mean quartz tube with grounded joints etc... eh!:)

Attachment: lamp1.rar (1.1MB)
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Magpie - 5-6-2010 at 08:26

Quote: Originally posted by Jimmymajesty  

P.S. Magpie seeing the apparatus you have, you should really give the lamp a try! I mean quartz tube with grounded joints etc... eh!:)


Thanks Jimmy for the photo. It looks like that scale is about 13 cm long?

That's an impressive looking piece of glassware. Unfortunately I don't have a local glassblower that will help me. We have one but he has his head up his ass. He'll only work for businesses or educational institutions. :mad:

I can't believe that you got that put together for only $30. You must not live in any "Western" country. That would be at least $100 where I live.

Jimmymajesty - 5-6-2010 at 10:23

The AA will sink to the bottom in cold water too.. sorry for my misleading information above. I checked it.

I also tried out the reaction with benzamide, I added AA to benzamide, as usually nothing happened, then a few drops of H2SO4 and heat, and the content of the test tube immediately turned into intense red, almost black.

Magpie yes 13cm long.
Here in my country.. In the heart of Europe:) I know at least two glass blower that would be happy to make such kind of useless stuff for almost nothing, Iam suprised that you do not have any..

It would be nice If you could make a similar lamp and calibrate it.. for reflux ratio, different pretreatement of the filament etc, and compare the resulsts with mine.

hypnos - 5-6-2010 at 19:41


Thanx not_important,,, much appreciated information...as you say,,not too good to be true.....just a "little tricky!!!":cool:
[Edited on 6-6-2010 by hypnos]

[Edited on 6-6-2010 by hypnos]

peach - 20-6-2010 at 18:06

Jimmy is becoming my new hero with gear like that.

Have you considered plating the tungsten? I'm sure it can be done, not only from the reactivity of tungsten but I've seen it online. I wouldn't be surprized if it worked out cheaper to do it yourself, or take it to a jewelery store.

Now I'm going hunting to see if I can find anymore pictures of your glass.

I'd love to take up scientific glassblowing. I'm sure it's tricky. But I doubt it's beyond me if TIG welding, diy'ing a furnace and casting metal isn't.

Jimmymajesty - 21-6-2010 at 00:04

I do not really understand you with your tungsten plating thing, you have to buy pure tungsten, molybdenum or platinum, other metals cannot be wetted by melted glass. tungsten is easy to get and cheap while the others are not.

I am also prefer to see pictures than imagine the glassware by dud descriptions, so... :)

The second picture is of the ice cube maker that is necessary to prevent acetone from boiling over, It keeps the cooling water temp @ ~6-10°C.

Attachment: lamp in operation.doc (1.6MB)
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densest - 21-6-2010 at 15:19

@peach - scientific glassblowing is fun, but it takes a -lot- of practice. The equipment required depends on the size & complexity of what you want... an annealer big enough to hold the completed piece is essential. Assembling pieces isn't that hard. Freehand creation of coils, globes, etc. takes much practice and specialized torches. You can get started with a propane-oxygen torch, a low temperature ceramic kiln with a ramp-hold temperature controller, and a set of crossed polarizers to see where the strains are. There are books & videos.

$30 for Jimmymajesty's piece is unbelievably inexpensive. Paying 100 euros to get it sent to the US would still be very inexpensive!

@Jimmymajesty - did your glassblower fuse the tungsten directly to ordinary borosilicate glass (pyrex, kimax, etc) or did he first bond the tungsten to a special glass which he then fused to the borosilicate tubes?

Jimmymajesty - 21-6-2010 at 22:42

Densest is right, a kiln is necessary, otherwise the glassware will crack on cooling, I also cracked some glassware even after annealing, especially the grounded glass joints the weak points.

My glassblower only work with pyrex, i.e. borosilicate, and uses acetylene-oxygen torch.

To make an electrode you have to heat the tungsten rod first, then melt a glass bead (also pyrex) and rub it on the surface of the rod, it will cling to it, then you can melt it into a tube with grounded glass joint.

The glassblower knows me well, but sent me to hell when I asked him to make spare electrodes.. so everyone draw their own conclusion:)

watson.fawkes - 22-6-2010 at 08:23

Quote: Originally posted by Jimmymajesty  
My glassblower only work with pyrex, i.e. borosilicate, and uses acetylene-oxygen torch.

To make an electrode you have to heat the tungsten rod first, then melt a glass bead (also pyrex) and rub it on the surface of the rod, it will cling to it, then you can melt it into a tube with grounded glass joint.
For the beading technique you describe, the initial heating of the tungsten rod should be done with an oxidizing flame. The oxide lowers the surface tension of the tungsten-glass contact layer and affords a more reliable seal.

It's possible that the beading glass wasn't the same exact glass used for the body of the device. Schott 8448 is specifically designed for sealing Duran (et al.) to tungsten. It has a coefficient of expansion (3.8) which is about at the geometric mean between borosilicate (3.0-3.35) and tungsten (4.6) (All coefficients are in μ/K) This is a borosilicate-like glass, with some other ingredients (unknown to me at this time) added to change the expansion coefficient. For example, Corning 3320 (evidently no longer in melt; it's not on their web site) was doped with uranium. I'd be interested in knowing if your glassblower was using a sealing glass or just beading with the same material as the body.

For those few doing this themselves, the common tungsten welding rods in the US are 0.125". According to my reference, these have a safe current-carrying capacity of 50A before overheating of the glass is a problem. This is for a single-lead device; for a pair of closely-space leads (as for a heater) this should be derated.

peach - 23-6-2010 at 16:36

Jimmy, I mean plating the tungsten with platinum, which could be done after the electrode was in the glass.

$30 is ridiculously cheap for something like that! Although, it depends what $30 means where you are I guess. If it's the US, it's not a lot.

I've also heard about the benefits of forming the oxide when producing hermetic seals with glass. I was heavily into Sam's Laser FAQ when I was about 11 (or something around that age) and they'd always be going on about glass work - amongst other strange (and very interesting to me) things, like high vacuum or high voltage gear.

I have a really nice oxy/acetylene torch that I bought when I was about 14, with all my pocket money. The whole kit cost something like $600 at the time. That was a lot of birthday and christmas gifts saved up over years. I've heard about using polarized filters for strain observation and annealing by hand, but even with the filters I wouldn't trust the latter.

So the main thing stopping me from having a go is the kiln. I could build one, as I've also spent years reading around casting metals (like iron) and have built a high temperature furnace before; the annealing temperatures for glass would be eeeeeasy (if you don't believe me, try cutting near pure alumina insulation first :P). But I don't have anywhere to put one at the moment.

Just as I was feeling all sad about that, I had a brainwave. How's about blowing hot air through the glass with a modified heat gun? The glass could be wrapped in glass wool for insulation and the cooling period set by PWM of the coil. Or fill the glass with something that'll conduct heat, insert some nichrome wire and wrap in wool?

Either way, I doubt the owners of my current home would appreciate me firing up acetylene fueled welding gear at the moment. :D

Jimmymajesty - 23-6-2010 at 22:53

Peach I see now.. but plating is not necessary since tungsten is inert enough, for such applications, even if the starting acetone contains some water, the forming acetic acid would not attack the tungsten (I think, I always use dry acetone though)

The glassblower did not used another type of glass to wet the electode, he showed some electrodes to me which was sold pre-wetted with some other type of glass, but he rather made new ones on his own instead of using the ones at hand, I do not know why.. maybe he likes challenge:)

Tungsten rod of 1mm diameter far enough for a lamp as far as current is concerned, but take care not to break it.. tungsten is rather fragile.

After the glasswork there was a rather thick oxide layer on the tungsten which was as solid as glass, also take care not to break the rod while you are removing it.

I know 30 dollar is not much, maybe I should ask him to make some for sale.. pity that there would not be a big market for them in my country:)

densest - 24-6-2010 at 04:28

@watson.fawkes - Schott 8448? Hmmmm.... thanks!

@peach - working borosilicate requires really good ventilation. Outdoors is best if you don't have a powerful exhaust fan. Used ceramic kilns are often sold by people who get bored with making pots. You could put it on a rolling cart. Again, outdoors is good. Use propane or natural gas not acetylene in the torch. Acetylene has too much carbon in it. And protect your eyes!!! Didymium glasses are not sufficient - they don't stop ultraviolet & infrared well. Use glasses designed for borosilicate work.

watson.fawkes - 24-6-2010 at 06:21

Quote: Originally posted by densest  
@watson.fawkes - Schott 8448? Hmmmm.... thanks!
Here's the data sheet, attached. Schott also makes other sealing glasses for Kovar and other materials used in vacuum gear. The Schott web site has a selector application (in Flash, unfortunately, so direct linking isn't worth it) for browsing their materials. Warning: the CoE for 8448 in that app is listed at 3.08 (which would be absurd for a W-seal), not the 3.8 in the data sheet.

