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Sauron
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The benzoyl chloride (HC Brown) method is as easy as they get.
So is the TCT method in acetone with TEA.
So is the phthaloyl chloride (Kyrides) method.
Those get you acetyl chloride which you then treat anhydrous NaOAc with to get Ac2O.
So is the oxalyl chloride (Roger Adams) method. This gets you acetic anhydride directly, or acetyl chloride, depending on ratios of reagents.
I listed these in increasing order of cost. The first two are the cheapest.
As to setups, read the articles, and if you don't understand them, try cracking a lab manual of basic organic chemistry. The procedures are
elementary. Any freshman chemistry student could do them in a practical lab course.
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jackson2004
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How comes another guys same post was dumped for this kinda topic to Detritus,
but when its a super admin talking he not only gets to put the topic where he wants,
but also gets to place it at the very top of the list. Kinda Unfair
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Polverone
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I don't know which post you're referring to that went to Detritus, but if it was about acetic anhydride it was probably dumped because we already have
this thread. You'll notice that this thread was started 5 years ago. Unless there's a lot of topical divergence, we prefer to keep one thread going
per topic. I don't think this thread was stuck at the top of the thread list until it was years old.
Edit: if you have questions about the running of the forum, start a topic in Forum Matters -- don't post in an unrelated thread like this one.
[Edited on 6-26-2007 by Polverone]
PGP Key and corresponding e-mail address
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omarshuja
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Since Acetic Anhydride is used in the production of Aspirin, Paracetamol, etc , is there any easy and economical way to recover it from those
medicines. Or is it better to prepare it right from the start.
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Sauron
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No you cannot "recover" acetic anhydride from aspirin nor paracetamol.
There are altogether about half a dozen good preps for Ac2)O.
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omarshuja
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I downloaded the book "Practical Organic Chemistry by Vogel" from the Library section to get more help in this regard but it is giving errors in Adobe
Acrobat version 4 as well as Foxit reader. This is making the programs hang and then close.
Which PDF reader are you using to view this file.
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Sauron
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That is a DejaVu file and not a pdf
You need the free Lizard Tech Deja Vu reader, or another similar ptogram.
However, for practical methods of making acetic anyhydride is not very useful, other than telling you what not to do.
It will tell you truthfully that thionyl chloride is not very useful for carboxylic acids lower than C4 or C5, because of proximity in bp. The same is
true of PCl3 and PCl5.
Those methods, for the higher MW acids, work well, to make the acid chlorides which you can then react with the anhydrous sedium (or potassium) salts
to obtain the anhydrides.
For Ac2O (C2 anhydride) you need different routes to AcCl and then, you can react NaOAc anhydrous, with AcCl to get Ac2O.
Those methods are detailed in this thread, in the propionyl chloride thread and the ketene lamp thread, and related thread.
The Vogel book is worth having, but it just a little lean on this subject. However it does not totally mislead you the way Wiki does.
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ahmed_gorka
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I have got a small sample of Acetic Anhydride (about 3-4 cc) from a friend. I want to have it analyzed in a laboratory in order to know that it is
actually Ac2O. The problem is that the ppl at lab told me that the sample size is very small and they need atleast 50 ml to conduct the test for
specific gravity.
50ml sample cant be purchased by me. Is there any method to analyze this small size sample and give result whether or not it is Ac2O.
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Nicodem
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Ever heard about boiling points?
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Eclectic
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If you can find or buy a scrap of Noryl plastic, it has approximately the same density as actic anhydride and should slighty float on pure acetic
anhydride.
(Your lab is incompetent)
Also melting point, smell, derivative melting point: see if it makes asprin with salicylic acid.
[Edited on 7-2-2007 by Eclectic]
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garage chemist
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Better yet, see if it makes acetanilide with aniline- the reaction is nearly instantaneous and acetanilide is a crystalline solid, contrary to the
aniline.
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Sauron
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This "lab" doesn't have a GC, a HPLC, a NMR?
Hogworts could do better.
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Filemon
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| Quote: | Originally posted by garage chemist
Acetic anhydride from sodium acetate, using S2Cl2
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Can it substitute for S2Br2?
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mayabiotech
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Thiophosgene
dear all, I am planning to manufacture Thiophosgene on large scale basis, can anyone help me by providing me the uses of thiophosgene and the further
molecules and products of thiophosgene..
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chloric1
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First. I want to wecome you to the forum.
Secondy, I say farewell, adios, goodbye etc.. because your kewlish question seems to me only a prelude to your eventual demise via accidental
poisoning.
Fellow molecular manipulator
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Sauron
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Why are you posting about thiophosgene in a thread about Ac2O?
And why are you contemplating "large scale" manufacture of thiophosgene if you do not know what thiosphosgene is used for or what sorts of compounds
can be synthesized with it?
See review on thiophosgene chemistry by S.Sharma (your compatriot)
The principle reactions of thiocarbonyl chloride (C(=S)Cl2 are formation of isothiocyanates; and thionation;
It stinks, it is lachrymatory, irritating, and highly toxic by inhalation, ingestion or skin absorption, being about 65% as toxic as phosgene but
lacking its insidiousness.
It is too toxic to be a riot control agent and not toxic enough to be a lethal agent. In short it is militarily useless, as was concluded very early
on in WWI.
