Sciencemadness Discussion Board

Acetic anhydride preparation

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Sauron - 23-6-2007 at 04:59

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.

jackson2004 - 26-6-2007 at 16:39

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

Polverone - 26-6-2007 at 17:43

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]

omarshuja - 30-6-2007 at 07:42

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.

Sauron - 30-6-2007 at 12:22

No you cannot "recover" acetic anhydride from aspirin nor paracetamol.

There are altogether about half a dozen good preps for Ac2)O.

omarshuja - 1-7-2007 at 07:27

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.

Sauron - 1-7-2007 at 08:41

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.

ahmed_gorka - 2-7-2007 at 09:49

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.

Nicodem - 2-7-2007 at 10:05

Ever heard about boiling points?

Eclectic - 2-7-2007 at 10:07

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]

garage chemist - 2-7-2007 at 14:11

Better yet, see if it makes acetanilide with aniline- the reaction is nearly instantaneous and acetanilide is a crystalline solid, contrary to the aniline.

Sauron - 2-7-2007 at 18:30

This "lab" doesn't have a GC, a HPLC, a NMR?

Hogworts could do better.

Filemon - 3-7-2007 at 11:39

Quote:
Originally posted by garage chemist
Acetic anhydride from sodium acetate, using S2Cl2



Can it substitute for S2Br2?

Thiophosgene

mayabiotech - 9-10-2007 at 12:57

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..

chloric1 - 9-10-2007 at 16:04

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.

Sauron - 9-10-2007 at 16:11

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]

Antwain - 9-10-2007 at 17:34

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.

Sauron - 9-10-2007 at 20:37

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.

Antwain - 9-10-2007 at 22:27

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)

Sauron - 9-10-2007 at 22:48

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?

Antwain - 10-10-2007 at 03:43

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)" :P

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.

Sauron - 10-10-2007 at 03:53

Antwain, you really think that governments know best?

Then read more history and less chemistry and you might learn otherwise.

Antwain - 10-10-2007 at 04:11

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.

Sauron - 10-10-2007 at 04:31

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.

franklyn - 4-2-2008 at 16:22

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]

Now T H I S is an explanation

franklyn - 4-2-2008 at 16:41

Excerpt shown below from
Practical methods of organic chemistry - Ludwig Gattermann
Download _
http://books.google.com/books/pdf/The_Practical_methods_of_o...
The Acetyl Chloride prep is on page 121 of this book


Acetic anhydride prep * * *
http://designer-drug.com/pte/12.162.180.114/dcd/chemistry/an...

Sauron posted the above in pdf here _
http://sciencemadness.org/talk/viewthread.php?tid=7701#pid87...
Direct download _
http://sciencemadness.org/talk/viewthread.php?action=attachm...

.

[Edited on 6-2-2008 by franklyn]

Prep of Ac2O.JPG - 387kB

lester - 16-2-2008 at 23:10

Two birds with one stone a facile reaction for producing acetic acid and acetic anhydride from acetaldehyde using manganese acetate and a mix of boric-oxalic acid mixture. The resulting product is useful for creating the needed acetate mixtures required for the reaction and later removal of the Calcium borate oxalate salts on neutralization.

GB 1012556
100 grams acetaldehyde and 2 grams of manganese acetate were placed in a glass reactor
and cooled to -50 C by dry ice acetone bath. One gram of Boric-oxalic acid mixture (1:1 molar ratio)
was then added and the reactor placed on a shaking apparatus where the reactor was flushed with oxygen and pressurized to 2.8 kg/cm^2 and heated to 69 C. A gas reservoir connected to the glass reactor was pressurized to to *4.5 kg/cm^2 and the valve between the reactor and reservoir was opened *note ( CAUTION I think there is a misprint in the patent and 4.5 kg cm^2 is meant. As acetaldehyde and oxygen can auto react explosively and produce peracetic acid Id research this further before attempting this reaction also have peroxide test strips, test for peracetic acid formation and preferably scale this down and perform behind a explosive screen for protection of some sort as well as fume removal hood ) The pressure is then maintained at between 4.2 kg cm^2 and 4.5kg cm^2 during the course of the run. The amount of reacted oxygen was measured by the pressure decreases in the reservoir. When absorption of oxygen stopped the reaction mixture was cooled, neutralized with 3 grams of calcium acetate,
filtered and analyzed by gas-liquid chromatography. The reaction time was approximately 3 hours and 20 minutes.
In two experiments the acetic anhydride in the recovered product was 40% and 32% by weight representing yields of approximately 30% and 25% respectively: The remainder was mostly acetic acid.
Example II
The procedure was the same except that the run was stopped after only three quarters as much oxygen had been absorbed the recovered reaction mixture was 52% by weight acetic anhydride a 40% yield