Attachment: Glass_8448_datasheet_english.pdf (35kB)
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peach - 28-6-2010 at 09:15

densest
You can't use acetylene even with the flame finely tuned? I know what you mean about carbon, just lighting the torch would have cobwebs all over the roof. A trick welders use is to purposefully set the flame carbonizing, deposit carbon on a piece of scrap and then turn the oxygen up until it'll remove the carbon. I have a pair of funky gas welding goggles which I'm sure would be fine for glass work, they're well shaded for UV and make the world an attractive lime green tone. I've seen those kilns too. A lot of them got thrown out by schools after healthy and safety said no to kids being involved with fire.

watson
I believe molybdenum is also used for hermetic glass seals.

jimmy
I would ask the guy if he's interested in selling some more of his products. I'd be interested in buying some of them.

All you need is a website and cheap shipping. Buy a stack of cardboard boxes and pack them full of scrumpled up newspaper. If scumpled correctly, it works just as well as bubble or peanut packing and is basically free. Use the economy courier options, like FedEx domestic. It's slower, but a lot cheaper. And I doubt any of the customers would urgently need the glass.

I suspect you'd probably get a few orders from this site, and others if we spread it around.

I think a lot of us tend to pay the prices for named glass for fear of how well it's been blown. I've received a condenser (a really cheap one probably made in a sweat shop in India or China) that had bubbles and a crack already in the glass, from new. I had it replaced and the second had bubbles. I don't criticize sweatshops too much though, because you can't expect excellence from overworked, underpaid slave labor. If he can blown glass well and is annealing it, and you can vouch for him with glass like the lamp, he'd probably get some good business.

He'd need to keep the prices lower than in the US and other parts of Europe, or it'd be easier to buy Quickfit / Corning glass. I'd recommend he also offers US and European tapers.

It wouldn't be at all hard to put together a quick website. If you ask, the moderators might even let you sell it through here.

watson.fawkes - 28-6-2010 at 11:31

Quote: Originally posted by peach  
You can't use acetylene even with the flame finely tuned?
You can, but it's not really about unburned carbon. The thing to remember is that CO2 is reactive, not inert, at flame temperatures. Apropos of this, the standard flame for working silica glass (more-or-less pure SiO2) is an oxy-hydrogen flame. Oxy-acetylene is hotter, which would otherwise be good for the very high heat required for silica, but the carbon contamination is evidently enough of a problem in practice that acetylene isn't much used. I believe (although I'm not certain) that the problem is SiC formation, which isn't soluble in the glass, and that SiC inclusions act as origins for crack propagation, weakening the glass. This is less of an issue with borosilicate, since you don't use such a high temperature, but then there's a new problem of lowering the flame temperature (using oxy-air-acetylene, as one way), or broadening the flame front, or being very careful to avoid point over-heating.

In addition, propane is significantly cheaper per unit heat than acetylene. For example, in scrap steel yards, where they need to cut long beams into pieces for transport and processing, oxy-propane is the norm, as propane gets the steel plenty hot enough to cut with oxygen.

Jimmymajesty - 28-6-2010 at 13:22

Peach apart from my total inexperience in selling things, it would not be a bad idea after all. Selling glassware is not illegal, isnt it?

We should name the ketene lamp something else, I mean when I hear ketene immediately acetic andhydryde.. drugs and explosives springs to mind.. rather than amateur experiments. It should be noted however that it can open a new world for the home chemist, you can study a lot of catalytic reactions with it, e.g. dehydrogenating cyclohexane to benzene, or pyrolyse lighter hydrocarbons to aromatics, just to name some.

I am gona ask the glassblower when I meet him next time, if he made some spare lamps, should the need arise.

It would be nice to see other chem enthusiasts works, in pioneering home pyrolysis, I have not got much time to make experiments at the moment.. I never had though:)

mr.crow - 1-7-2010 at 09:55

Pyrolysis Lamp :D I would buy one.

Maybe some things could be simplified to make it easier/cheaper to make.

peach - 2-7-2010 at 11:43

Watson
Thanks for the explanation, things like carbon are also incredibly important with steels, where you'll get interstitial carbon and cotrell atmospheres that either help arrest crack from propagating or initiate them when it's present in amounts large enough to form brittle crystals. Methods of treating steels rely on the distribution of things like carbon, e.g. solution treatment refers to putting them into a solution like state.

I've seen hydrogen generators before for welding, places like Rio Grande sell them for jewelers. Or there are welding sized ones as well. I actually swapped my acetylene tank for a propane at one point, realizing it was so much cheaper. It does work for cutting, but it also becomes a pain in the ass waiting for things to heat up, there's a very tangible difference in the speed between the two if you're using similar nozzle sizes.

One exciting fact I know about hydrogen is that 'sniffing' cylinders of it (knocking the valve open to clear the nozzle) can ignite the gas, apparently.

Jimmy
Don't worry about that. Even if you post one to a country were it is illegal, the most that'll happen is you'll get complained at by their customs officers and told not to send anymore. There's no way you'd be extradited and jailed for posting an everyday piece of glassware; e.g. not a 12 liter, multinecked flask.

I'd call it a reactor lamp, catalysis lamp, catalysis reactor, etc. Or 'Jimmy'. It looks a bit like a Soxhlet extractor. I'd talk to him about the electrodes in particular. You mentioned he was getting annoyed about making more them, so ask him what was difficult and maybe one of us could suggest a something to make it easier, so he can produce them without having to put the price up.

As for selling things, it's easy now. There are a ton of sites that basically build your shop for you. I might be able to help with that if he wants to go ahead.

[Edited on 2-7-2010 by peach]

densest - 2-7-2010 at 20:46

@watson.fawkes - Schott has sent me to a fabricator. They don't sell in less than case or melt quantities which is not at all surprising. They do say that 8448 is very expensive. It sounds like it's about 10x - 20x borosilicate prices, which isn't surprising either, and if one only needs a cm or two per joint, 1-2m of small tubing goes a very long way. $3000 or so for a box of it is a bit much - I wouldn't use that much in several lifetimes, though I'd be willing to retail it for a suitable markup....

If I find an inexpensive source of graded seals for tungsten-to-borosilicate connections I'll be sure to mention it. A reasonably simple capacitor discharge welder would be sufficient to attach various interesting contraptions to such an electrode.

Every maker of graded seals I've found says "call for quote" = you can't afford it, you peasant... I hate "call for quote" - it usually means a company who wants to rape you for everything you have. Or the company has so much overhead they can't make any money on orders less than $10,000. Ugh. No wonder the US doesn't have any manufacturing left.



watson.fawkes - 3-7-2010 at 05:40

Quote: Originally posted by densest  
@watson.fawkes - Schott has sent me to a fabricator. They don't sell in less than case or melt quantities which is not at all surprising. They do say that 8448 is very expensive. It sounds like it's about 10x - 20x borosilicate prices, which isn't surprising either, and if one only needs a cm or two per joint, 1-2m of small tubing goes a very long way. $3000 or so for a box of it is a bit much - I wouldn't use that much in several lifetimes, though I'd be willing to retail it for a suitable markup....
Give Wale Apparatus a call. It's not listed on their web site, but they seem to the last general-purpose scientific glass supplier standing. There are a number of others (like Pegasus and Ace), but they've all specialized in some way. Wale should at least be able to steer you to someone that's willing to deal with an odd lot order.

peach - 3-7-2010 at 16:33

Quote: Originally posted by densest  
"call for quote" = you can't afford it, you peasant... I hate "call for quote" - it usually means a company who wants to rape you for everything you have.


Ha ha ha, yep. I've tried emailing a lot of the custom blowers and they don't even bother replying. Fine. Fuck them. I'll spend all the hundreds elsewhere whilst their art dies.

Jimmymajesty - 6-7-2010 at 01:42

I have not been at him lately, and do not really know when I will.
Seeing that the acetic anhydride thread turned into a meeting place of glass blowers (and wannabees:) Why not make the whole upper part of a teflon block? This was my original idea in case of the glassblower could not make it out of glass. I would drill two small hole into the block which would be previously forged to fit in the large grounded female joint, then I would drill an another for a glass rod with a screwed end, it should work, teflon is smiling up to 450°C IIRC, keep the reflux high and It will keep smiling even at higher filament temps.

hissingnoise - 6-7-2010 at 01:56

Teflon begins to decompose @ 260*C and melts @ ~327*C; you'll find you'll have teflon flu symptoms from the decomposition products. . .