It is produced commercially mostly by Akso and it is mainly used in the pharmaceutical industry as far as I know.
Its classical preparation is by catalytic thermolysis of trichloromethyl sulfenyl chloride, itself an unplesant toxic failed WWI war gas. The
byproducts are molten sulfur and a lot of hot angry and very lethal H2S. Does this sound like fun yet?
[Edited on 10-10-2007 by Sauron]
Sic gorgeamus a los subjectatus nunc.
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Antwain
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Hahaha. This last page is like a comedy of errors.
Also, I'm not so sure that benzoyl chloride is the best method for amateurs (who usually don;t have a hood. It stinks to high heavens. Once I had to
use 6mL of the stuff. I decided to smell it carefully with the old waft test. Bad idea, that stuff is damn potent. It hits you with a dirty aldehyde
smell which unsurprisingly changes to HCl ish smell after a second or two. And if you get any on anything it stinks for hours even if you wash it.
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Sauron
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Nevertheless, benzoyl chloride is one of the simplest way to make volatile acid chlorides.
Acetyl chloride is no perfume itself. The "classical" methods of making it ALL involve some nasty smelly and often these days unavailable reagents:
SOCl2
S2Cl2, S2Br2
POCl3
PCl5
Oxalyl chloride
Phthaloyl chloride
Cyanuric chloride (TCT)
Those are the classical and non-classical reagents for acid chlorides, Which ones would you prefer to be upclose and personal with over benzoyl
chloride?
Quite a few of us do have fume hoods despite amateur status. Some build there own, some buy them used, I am buying mine new. I regard it as a sine qua
non.
Sic gorgeamus a los subjectatus nunc.
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Antwain
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There is a guy selling one on ebay for not much about 600km away from me (as you probably know in Australia thats not far, a day trip  ) but my shed is ~ 2m * 1.5m so no dice. I would have thought that benzoyl chloride
would be on the forbidden list too?
Cyanuric chloride. A no-brainer. (not familiar with phthaloyl chloride, though)
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Sauron
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Cyanuric chloride is the least offensive on that list, because it is a solid, albeing a pungent one.
No, nobody cares about benzoyl chloride. Nor phthaloyl chloride. The latter is the acid chloride of phthalic acid and is a little expensive, but can
be prepared from phthalic anhydride and benzotrichloride with a little ZNCl2 catalyst, in an autoclave for 20 hrs. It has some unique properties.
Thionyl chloride is demonized solely because of it's popularity with Iran and for former Iraq regime for making mustard vesicant agent out of
thiodiglycol.
There are other and better ways of making same, and other and just as good agents for chlorinating thiodiglycol, including - get this - plain old
hydrochloric acid, aka muriatic acid. However, be that as it may. Such is the illogic of the dips who draft these asinine control regimes.
Why on earth would you expect benzoyl chloride to be restricted?
Sic gorgeamus a los subjectatus nunc.
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Antwain
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1) Because I sometimes, accidentally, credit the powers that be with intelligence, if not sense.
2) BECAUSE it can be used to MAKE a bunch of stuff that IS restricted and/or watched.
3) see "1)" 
PS. I don;t like thionyl chloride because it produces SO2, which in turn makes me gag (I haven't used it, although I have a small amount on the off
chance I ever need to). At the moment, not having a fume hood + scrubber, I basically only have it because it will become more impossible to get in
the future.
PPS. I could be wrong, I am not privy to the forms that must be signed at uni to get reagents, but I think that anything "P" gives off more bad vibes
over here than a mere "S" compound like thionyl.
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Sauron
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Antwain, you really think that governments know best?
Then read more history and less chemistry and you might learn otherwise.
Sic gorgeamus a los subjectatus nunc.
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Antwain
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No, its just that I sometimes think that governments will do a FOOLISH thing well. As opposed to doing a foolish thing and cocking it up completely,
wasting money, inconveniencing people and completely failing to achieve their initial goal.
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Sauron
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Benzoyl chloride is useful for making scores or hundreds of acid chlorides. Only one or two of them are regulated or watched for any reason. And those
two can be prepared in many other ways so that regulating benzoyl chloride would accomplish nothing.
What is more, benzoyl chloride itself is easy to make in a variety of ways, and therefore, it would be worthless to regulate it unless you also want
to regulate everything that it can be made from, and everything that its precursors can be made from, and so on. And that is a long list.
Not even the governments want to start down THAT slippery slope.
Sic gorgeamus a los subjectatus nunc.
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franklyn
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The Hoechst - Knapsack Process
From page 254 of
Petrochemical Processes:Technical and Economic Characteristics
Alain Chauvel, Gilles Lefebvre
and page 64 of
Organic Chemistry: A Comprehensive Degree Text and Source Book
Hans Beyer, Wolfgang Walter
Another process converts acetylene and acetic acid to Ac2O
From page 66 of
Organic Chemistry: A Comprehensive Degree Text and Source Book
Hans Beyer, Wolfgang Walter
Just one more thought
Calcium acetate gassed with sulfer trioxide would likely produce Calcium Sulfate releasing Ac2O
Ca(CH3C(O)O)2 + SO3 => CaSO4 + (CH3CO)2O
[Edited on 6-2-2008 by franklyn]
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