Sciencemadness Discussion Board - Acetic anhydride preparation

Acetic anhydride preparation

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Sauron - 8-3-2007 at 03:27

I see. It is speculative at this point.

Well, I guess you guys can always build yourselves ketene lamps and run the ketene into acetic acid. If I remember correctly this gets you about half a mol an hour.

The hassle is carbonization on the nichrome filament. The OTHER hassle is that ketene will kill you if you let it. But it's a reliable process and as long as you can get acetone or make it from 2-propanol, you are good to go.

If you make 2-3 filament assys you can change them out when one gets dirty and clean that one while the other is working.

The lit. describes scraping the carbon off the nichrome. There must be a better way. Burn it off? Ultrasound? Anyone have any ideas? How about using chlorine or bromine to react with the carbon? Ought to work, especially if the nichrome is electrified to an appropriate temperature. The nichrome ought to be immune, or at least react slowly relative to the carbon. Worth a try?

I'm not going to mess with ketene myself, I have no problem buying TCT, oxalyl chloride, and benzoyl chloride, already have beaucoup TCT on hand. Lucky me.

[Edited on 8-3-2007 by Sauron]

Per - 11-3-2007 at 05:29

Quote:

you ca make acetyl chloride from benzoyl chloride and then react the acetyl chloride with sodium acetate.

Great, I´ve benzoyl chloride but don´t know how to prepare acetyl chloride with it.
Can you give me a instruction for this preparation please?

Or ís it possible to prepare acetyl chloride by reakting acetic acid and Cl2?

Sauron - 11-3-2007 at 05:41

The use of benzoyl chloride to prepare volatile acid chloride (and acetyl chloride is one of the most volatile) is detailed in the H.C. Brown article from JACS in the 1930s attached earlier in this thread. Volatile here means more volatile than benzoyl chloride. You mix the benzoyl chloride in excess with the acid (acetic acid in this instance) and react them under reflux, the acid chloride will distill over. The yield is about 90%, the article gives details. About 12 examples are given including acetyl chloride.

H.C. "Boron" Brown was a very famous chemist. It's a good procedure. Let me know if you can't find it in this thread and I will post it again or else email it to you (PM me with your email address if it is not listed in member directory)

You can also make acetyl chloride from acetic acid (or sodium acetate) and TCT (cyanuric chloride) or oxalyl chloride.

You can make oxalyl chloride from oxalic acid or sodium oxalate and TCT.

But if you already have benzoyl chloride then you are all set.

It is not possible as far as I know to prepare acetyl chloride directly from Cl2. It is possible to prepare acetic anydride from Cl2 or Br2 and sulfur (making the sulfur halide in situ) and anhydrous sodium acetate but it is not very convenient in the case of chlorine unless you preform the SCl2 by running dry Cl2 into molten sulfur, or by chlorinating CS2 over granular activated carbon then distilling the SCl2 from its mixture with CCl3SCl. Nasty stuff! (well, both of them). Then you could convert the Ac2O to acetyl chloride but most of us would go in the other direction.

Anyway all that is the long way round the block compared to the simple elegant benzoyl chloride method.

Link to H.C. Brown article:

http://www.sciencemadness.org/talk/viewthread.php?action=att...

[Edited on 11-3-2007 by Sauron]

Per - 12-3-2007 at 11:09

Thanks Sauron,
theres one more thin:
benzoyl chloride is C7H5OCl, right?
I´ve just C6H5Cl,

I confused them I think.

By this I would say that the Na2S2O7 method is the best for me, theres just the problem with the price of Na2S2O8.

Because we´re talking about chlorination(hope this word exists) I would ask if it´s possible to chlorinate oxalic acid with S2Cl2, ones say that it´s possible and the others say that it wouldn´t work.

Sauron - 12-3-2007 at 12:42

More like;y SCl2 if at all. And starting with sodium oxalate (anhydrous). I have not seen any examples of this reaction in the literature with formation of oxalyl chloride but at least there's analogy to other chlorides.

Oxalyl chloride is best prepared from anhydrous oxalic acid by PCl5 if you have it; and by TCT or TCT/DMF if you don't.

Too bad you have chlorobenzene not benzoyl chloride.

Per - 13-3-2007 at 09:34

I haven´t red phosphorous jet so I don´t have any PCl5 too.
Also would a sulfuric chloride be much cheaper than a phosphorous chloride.

After all S2Cl2 doesn´t work and I imagined that I found a good synthesis for cheap preparation of oxalyl chloride.

I couldn´t find anything about TCT in german, can you give me please a structure or the full name?
But i´ve an suspicion, is it C3N3O3Cl3?

Sauron - 13-3-2007 at 09:55

TCT is cyanuric chloride (CC) an inexpensive feedstock for agro chemicals, it is the trimer of cyanogen chloride. But I am told that in Germany you will have a hard time buying it because they classify it as toxic.

If you do a search on this forum tou will find quite a few threads about CC aka TCT (trichloro-s-triazine) relating to its application to making alkyl chloriced and acid chlorides.

SCl2 not S2Cl2 can chlorinate acetic acid or sodium acetate (anhydrous, fused) and that procedure (using SBr2) can be found on this forum as well as in Rhodium archive.

If you can't find the CC/TCT refs let me know and I will dig them up for you. But they won't do you much good if you can't buy CC, and you can't really make it yourself unless you like working with neat HCN and anhydrous HCl. CC is a pungent solid easily manipulable and I do not know what the fuss is about, I have many Kg of it in my house.

By the way do not confuse it with TCCA which is related but not same. That is trichloroisocyanuric acid.

garage chemist - 13-3-2007 at 10:10

TCT is a chemical which has until now not been mentioned on the german forums. It is not available OTC, and it is classified as T+. You would have to order this from a chemical supplier via e.g. a pharmacy which is willing to cooperate.

Sauron - 13-3-2007 at 18:29

If in Germany you can buy SOCl2 more easily than CC/TCT then why not do so and use that to make your benzoyl chloride? Or use whatever method to make benzoyl chloride that is available to you, then employ the benzoyl chloride to make oxalyl chloride and you are home free.

If you want to prepare SCl2 by chlorination of molten sulfur the hassle is that a lot of sulfur will remain dissolved in the resulting mixture of SCl2 and S2Cl2. The product needs to be distilled at reduced pressure and still tends of throw a thin layer of S on all glass surfaces. The best technique for obtaining a pure and unequivocal SCl2 is to slowly run it through a column of granular AC at 40-60 C and all S2Cl2 is converted to SCl2. I have references in English and German on this if you want them. The technique is used to remove S2Cl2 from the mix produced by chlorination of CS2 which simplifies distillation of the mix, prior to reducing one of the two components (CCl3SCl) to CCl4 with iron filings. That is the best way to make SCl2 by the way and gets you CCl4 besides. the hassles are that CS2 is so flammable, and that the intermediates stink and are corrosive and toxic.

S.C. Wack - 15-3-2007 at 02:28

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:

Sauron - 15-3-2007 at 03:00

Some members, despite these issues having been covered in other threads, obviously still are perplexed about how to achieve very simple and basic transformations such as Ac2O, acetyl chloride, propionyl chloride, benzoyl chloride, oxalyl chloride etc. @Per seems neither lazy not stupid and I'd rather be helpful than just brush him off with a "Use the search engine" or some such dismissal.

If for helping a fellow member I earn only scorn from you, well, then I don't want your approval.

Per - 17-3-2007 at 10:50

Yes, I should search before I´d ask some questions.

I would prepare my SCl2 by chlorination of sulphuric under boiling CHCl3.
The problem with SCl2 is that I can´t distill it without vacuum because it´s decomposing at 59°C.
Maybe I could try to produce it with S2Cl2 and Cl2 ( should work with liquid Cl but I don´t know if it´s work with the gas).

I don’t know if it’s easy and cheap to buy SOCl2 in Germany (would inform me about that).

And thanks for helping me and the Gmelin instruction.

Sauron - 17-3-2007 at 13:25

You can't make SCl2 from S2Cl2 and Cl2

That's because you make S2Cl2 from SCl2 and Cl2!

When chlorinating molten sulfur SCl2 forms first and continued chlorination gives S2Cl2. In practice this is complicated by the great solubility of sulfur in SCl2 (60%) and you will always have a mixture of SCl2 and S2Cl2 plus dissolved sulfur in the pot. You need to continue chlorinating till all the sulfur is reacted and that means you predominantly have S2Cl2.