Jimmymajesty - 6-7-2010 at 02:18

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 - 6-7-2010 at 06:45

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. :D

[Edited on 6-7-2010 by peach]

Jimmymajesty - 6-7-2010 at 07:48

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 - 6-7-2010 at 09:27

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 - 12-7-2010 at 07:33

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 - 4-8-2010 at 08:57




franklyn - 4-8-2010 at 09:00

Attached image excerpted from
A Dictionary of Applied Chemistry Vol 1 - T.E. Thorpe
Sidebar reference cited , 4 th entry down here _
http://www.lambdasyn.org/upload/acetylchloride-thread/beills...
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
Acetic Anhydride.gif - 128kB


[Edited on 5-8-2010 by franklyn]

Attachment: DE000000210805A_all_pages.pdf (112kB)
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JohnWW - 4-8-2010 at 09:22

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 - 4-8-2010 at 10:37

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 - 10-8-2010 at 00:49

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

PICT0001.JPG - 76kB PICT0002.JPG - 75kB PICT0014.JPG - 78kB

Jimmymajesty - 10-8-2010 at 13:28

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 - 18-8-2010 at 05:34

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:D

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bbartlog - 18-8-2010 at 11:37

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 - 18-8-2010 at 16:53

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.

zed - 26-8-2010 at 12:09

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!).

Some may have access to isopropenyl acetate, but not acetic anhydride.

I don't know if this is a viable synthesis, as I haven't seen the full article. Perhaps someone can find a free link to the full article?

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 - 4-9-2010 at 04:46

IMHO One of the only, truly realistic approaches to (Ac)2O for the amateur chemist remains that of the silica tetraacetates.

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hector2000 - 12-9-2010 at 05:15

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 )

* Beakers and flasks shouldnt made of glass
* SiO2 is available every where


[Edited on 12-9-2010 by hector2000]

maxidastier - 12-9-2010 at 08:13

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 - 14-9-2010 at 12:55


Regarding this post on Ac2O formation.
http://www.sciencemadness.org/talk/viewthread.php?tid=9&...

@ Jimmymajesty
http://www.sciencemadness.org/talk/viewthread.php?tid=9&...

@ maxidastier
http://www.sciencemadness.org/talk/viewthread.php?tid=9&...

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
http://www.sciencemadness.org/talk/viewthread.php?tid=9&...
but that is just me wondering out loud.

.

madscientist - 12-10-2010 at 21:56

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.

Luton - 13-11-2010 at 02:34

Is it possible to use Ethyl Acetate CH3COOCH2CH3 instead of Acetyl Chloride to make Ac20

madscientist - 13-11-2010 at 03:03

Nope.

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

Luton - 13-11-2010 at 03:08

Has anyone successfully tried using Acetyl Chloride with Sodium Acetate to make Ac2O, if you could you please take me step wise :o

hissingnoise - 13-11-2010 at 12:26

This simple reaction is very well documented - try googling it!


Luton - 22-11-2010 at 03:43

Well I guess by using Acetyl Chloride + Sodium Acetate = Ac2O is the most common.

But what I did not understand was,why use H2SO4, wouldn't the Acetyl Chloride and Sodium Acetate react without H2SO4.

If H2SO4 is still needed, does anyone know how much to use in Lab.

Too much Googling is bad for health :D

hissingnoise - 22-11-2010 at 04:13

Quote:
But what I did not understand was,why use H2SO4, wouldn't the Acetyl Chloride and Sodium Acetate react without H2SO4.

Beats me too. . .
Anyway, keeping moisture out of the reaction is the important consideration!

http://www.erowid.org/archive/rhodium/chemistry/anhydrides.h...



SHADYCHASE54 - 20-1-2011 at 12:17

I am sorry if it seems like I'm beating a dead cat, resurrecting an old and well covered issue however, I have a question about Ac20 prep. via P2O5 dehydration. I have attempted this synthesis myself with much of the same result as previous posters, black sludge that gave nothing but my glacial back to me. A long time ago I remember reading a paper that for the life of me i cannot place that claimed that the P2O5 dehydration works when 2 carboxylic acids are mixed producing the anhydride of each component as well as a mixed anhydride.

any thoughts...

hissingnoise - 21-1-2011 at 02:50

Yes, acetic anhydride cannot be prepared by dehydration of acetic acid . . .


SHADYCHASE54 - 22-1-2011 at 14:27

Yesm I too am aware that simple dehydration of glacial will result in glacial however my question was about a mixture of the two. Now I realize that there might seem to be little difference between the dehydration of one as apposed to two. But like I said I believe I did at one time read a paper on this that suggested this works. In the article the two carboxylic acids were glacial acetic & propinoic acid which were dehydrated with P. pentoxide resulting in...
acetic anhydride + propinoic anhydride + acetic-propinoic anhydride. I have budgeted for some propinoic acid next month so come mid month I will try to duplicate what i remember and post my results, or my lack there of.

hissingnoise - 23-1-2011 at 02:37

Quote:
. . . were dehydrated with P. pentoxide resulting in...
acetic anhydride + propinoic anhydride + acetic-propinoic anhydride.

I think that should be a chloride of phosphorus, not the pentoxide . . .



mr.crow - 11-2-2011 at 11:28

I had a crazy idea, maybe someone can tell me if its feasible or not.

Vinyl acetate can be reacted with acetic acid to make acetic anhydride and acetalydehyde, which escapes and drives the reaction forward. There is only a few mentions of this reactions on this forum but it seems to be possible.

Instead of vinyl acetate my theory is isopropenyl acetate, also known as acetone-enol acetate, can be used. Heating the mixture will distill off acetone and form the Ac2O. It also might be possible to make this at home with acetone, acetic acid, an acid catalyst and dehydration to form the enol and create an ester.

madscientist - 11-2-2011 at 18:16

I think you're more likely to just get a mess of aldol condensation products. :(

Waffles SS - 12-2-2011 at 05:51

Quote: Originally posted by mr.crow  
I had a crazy idea, maybe someone can tell me if its feasible or not.
Vinyl acetate can be reacted with acetic acid to make acetic anhydride and acetalydehyde, which escapes and drives the reaction forward. There is only a few mentions of this reactions on this forum but it seems to be possible.


I did this reaction many time and i am sure this method is wrong.
No anhydrid produce just acetaldehyde and tar.
Vinyl acetate wont decompose to acetic anhydrid(I promise you)


[Edited on 12-2-2011 by Waffles SS]

mr.crow - 12-2-2011 at 09:27

Thanks. My idea was based on a patent from the 30s and we all know how accurate those can be.

I could try to buy the vinyl acetate but what fun is that?

Waffles SS - 12-2-2011 at 11:44

Vinyl acetate method(above patent) and pyrosulfate method(sodium pyrosulfate+AcONa) is scam!!(I swear)
Dont waste your time by this method.

Waffles SS - 4-3-2011 at 11:54

Quote:



Prepare 100g freshly fused NaOAc and 65g S2Cl2. A small quantity of NaOAc is placed in a thin-walled glass cooled in an ice bath. To this is added some sulfur chloride, the mixtr is vigorously stirred w/a wooden spatula, not allowing the temp to rise. Then some NaOAc is added again, and the process is repeated several times until all is mixed in. The semi-liquid mass is transferred into a 1 liter RBF. The previous operation is repeated 4 times, so that 400g NaOAc and 260 g S2Cl2 total are taken into work. The RBF is then equipped w/a reflux condenser and gently heated on a water bath to ~80-85C. As soon as the rxn starts, the heating is removed, and in case the rxn gets too vigorous it's cooled w/cold water. After 20-30 min SO2 evolution ceases and the mixture is heated for 10 more min's on a boiling water bath. The rxn product is then distilled off under vacuum, then fractionally re-distilled at ordinary pressure, collecting the fraction boiling between 132-142C.


According to Stoichiometry of this reaction every 2 mol of sodium acetate need one mol of S2Cl2 this mean 400 gram sodium acetate need 329 gram S2Cl2 but this patent use 400 gram sodium acetate and 260 gram S2Cl2 !

2AcONa + S2Cl2 = AcO-S-S-OAc + 2NaCl

Also i think in this method for better mixing and better distill we need solvent (high boiling point solvent is better but which one?).



[Edited on 4-3-2011 by Waffles SS]

Partial success with acetic anhydride synthesis and a question

goahead - 11-3-2011 at 09:05

Hello everyone,

I've tried the reaction with sodium acetate/Br2/S twice. The first reaction resulted in roughly 5ml of a clear yellowish liquid, which distilled at 55°C at a vacuum of unknown strength, with a stingy smell, which turned to acetic quickly. The liquid sank in water and dissolved in it after about 30 minutes. It burned with a weak blue flame.