P.S. Best patent Ive seen for production of acetaldehyde is GB344554 Alcohol passed through
copper hydroxide with ceric oxide intimately mixed in negligible amounts

*note ( CAUTION I'm pretty sure this is a misprint and 4.5 kg cm^2 is meant not 45 kg cm^2.
The patent later says keep oxygen pressure between 1 to 5 kg /cm^2. As acetaldehyde and oxygen can auto react explosively and also produce peracetic acid Id research this further before attempting this reaction also have peroxide test strips, test for peracetic acid formation and preferably scale this down and perform behind a explosive screen for protection of some sort as well as fume removal hood Preferably do it remotely and test for peracetic afterwards )

Fashist - 17-2-2008 at 10:22

POCL3+4ACONA->2AC2O+3NACL+NAPO3
Good idea
any body has idea?

Sauron - 17-2-2008 at 19:41

POCl3 is not easy to come by these days, far too precious to expend on making acetic anhydride.

Acetyl chloride is much easier to acquire or prepare and so making Ac2O from it makes a lot more sense.

Fashist - 17-2-2008 at 20:55

6 PCl5 + P4O10 → 10 POCl3

"Phosphorus pentachloride also forms POCl3 by reaction with water, but this reaction is less easily controlled than the above reaction."
Here P2O5 is available and This is not Difficult To buy PCL5(Not Expensive)

Sauron - 18-2-2008 at 16:53

I do not know where "here" is for you, but in most places in the world, PCl5 along with PCl3 and POCl3 are highly restricted chemical weapons precursors under the Chemical Warfare Convention.

In the US they are watched by DHS like a hawk, and where I live, cannot be imported without a special license from the office of the Permanent Secretary, Ministry of Defense, which is highly unlikely to be forthcoming.

PCl5 is ALWAYS expensive, relative to PCl5 and POCl3, because of the substantially larger amount of chlorine required to produce it.

I know of two ways to makes POCl3 without using PCl5.

One requires a different expensive reagent ($600/Kg) and the other, an expensive pressure reactor setup.

Altogether, POCl3 is NOT a practical reagent for making Ac2O, on economic grounds.

If this is different where you reside, bully for you. But, as for the rest of us, no.

franklyn - 18-2-2008 at 19:14

Quote:
Originally posted by lester
*note ( CAUTION I'm pretty sure this is a misprint and 4.5 kg cm^2 is meant not 45 kg cm^2.


The equivalent US3281462 refers to 60 ~ 70 P.S.I.G.

.

Sauron - 18-2-2008 at 22:43

60-70 PSIG is within recommended limits for a Parr shaker type apparatus, using Pyrek (borosilicate) bottles, or stainless steel.

Not a lot of capacity, largest has a working capacity of about 1300 CC and the more usual one about 300 cc.

Anyway all I mean to say is that this is a low pressure reaction, apparently.

We have previously expended a lot of time on a similar patent that could not be replicated, thus far anyway. As I have said many times - patents are like that.

[Edited on 19-2-2008 by Sauron]

Fashist - 18-2-2008 at 23:23

i think this is not good method because pocl3 is very toxic.
anybody has experience with sodium pyrosulphate method?
i try to decopose nahso4 to na2s2o7 but i wasnt successful.
i think disulphate method is cheaper and better method
anybody has idea?
thx

Sauron - 19-2-2008 at 03:16

Isn't fashist our old friend from Iran under a different handle?

Still after acetic anhydride? I thought you had abandoned your cellulose acetate project?

I guess not, huh?

Still in the glue business, or what is it now?

As the Gattermann ref. clearly states, the best shortcut to anhydrous, freshly fused sodium acetate is not to start with the trihydrate at all, but with commercially available anhydrous sodium acetate. Rather than having to be fused twice, like the trihydrate, with danger of charring from decomposition, the commercial anhydrous salt needs only one melting, to remove any traces of moisture that might have been reabsorbed in storage.