You can follow the progress of the reaction by weight.

As it is SCl2 you want, and not S2Cl2, you convert the mixture to pure S2Cl2 by passing it through a granulated AC column at c.60 degrees as detailed by Rupp and Meyer.

I can give you the references.

It is actually easier though no less unpleasant to chlorinate CS2 which afford you about half CCl3SCl and halg SCl2/S2Cl2 and you pass this mixture through such a column and eliminate the S2Cl2. Then it is easy to seperate the remaining two components by fractionating under reduced pressure. The CCl3SCl you can use to prepare CCl4 by treating it with Fe filings.

My guess is that you will have a hard time buying SO2Cl2 in Germany but it is easy to make - although once again, irritating and smelly. SO2Cl2 is prepared from SO2 and Cl2 by passing them through yet another GAC column bed (this time with cooling). Camphor is also a good catalyst for this.

[Edited on 18-3-2007 by Sauron]

Per - 18-3-2007 at 00:37

Then maybe it´s the best way for me to only produce S2Cl2 which seems to be very easy.

The difficult with CS2 is that it´s very expensive. Sulphur cost´s me much less than CS2, 1kg just a few €.

I don´t know how strong the separate chlorination reagences are, so I don´t know if it´s worth to produce some else than S2Cl2, is there a big difficult between S2Cl2 and SCl2, SO2Cl2?

How is the rating of them, maybe:
S2Cl2 < SCl2 < SO2Cl2 ?

Sauron - 18-3-2007 at 00:51

For the preparation of Ac2O you want SCl2 not S2Cl2. I do not know of any way to easily end up with only S2Cl2 anyway because it disproportionates to SCl2 on standing anyway and in the chlorination of S there will always be both products plus dissolved sulfur.

The Rupp-Meyer method is good for purifying SCl2 not S2Cl2.

Their method applies both to the mixture from chlorination of CS2 and to the mixture from chlorination of molten sulfur.

I will prepare a zip file of the articles and patents and attach for you. The information you need is in there, you will need to read a bit to find it.

[Edited on 18-3-2007 by Sauron]

Attachment: AF.zip (1.1MB)
This file has been downloaded 957 times

Per - 18-3-2007 at 01:46

Thanks for the zip file,
I would try the synthesis with sulfur and CHCl3 and talk about the results later.
If I distil the reactions product after I distilled the CHCl3 away I should obtain pure S2Cl2 I think, firstly S2Cl2 should be enougt.

Sauron - 18-3-2007 at 11:12

Pardon me, what reaction of S and CHCl3 to give S2Cl2? I have never heard of such a reaction. References please.

Once again why do you want S2Cl2? Because I thought you wanted to make Ac2) and S2Cl2 is useless for that.

Also SO2Cl2 is useless for that.

With some effort you can make SCl2 from S2Cl2 or from SO2Cl2 but that is going long wway round.

If you want these for other purposes just say so.

Per - 19-3-2007 at 06:48

The CHCl3 doesn´t react in my synthesis, it´s just a solvent for the sulfur because when the sulfur is molten it´s very nasty to clean the reaction bottle. While the reaction you have to condense the CHCl3 in a reflux cooler but you´ve to heat just to 61°C, these are big advantages against the method with molten sulfur.

With the S2Cl2 I want to try to make Oxalic chloride and I want to prepare it because I haven´t it until jet.
I would try to make the Ac2O otherwise, maybe it´s a good method to make it with Na2S2O7 which I´ve to get from Na2S2O8 which I got from Conrad electronics.
That woudn´t be a cheape but easily.

Sauron - 19-3-2007 at 09:02

Well, I wish you luck trying to make oxalyl chloride with S2Cl2. That would be quite novel.

I only know two methods to make this:

oxalic acid and PCl5

Oxalic acid and TCT (or sodium oxalate and TCT)

Per - 21-3-2007 at 08:52

Now other persons told me that it wouldn´t work with S2Cl2, but it should work with SOCl2, but the gases (SO2, HCl) would make the yield low.

If I´ll find an cheap supplier I´ll try this method.

Sauron - 22-3-2007 at 04:31

According to Ullmann's (2003) CD edition, vinyl acetate (cheap solvent) can be reacted over Pd(II) catalyst (most likely PdCl2/CuCl2 system) to give a mixture of acetaldehyde and acetic anhydride, and that formerly this was an industrial process for acetic anhydride production. They also mention ethylidene diacetate but that is a LOT more expensive so don't bother with it. Vinyl acetate 2.5 L from Acros $33.3 US, ethylidene diacetate 100 g same supplier $122 US.

Ref: Ullmann's 3 ed 6, 804. I do not have access to this print edition, this was cited in the CD-ROM damn it. Can anyone obtain the details?

Also the 2003 edition CD describes reaction of three chlorinating reagents with sodium acetate in a two stage reaction. First stage one eq acetate reacts to form acetyl chloride, second stage the acetyl chloride formed in situ reacts with second eq sodium acetate to give acetic anhydride.

The three usable chlorinatign reagents are:

SOCl2
SO2Cl2
POCl3

My comments are: the sodium acetate needs to be anhydrous (freshly fused). Otherwise water will use up reagent and depress yield.

Also, I would add the following reagents to the list:

TCT (CC)
Oxalyl chloride (not reacted w/sodium acetate but with acetic acid in appropriate ratio produces either acetyl chloride or acetic anhydride per Roger Adams in JACS articles 1916-1920. Furthermore you can make oxalyl chloride from TCT w/oxalic acid (anhydr.) or sodium oxalate (anhydr.)

So your choice of the above depends on what you can get. Need we poit out that thionyl, sulfuryl, oxalyl and phosphoryl chlorides are operating here not as chlorinating agents per se but as dehydrating agents?

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

Kirk-Othmer has a little bombshell hidden well away. In a small section of their Acetic Anhydride monograph devoted to prosspective future processes they mention a 1930s Russian discovery that they deem to still be of some potential. The dry reaction of anhydr. sodium acetate with dinitrogen tetroxide (N2O4) produces acetic anhydride and sodium nitrite in 85% yield. See Ref.48 which is a trio of abstract citations, two in C.A. and the third in Chem.Zentr. They point out the favorable economics of this reaction as the N2O4 is regenerable.

V.M. Rodionov, A.I.Smarin, T.A.Obletzeva, C.A. 30, 1740, 4149 (1936)

V.M.Ridionov, T.A.Obletzeva, Chem.Zentr. 1938(II) 4054

V.M.Rodionov, T.A.Obletzeva, C.A. 34, 6572 (1940)

2 NaOOCCH3 + 2 N2O4 -> (CH3CO)2O + 2 NaNO2 + N2O3

The reaction proceeds according to:

This is extremely tantalizing as both Ac2O and NaNO2 are highly desirable.

Incidentally Kirk-Othmer states that the Russians reported sodium propionate was converted in similar high yield to propionic anhydride and sodium butyrate to butyric anhydride. This ought to pique the interest of those who are into such reagents.

[Edited on 23-3-2007 by Sauron]

S.C. Wack - 23-3-2007 at 02:41

Pd may not be necessary with vinyl acetate. See US1856251, which may work as detailed there or not.
The oxychlorides of Si can also be used with acetate salts, not that they are any more OTC than the SiCl4 already mentioned.
US1870601 claims AA from hydrolysis above the BP of the banned TCE solvent methyl chloroform, without providing an experimental.
The N2O4 citation has already been mentioned in this thread.
Yeah, I'm so way off base; and unable to see how people are, and make predictions based on this.

Sauron - 23-3-2007 at 03:02

Kirk-Ohmer mentioned two other "prospective" routes but these seemed so far fetched that I have paid little attention to them, I will review them here for sake of completeness.

Ethylene + carbon oxides -> ketene according to a French patent

Sodium acetate (aq) + carbon dioxide -> sodium bicarbonate + Ac2O

The problem with second being how to get the anhydride out of the water before it is destroyed, the devil is always in the details. Another French patent.

Kirk-Othmer also mentioned the dry distillation of metal acetates including silver and copper and nickel but not lead. They recited various obstacles to the industrialization of this simple method, mainly limitations on solid handline and a lack on knowledge of process details. The latter seems a bit weak. More excuse than reason.