Since the small amount of product wasn't sufficient for a second distillation at normal pressure, the reaction was performed one more time. This time the sodium acetate was added to the sulfur bromide instead of the other way round, which proved to be more difficult because of bromine vapors escaping. From 21.5g bromine 15g of a clear, pungent liquid was obtained.

This liquid also sank in water but dissolved in it rapidly. The smell was more pungent-garlic like and the acetic component almost missing / much weaker. The liquid distilled at normal pressure in the range of 80-100°C.

Any ideas what this product might be?

Waffles SS - 16-7-2011 at 07:09

US2073686
Quote:

Proocess for manufacture of acetic anhydrid, which comprises heating to a temperature between 200-450c a mixture of cupric acetate with copper salt of a strong of hydrochloric acid and sulfuric acid




http://www.sciencemadness.org/talk/files.php?pid=216018&...

[Edited on 16-7-2011 by Waffles SS]

Bitburger - 30-7-2011 at 05:52

With 2 simple chemicals: sodium acetate and ammonium chloride!

When you mix it up and do a dry distillation, then a aqueous solution of ammonia comes over first, with some acetamide in it. But if all water is boiled, temperature rises and the destillation apparatus is then filled with smoke: a oily liquid floating on the top will come over. This is ethanoyl anhydride.

I prepare it by incident - if you read my topic "Synthesis of propanamide" then you will see the yellow propanoyl anhydride.

By heating it up with NaOH, the mixture became a solid, waxy compound when cooled. This is sodium propanoate. Furthermore, it is very soluble in diethyl ether - like propanoyl anhydride. Also, the density was established.

I still have a sample of it.;)

[Edited on 30-7-2011 by Bitburger]

Waffles SS - 30-7-2011 at 07:47

Did you test your Acetic anhydrid?really that is acetic anhydrid or acetic acid?
I confirm that dry distillation of sodium acetate and ammonium chloride produce acetamide but i Doubt acetic anhydrid may produce by this method

Bitburger - 30-7-2011 at 11:40

Quote: Originally posted by Waffles SS  
Did you test your Acetic anhydrid?really that is acetic anhydrid or acetic acid?
I confirm that dry distillation of sodium acetate and ammonium chloride produce acetamide but i Doubt acetic anhydrid may produce by this method


No, I confirmed that propanoyl anhydride was formed if you are patient. Common practice said to me that this method also must work for making acetic anhydride. Maybe it don't work for the synthesis of ethanoyl anhydride...

Did you ever performed this reaction with sodium ethanoate and ammonium chloride until the distillation apparatus was filled with smoke?

Nicodem - 30-7-2011 at 12:42

Quote: Originally posted by Bitburger  
With 2 simple chemicals: sodium acetate and ammonium chloride!

When you mix it up and do a dry distillation, then a aqueous solution of ammonia comes over first, with some acetamide in it. But if all water is boiled, temperature rises and the destillation apparatus is then filled with smoke: a oily liquid floating on the top will come over. This is ethanoyl anhydride.

Signature:
Quote:
Good to be wrong

bbartlog - 30-7-2011 at 13:07

Quote:
Common practice said to me that this method also must work for making acetic anhydride.


Common sense would suggest that if it were that easy, we would not have a thirty page thread devoted to it. Or do you think you are the first person to combine these chemicals and heat them? They were known to the alchemists even. Anyway, the anhydrides of carboxylic acids get progressively harder to make as the number of carbons decreases; many methods that might be applicable to the synthesis of propionic anhydride would not work for acetic anhydride. Which is not to say that I think you made propionic anhydride either.

Bitburger - 5-8-2011 at 08:50

A hypothetical consideration is the reaction between acetic acid and acetaldehyde in the presence of a base. The last step could be achieved by a mild oxidation.

azijnzuur anhydride.jpg - 13kB


Click on the picture to enlarge

simba - 18-9-2011 at 08:39

Quote: Originally posted by Bitburger  
A hypothetical consideration is the reaction between acetic acid and acetaldehyde in the presence of a base. The last step could be achieved by a mild oxidation.



Click on the picture to enlarge


Looks too good to be true...I think it is more likely to get just acetate salts and water from this.

MeSynth - 3-10-2011 at 21:34

When all else fails.... http://www.elementalscientific.net

497 - 6-10-2011 at 22:13

I stumbled into a neat way to make acetyl chloride. I make no claims that it is easier than the alternative routes, but I thought I'd bring it up since no one has.

Alkyl disulfides in glacial acetic acid react to form alkyl sulfenyl chlorides and acetyl chloride. The AcCl can be distilled out of the mixture. The sulfenyl chloride could be recycled back into disulfide, or used to make other things such as sulfinyl chloride, sulfinic acid, sulfonyl chloride, or sulfonic acid.
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV5...

The required alkyl disulfide can be easily made from an alcohol via the alkyl bromide reacting with either sodium polysulfide or thiosulfate. Pretty easy looking stuff.

Bitburger - 20-10-2011 at 12:53

Quote: Originally posted by shivas  
Quote: Originally posted by Bitburger  
A hypothetical consideration is the reaction between acetic acid and acetaldehyde in the presence of a base. The last step could be achieved by a mild oxidation.


Looks too good to be true...I think it is more likely to get just acetate salts and water from this.


What happens with this reaction when a non-nucleophilic base, e.a. Et3N is used instead of a hydroxide salt?

peach - 27-12-2011 at 08:28

Manufacture of fatty acid anhydrides - Henry Dreyfus - US patent number 2073686


Almost a year ago, after receiving a power supply in the post, I decided to give it a test making some copper acetate using acetic and copper wire. I then distilled the results, mainly out of curiosity to see roughly how it behaved rather than achieve anything significant.

Fast forward and I was chatting with someone from the forum who mentioned seeing a patent, the patent above, regarding the production of anhydrides from acetates. The patent specifically mentions copper acetate being distilled with copper sulphate. Both the salts are dried prior to distillation. Approximately 30 to 60% w/w of the sulphate is added per unit of acetate.

Some might call this squirreling, but...

I still had the finely powdered copper left over from the last time I made copper acetate:

<img src="http://img85.imageshack.us/img85/3724/img1939jk.jpg" width="400" />

I decided to try the distillation again, but this time including copper sulphate and well drying the materials prior to use.

I combined the piles of copper powder in a small beaker, checked the mass and then added Glacial Acetic. On top of that, I dripped in some 35% peroxide. The reaction is somewhat busy. I then left it to bubble away on a hotplate for about thirty minutes to get it all (hopefully) to the (II) acetate.

Meanwhile, I found a lump of copper sulphate I had been watching turn into crystals for the last year and scooped them out.

The acetate by now had absorbed so much of the acid it I could turn the beaker upside down and it wouldn't drip. I emptied that onto a large watch glass and the sulphate into a petri dish and put both in the oven at around 75C for six hours. Periodically removing them to crush them (particularly the sulphate) into dust.

The glassware was left in the oven for a few hours to ensure that was also dry.

I then put the acetate under about 80mbar of vacuum and heated that to 140C for four hours, leaving the bottle capped after removing it. I repeated the process for the sulphate but allowed it to become a colourless mass (which should be anhydrous, or close).

I emptied all of the acetate into a preweighed flask and determined that I had about 16g of it. Then was added 60% of this w/w of the sulphate. The two were shaken together and set up for simple vacuum distillation.

The powders are notably free flowing, to the point that they are carried through a still by the vapours. It occurs readily enough to line the entire still, as per the photos in the other thread. This time, I wadded the base of the column with some glass wool. Despite this, I could still see faint traces of powders filtering through the wool. It was, however, no where near as bad as the example in the other thread.

The distillation was run around 80mbar and I was recovering a colourless liquid at 35C into a preweighed flask. When the temperature fell, I checked the flask and it was now entirely brown, indicating the end. I had recovered approximately 5g of liquid. This was placed in the freezer at -17 / - 18C. Returning shortly after, it had all frozen solid. A bad sign in terms of acetic anhydride, as it's melting point is -73.1C, so there must be at least some moisture in there.

I then swapped it over to the fridge. I had two digital thermometers in there reading between 7 and 8.6C. I have also had some flasks of cyclohexane in there for months, which are constantly going into and out of solids and liquids, or half and half. The melting point of cyclohexane is 6.5 to 7C, so that seems realistic. The material in the flask also became a liquid, over the coarse of many hours. It's own MP will be somewhere close to that of cyclohexane.

Inspecting the flask I could see traces of the powdered reagents in there. It was a faint baby blue, indicating copper sulphate monohydrate.