IIRC, Merck will not sell to you. Maybe Russia, India, or China? Aren't they all still pals with Teheran?



[Edited on 19-2-2008 by Sauron]

Fashist - 19-2-2008 at 03:56

Now i cant Product any acetic anhydrid because merck dont sale acetyle chloride.(germany cut its trade with iran)
i am searching for good method for anhydrid and then for our glue.
there is old pcl5 in the our market (probably for 10 years ago) but this method isnt suitable.
mr sauron you have no news from va method?
i try it before but no result.
soon i will try pdcl2+va
sodium acetate is very cheap here.and we have no problem with dry sodium acetate(isnt difficult)
again anybody has experience with pottasium or sodium pyrosulphate method?
thx


[Edited on 19-2-2008 by Fashist]

Fashist - 19-2-2008 at 04:41

I will try
K2S207+ACONA->AC2O+na2so4+k2so4
i just find pottasium pyrosulphate(old merck product)
anybody has idea?
thx

lester - 19-2-2008 at 05:23

Thanks franklyn I think you are right about the use of oxygen at higher pressures.


Im assuming the Mn ion breaks down the peracetic forming the anhydride.
Normally the peracetic would build up as this is used to produce peracetic acid

The boric acid/ oxalic acid mixture recycles the Manganese oxidation state. Oxygen possibly playing a role also?

I tried looking up the mechanism for this recycling as obviously its fairly efficient working at higher pressures.
Can anyone hazard a guess how its operating?

Cheers

Sauron - 19-2-2008 at 08:25

PdCl2 is way way too expensive.

I now have VA on hand but am awaiting installation of fume hood, also arrival of Parr pressure reactor and controller.

I don't have much real faith in this methos, but, more than in the patents.

Fashist - 20-2-2008 at 01:24

Mr sauron you think potassium pyrosulphate wont work?
K2S207+ACONA->AC2O+na2so4+k2so4?
or
NA2S207+ACONA->AC2O+na2so4?
which one?
i want to buy merck potassium pyrosulphate(old product) and if you think potassium wont work and sodium will work then i wont buy it
please guide me
thx

Sauron - 20-2-2008 at 06:17

I have no experience with potassium pyrosulphate in this application and so I have no basis for opinion. Better ask someone who has tried it.

Fashist - 22-2-2008 at 13:57

Today i test the pyrosulphate method but no result!
i mix 250gram k2s2o7 and 165gram acona and add 20cc glacial actic acid
and mix well.some heat produced .
again i add more glacial acetic acid (about 50cc)
then i distil and i recieved no anhydrid(after mixing).
do you think this patent is true?

JohnWW - 24-2-2008 at 20:32

Quote:
Originally posted by Sauron
I do not know where "here" is for you, but in most places in the world, PCl5 along with PCl3 and POCl3 are highly restricted chemical weapons precursors under the Chemical Warfare Convention. In the US they are watched by DHS like a hawk, and where I live, cannot be imported without a special license from the office of the Permanent Secretary, Ministry of Defense, which is highly unlikely to be forthcoming. PCl5 is ALWAYS expensive, relative to PCl3 and POCl3, because of the substantially larger amount of chlorine required to produce it.

I wonder if AsCl3 could be used as a substitute for PCl3 or PCl5 for obtaining carboxylic acid chlorides, although more precautions against toxic fumes would be needed. In one of my lab classes when I was studying for my B.S. degree, we used AsCl3, which came as a colorless liquid in sealed 50 or 100 cc ampoules. Although this was many years ago, I think we used it for some sort of chlorination reaction, which required rigorous exclusion of water vapor and of other extraneous substances which could have hydrolysed the AsCl3. During this lab class, I somehow inadvertently allowed some AsCl3, which I think was in an organic solvent, to come into contact with a ferric salt, - the result was an immediate very intense deep red color, possibly due to formation of [Fe(AsCl3)6]+++ or similar.

Another possible substitute for restricted PCl3, POCl3, PCl5, S2Cl2, SCl2, or SOCl2 for producing carboxylic acid chlorides could be SiCl4; has anyone tried it?