Sauron - 23-3-2007 at 05:33

@S.C., those two US patent number you cited appear to be wrong, two different patent sites rejected them (www.freepatentsonline.com and patentstorm) and Google drew a blank.

Can you let me have inventor name and/or date?

Tacho - 23-3-2007 at 08:00

Quote:

Kirk-Othmer also mentioned the dry distillation of metal acetates including silver and copper and nickel but not lead. They recited various obstacles to the industrialization of this simple method, mainly limitations on solid handline and a lack on knowledge of process details. The latter seems a bit weak. More excuse than reason.

Simply dry distilling something like copper acetate sounds really simple. Too simple, in fact. However, it would not be the first time I see a thread several pages long discussing complicated routes to a product that has one rather simple sinth.

Sauron - 23-3-2007 at 11:21

Thee and me. However, you also see I'm sure that a lab bench procedure that might work, is not the same as a route to 20-50 Kg/day of product process (which is still just a prototype or pilot scale) much less an industrial process. I'm not a CE of any sort, just an old wet lab synthesist out to seed, but even I can see that those anhydrous tansition metal or heavy metal acetates have a rather small percentage of acetate relative to metal and that therefore even if they are succesfully induced to give off Ac2O there won't be much of it per Kg starting material or Kg of metal oxide fused crap left in the pot that has to be removed somehow or else the flask needs to be trashed after every run. I used to know a guy who made P2P by dry distillation of lead acetate and phenylacetic acid, a procedure he found in a 1920s entry in CA from a Japanese forensics journal. Japan had a huge meth problem 80-90 years ago, and this dry distillation was main process for making phenylacetone. The mix would sit nicely as a melt until the P2P would flash off and a solid block of lead was left behind in the flask. He tried everything including RFNA to dissolve that but in the end he had to throw away a lot of 1 iter 3-necked 24/40 flasks.

So let's just say I am skeptical about the practical aspects of making Ac2O from metal acetates the dry way.

S.C. Wack - 23-3-2007 at 14:43

There is nothing wrong with my patent numbers, only the crap sites that you use to look them up.
http://ep.espacenet.com/numberSearch?locale=en_EP
http://patft.uspto.gov/netahtml/PTO/srchnum.htm

Those other things you say K-O says have already come up here also. There is no secret information that only K-O knows. Nor are you the first here to install Ullmann's or K-O by far. CA (usually), Beilstein, and Gmelin's have everything worth mention. What is missing is the usually foreign-language journals that they reference that give the essential details that none of the blurbs ever contain.

Sauron - 23-3-2007 at 20:44

I have been using www.freepatentsonline for several years and while I think their search engine sucks, for a situation where I have patent number they are fast and reliable and easy. And they are free. Recently they did a redesign and perhaps they now have a cutoff date, which would be annoying if true. Previously older patents were not available except as PDF or TIFF images but they were available. I have many many such patents retrieved from this site.

I do not share your view that this site is "crap" - a description you also chose to apply previously to my browser for no apparent reason, without even knowing which browser it was.

So I am obliged to come to the conclusion that you are an ill mannered, ill tempered lout of a curmudgeon and unfit for human society. Rarely have I encountered as obnoxious a piece of work as you. Kindly stay the hell away from my posts in the future. I am not interested in communicating with you in any fashion.

By the way and FYI I used to suscribe to Delphion when it was $75 a month. Then Thomson took it over and it quickly climbed to $125 a month and I cancelled. In my experience www.freepatentsonline is almost as useful as Dephion used to be but without the rapine and avarice that Thomson introduced.

S.C. Wack - 24-3-2007 at 05:22

Quote:

Originally posted by Sauron
Kindly stay the hell away from my posts in the future. I am not interested in communicating with you in any fashion.

This does not match what you said above. You asked and I replied. Tough shit if you don't like what I have to say. You say a perfectly fine image must be resized in your erased post, so I call bullshit on your browser. So what? You can't find US patents with your crap patent-finding sites, so you know what? That makes them crap sites. Really. I will not hesitate to say whatever I feel appropriate in response to your posts, so sorry. No trolling or games, just an honest desire for a better forum combined with straight talk. Read all of my posts, and the many posts that I haven't made, and see if this can be doubted. Feel free to argue with any and all of my posts as well. Now, don't get the impression that I actually care what you think...

On-topic, to clarify my point about K-O, it is a great compact reference for certain data, but it gives false impressions due to the spare language that it uses, and its references when looked up are generally impractical on anything but an industrial scale.

jimmyboy - 24-3-2007 at 07:07

ooooo catfight.. you guys are totally ridiculous... can we please focus on the question at hand here -- if you want to flame each other take it to private messages...

Anyways i was wondering about just drying out glacial acetic acid with sodium...

Acetic anhydride can also be dried by standing with Na wire for up to a week, removing the Na and distilling from it under vacuum. (Purification of Laboratory Chemicals 4ed. pg 66)

Since all the other routes involve ketene and hydrogen sulfide and all sorts of wonderful nasties.. as far as i know sodium won't kill you - it may burn or blow up under the right conditions but it wont make you die usually.. and is fairly easy to make as well - slow but makeable -- this won't be fast (a week) -- but you won't have to worry about fume hoods or the batf knocking down your front door.. the only other drying agent i saw was P2O5..

Sauron - 24-3-2007 at 07:18

"Drying" Ac2O is a unique concept since Ac2O reacts with water, and is a well known dehydrating agent for many reactions itself.

Likewise any mixture of AcOH and Ac2O that contained moisture, would not contain moisture for long, would it? Save your Na wire for something that needs it.

not_important - 24-3-2007 at 07:46

Quote:

Originally posted by jimmyboy...
Anyways i was wondering about just drying out glacial acetic acid with sodium...

Acetic anhydride can also be dried by standing with Na wire for up to a week, removing the Na and distilling from it under vacuum. (Purification of Laboratory Chemicals 4ed. pg 66)
...

Acetic anhydride doesn't react with sodium in the cold, it has no free reactive/acidic hydrogen. The sodium reacts with traces of water and/or acetic acid in the anhydride.

Acetic acid does have an acidic hydrogen, which will react with sodium to give hydrogen and sodium acetate and a fair amount of energy. As someone who has tossed a 2.5 kg chunk of sodium into water, I can say that such reactions can be quite exciting and best viewed from a distance.

Per - 24-3-2007 at 09:54

Quote:

2 NaOOCCH3 + 2 N2O4 -> (CH3CO)2O + 2 NaNO2 + N2O3

Thanks Sauron, that seems to be a great reaktion if it´s working.

NO2 is easy to make but I tried to condense it further and it doesn´t work althougt it´s boiling point is 21°C.

Have the N2O4 and NaOOCCH3 are only mixed in the cold or is there something else to look after?

Don´t know if it´s discussed in this board further so I´m asking for it here, how can NO2 condensed to N2O4?
Is a Liebig-cooler and -10°C enougt?

jimmyboy - 24-3-2007 at 10:01

Well - it doesnt give many details on the how and technique used in the book -- I had my doubts as well - I guess we are kind of stuck with a ketene lamp and a ton of scrubbers..

Sauron - 24-3-2007 at 17:18

I'd go lower than -10 for the coolant, and use a high surface area condenser rather than a simple Liebig.

I was told that this reaction was mentioned earlier in the thread but I have not been able to locate those posts so far.

S.C. Wack - 24-3-2007 at 21:49

The abstract strongly suggests that the N2O4 was in the gas phase and does not mention temperature, amounts used, time, etc.

edit:

http://www.sciencemadness.org/talk/viewthread.php?tid=1937
http://www.uspto.gov/patft/help/images.htm

The images display fine for me, but I rarely use uspto, and all of my direct patent links that I post are to espacenet pdf. They have available pretty much every patent ever, however. Pre-1976 patents are as TIFF, that is just how it is, and even alternatiff is better than chem patents in HTML or whatever that is as on newer patents and other sites IMHO.

[Edited on 25-3-2007 by S.C. Wack]

Sauron - 24-3-2007 at 22:07

I just went to the UG Patent Office web site as recommended by one of our illustrious fellow members located at

http://patft.uspto.gov/netahtml/PTO/srchnum.htm

and I pasted in the US patent number he cited into the box indicated and was informed full test was unavailable and to click on IMAGES. I did so and sat and waited and waited and waited.