I then decided to distill it through a column, but at atmospheric, such that I could check that BP. Which I did, with the aid of some argon and CaCl2 on the outlet. The BP of the anhydride is 139.8C, that of GAA is 118 to 119C. The Y is in Celsius, the X is time, in minutes.

<img src="http://img851.imageshack.us/img851/4886/screenshotat20111226210.png" width="400" />

Not looking too good for the anhydride!

To be more sure, I titrated 1ml of the liquid and obtained an acetic molarity of 17.9, with the molarity of GAA being 17.5M.

Comments

YAY! I've made acetic acid!

Errors and improvements

The hydration states of the materials are obviously very important if the goal is the anhydride. In the patent, Henry specifically mentions that the acetate may be not entirely anhydrous, but the sulphate should be as close as possible.

The acetate is difficult to dry without accidentally decomposing. Hard vacuum would be a good idea.

I don't think checking the hydration states by the signs of decomposition or colourloss alone are going to be good enough. It seems to require that they are insured with mass checks.

I started with a known mass of copper, but in an unknown oxidation state. So I could estimate the amount of acetic that would be required, but I could not actually check which acetate I had and if I had solely that acetate. I relied instead on it simply being that acetate due to the excess of GAA and heating.

On that point, the amount of GAA yielded seems low by comparison with the mass of liquid (likely GAA, or something close) that I have received back. Indicating that the mass of acetate I weighed after drying was either partially decomposed (doubt that's significant, it was all green), partially the lower (I) acetate (it was definitely green), still damp to some degree (decomposition had just begun as I turned off the heating, indicating it must be close to fully dehydrated) or a combination of all three.

I spent about a day in total drying glass and salts for this, and have yielded bum all anhydride, indicating the importance of keeping track of the actual mass changes occurring. If I try this again, I will be following it from start to distillation with carefully checked masses and states. I may also use an excess of the sulphate.

I could do with getting some aniline, to follow Len's suggestion to ?Lambda? of using that to check his results.

Obligatory photos


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[Edited on 27-12-2011 by peach]

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: reduced image size(s)]

[Edited on 9.12.13 by bfesser]

Waffles SS - 27-12-2011 at 09:06

Quote:

The mixture is then subjected to decomposition at a temperature of about 250 to 270 c under an absolute pressure of about 10 to 15mm hg

I tried acetate salts Pyrolysis under vacuum method but only salt that made AC2O was silver acetate.I think Henry Dreyfus was mad and he published lie full patents during 1922-1937(like US1430304 for making anhydrid from pyrosufate salt)
Maybe on 1922 everyone was able to publish everything!



Quote:

Band 61 B5, Seiten 125-6.

2.2.7.2 Thermische Zersetzung

Die Zersetzung von AgCH3COO, die bereits von Chevenix [1] beim Erhitzen über einer Kerzenflamme (starker Geruch nach Essigsäure) beobachtet wurde, setzt bei 210°C ein (Dunkelfärbung), erfolgt hauptsächlich zwischen 220 und 240°C und ist vollständig bei etwa 300°C [2]. Beim Erhitzen im offenen Rohr oder im bedeckten Porzellantiegel werden als Zersetzungsprodukte im wesentlichen Essigsäure und Ag neben wenig C02 und C beobachtet entsprechend 4AgCH3COO ->4Ag + 3CH3COOH + CO2 + C [3 bis 5]. Von Kachler [2] werden als Reaktionsprodukte gefunden (in Gew.-%, nach vorstehender Gleichung berechnete Werte in Klammern): 64.61 Ag (64.67), etwa 26 bis 27 Essigsäure (26.95), 4.09 bzw. 8.42 CO2 (6.59) und 1.21 C (1.79). Auch bei thermogravimetrischer Untersuchung wird als Zersetzungsprodukt (bei 280°C) metallisches Ag und kein Ag2O erhalten [6]. Erfolgt die Zersetzung jedoch unter streng wasserfreien Bedingungen, so werden als Zersetzungsprodukte nur Ag2O und Essigsäureanhydrid erhalten nach 2AgCH3COO -> (CH3CO)2O + Ag2O. Bei der Zersetzung von 2.1077 g trocknem AgCH3COO bei 300 bis 400°C in einem Quarzgefäß unter Argon (1 atm) werden nahezu quantitativ Ag2O (96% der Theorie) und Essigsäureanhydrid (93%) gebildet neben wenig Ag (0.012 g) und CO2 (0.016 g) [7]. Die primäre Essigsäureanhydridbildung ist bereits von Kanewskaja, Schemiakin [8] bei Untersuchung der thermischen Zersetzung von AgCH3COO (im Gemisch mittrocknem Sand) unter einem CO2-Strom von 20 bis 25 Torr angenommen worden. Zwar fanden diese Autoren nur wenig Essigsäureanhydrid neben viel Essigsäure (entsprechend den früheren Angaben von Kachler [2] und Iwig, Hecht [4]), doch ist dies auf die leichte Hydratisierung des Essigsäureanhydrids zurückzuführen, die sowohl durch H2O-Spuren in dem schwer zu trocknenden Silberacetat als auch durch H2O erfolgen kann, das beim teilweisen Zerfall der Essigsäure gebildet wird.
Für die vollständige thermische Zersetzung von AgCH3COO in Gegenwart von H20 muß auf etwa 230 bis 340°C erhitzt werden. Abweichend von der trocknen Destillation wird neben den Hauptprodukten der Zersetzung Ag, Essigsäure und CO2, kein Kohlenstoff gefunden [2].
Über die Darstellung von Ag-Schwamm durch Erhitzen einer getrockneten Paste von AgCH3COO im Tiegel auf 400 bis 500°C s. [10].

...

[1] R. Chevenix (Ann. Chim. [Paris] 69 [1809] 5/58, 19, 22; Ann. Physik 32 [1809] 156/201, 167, 179). — [2] J. Kachler (Monatsh. Chem. 12 [1891] 338/49, 340). — [3] K. Birnbaum (Ann. Chem. 152 [1869] 111/21, 119). — [4] F. Iwig, 0. Hecht (Ber. Deut. Chem. Ges. 19 [1886] 238/42). — [5] J. Redtenbacher, J. Liebig (Liebigs Ann. Chem. 38 [1841] 113/40, 131).
[6] D. A. Edwards, R. N. Hayward (Can. J. Chem. 46 [1968] 3443/6). — [7] A. D. Kirschenbaum, A. G. Streng, M. Hauptschein (J. Am. Chem. Soc. 75 [1953] 3141/5, 3143).— [8] S. J. Kanewskaja, M. M. Schemiakin (Ber. Deut Chem. Ges. 69 [1936] 2152/7, 2154). — [9] V. I. Yakerson (Izv. Akad. Nauk SSSR Otd. Khim. Nauk 1963 1003/11, 1007; Bull. Acad. Sei. USSR Div. Chem. Sci. 1963 914/21, 916). — [10] T. Yamanaka, H. Nidorikawa (Japan.P. 6720 [1956] nach C.A. 1958 10462).
http://www.sciencemadness.org/talk/viewthread.php?tid=9&...



[Edited on 27-12-2011 by Waffles SS]

peach - 27-12-2011 at 09:57

Thanks for the reply Waffles.

I would have preferred to do it at 10-15 mm but was seriously concerned about just how mobile the powders were, and them potentially ending up in the pump, grinding away. And also the difficulty of trapping the liquids.

I didn't see too much of a problem in doing it around 80, which reduced the temperature right down to about as low as I could trap any liquid and, with it being a diaphragm pump, it'd be easier to clean out if it did end up full of muck. Neither should there be a whole lot of moisture present relative to the amount of anhydride the mass of salts should produce.

When you tried the copper salts, did you allow those to dry under hard vacuum for hours and use them immediately? The only major source of moisture I can think of in my try would be the salts themselves. Both the salts can be dried to anhydrous, and the acetate did decompose to copper / an oxide of copper.

Anyway, I will likely be following this up soon. I am interested in filtering the results, with some water. If all of the acetate has decomposed to some form of copper or oxide thereof, I should end up with that stuck in the filter and can have a look at the mass. And then the mass of sulphate.

Looking at the wiki for copper sulphate, I think it's possible I still had some mono hydrate as I doubt the temperature of mine went much over 200C when drying. I could have been rougher with that.

I have been having an investigate into the Henry Dreyfus of this patent.

I discovered there is a postdoctoral awards program named after himself.

Indeed, there is even a wiki page.

Here.

The topic at hand and the dates suggest this is the same Henry Dreyfus.