S.C. Wack - 24-2-2008 at 22:47

Non-members have at least...see JACS 49, 2114 (1927) "SILICON TETRACHLORIDE AS A REAGENT FOR THE PREPARATION OF ACID CHLORIDES".

There is also the claims of DE394730 for obtaining anhydrides with SiCl4; and DE171146, where anhydrides are allegedly produced from the Na or K salt with SiF4 from sand, fluorspar, H2SO4, and heat.

There is also JACS 34, 1598 (1912) "NOTE ON THE ACTION OF OXYCHLORIDES OF SILICON ON SODIUM SALTS OF FATTY ACIDS", which uses cpds. fitting said description on acetate and propionate to give 82 and 60% yields of the anhydrides, based on the oxychloride if you happen to have some around.

Sauron - 24-2-2008 at 23:45

AsCl3 is very very restricted becausew of its application to the preparation of the Lewisite family of military vesicants. It is also quite toxic in its own right.

I have no experience with silicon tetrachloride or oxychloride. I'm unfamiliar with their properties, availability, cost, or preparation. They have been mentioned before in the same connection, but the matter seems to have dead-ended. I will have a look in Merck and Bauer etc, and see what I can see.

SiCl4 is readily available for about $100/Kg (Acros) and is a liquid boiling at 58 C.

Acros, Alfa, Aldrich all negative for silicon oxychloride.

The preparation of SiCl4 from Si and 2 Cl2 in a tube furnace is desribed by Brauer. Same apparatus is used for the chlorosiloxanes, which I take to be "silicon oxychloride".

It appears to me that commercial SiCl4 is more practical than DIY. I have not done the arithmetic to see whether this is a more or less economical alternative to the more usual routes to Ac2O.

I have requested the JACS paper on SiCl4 as reagent for making acyl chlorides. While awaiting succor from the gos of References I perused first page courtesy of ACS. The yield with acetic acid is 85% but with propionic acid (chemrox's TM) only 50% and such yields or less are typical of most acids. Benzoic gave 77%. A number of acids failed entirely.

So this would appear to be rather specific for acetyl chloride only.

The stoichiometry is 2 mols of SiCl4 to 4 mols acid. So, a Kg SiCl4 is sufficient to convert approx 11 mols acetic acid to c.9 mols acetyl chloride. That is about $11/mol of product.

The acetyl chloride can then be reacted with anhydrous sodium acetate and worked up to acetic anhydride.

This may be a worthy alternative to the TCT route to acetyl chloride, which is however more versatile, or to the benzoyl chloride route, likewise much more general and consistently high yielding.

The first half of the reaction described in JACS is preparation of silicon tetraacetate from 4 mols acetic acid and 1 mol SiCl4. The second half of the reaction is reaction of the tetraacetate with a second mol SiCl4 to give 4 mols acetyl chloride and SiO2 and HCl.

See also Brauser p 701, part II, for acetic acid and SiCl4 but the isolated yield given for the tetraacetate is only 30%. This is about 1/3 of the JACS yield of the acid chloride without isolation of the intermediate tetraacetate.

Part I of the Brauser entry described preparation of the tetraacetate from SiCl4 and Ac2O in 85% yield, acetyl chloride being byproduct.

Silicon tetraacetate is the mixed anhydride of silicic and acetic acids.

[Edited on 26-2-2008 by Sauron]

DJF90 - 25-2-2008 at 11:30

Suggesting the use of AsCl3 and SiCl4 as chlorinating agents to produce the acyl chloride started me thinking about other non-metal chlorides. IIRC quite a few of them react quite rapidly with water to produce the nonmetal oxide and HCl. Maybe they can be applied as chlorinating agents also as the displacement of the OH by the chlorine is similar for both water and alcohols, and I would expect carboxylic acids to react in a similar fashion also. If this is the case then perhaps compounds that can be made fairly easily in the lab could be used in the production of acyl chlorides ( perhaps sulphur chlorides?) Its just an idea but it might actually work.

Sauron - 25-2-2008 at 18:10

According to the JACS 1927 paper, not only can SiCl4 give 85% yield of acetyl chloride when reacted with acetic acid.

SiCl4 when reacted with anhydrous sodium acetate in a diluent gives acetic anhydride directly.