Nothing came up.

What bullshit is this?

US1856251
US1870601

Anyone else have any luck retrieving these rather elderly patents? If so kindly post the pdf's here.

I have retrieved hundreds of patents over the years some of them older than these, without any difficulty.

[Edited on 25-3-2007 by Sauron]

not_important - 24-3-2007 at 22:12

Quote:

Originally posted by Sauron
I just went to the UG Patent Office web site as recommended by one of our illustrious fellow members located at

http://patft.uspto.gov/netahtml/PTO/srchnum.htm

and I pasted in the US patent number he cited into the box indicated and was informed full test was unavailable and to click on IMAGES. I did so and sat and waited and waited and waited.

Nothing came up.

What bullshit is this?
...

Do you have a TIFF viewer plugin?
.

Sauron - 24-3-2007 at 22:19

I have Photoshop and ACDC both recent versions. When www.freepatentsonline.com pulls up an older patent which they do from same USPTO database they give me a choice between TIFF and PDF. I never did get TIFF to work right, but PDF always works.

Why won't these TIFF images just come up in Photoshop or ACDC?

Anyway I Googled "TIFF viewer plugin. One of the links was to the USPTO site so I went there and they linked to a plugin called InnoVUE 7.0. I downloaded and installed it. It halfway worked, in that I could now view the patent images but as soon as I tried to save it shut down my browser. Several times. So I uninstalled it. Went and found another plugin called AlternaTIFF and this one works fine.

I still do not see why this is necessary. But whatever. I now have these two old and admirably brief patents so I can see whether or not they were worth the bother.

I suppose all this is because TIFF is not a native Internet graphic format like GIF, JPG or PNG? However that then begs the question of why USPTO used TIFF instead of JPG damn it. I hate having to jump through hoops for bullshit like this.

Fortunately the two patents were indeed interesting and if in fact they work, useful. The second one of more limited utility because it depends on access to 1,1,1-trichloroethane which is banned in many places.

[Edited on 25-3-2007 by Sauron]

Eclectic - 25-3-2007 at 04:54

Have a look at http://www.espacenet.com/

You can do worldwide patent searches and download the complete patent in one PDF.

Sauron - 25-3-2007 at 19:52

Thanks @Eclectic.

Hmmm. If 1,1,1-trichloroethane can be hydrolyzed by water and catalyst (H2SO4) in an autoclave to acetic acid, acetyl chloride, or acetic anhydride (depending on ratio of water to tric) then doesn't it seem reasonable that hexachloroethane would hydrolyze to oxalic acid or oxalyl chloride similarly? There isn't any oxalic anhydride of course.

On the other hand hexachloroethane is a solid so one of the conditions (raising it above bp at normal pressure) might be a trifle hard.

Just thinking out loud.

The reaction described in US 1,856,251 is between vinyl acetate and acetic acid in presence of acid catalyst e.g. H2SO4, ZnCl2, CoCl3, Cl2, FeCl2 etc. Liquid phase reflux 10 hrs with stripping of acetaldehyde formed through a fractionating column. Claim is made that 77% acetic anhydride present in reaction mix (after acetaldehyde removed) along with unreacted VA and by product ethylidene diacetate, and that fractionation of this mix allows 95% recovery of that Ac2O.

Industrially this facile process (even if it works) would be of limited value since after all, how is VA made? From Ac2O and acetaldehyde. However for the rest of us this process may well be highly useful.

Compare to Gulf Research's reported reaction of vinyl acetate in AcOH soln containing sodium acetate and catalyzed by PdCl2. This requires 24 hrs, with 55% conversion of VA to approximately equimolar amounts of acetaldehyde and Ac2O. The catalyst cost is high (about one mol (177 g) PdCl2 per Kg Ac2O produced) and that is expensive even though PdCl2 is not consumed and can be reused. ZnCl2 was inactive with these reactants under these conditions.

An obvious difference is that the patented reaction employs the carboxylic acid as reactant with VA while the Pd(II) catalyzed reaction employs sodium acetate. An examination of the mass balance indicates that the sum of the masses of the Ac2O and acetaldehyde produced is greater than the VA consumed. As the reaction will not proceed in absence of the sodium acetate it appears that sodium acetate is being consumed. Perhaps it is regenerated from the AcOH solvent in which case the amount of solvent will be down. The authors are silent on these points. In any case ecpnomically this reaction with this catalyst is as dead as a herring in the moonlight.

The patented reaction produces acetaldehyde which can be oxidized to AcOH and utilized in next batch; and ethylidene diacetate which is added to next batch and is alco converted to Ac2O and acetaldehyde. All this is attractive and convenient - if it works.

[Edited on 26-3-2007 by Sauron]

12AX7 - 25-3-2007 at 19:54

Quote:

Originally posted by Sauron
There isn't any oxalic anhydride of course.

Why not? And why not polyanhydride species?

Tim

not_important - 25-3-2007 at 20:20

The anhydride would be a three member ring - an oxirane - with the additional strain caused by the two carbonyl oxygens. A polymeric, even dimeric, compound would have less such stress, true.

You can get oxalic anhydride as a transition state or under goodly amount of pressure.

Attachment: oxalate_from_CO2&CO.pdf (345kB)
This file has been downloaded 2252 times

Sauron - 25-3-2007 at 21:23

Even oxalyl chloride isn't quite as stable as we would like, which has always limited its utility beyond the bench scale.

Per - 28-3-2007 at 08:00

Quote:

I'd go lower than -10 for the coolant, and use a high surface area condenser rather than a simple Liebig.

Ok, then I´ll try it again with -20°C cool alcohol.

When I find the time for the experiment I´ll try it out and post here my experience, but that can take still much time, because I´ve some other thing to do.

Sauron - 28-3-2007 at 17:53

Liquification is only necessary (I suspect) if you want to accumulate and store N2O4 in a Dewar or cylinder.

Else just generate and dry it and run it into the reactor as it forms.

Also, did you see the posts on vinyl acetate acetylation?

Vinyl acetate is cheap and readily available. VA + acetic acid catalyzed by mineral acids or Lewis acids -> acetaldehyde and acetic anhydride. Claimed 77% Ac2O in product mic and 95% recovery of that. H2SO4 suffices. HCl and HBr also work. Lewis acids divalent chlorides of Zn, Cu, Fe. Also arylsulfonic acids and sufur halides claimed. See US patent referenced above.

Per - 29-3-2007 at 02:44

I think it´s much more convenient to work with solid N2O4 than with NO2 gas, also the yield should be higher if a solid is used, but if I can´t condense the NO2 I´ll try it with the gas.

Firstly I prefer this method because I claime all necessary chems for it and because NaNO2 is also obtained, but the vinyl acetat method seems also to be very interested.

Sauron - 29-3-2007 at 19:04

I'm sure many of us look forward to hearing how the N2O4 method works out.

Good luck with it!

garage chemist - 29-3-2007 at 23:37

I would use gaseous NO2, lead through anhydrous powdered NaOAc in a glass tube if I were to try this process.

NO2 is not so easy to dry- H2SO4 reacts with it, forming nitrosylsulfuric acid. CaCl2 would form nitrosyl chloride, at least to some extent. Silica gel would probably adsorb NO2.
What would be a preferred method of drying NO2? P2O5, yes that would be ideal, but not suitable if the gas is quite wet in the beginning. A drying agent with higher capacity, and not so high intensity, is needed first.

Sauron - 30-3-2007 at 00:02

Brauer gives drying directions. His prep of N2O4 is from lead nitrate. He freezes out the majority of moisture with first trap at -10--20 C, then passes through PbO2 and finally P2O5 before liquifying at -78 C (obviously dry ice/acetone trap).

Gives a tantalizying reference to extra pure N2O4/NO2 from N2O5 but I don't think that is necessary for this purpose.

Pages 488-489 from Brauer attached.

[Edited on 30-3-2007 by Sauron]

Attachment: Pages from brauer_ocr.pdf (79kB)
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Per - 30-3-2007 at 04:18

Firstly I wanted to use CaCl2, but when there´s NOCl envolved I´d use MgSO4 as drying reagence.

Also I´d prepare the NO2 with lead nitrate which I´ve to produce in the next days.

Hope that 350°C are enought to make the NO2.