Waffles SS - 27-12-2011 at 10:42

My dear friend peach,
I used Merck anhydrous Copper(II) Sulfate and also Anhydrous Copper acetate(Indian lab chemical)
I reached 10mmhg by Edwards high vacuum Pump and i used full stainless steel Distillation System.i repeated several times this method but every time i got acetic acid.i strongly advise that dont waste your time by this method.i suggest you Ethylidene diacetate method because i tried it and that was successful and easy method
US1720184 best and easier way for make Ethylidene diacetate
US1578454 best and easier way for make Ac2O from Ethylidene diacetate

For testing Ac2O: just add one drop of it in water and watch it.it should fall down and reach at bottom of beaker and make very small oxygen balloon on it head.(i hope you understand what i mean)also it has very pungent odor(like garlic odor for me!)
Attachment: US1578454.pdf (153kB)
This file has been downloaded 1173 times

Attachment: US1720184.pdf (186kB)
This file has been downloaded 1132 times




[Edited on 27-12-2011 by Waffles SS]

Formatik - 27-12-2011 at 23:05

There is quite a bit of info on copper acetate in Gmelin (Cu [B], 683) also:

Quote:
- Beim Erhitzen des Monohydrats auf 140º unter vermindertem Druck werden die letzten Spuren
H2O vertrieben. Oberhalb 160º erscheinen weiße Dämpfe, die sich als wasserklare Fl. kondensieren.
Diese Fl. wird später durch sublimiertes CuCH3CO2 (vgl. S. 677), das bei 180º bis 185º erscheint,
blau gefärbt. Bei 220 bis 230º treten in reichlicher Menge CO2 und CO neben wenig KW-Stoffen auf.
Nach längerem Erhitzen auf 270º erscheint kein Destillat mehr. Das bei Drucken unterhalb ~ 80 Torr
erhaltene Destillat besteht aus 13.3 bis 15.2% H2O, 5.8 bis ~6.4% (CH3CO)2O und 35.8% bis 38.2%
CH3CO2H sowie Spuren von Aceton. Oberhalb ~80 Torr nimmt die Ausbeute von (CH3CO)2O
zugunsten derjenigen an CH3CO2H ab und wird oberhalb 300 Torr gleich Null. Die beste
Ausbeute an (CH3CO)2O wird beim Erhitzen im Vak. von ~10 Torr und einer Aufheizgeschw.
von 0.5º/Min. erhalten. Der hellbraune, pulverförmige Dest.-Rückstand enthält im Mittel
83.7% Cu, 9.1% C, 1.4% H2 und 5.9% O2, T.-Y. Chang, P. Kao (J. chem. Engg. China 4 [1937]
160/3).


Basically above about 80 Torr the yield of Ac2O decreases in favor of more AcOH yield, where at 300 Torr Ac2O is about zero. The best yield (I don't know what that is, see original reference) of Ac2O is obtained by heating in a vacuum at ~10 Torr (10 mmHg) and a heating rate of 0.5º/min.

Waffles SS - 29-12-2011 at 06:48

@Peach,I hope you success in your experience but i am not sure that you get Ac2O, try to reach 10mmhg in pyrolysis step(if you success then i will find out that my Copper acetate or sulfate was hydrated and i will try this method again)
Please share your result with us


peach - 30-12-2011 at 10:01

Quote:
I tried acetate salts Pyrolysis under vacuum method but only salt that made AC2O was silver acetate


Did you try any other salts that are mono acetates?

Thanks again Waffles and Formatik.

I was again chatting with the other SM member about the points you made and the odd results. I have had a closer look at the results;

I left the reactants in the flask until they were back at room temperature prior to emptying them out. Let's see what's inside!
<a href="http://img818.imageshack.us/i/img2088h.jpg/" target="_blank"><img src="http://img818.imageshack.us/img818/7792/img2088h.jpg" width="400" border="0"/></a><br>

Redissolving in about 100ml of water, and then the remains rinsed through the funnel with another 100.
<a href="http://img402.imageshack.us/i/img2089ai.jpg/" target="_blank"><img src="http://img402.imageshack.us/img402/4627/img2089ai.jpg" width="400" border="0"/></a><br>

<a href="http://img851.imageshack.us/i/img2090p.jpg/" target="_blank"><img src="http://img851.imageshack.us/img851/4425/img2090p.jpg" width="400" border="0"/></a><br>

<a href="http://img528.imageshack.us/i/img2091v.jpg/" target="_blank"><img src="http://img528.imageshack.us/img528/8206/img2091v.jpg" width="400" border="0"/></a><br>

The insoluble products.
<a href="http://img220.imageshack.us/i/img2092y.jpg/" target="_blank"><img src="http://img220.imageshack.us/img220/5100/img2092y.jpg" width="400" border="0"/></a><br>

Copper sulphate is clearly still present.
<a href="http://img560.imageshack.us/i/img2093cg.jpg/" target="_blank"><img src="http://img560.imageshack.us/img560/3003/img2093cg.jpg" width="400" border="0"/></a><br>

<a href="http://img827.imageshack.us/i/img2094oi.jpg/" target="_blank"><img src="http://img827.imageshack.us/img827/4213/img2094oi.jpg" width="400" border="0"/></a><br>

<a href="http://img217.imageshack.us/i/img2096k.jpg/" target="_blank"><img src="http://img217.imageshack.us/img217/3047/img2096k.jpg" width="400" border="0"/></a><br>

<a href="http://img696.imageshack.us/i/img2097eg.jpg/" target="_blank"><img src="http://img696.imageshack.us/img696/1306/img2097eg.jpg" width="400" border="0"/></a><br>

I removed the water at 75 to 100C. I did this in an Erlenmeyer precisely so as to avoid any splatters leaving the clean up. I even went to the trouble of rinsing that drip off the end of the thermometer and back into the flask.
<a href="http://img846.imageshack.us/i/img2098h.jpg/" target="_blank"><img src="http://img846.imageshack.us/img846/2182/img2098h.jpg" width="400" border="0"/></a><br>

The filter has been sat in the oven all day to dry the cake out.
<a href="http://img830.imageshack.us/i/img2099y.jpg/" target="_blank"><img src="http://img830.imageshack.us/img830/8641/img2099y.jpg" width="400" border="0"/></a><br>

That's good. I had 9.02g of copper going in. Copper which had in part been obtained from the results of the last try of this, and the other part coming from when I ran the cell generating the acetate. Some of the copper going in was likely elemental copper, whereas this will be oxide (I may try redissolving it in a bit to check that).
<a href="http://img3.imageshack.us/i/img2100qw.jpg/" target="_blank"><img src="http://img3.imageshack.us/img3/3659/img2100qw.jpg" width="400" border="0"/></a>

To obtain a usable mass from the sulphate, I needed it get it into a hydration state I could be more sure of. So it was redissolved into a small volume of water, emptied into a preweighed dish and the flask rinsed a few times to make sure it was all across. This way we can be sure, it is fully hydrated at this point in time.
<a href="http://img254.imageshack.us/i/img2101t.jpg/" target="_blank"><img src="http://img254.imageshack.us/img254/2050/img2101t.jpg" width="400" border="0"/></a><br>

The mass of the dish prior to adding the solution of sulphate.
<a href="http://img534.imageshack.us/i/img2102kg.jpg/" target="_blank"><img src="http://img534.imageshack.us/img534/8195/img2102kg.jpg" width="400" border="0"/></a><br>

<a href="http://img546.imageshack.us/i/img2103e.jpg/" target="_blank"><img src="http://img546.imageshack.us/img546/8383/img2103e.jpg" width="400" border="0"/></a><br>

<a href="http://img202.imageshack.us/i/img2104gy.jpg/" target="_blank"><img src="http://img202.imageshack.us/img202/5554/img2104gy.jpg" width="400" border="0"/></a><br>

The sulphate begins loosing water of crystallisation at 63C, so I loaded it into the oven on the 50C defrost setting with the door open, checking the temperature. Then, going to bed, left it on top of the radiator (40C). I should have largely the pentahydrate.
<a href="http://img249.imageshack.us/i/img2105et.jpg/" target="_blank"><img src="http://img249.imageshack.us/img249/1492/img2105et.jpg" width="400" border="0"/></a><br>

<a href="http://img838.imageshack.us/i/img2106hr.jpg/" target="_blank"><img src="http://img838.imageshack.us/img838/5181/img2106hr.jpg" width="400" border="0"/></a><br>

This is interesting, because I did not spill a single drop of the sulphate. Nor did I come anywhere close to boiling it. Yet it is climbing the sides of the dish. There is something worry with the mass here!
<a href="http://img46.imageshack.us/i/img2109v.jpg/" target="_blank"><img src="http://img46.imageshack.us/img46/1924/img2109v.jpg" width="400" border="0"/></a><br>

This all looks blue to me, in person. But I see the camera has picked up a faint trace of green in a spot there.
<a href="http://img848.imageshack.us/i/img2110b.jpg/" target="_blank"><img src="http://img848.imageshack.us/img848/2702/img2110b.jpg" width="400" border="0"/></a>

Copper acetate and oxides

Those look okay. It appears the acetate has decomposed.