Yield 75% when diluent is acetic anhydride itself, and 50% when diluent is benzene.

This is more to my liking.

[Edited on 27-2-2008 by Sauron]

-jeffB - 26-2-2008 at 09:57

Sigma-Aldrich lists SiCl4 (99%) at US$56.20/kg. They note "Packaging fee -- large can"; does this imply they'll add more to the cost, or that the quoted price includes the fee?

I assume hazmat charges will apply too, as the stuff is volatile and corrosive.

garage chemist - 26-2-2008 at 10:09

SiCl4 is easily made from the elements in a heated tube, the SiCl4 is condensed at the output by cooling.

There is also a thermite style reaction procedure used to make elemental Si from SiO2, Al and sulfur. The sulfur serves to increase the heat of the reaction by reacting with a part of the Al, without it the reaction isn't self sustaining.
Also, Mg will reduce SiO2 to Si nicely. Use a slight excess of SiO2 to avoid magnesium silicide formation.

JohnWW - 26-2-2008 at 10:50

Quote:
Originally posted by S.C. Wack
Non-members have at least...see JACS 49, 2114 (1927) "SILICON TETRACHLORIDE AS A REAGENT FOR THE PREPARATION OF ACID CHLORIDES".

That article has been posted in the References section, under the wanted references thread.

Sauron - 26-2-2008 at 17:53

count on Aldrich applying a packing surcharge, and doubtless, Hazmat charges will also be applied.

Anyway the online price at Aldrich Singapore is $142 Sg$ which is over $100 US and that would just increase again by the time it gets to Bangkok, Aldrich is way overpriced here and I never buy from them if I can get it elsewhere. Acros and Merck are much more reasonable.

Let me reiterate: SiCl4 is NOT a general chlorinating reagent for acid chlorides. Yields are competitive only for acetyl and benzoyl chlorides (85% and 77%). With other acids yields were less than 50%, often 30%. For pyruvic acid and all tested dicarboxylic acids no reaction occurred.

SiCl4 reacts with anhydrous sodium acetate to give acetic anhydride directly, in 75% yield, but only in presence of a substantial amount of Ac2O as diluent. If benzene is substituted as diluent, yield drops to 50%. So, benzene can be used in initial procedures, and Ac2O so obtained can be used in subsequent runs.

[Edited on 27-2-2008 by Sauron]

LSD25 - 26-2-2008 at 19:09

The article is here, I think it has actually even been referred to in this topic (if anyone wants to look)

Montonna, 'Silicon Tetrachloride as a Reagent for the Preparation of Acid Chlorides' (1927) 49(8) JACS2114: http://tinyurl.com/2l7u56
Quote:
Preparation of Acetyl Chloride.-Three hundred and sixty g. (six moles) of glacial acetic acid and 672 g. (six moles) of toluene are placed in a liter, round-bottomed, Pyrex flask fitted with a rubber stopper through which passed a dropping funnel and a reflux condenser. The upper portion of the latter is filled with glass beads and the condenser itself is, in turn, connected to an absorption system consisting of two washbottles containing acetic acid. The mixture is heated to 50' and at that temperature 510 g. (three moles) of silicon tetrachloride is added from the dropping funnel during a period of 30 minutes. The same temperature is maintained until the vigorous evolution of hydrochloric acid almost ceases. The upright condenser is then replaced by a Glinsky or Hempel column carrying a thermometer and attached to a downward condenser, and the product fractionated over a free flame until the thermometer registers 80-85 ".

The product on redistillation gives 400 g. of acetyl chloride, b. p., 50-55"; yield, 85%.



[Edited on 26-2-2008 by LSD25]

Sauron - 26-2-2008 at 21:42

The article was cited upthread by S.C.Wack, requested by me, and posted in References by jokull. There is no need to cite it again. Anyway the more interesting reaction contained in same article, giving Ac2O directly, rather than AcCl, is as follows:



130 g (1.6 mols) anhydrous sodium acetate in 300 ml acetic anhydride as diluent is warmed to 50 C, and 67 g (400 mmol)SiCl4 is added with stirring over a period of one hour. The temperature rises to 80 C. Heating and stirring are continued for three hours at 90 C.

Yield 75% of 96% acetic anhydride.