Sauron - 30-3-2007 at 05:24

Merck Index is silent regarding melting point, Brauser does not state reaction temperature for prodn of NO2, Acros says mp of lead nitrate is 470 C. So I would seek further information about decomposition to nitrogen dioxide if I were you.

Brauer did specify high melting glass, which is not very specific is it? Anything from Pyrex to Vycor could be implied.

Also you need a slow stream of O2.

Per - 31-3-2007 at 07:31

I don´t understand why I need a O2 stream, because O2 is already produced in this reaktion.

Also I still produced Pb(NO3)2 and there were little problems, in the first time just a white powder were produced, I think it has to be PbNO3 but heating the reaction mixture longer gaves a clear solution.
With that I´d try it out if 350°C are enougt, but firstly it has to be dry.

S.C. Wack - 1-4-2007 at 02:00

I had until now forgotten that I have a 1913 patent on the N2O4 method.

Per - 2-4-2007 at 05:13

Now I’ve tried the method with Pb(NO3)2.
Firstly drying the lead nitrate solution was really nasty, and then I heated the white crystals (looking like TATP) to about 350°C and nothing happened.
Then I heated a few crystals in an reagence glass an heated them with an burner. It envolved a red gas looking like NO2, so this method was successful.
Soon I produce more Pb(NO3)2 then I can try the Ac2O synthesis.

Patente:
In the patente is mentioned that the NO2 + CH3COONa process is really successful to produce Ac2O and that it´s possible to produce a Ac ans Ac2O mix by heating concentrated HNO3 and lead the gases into sodium acetate.

Per - 5-4-2007 at 06:04

It took a long time but now I´m the proud owner of 401g dry lead nitrate.

In the morning I tried to produc Ac2O, I lead the brown NO2 gases over dry sodium acetate.
And what should I say, after a few minutes the cristals converted into white cristals and I coud recognice a small amount of a solid.
Now I need a good idea to recover the solid from the NaNO2.
Have anybody any ideas?

Sauron - 5-4-2007 at 06:16

Did you dry your NO2 as described in Brauser?

Cold trap for gross moisture then PbO2 then P2O5?

What do you reckon the solid might be and why is there no Ac2O formed?

Per - 5-4-2007 at 08:07

I don´t know if theres Ac2O formwed or not.
I just can say that there´s envolved a solid after I lead the dry NO2 gas into the sodium nitrate and that the layer of the sodium cristals changed.

But now I need a method to isolate the Ac2O from the NaNO2 which is formed while the reaction.

My feeling says that there´s formed Ac2O.

Sauron - 5-4-2007 at 08:47

@Per, wash the solid with a solvent that dissolves Ac2O but not NaNO2 or BaOAc. Filter. Then remove solvent. What's left is your product.

The lead nitrate method does not produce a whole lot of nitrogen dioxide per unit of weight.

What is your objection to the reaction of HNO3 with Cu metal? If you subject the gas stream to same rigorous drying as with lead nitrate won't this be just as satisfactory?

Per - 5-4-2007 at 09:01

Quote:

Mr per in what temp the leadnitate decompose to no2 and pbo?

At 350°C it decomposes definitively not, then I used a burner and it worked but I didn´t measure the temperature,
think that 470°C could be right.

What solvent would you suggest, maybe CHCl3?
But that would maybe react with the rest of the sodium acetate.

Quote:

The lead nitrate method does not produce a whole lot of nitrogen dioxide per unit of weight.

That´s right, but when I use Cu(NO3)2, I´ve very much copper nitrate which I don´t need and drying copper nitrate is very difficulty.
And PbO could easyly regenerate with HNO3.

Sauron - 5-4-2007 at 09:35

Try something more inert like petroleum ether or toluene. Look up to double check they won't dissolve the Na salts but I would not expect them to.

Also I don't know what rxn you would expect between NaOAc and chloroform?

Sauron - 5-4-2007 at 21:58

When I was a teenager I "discovered" a reaction that I have never bothered as an adult to elucidate.

Sodium thiosulphate (powder) and conc HNO3 -> lots of brown gas presumably NO2 + elemental S and apparently water.. Maybe some sodium nitrate.

Obviously some sort of redox, if anyone knows what the stoichiometry is I'd like to hear it. Also whether or not any other gases are evolved besides nitrogen oxides.

guy - 6-4-2007 at 01:26

S2O32−(aq) + 2H+(aq) → SO2(g) + S(s) + H2O

source Wikipedia

Sauron - 6-4-2007 at 01:47

SO2 is not rich dark red-brown. SO2 is colorless. I am well familiar with the smell of SO2 having made a lot of it and what I made was at least predominantly NO2.

Try it for yourself but don't breathe the results.

Per - 6-4-2007 at 07:26

Quote:

Also I don't know what rxn you would expect between NaOAc and chloroform?

I thought that maybe NaCl could be formed but that´s just an idea.

Sure that toluene and petrol ether aren´t react with NaNO2 when I want to purify it by evaporating the rest of the solvent?

Sauron - 6-4-2007 at 07:49

No reaction I ever heard of.

guy - 6-4-2007 at 14:02

Quote:

Originally posted by Sauron
SO2 is not rich dark red-brown. SO2 is colorless. I am well familiar with the smell of SO2 having made a lot of it and what I made was at least predominantly NO2.

Try it for yourself but don't breathe the results.

Yeah Im sure SO2 also reduces nitric acid in the process. So there are 2 reactions happening. One forms sulfur and one forms NO2.

Sauron - 6-4-2007 at 20:57

That is perfectly resonable.

It is an extremely rapid process, as I recall, and not a slow evolution. If you throw thiosulfate crystals into HNO3 you get an instant large cloud of NO2 (at least mostly)

I never tried dripping HNO3 slowly onto thiosulfate but that might serve as a NO2 generator. If we can figure out the stoichiometry this might serve as basis for a NO2 generator, and have neither the large residue of Pb oxide nor copper nitrate that are the bugbears in the lead nitrate pyrolysis and the dissolving-copper processes.

Will there be any SO2 to scrub from the NO2 stream? I don't know.

Per - 8-4-2007 at 03:46

Is it also possible to use acetone as solvent?
It´s cheaper and it´s boiling point is more convenient, but I don´t know if it´s too reactive.

Also could somebody try the prepartion with Cl2 instead of NO2, when NaCl is formed the Ac2O could be easily distilled.

chemicalpower - 8-4-2007 at 11:21

how is acetic anhydride identified
like what are the basic tests for identifying or telling if a chemical is acetic anhydride or not

not_important - 8-4-2007 at 11:45

Quote:

Originally posted by chemicalpower
how is acetic anhydride identified
like what are the basic tests for identifying or telling if a chemical is acetic anhydride or not

Boiling point
Density/Specific gravity
Refractive index
React it with an alcohol and verify the ester's boiling point
React it with aqueous ammonia to form acetamide, and with aniline to form acetanilide, recrystallise and confirm proper melting point.

Sauron - 8-4-2007 at 19:17

Boiling point is easy. AcCl boils low, AcOH 117, Ac2O 140.

AcOH is nonflammable, Ac2O is very flammable. Remember that.

Density is easy, even without a set of hydrometers

All you need is a scale and a volumetric flask

Refractive index you need a refractometer or access to one

vulture - 9-4-2007 at 04:14

Quote:

Sure that toluene and petrol ether aren´t react with NaNO2 when I want to purify it by evaporating the rest of the solvent?

Only if you boil it down so vigorously your solvent catches fire...

Per, learn the basics before cluttering this thread with obsolete questions. Crawl first, then walk.

tupence_hapeny - 9-4-2007 at 10:22

Would P2O5 do the trick, I know it can be used to make some anydrides, however, I am unsure if it will do the trick with this one?

If it will, look up how to make Calcium Phosphide, as the phosphine given off by its reaction with water burns in oxygen to make P2O5... Or use the zinc phosphide method in this patent (which produces zinc phosphate as a byproduct - which is also the first stage of the synthesis)

http://www.freepatentsonline.com/4128620.html

In a related area, if H3PO4 is dehydrated (at a low red heat) with charcoal, it is transformed (at around 250C) to pyrophosphate and then at the low red heat to metaphosphate (HPO3) which is supposed to be almost as good a dessicant as phosphorus pentoxide.

http://www.freepatentsonline.com/4082677.html (A patent for drying phosphoric acid by absorbing into wood shavings and heating to 200C in the oven - turning the wood to carbon in the process).