When distilling the results, my empty flask weighed 18.13370 and it was 22.26773g when full. Giving a mass of 4.13403g for the liquid I distilled off.

The sulphate

Having added 16.0546g of acetate to the flask, I then added around 60% w/w of the (supposedly) anhydrous copper sulphate, with the final mass displayed being 25.0738g. That indicates an addition of 9.0192g anhydrous sulphate.

Here's the problem.

Prior to adding the sulphate to my dish, the dish weighed 51.67447g. After filling it and allowing the water to gently evaporate off, it now weighs 59.63433g. The mass change is 7.95986g.

That is an entire grams worth of sulphate missing between those two.

And far worse, the sulphate should now weigh considerably more given that it is in the pentahydrate state.

In fact, assuming my original mass of sulphate was anhydrous;

9.0192g in / 159.62 g/mol (anhydrous) = 0.05651 moles
0.05650 moles in x 249.70 g/mol (pentahydrate) = 14.1091g out

If the sulphate has not actually taken part in the reaction beyond absorbing moisture, that is 6g of error.

[Edited on 30-12-2011 by peach]

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: reduced image size(s)]

[Edited on 9.12.13 by bfesser]

Waffles SS - 30-12-2011 at 23:00

@Peach,
I just tried successful Silver Acetate Pyrolysis(as mono acetate state)
I like your glassware(it seems you are well equipped)My glassware joint is not suitable for vacuum work and all of that have leak(here all of glassware made on china and has leak).What is brand of your glassware?Schott?isoglass?
good for you
Again you got acetic acid?



[Edited on 31-12-2011 by Waffles SS]

peach - 31-12-2011 at 09:05

I believe so.

The melting point of what has been produced was too low for GAA, by a reasonably large gap. I can't find a graph of acetic's melting points right now, but I estimated the water content must be on the order of 4.8%+. Which would put it's molarity at around 17.2M. Whereas I found mine to be 17.9M. That instantly made me want to think the melting point being down was the result of the liquid actually being GAA with a small amount of anhydride in it, which would drastically depress the melting point and also increase the measured molarity.

But, to measure the molarity, I used a 1ml syringe to collect the sample of raw liquid, which won't have been all that accurate and could account for the slight difference in molarities.

If it was true that this was GAA with a small amount of anhydride in it, that does not combine well with the atmospheric boiling point I measured, which was actually below that of GAA. The anhydride boils a good amount above GAA. If anything, had it been GAA with anhydride, the temperature should have been at that of GAA or slightly over it.

So I'm going with, it's about 95.2% acetic.

The glassware comes from numerous places. I even have US and UK glass suggestively greased up sliding into one another.

Acetic anhydride

cal - 10-2-2012 at 22:14

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

Youtume has avideo on making it.

Vikascoder - 8-6-2012 at 18:51

Well i was reading some chemistry organic books in O.P Tandon i found that acetic anhydride can also be prepared from sulphuric acid and glacial acetic acid . Will someone please tell me about this process.

Acetic anhydride

cal - 3-8-2012 at 18:51

Check you tube for the video on it.http://www.youtube.com/watch?v=p6OZ2vLxHDo&playnext=1&list=PL42B498CA5569E3CC&feature=results_video

detonator - 31-8-2012 at 06:24

I only know that these feasible solutions:

Acetic anhydride is produced by carbonylation of methyl acetate:[3]
CH3CO2CH3 + CO → (CH3CO)2O
This process involves the conversion of methyl acetate to methyl iodide and an acetate salt. Carbonylation of the methyl iodide in turn affords acetyl iodide, which reacts with acetate salts or acetic acid to give the product. Rhodium iodide and lithium iodide are employed as catalysts. Because acetic anhydride is not stable in water, the conversion is conducted under anhydrous conditions. In contrast, the Monsanto acetic acid process, which also involves a rhodium catalyzed carbonylation of methyl iodide, is at least partially aqueous.
To a decreasing extent, acetic anhydride is also prepared by the reaction of ethenone (ketene) with acetic acid at 45–55 °C and low pressure (0.05–0.2 bar).[4]
H2C=C=O + CH3COOH → (CH3CO)2O (ΔH = −63 kJ/mol)
Ketene is generated by dehydrating acetic acid at 700–750 °C in the presence of triethyl phosphate as a catalyst or (in Switzerland and the CIS) by the thermolysis of acetone at 600–700 °C in the presence of carbon disulfide as a catalyst.[4]
CH3COOH H2C=C=O + H2O (ΔH = +147 kJ/mol)
CH3COCH3 → H2C=C=O + CH4
The route from acetic acid to acetic anhydride via ketene was developed by Wacker Chemie in 1922,[5] when the demand for acetic anhydride increased due to the production of cellulose acetate.
Due to its low cost, acetic anhydride is purchased, not prepared, for use in research laboratories.

From Wikipedia.

Waffles SS - 27-9-2012 at 23:40

Interesting method:

CH3CONH2+CH3COOH+HCl->(CH3CO)2O+NH4Cl
2CH3CONH2+2CH3COOH+H2SO4->2(CH3CO)2O+(NH4)2SO4


[Edited on 28-9-2012 by Waffles SS]

Attachment: Ac2O by HCl.djvu (21kB)
This file has been downloaded 1093 times

Attachment: Ac2O by H2SO4.djvu (56kB)
This file has been downloaded 998 times


Dave Angel - 28-9-2012 at 09:35

Quote: Originally posted by Waffles SS  
Interesting method

Interesting? I'd say revolutionary - for the home chemist at least; all components are derived from materials available OTC with cash.

A very nice find, let's hope we can get it to work, I was planning an acetamide synthesis for acetonitrile anyway...

Waffles SS - 28-9-2012 at 10:00

I found it on hyperlab.info website,This is russian patent and unfortunately i cant translate it

Dave Angel - 28-9-2012 at 16:34

I have an old Russian-English technical dictionary hidden away somewhere so I'll see if I can pick out the odd useful word or phrase here and there when I get a chance.

The H2SO4 patent mentions 'Noyes and Gobel, Americ. Soc. 44, 1922' which is a reference to the method of acetamide production, described at OrgSyn, and the HCl one makes reference to 130-142° but this could be a boiling range or reaction temperature - who knows?

I'm hoping the percentages in the 90's are yields though :)

manimal - 17-10-2012 at 20:15

The sodium pyrosulfate method works in conjunction with calcium propionate to form propionic anhydride, but the reagents must be well-dried (duh).

The following method was attempted: first, sodum bisulfate was heated in an enameled pan over a medium-high flame. It melted and white smoke began to be evolved after only a few minutes. I found that the bisulfate must be heated strongly for approx. 45 min, during which time smoke evolution is vigorous, in order for it to lose the theoretical amount of weight required to form pyrosulfate (it wouldn't actually be theoretical, since some of the weight loss is due to SO3 formation, but it's close enough. SO3 is effective at producing smoke in small quantities, so a little seems like a lot, and not much is lost).

Commercial calcium propionate was found to be partially hydrated; it was effectively dried by heating in a pan under a medium-low flame, stirring constantly to prevent charring. It first begins to crackle and pop as it loses water. After the popping stops, the salt is dry. A sample dried in this manner was heated in a test tube until it melted and began to char and the odor of diethyl ketone became apparent. No water condensation was noted in the neck of the tube. Weight loss indicated that about half of the commercial propionate was present as the monohydrate.

Sodium pyrosulfate and calcium propionate prepared in this manner were mixed in 1.5:1 molar proportion, respectively, and finely powdered together in a blender. This was placed in a flask with a condenser set up for reflux, and was heated in an oil bath at 200+C temps for one hour, during which time there was some liquid condensate visibly dripping back into the flask. Then, the setup was setup for simple distillation and liquid collected for as long as it would come over. The yield, however, was disappointing: only 15-20%. There is no doubt, however, that the liquid collected contains propionic anhydride: as was mentioned elsewhere, it has a distinct garlic-like odor. A single drop placed in cold water did not dissolve, but sank to the bottom as an oily blob. The powder left over in the flask did not look like it had changed much: it was still loose and powdery. A sample was removed and heated strongly in a test tube, upon which the familiar garlicky odor was detected and condensation appeared on the tube. It appears to be amenable to the formation of anhydride upon strong heating, but the mixture is very refractory. Oil bath temps do not seem to be high enough to drive off the anhydride in high yield. I guess that was the point of the diluent proscribed in the patent.

manimal - 19-10-2012 at 18:52

Would the anhydrous acid refluxed in sodium pyrosulfate yield the anhydride?