Same reaction with benzene as diluent: stirred 5 hours at 50-60 C, 50% yield.

I would be inclined to try a higher boiling diluent than benzene, such as toluene or xylene, and see whether yield improves.

The usual cavetas apply regarding anhydrous sodium acetate. It is preferable to start with a freshly opened bottle of commercial anhydrous NaOAc, in which case a single melting will suffice. Starting with the trihydrate, the material must be fused twice, the second fusion being done cautiosly so as to avoid charring (loss of material.) A forced air, temperature controlled drying oven is a major convenience in this process.

If you use your SiCl4 to make AcCl, you still need to react that with anhydrous NaOAc to obtain Ac2O.

Better to go straight for the anhydride.

If you have no Ac2O to use as diluent, then do a couple runs using benzene (or IMO, better toluene or xylene.) Then you will you have some of the preferred diluent.

I'm going to have a look at S.C.Wack's other citation, re Si2OCl6 ("silicon oxychloride" but without any real hope of practical advantage over SiCl4.

This material is much more difficult to come by, as far as I can determine it is commercially unavailable. As the paper states on its first page, its preparation is far from easy, yields are low, and seperation of the desired product from higher oxychlorides of silicon very difficult. The claimed yield of 82% of acetic anhydride from sodium acetate (anhydrous) is only a little better than that obtained from SiCl4. So unless there are some surprises in the paper, it's a non-starter.

[Edited on 27-2-2008 by Sauron]

S.C. Wack - 27-2-2008 at 03:22

The reason why I said "if you happen to have some around" was because AFAIK it is no easier to prepare than SiCl4. It seems that in the preparation of mixed oxychlorides in the article, SiCl4 was in fact the main product. Just mentioned it as summing up what I've got on acetic anhydride from Si cpds.

Attachment: 34_1598_1912.pdf (220kB)
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Sauron - 27-2-2008 at 03:43

Yes, S.C> I figured that was what you meant. As it happens SiCl4 is rather easy to purchase, and not *too* expensive at $100 a kg. With a price like that I would not consider making it. After all I am paying a lot more for oxalyl chloride (a LOT more) and while I could make that, I don't bother.

The stoichiometry of SiCl4 in reaction with anhydrous NaOAc makes it attraactive, one mol SiCl4 plus 4 mols acetate giving theoretically 2 mols anhydride and in practice, 1.5 mols.

That helps compensate for the cost of reagent.

Si2OCl6 on the other hand seems to be unobtainium commercially.

Pity that SiCl4 is not more generally applicable to the preperation of acyl chlorides and anhydrides.

Anyway thanks for all the assistance.

LSD25 - 27-2-2008 at 05:37

To S.C. Wack, I honestly thought that you were referring to and citing a different article

Here is the one I was thinking of:

Quig & WIlkinson, 'Preparation of Disilicon Hexachloride' (1926) 48(4) JACS 92: http://tinyurl.com/23fj3t

It does not actually fit here and I am more than happy to shift it if that is required, although I wanted to put it here as it fits (or so I thought) with the discussion.

Sauron - 27-2-2008 at 06:30

Silicon tetraacetate is, according to the first JACS paper above, the initial product of reaction of 4 parts glacial acetic acid and one part SiCl4, byproduct being 4 HCl.

Silicon tetraacetate is commercially available, but sold in small packaging only (10 g) for several dollars a gram.

Si(OAc)4 reacts with equimolar SiCl4 to give 4 AcCl. If this stuff were available in qty and not too expensive then the preperation of AcCl could be done without use of anhydrous NaOAc, with its tedious and persnickety fusions. Alas this seems unlikely.

Preparation of Si(OAc)4

Four moles glacial acetic acid and 1.5 moles SiCl4 in 200 ml abs. Et2O are refluxed 48 hrs in a dry apparatus with exclusion of moisture. After standing in the cold a further 48 hrs, the precipitated crystals are collected in a dry box, and a second crop collected after concentration of the mother liquor. Yield 70 g or 30% on GAA basis.

The product is extremely hygroscopic.

It can be efficiently prepared from Ac2O and SiCl4, but that is useless for making Ac2O. The byproduct is AcCl.

Si(OAc)4 reacts with SiCl4 to give 4 mols AcCl per mol.