I think the phosphoric/phosphorus acids are soluble in some organic solvents too aren't they?

If so, make the metaphosphate - using dry everything extract it with an organic solvent (dry for preference) and mix that with the glacial acetic acid. Presumably the acetic anhydride could be distilled off the pyrophosphoric acid (made by absorbing water into metaphosphoric acid).

However, Nicodem has already said that these acids aren't nice to glassware.... be quick, be careful.

tup

PS I have no idea if this works, I believe it very well might, however, finding out is up to whomever wants to try it out. If the metaphosphoric acid works (metaphosphoric acid is what reacts with iodine to make HI in the synthesis on Rhodiums page - thus the 400C temperature from phosphoric acid before the reaction starts), and it COULD being an acid anhydride itself, that would be great - if it does not, the pentoxide is supposed to work.

[Edited on 10-4-2007 by tupence_hapeny]

Sauron - 9-4-2007 at 11:41

The short answer is no, theose won't work, or aren't practicable, and anyway they have already been discussed in detail in this thread and elsewhere.

tupence_hapeny - 9-4-2007 at 12:51

What precisely is the problem with the concept?

If not the concept that a dehydrating agent will in fact dehydrate a carboxylic acid – giving an acid anhydride (which is basically all that ketene does in the propionic anhydride synthesis – giving propionic anyhydride and acetic acid), which would appear to be somewhat settled, is the problem with the preparation of the metaphosphoric acid?

I realize that the nasty nature of this compound, as discovered on this forum: here

http://www.sciencemadness.org/talk/viewthread.php?tid=4409&a...

here

http://www.sciencemadness.org/talk/viewthread.php?tid=1779&a...

etc.

May be the problem when dealing with it in its liquid form, however, P2O5 is supposed to be fairly easy to use when dealt with in an admixture with DMSO, so I suggest that the easiest way to deal with the metaphosphoric and pyrophosphoric acids would be to make them via dehydrating them with charcoal (as per the patent), which would basically prevent the problems dealt with in the references above, and provide a dry medium from which they could be extracted with DMSO, DMF or (dare I say it) NMP (or whatever will work). Alternatively, the glacial acetic acid could be passed through a filter containing the charcoal/metaphosphoric acid mixture – giving acetic anhydride and charcoal/pyrophosphate.

NB For the synthesis of polyphosphate, see the synthesis of HI from H3PO4 on Rhodium’s site, the acid mixture is heated to 400C (which would cause the formation of HPO3) and then reacts with iodide to produce HI and a white, waxy, polymeric substance. I suggest that this may in fact be P2O6 (2HPO3 + I2 = 2HI + P2O6) which is, after all, a waxy, white, polymeric substance.

http://www.erowid.org/archive/rhodium/chemistry/hydriodic.ar...

Also see how else this same HI can be made, oh look, P2O5:

http://www.erowid.org/archive/rhodium/chemistry/anhydrous.hi...

BTW, I haven’t yet seen anywhere where this particular approach has even been attempted.

I intend to grab some phosphoric acid today, although that means that I also have to get some fucking bicarb, vinegar, dry acid, etc. as well.

The reason I suggested the metaphophoric acid is basically because it appears to act as a de facto higher phosphorus compound, plus the fact that it is a very strong dehydrating agent.

I suggested this method, as the production of elemental phosphorus goes from phosphoric acid, to pyro-metaphosphoric acid, while absorbed on carbon - I have seen no industrial process where anybody tries to do so in the liquid form - cause there ain't much it won't eat. The added benefit of the method from wood shavings is that if something is going to be dehydrated and oxidised, it will be the wood.

Anyhow, if you've tried it and it didn't work - that is a different story, however, I see no report from anyone that they have even made it this way- let alone tried it.

Sauron - 9-4-2007 at 13:07

I'm not interested. It's your idea, you try it. That way if it works you get the credit. And if it doesn't the only time wasted is your own.

I do have uses for P2O5 but this is not one of them.

I know multiple ways to make Ac2O that work very well. If I want Ac2O I use one of them. Same goes for acetyl chloride.

Some of the guys and gals have trouble getting some of the reagents, like TCT and oxalyl chloride. Fortunately I do not have his problem.

tupence_hapeny - 9-4-2007 at 13:52

Sauron,

I have only, by UTFSE and reading my way through this entire post, only found one person who made any serious reference to this approach:

S.C. Wack

Quote:

Sort of. A Turkish professor unaware of it was studying the heating of metaphosphate with various salts in the 50's. Halogens were produced in an earlier article by heating the alkali halide salts with metaphosphate; and in this article the good doctor uses the theoretical amounts on a small scale with the halates, nitrite, nitrate, acetate, carbonate, sulfite, oxalate, and chlorides of Al, Mn, Cd, and Ni.

The dry acetate was heated with alkali metaphosphate to 280-370C.
2 CH3COONa + Na2P2O6 --> Na4P2O7 + (CH3CO)2O, or so the author thinks.
The patent used lower heat and GAA mixed in.
The author's name gives no inventor hits at espacenet.
There is nothing in the article that I can see (not speaking cheese-eating surrender monkey is a slight handicap) which suggests that the vapors were condensed and analyzed, which is not surprising given the small scale.

At the end of the article, she seems optimistic that this can be used as a preparative method for acetic anhydride and promises to publish an investigation of this. Later. She died in 1992.

So someone is going to have to try this, and I don't have metaphosphate on hand.

It should be mentioned that except for this and the Pb acetate article that I mentioned earlier, there isn't a whole lot out there on heating acetates and not getting acetone or methane. There are some German patents and some Russian articles on heating Cu, Fe, Ni, Co, Ag, and basic Al acetates alone and getting the anhydride, but AFAIK these all use vacuum.

Attachment: bull_soc_chim_fr_1259_1956.djvu (426.23 KiB)
This file has been downloaded 99 times

As far as I can see, it should be possible, using that patent, to dehydrate the phosphoric acid/carbohydrate mix at between 150-200C. Unfortunately, at these temps it may still eat some glass. However, as most households contain at least one temperature controlled, self-contained heating, acid impervious (at that temp) appliance (electric frypan with teflon), it should be possible to get down to under 10% moisture.

From that point, the moisture limitations should prevent serious interaction between the pyrophosphoric/metaphosphoric acid and glass/ceramic, so in such way can it be taken to 400C and metaphosphoric acid.

Once carbon/metaphosphoric acid are to hand, it should be theoretically possible to simply mix the dry carbon/metaphosphoric acid with the glacial acetic acid and let the metaphosphosphoric acid slowly absorb water and transform itself into pyrophosphoric acid. All that would be needed is a sealed glass bottle/container - to prevent atmospheric moisture being absorbed.

My question is, is it possible to separate acetic anhydride from glacial acetic acid by fractional crystallisation, or is glacial acetic acid soluble in the anhydride?

tup

Sauron - 10-4-2007 at 12:55

You want to do a pressure reaction in a home appliance with two highly corrosive compounds?

The procedure you describe calls for a nice autoclave made of some nice corrosion resistant metal like SS or better, Hastalloy. Ac2O boils at 140 C, and is highly flammable. Any accident with your home appliance will rapidly degenerate into a disaster.

If you can't afford proper equipment don't do this reaction.

Of course, AcOH boils at 117 and is nonflammable. I doubt you will get any Ac2O so at least the fire hazard might not happen. But you will still have a bomb of hot angry glacial acetic acid and hot phosphoric acid (still liquid) -- no thanks! VERY unsafe.

[Edited on 11-4-2007 by Sauron]

tupence_hapeny - 10-4-2007 at 13:55

Not a pressure reaction, I want to dehydrate the phosphoric acid with rice husk. I intend to start with an excess of rice husk and as it boils down, at 130-150C I will add the rest of the phosphoric acid. Of course, this is not suitable for the pressure reaction, that would be daft, would it not?

I will then transfer the mix to a baking tray (pyrex) and heat it in the oven at 250 for a number of hours. (Still without the acetic acid or even the sodium acetate). That will come separately.

BTW Am I the only one who thinks that the dichloroacetyl chloride from trichloroethylene could be converted into its anhydride rather simply?