ANFO_ - 27-10-2012 at 05:24

I found an interesting patent on the oxidation of acetaldehyde process, which makes use of paraldehyde and a depolymerizing agent which means the reaction doesn't have to be performed under pressure to keep the acetaldehyde from evaporating.

http://www.google.com/patents/US2405471 :)

manimal - 1-11-2012 at 03:32

I found that refluxing the pyrosulfate/propionate mixture (prepared as described above) in a sand bath on high heat for 1-2 hours, and then distilling, gives a more satisfactory yield, around 70-80% :cool:.

There is definitely some subvalent sulfur products forming. A sulfurous stench was apparent during and after the reflux and a yellow deposit formed in the condenser. A post-distillation rinse in bleach removed most of the odor, but not the yellow stain. Something is reducing the sulfate.

[Edited on 1-11-2012 by manimal]

jon - 8-11-2012 at 21:10

your distilling it to hot i've made that mistake and heated this polluted anhydride under vacum and it cleared up the turbidity too.

Polesch - 7-3-2013 at 12:21

This synthesis might not be very useful, but you can prepare acetic anhydride by distilling a mixture of acethyl chloride and sodium acetate. Anybody tried this? I did not read the 28 pages before replying.

mnick12 - 7-3-2013 at 20:36

Yeah,

The acetyl chloride and sodium acetate method has been mentioned here and quite a few other places, and it does work quite well. I would recommend mechanical stirring and look out for charring. Honestly though if you have acetyl chloride I do not really see any reason for converting it AA, that is of course some reaction explicitly calls for it.

cal - 9-4-2013 at 05:41

Quote: Originally posted by S.C. Wack  
As promised, Gmelin. Its enthusiasm is indeed from that JACS article.

Band 61 B5, Seiten 125-6.

2.2.7.2 Thermische Zersetzung

Die Zersetzung von AgCH3COO, die bereits von Chevenix [1] beim Erhitzen über einer Kerzenflamme (starker Geruch nach Essigsäure) beobachtet wurde, setzt bei 210°C ein (Dunkelfärbung), erfolgt hauptsächlich zwischen 220 und 240°C und ist vollständig bei etwa 300°C [2]. Beim Erhitzen im offenen Rohr oder im bedeckten Porzellantiegel werden als Zersetzungsprodukte im wesentlichen Essigsäure und Ag neben wenig C02 und C beobachtet entsprechend 4AgCH3COO ->4Ag + 3CH3COOH + CO2 + C [3 bis 5]. Von Kachler [2] werden als Reaktionsprodukte gefunden (in Gew.-%, nach vorstehender Gleichung berechnete Werte in Klammern): 64.61 Ag (64.67), etwa 26 bis 27 Essigsäure (26.95), 4.09 bzw. 8.42 CO2 (6.59) und 1.21 C (1.79). Auch bei thermogravimetrischer Untersuchung wird als Zersetzungsprodukt (bei 280°C) metallisches Ag und kein Ag2O erhalten [6]. Erfolgt die Zersetzung jedoch unter streng wasserfreien Bedingungen, so werden als Zersetzungsprodukte nur Ag2O und Essigsäureanhydrid erhalten nach 2AgCH3COO -> (CH3CO)2O + Ag2O. Bei der Zersetzung von 2.1077 g trocknem AgCH3COO bei 300 bis 400°C in einem Quarzgefäß unter Argon (1 atm) werden nahezu quantitativ Ag2O (96% der Theorie) und Essigsäureanhydrid (93%) gebildet neben wenig Ag (0.012 g) und CO2 (0.016 g) [7]. Die primäre Essigsäureanhydridbildung ist bereits von Kanewskaja, Schemiakin [8] bei Untersuchung der thermischen Zersetzung von AgCH3COO (im Gemisch mittrocknem Sand) unter einem CO2-Strom von 20 bis 25 Torr angenommen worden. Zwar fanden diese Autoren nur wenig Essigsäureanhydrid neben viel Essigsäure (entsprechend den früheren Angaben von Kachler [2] und Iwig, Hecht [4]), doch ist dies auf die leichte Hydratisierung des Essigsäureanhydrids zurückzuführen, die sowohl durch H2O-Spuren in dem schwer zu trocknenden Silberacetat als auch durch H2O erfolgen kann, das beim teilweisen Zerfall der Essigsäure gebildet wird.
Für die vollständige thermische Zersetzung von AgCH3COO in Gegenwart von H20 muß auf etwa 230 bis 340°C erhitzt werden. Abweichend von der trocknen Destillation wird neben den Hauptprodukten der Zersetzung Ag, Essigsäure und CO2, kein Kohlenstoff gefunden [2].
Über die Darstellung von Ag-Schwamm durch Erhitzen einer getrockneten Paste von AgCH3COO im Tiegel auf 400 bis 500°C s. [10].

...

[1] R. Chevenix (Ann. Chim. [Paris] 69 [1809] 5/58, 19, 22; Ann. Physik 32 [1809] 156/201, 167, 179). — [2] J. Kachler (Monatsh. Chem. 12 [1891] 338/49, 340). — [3] K. Birnbaum (Ann. Chem. 152 [1869] 111/21, 119). — [4] F. Iwig, 0. Hecht (Ber. Deut. Chem. Ges. 19 [1886] 238/42). — [5] J. Redtenbacher, J. Liebig (Liebigs Ann. Chem. 38 [1841] 113/40, 131).
[6] D. A. Edwards, R. N. Hayward (Can. J. Chem. 46 [1968] 3443/6). — [7] A. D. Kirschenbaum, A. G. Streng, M. Hauptschein (J. Am. Chem. Soc. 75 [1953] 3141/5, 3143).— [8] S. J. Kanewskaja, M. M. Schemiakin (Ber. Deut Chem. Ges. 69 [1936] 2152/7, 2154). — [9] V. I. Yakerson (Izv. Akad. Nauk SSSR Otd. Khim. Nauk 1963 1003/11, 1007; Bull. Acad. Sei. USSR Div. Chem. Sci. 1963 914/21, 916). — [10] T. Yamanaka, H. Nidorikawa (Japan.P. 6720 [1956] nach C.A. 1958 10462).

And now, quite possibly pages of off-topic prattle on subjects that have already been discussed elsewhere:


The decomposition of AgCH3COO, already observed by Chevenix [1] when heated over a candle flame (strong smell of acetic acid) is, at 210 ° C. (darkening) is mostly between 220 and 240 ° C and is complete at about 300 ° C [2]. When heated in an open tube or in a covered porcelain crucibles are seen as corresponding to decomposition products mainly acetic acid and Ag next little C02 and C 4AgCH3COO -> 4Ag 3CH3COOH + + CO2 + C [3 to 5]. By Kachler [2] are found as reaction products (in weight -%, calculated according to the above equation in parentheses): 64.61 Ag (64.67), about 26 to 27 acetic acid (26.95), 4.09 and 8:42 CO2 (6.59) and 1.21 C (1.79). Even when thermogravimetric analysis is used as a decomposition product (at 280 ° C) of metallic and no Ag Ag2O obtained. [6] Ie digestion but under strictly anhydrous conditions, so as to be decomposition products only Ag2O and acetic anhydride according 2AgCH3COO -> (CH 3 CO) 2 O + Ag2O. In the decomposition of 2.1077 g dry AgCH3COO at 300 to 400 ° C in a quartz vessel under argon (1 atm) almost quantitatively be Ag2O (96% of theory) and acetic anhydride formed (93%) along with a little Ag (0.012 g) and CO2 ( 0016 g) [7]. The primary Essigsäureanhydridbildung is already Kanewskaja, Schemiakin [8] study on the thermal decomposition of AgCH3COO (mittrocknem mixed sand) adopted under a CO2 stream of 20 to 25 torr. Although these authors found little besides much acetic acid (according to the earlier information of Kachler [2] and Iwig, pike [4]), but this is due to the ease of hydration of acetic anhydride, the H2O to both tracks in the hard drying can be performed as well as silver acetate H2O, which is formed in the partial decomposition of the acetic acid.
For the complete thermal decomposition in the presence of H20 of AgCH3COO must be heated to about 230 to 340 ° C. Notwithstanding the dry distillation is found next to the main products of the decomposition of Ag, acetic acid and CO2, not carbon [2].
Concerning the presentation of Ag sponge by heating a dried paste of AgCH3COO in the crucible at 400 to 500 ° C, see [10].

...

Metacelsus - 13-4-2013 at 06:25

Has anyone tried copper(I) acetate? Might it behave the same as silver acetate?
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