So that is you have lots of SiCl4 and GAA this is a pretty good way to make AcCl.

Of course, you need not bother to isolate the tetraacetate at all, just proceed as in the JACS article and you get a much better yield in a single step.

[Edited on 28-2-2008 by Sauron]

Fleaker - 27-2-2008 at 10:50

Hm, so to make this useful one would need a good source of dry chlorine, a tube furnace, and some silicon powder.
Silicon is fairly cheap, chlorine is easy to make, but some of us here do not have access to a tube furnace.

I am seriously considering running this reaction--it looks very easy to do.

microcosmicus - 27-2-2008 at 11:07

Tube furnaces are not that hard to make either. Basically, you wrap some resistance
wire around a tube and insulate it. What material is suitable for the tube and what
wire can be used are determined by the temperature you are trying to reach. (By the
way, what temperature is needed for your reaction between Si and Cl2?) Brauer's
Handbook of Preparative Inorganic Chemistry, which is available in the SM library, has
a detailed discussion of how to make a tube furnace. Also, since it is a resistive
device, you can use a lamp dimmer to control your tube furnace.

Fleaker - 27-2-2008 at 14:13

:-) By some of us I did not mean me, I have several that I can use. Soon I'll have a very nice one at home too.
Brauer, which I have downloaded a long time ago (excellent text!!) should have information on SiCl4. If not, I can simply ramp up the heat until I see the SiCl4 condensing.


I need to get a kilogram of silicon powder first. I have already the reaction vessels.

microcosmicus - 27-2-2008 at 14:55

Quote:

:-) By some of us I did not mean me, I have several that I can use.


That comment was mean for those people you referred to as "some of us",
not for you :)

According to Brauer, the temperature required is 400C. Thus, heating it should
not be a problem --- even without a tube furnace, putting a burner under the tube
containing the silicon or some such thing should work. However, because
SiCl4 decomposes easily upon exposure to water, one must take care to
rigorously exclude water from the system. Brauer suggests drying the chlorine
by passing it through sulphuric acid and placing a tube of CaCl2 where the
system communicates with the atmosphere.

Sauron - 27-2-2008 at 19:54

I don't get excited about making something that only costs ten cents a gram, not if it is not the end product, and not if I can purchase it easily.

No one is looking over anyone's shoulder for buying silicon tetrachloride. This is NOT true of:

thionyl chloride,
sulfuryl chloride
sulfur I or II chloride
phosphorus III or V chloride
phosphorus oxychloride
arsenic trichloride

Oxalyl chloride costs 6X as much

So SiCl4 is useful, but just about only for acetic anhydride/acetyl chloride. It's not very good for most other acids than acetic and benzoic. As general reagents for this purpose, benzoyl chloride, TCT, phthaloyl chloride and oxalyl chloride are still on top, and in approximately that order. Thionyl chloride, if you can get it, is a good general reagent for acid chlorides higher than C3. Same for POCl3, but you will have DHS breathing down your neck. Sniffing around for tabun nerve agent. Well, no one cares about SiCl4.

I noticed a peculiarity in the primary lit. on this reaction.

In the 1927 JACS article, the authors used 6 mols of glacial acetic acid to 3 mols SiCl4 in 6 mols toluene as diluent, and warmed the mixture to 50 C till HCl evolution was almost over. Fractionation then gave 85% acetyl chloride. The reaction was describedas occuring in two steps as follows:

4 AcOH + SiCl4 -> Si(OAc)4 + 4 HCl
Si(OAc)4 + SiCl4 -> 4 AcCl + 2 SiO2

Reaction time is not given but in the reaction of SiCl4 with anhydrous NaOAc, times of 3-5 hours were reported, with yields up to 75% of acetic anhydride.

Compare the procedure described in Brauer, p.701 for preparation of silicon tetraacetate from glacial acetic acid and SiCl4.

In this procedure, absolute Et2O was solvent, at reflux, time 48 hrs, followed by 48 htrs in the cold. Molar ratios 4 mols GAA to 1.5 mols SiCl4. Yield of 70 g from two crops is onoly 30% on GAA basis.

This is a large disparity in what should be the same reaction.

The use of 50% excess SiCl4 may have converted half the Si(OAc)4 to AcCl and SiO2 but that should have been obvious.