Anyhow, here are two links (although I cannot access the full articles), in one P4O10 is used to make the anhydride of difluoroacetic acid:

http://jb.oxfordjournals.org/cgi/reprint/73/4/749.pdf

And in the other it is used to dehydrate dichloroacetic acid to its anhydride:

http://www3.interscience.wiley.com/cgi-bin/abstract/35000249...

If someone could get these articles I would be eternally grateful.

Another interesting aspect of this idea is that P205/Al2O3 is used to convert aldehydes to acylals with acetic anhydride. The supported reagent is used without solvent and is easily separated from the product(s) by filtration.

[Edited on 11-4-2007 by tupence_hapeny]

Attachment: Tetrahedron Letters 48 (2007) 2881–2884, 'P2O5-Al2O3 Catalysed Aldehyde to Acylal'.pdf (129kB)
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Sauron - 10-4-2007 at 14:01

Goget the DOIs for those articles and request them yourself in References. That's what it is for.

tupence_hapeny - 10-4-2007 at 14:20

I cannot get in there

einstein(not) - 10-4-2007 at 21:25

Has anyone looked at this patent?
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=GB299342&a...

not_important - 10-4-2007 at 22:05

Quote:

Originally posted by einstein(not)
Has anyone looked at this patent?
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=GB299342&a...

That's what 2¢_½¢ has been talking about.

Sauron - 11-4-2007 at 07:34

@tup, email Polverone or another moderator and request PW for References.

Heavan's gate will swing wide.

Just remember to always provide DOI

chemrox - 16-5-2007 at 23:33

Which Na(x)PO4 is it? NaH2PO4? which one do you get mixing NaOH and H3PO4? is there a way to manipulate the outcome of mixing these?

[Edited on 17-5-2007 by chemrox]

tupence_hapeny - 1-6-2007 at 16:24

I have just found some rather interesting articles on the topic (JACS)...

Here they are in order (3 part series) - they utilize benzoyl peroxide as a catalyst and proceed to perform some EXTREMELY interesting work with poor old, much maligned, sulfuryl chloride (see the third article):

http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/1939/61/i08/...

http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/1939/61/i12/...

http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/1940/62/i04/...

They also use this compound to make benzotrichloride, which can be used to prepare phosphorus halides (from various phosphoric acids & the pentoxide), thionyl chloride, phthaloyl chloride, etc.

Just goes to show, there really is nothing new under the sun...

tup

Sauron - 1-6-2007 at 20:17

Perhaps you are unaware that the coauthor of those papers is the famous H.C."Boron" Brown, father of organoboron chemistry?

Anyway free radican chlorination with SO2Cl2 and an initiator is very well known and has been discussed on this forum previously, see the Chlorination of Methyl Formate thread and its references.

A more contemporary method is to use AIBN as FR initiator rather than dibenzoyl peroxide.

These are alternatives to photocatalyzed direct chlorination.

Main problem is pretty much same:

Where will you get your sulfuryl chloride? In most countries (mine included) you can't buy it. You can make it but you need oodles of DRY chlorine and so you are in the Cl2 generating biz and with an elaborate drying train betwixt generator and reactor to scrub the water. In the case of SO2Cl2 you can also expect to need a tank of SO2, or another gas generator with its own and different drying train. You then pass both gases over catalyst (proper grade of GAC) in a cooled tube, as reaction is exothermic. You can make maybe half a liter of sulfuryl chloride a day with this setup.

Sulfuryl chloride and its vapors attack the skin and eyes, you will need to protect yourself with fume hood, gloves, mask, etc.

This entire technique is pertinent neither to acid anhydrides nor acid chlorides as you will see when you study the articles. Thanks for the papers, they are useful but not for acetic anhydride. You might consider starting a free-radical chlorination thread or joining Organikum's thread on toluene chlorination which can be done this way.

garage chemist - 1-6-2007 at 23:03

Sulfuryl chloride can be prepared by an easier, discontinuous method, using camphor as catalyst. Look in Sartoris "The War Gases".

Free radical chlorination of hydrocarbons like toluene with sulfuryl chloride is well known and described even in my old Organikum book.

But I wonder what happens if one reacts sulfuryl chloride with e.g. sodium acetate? Sulfuryl chloride is an acyl halide in itself, although one of relatively low reactivity.

Sauron - 2-6-2007 at 00:42

Camphor indeed catalyzes the rxn of Cl2 and SO2 but both still need to be in well dried condition or the moisture will destroy the sulfuryl chloride as fast as it forms.

Also quite a bit of product ends up trapped in the camphor. It's a mess. The GAC (granulated activated carbon) process is better and as soon as you have a few hundred mls of SO2Cl2 can be run very advantageously as a loop reactor with the sulfuryl chloride acting as a solvent for the gases being introduced. The reaction tube is water jacketed to remove heat of reaction, otherwise the GAC turns into CCl4.

The advantage of the loop reactor (using peristaltic pumps with PTFE heads and PTFE tubing because sulfuryl chloride desroys Viton rather rapidly) is that you can run with excess SO2 or excess Cl2 and then at the end, just shut off the component that is in excess. If SO2 is in excess then add Cl2 slowly till the product turns a very pale yellow-green, signalling that Cl2 is now in slight excess. If Cl2 is in excess then shut it off and slowlyadmit SO2 till the pale gren color disappears.

I have a US patent file that does all this on a bench scale with Masterflex pumps, a UV-Vis to monitor the color at peak for Cl2, and mass flow controllers to control the stoichiometry of the gases. I have everything to do this now except for the MFCs. Those have to be calibrated for the specific gases and set for pressures just over 1 atm to work with a gas generator rather than gas cylinders. Anyway the MFCs are not necessary, as mentioned the process works fine with one component in excess. More important is controlling the rate of gas production which I do by controlling the feed to the gas generator using again, peristaltic pumps. Altogether it is a pretty elaborate setup but it will reliably turn out about 60 ml an hours of sulfuryl chloride so how much do you need?

I talked two or three AC sellers out of about a dozen half-Kg samples of GACs of appropriate sizes and types. Cost me nothing. The dozen or so Masterflex pump drives and heads I have came off LabX cheap, and only three are require for this setup. One is a PTFE diaphragm pump and the others are peristaltic pumps to move much less agressive fluids for the gas generators. Very mundane tubing handles conc HCl with impunity. It's only the sulfuryl chloride that is a bitch. But PTFE shrugs it off.

This takes a rather large hood to do, what with three pumps, and the colorimeter, the CSLR and reactor tube, and connections out to recirculating chiller. It's the hood that is holding me up. A 2.5 meter wide 1 meter deep hood. I do expect to have this installed before the end of the year. I'll post pics of the hood and this setup at that time.

Maybe I can set up the CSLR and tube and colorimeter in my glove box and feed the Cl2 and SO2 from generators and drying trains outside the box. The glove box is here already. This could be set up much sooner. The box would be sufficient barrier to protect me from the SO2Cl2 so why not? It's a big old Labconco.

Would you care to see the patent?

[Edited on 2-6-2007 by Sauron]

Attachment: 5498400[2].pdf (444kB)
This file has been downloaded 1220 times

tupence_hapeny - 2-6-2007 at 05:39

Hang on,

If the peroxide-catalyzed chlorination of toluene proceeds effectively the same as the photo-induced chlorination of toluene (which it appears to do - barring the solvent effect) and the product of each - firstly benzyl chloride, then benzodichloride then benzotrichloride are the same - whether achieved with SO2Cl2/Peroxide or Cl2/UV - then it should be possible to di & trichlorinate the initial benzyl chloride simply by adding additional chlorinating agent (& perhaps additional catalyst?)?

I suggest that TCCA (once again, apologies to those offended by the continued reference to this widely available and useful chemical) could be used instead. This has even been mentioned (in a vague way) by someone here (insofar as using an excess of toluene it should be possible to keep the percentage of di/trichlor down).

As to whether this is on or off topic, I hesitate to call it - simply because fully half of the posts here deal with the usefulness and synthesis of a variety of halogenating agents - to the extent that they produce the AcCl which is then turned into Ac2O in-situ... I would regard it as being particularly unfair if I am called for being off-topic in relation to the original post - when 'most' of the posters to this topic have been similarly off topic.

tup

PS I am interested in this precisely because TCCA is so widely available (as is toluene) and such a route would provide direct access to Ac2O without seriously expensive chlorinating agents (which could also be prepared via benzotrichloride)... Imagine - highly sought after & seriously restricted chemicals becoming widely available?

PPS Sauron, before you say it, where this was discussed earlier, alternative solvents were provided, and other members of this forum provided details of their results using TCCA for the preparation of benzyl chloride (in which reaction TCCA is used a virtual replacement for sulfuryl chloride) - so this MIGHT work - I cannot say for certain that it will.

[Edited on 2-6-2007 by tupence_hapeny]

Sauron - 2-6-2007 at 06:44

The only relevance of your posts to THIS thread is the rather distant one that benzotrichloride can be employed to make phthaloyl chloride which can be in turn utilized to make acyl chlorides and thus acid anhydrides.

Free radical chlorination is the subject of a DIFFERENT thread.

TCCA and sulfuryl chloride are mechanistically very different.

Chemically and structurally totally different. And benzyl chloride is NOT a subject of this thread, benzoyl chloride is (slightly) but those are two different compounds. And you don't make benzoyl chloride with TCCA.

So IMO you remain OT here, and you should start your own thread or move this material to Organikum's thread which DOES deal with free radical chlorination.

tupence_hapeny - 2-6-2007 at 09:08

Right,

Is this still off-topic (in my view, NO it is not, may not work - fuck knows why - but it ain't off topic - BTW how fucking OTC would that be?).

As to sulfuryl chloride, here are a series of three articles on the subject by McKee & Salls, in the first - they deal with the production of sulfuryl chloride using activated charcoal - the biggest problem being the condensation of the same - was solved by using the chlorosulfonic acid generated in-situ by reaction of some of the as formed sulfonyl chloride with water - which then dissolves more SO2 & Cl2 (+SO2Cl2) improving the yield. Note that one of the earlier processes used glacial acetic acid - probably making AA in-situ, as AA was also used to condense the shit...

If not, simple addition of benzoyl peroxide to the final mixture would solve that problem (provided NaAc was added as well).

In the second paper they deal with making the sulfuryl chloride by reacting liquid chlorine & liquid sulfur dioxide (low temps are a must) and using the SO2Cl2 as a solvent for the resultant mix of Cl2/SO2 & SO2Cl2. Apparently GAA could also be used as a solvent...(may not be in this paper - I cant remember).

The third paper deals with the hydrolysis of SO2Cl2 to give hydrochloric and sulfuric acids... It is therefore off-topic, but mentioned all the same simply to provide the remainder of the necessary information.

PS Do you seriously dispute the fact that the majority of posts on this topic has been similarly off-topic?

EDIT BY POLVERONE: DO NOT DIRECTLY LINK TO ARTICLES WITH THE JACS TRICK. IT WILL HASTEN THE ARRIVAL OF THE DAY THAT ROUTE IS CUT OFF FOR ALL OF US.

[Edited on 6-2-2007 by Polverone]

Eclectic - 2-6-2007 at 09:23

Hey $0.025, I don't really care about the oxidation of acetaldehyde, cause scavenging the water formed in the reaction is problematic (although 3A molecular sieve in the reactor...), but could you post the article on the last page re. CS2 in the making carbon disulfide thread?

Nevermind. All you have to do is change the last few characters in the above link from *024.pdf to *025.pdf.

[Edited on 6-2-2007 by Eclectic]

tupence_hapeny - 2-6-2007 at 14:06

Quote:

EDIT BY POLVERONE: DO NOT DIRECTLY LINK TO ARTICLES WITH THE JACS TRICK. IT WILL HASTEN THE DAY THAT ROUTE IS CUT OFF FOR ALL OF US.

Sorry...

I will download & link to a share-provider - suitably chastened & will not recur.

NOTE

Sulfuryl chloride will not, either directly or with the aid of benzoyl peroxide, chlorinate acetic acid... This was wrong, as even a momentary perusal of Brown's article on chlorinations with benzoyl peroxide will show.

Thus, unfortunately, a simple route is cut off....

On the other hand, another step is possible - condense the SO2Cl2 (with minimal SO2 & Cl2 dissolved in it) in the chlorosulfonic acid - distill off the sulfuryl chloride and pass that into a vessel containing Toluene & benzoyl peroxide. From the benzoyl peroxide make an agent that will chlorinate the acetic acid. Major fuck around, I know, but I see no easier (OTC) way there, on the other hand - I have always wanted thionyl chloride but certainly am not allowed to buy it - so that is the long and the short of it unfortunately...

tup

Sauron - 2-6-2007 at 14:22

Thionyl chloride is inappropriate for chlorinating acetic and propionic acids because the bp's of those acyl chlorides are too proximate to that of the thionyl chloride (always used in excess) and therefore, the reaction mixture is too hard to seperate. See Vogel.

So the fact that you can't get thionyl chloride, is immaterial to the acetic anhydride/acetyl chloride and propionyl chloride problem. This point has been emphasized and re-emphasized several times in the last 12 pages of this thread.

Some of us can buy thionyl chloride (but not me, and not you.) It's a useful reagent for most acid chlorides, just not the lower few.

tupence_hapeny - 2-6-2007 at 14:56

Quote:

Sauron Said
Thionyl chloride is inappropriate for chlorinating acetic and propionic acids because the bp's of those acyl chlorides are too proximate to that of the thionyl chloride (always used in excess) and therefore, the reaction mixture is too hard to seperate. See Vogel.

So the fact that you can't get thionyl chloride, is immaterial to the acetic anhydride/acetyl chloride and propionyl chloride problem. This point has been emphasized and re-emphasized several times in the last 12 pages of this thread.

Some of us can buy thionyl chloride (but not me, and not you.) It's a useful reagent for most acid chlorides, just not the lower few.

For acetic anhydride I would actually prefer phthaloyl chloride, I have details of the reactions with it for one thing...

I have (for some bizarre and fucked up 'psyche' reason probably) actually always wanted thionyl chloride, in fact I would probably if ever given the choice take a liter of that over a liter of AA if someone wanted to sell it (Fat Fucking Chance). Consequently my musing at the end...

Ummm, would it be sufficient in future when citing JAC/JOC simply to give a link to the abstract? Or should I not even do that? Perhaps just provide the citation in full?

tup

Sauron - 2-6-2007 at 15:25

Thionyl chloride is relatively hard to make (relative to sulfuryl chloride.)

This is because you need SO3 or 65% oleum to do it, and that is expensive stuff and a bitch to handle. See Brauer on thionyl chloride lab prep.

Thionyl chloride has been so demonized that many countries simply ban its import without a special permit. In this country I also can't buy SO3, although I can buy oleum, up to 65% and have done so but it was very costly. How costly? $750 US a liter. OK bear in mind that a liter of 65% oleum is 2 Kg and that 65% of that 2 Kg is SO3 so it's about 50 cents a gram based on SO3. Ouch.

For the same reasons chlorosulfonic acid is a problem. The MOD restricts it and in order to make it you need SO3 or oleum and big brass balls, because running dry HCl into high percentage oleum is very exothermic.

There's another way to make chlorosulfonic acid, from sulfuryl chloride, using Hg salts, and this would probably be the way to go.

But back on topic:

Phthaloyl chloride does work, but it doesn't work any better than benzoyl chloride for making acetyl chloride and it is more expensive. If you make your own phthaloyl chloride you can get the cost down to about the same as that of benzotl chloride. You make it from phthalic anhydride and benzotrichloride.

Making your own benzoyl chloride does not achieve any similar economy because the cost of sodium benzoate is rather high. It actually costs as much as benzoyl chloride.

For those who can't purchase TCT, benzoyl chloride is the best choice for a reagent to prepare acetyl chloride. Second best if you make your own is phthaloyl chloride. But if you can get TCT do so because it is far cheaper than either.

Polverone - 2-6-2007 at 19:04

Quote:

Originally posted by tupence_hapeny
Ummm, would it be sufficient in future when citing JAC/JOC simply to give a link to the abstract? Or should I not even do that? Perhaps just provide the citation in full?
tup

Linking to the abstract is fine. If you want to provide full articles, download them with the trick and then attach them to your message.

omarshuja - 23-6-2007 at 03:30

A number of methods have been discussed regarding preparation of Acetic Anhydride. Out of all of these which method is the easiest to be tried in the lab. I'll appreciate if some one could send pictures of the setup of the apparatus.

Are all the reagents discussed in this method easily available.

Thanks and awaiting your reply.

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