Or is the two step reaction accurately representing what is going on?

Why so long a reaction time in the Brauer procedure?

Would changing from ether to toluene be advantageous?

Reaction temperatures were only 15-or so degrees apart.

If the reaction of GAA and SiCl4 occurs as described, why not add only 1 mol SiCl4 to 4 mols GAA in solvent, then when HCl evolution ceases, add a second mol.

In the prep of Si(OAc)4, I'd be tempted to conclude that a lot of product must be left behind in the mother liquor still, if it wasn't converted to AcCl by that seemingly unnecessary 50% excess of SiCl4. I think I will look up Brauer's ref for that prep. I think it is Inorg.Syn. v.4.

[Edited on 28-2-2008 by Sauron]

LSD25 - 27-2-2008 at 20:40

As not everybody has the time or the patience to go through the first half of the Brauer PDF book, The following quote was lifted from Braeur, Handbook of Preparative Inorganic Chemistry, pages 682-3 (pages 707-8 of the OCR PDF from the Library):
Quote:
Silicon Tetrachloride SiCl4

Si + 2C12 = SiCl4
28.1 141.8 169.9

Silicon (prepared as shown above) or coarsely ground ferrosilicon (which should contain as much Si as possible) is placed in a boat inserted into a Pyrex tube about 60 cm. long and 2-3 cm. in diameter, through which a stream of Cl2 is passed (Fig. 223). The Cl2 is predried over concentrated H2SO4. A condenser is attached to the other end of the tube by means of an adapter; the tube itself is heated in an electric furnace. The tube should incline toward the condenser to prevent the SiCl4 from backing up.

The condenser end of the reaction tube should project out of the furnace for some distance so that the invariable byproduct FeCl3 may deposit without plugging the condenser. The condenser discharges into a distilling flask which is set in an ice bath. All joints must be tight and the entire apparatus carefully dried before the start of the run. A CaCl2 tube is attached at the end of the side arm of the distilling flask. If this precaution is overlooked, the side arm will immediately be plugged with silicic acid produced by reaction with atmospheric moisture. The reaction tube is heated to about 400°C and the Cl2 flow is then started.

If, in addition to SiCl4, the higher Si chlorides are desired (Si2Cl6 and Si3Cl8), the temperature of the tube should be as low as possible, but no lower than just below 400°C. When the reaction is well established, heating may be sharply reduced since the reaction itself evolves considerable heat. The crude chloride, which is accumulated in the distilling flask, may be purified by fractional distillation. If an absolutely Cl-free preparation is desired, a second distillation over Cu turnings is performed. Both distillations must be run in absolutely dry equipment. The ampoules into which the SiCl4 is distilled should be fused to the distillation apparatus, since it is impossible to obtain a non-turbid product if this is not done. Yield is quantitative.

PROPERTIES:
Clear, colorless liquid; fumes heavily upon exposure to air. Rapidly hydrolyzes in water to form a SiO2 gel. Miscible with benzene, ether, chloroform and saturated hydrocarbons. Forms esters of silicic acid with alcohols. B.p. 57.5°C, m.p.-68C, d 1.52.


I could not get the picture, which simply shows the furnace (horizontal) connected to a condenser (vertical & orientated downward @ 45 degrees) to the receiver. The Cl2(g) coming in is dried in a vessel attached to the front of the furnace tube with H2SO4 and then comes into contact with the silicon in the furnace tube.

[EDIT] I wonder if the output from the tube-furnace could be led directly into a vessel containing NaOAc with toluene/xylene as diluent? This would save a whole lot of fucking around purifying the intermediates, which providing atmospheric water is excluded and the reagents are anhydrous to start with, should probably not interfere too much with the reaction itself.

[Edited on 27-2-2008 by LSD25]

microcosmicus - 27-2-2008 at 21:03

Quote:

As not everybody has the time or the patience to go through the first half of the Brauer PDF book


I didn't have the patience to go through it --- I simply looked up Silicon Tetrachloride
in the table of contents and jumped to that page. The total time required was under a minute.

LSD25 - 27-2-2008 at 21:13

I have a very fucking slow connection (as do others) and simply had to wait for the pages to load and go through one at a fucking time. Talk about a headfuck.

PS The same slow-arse connection precludes me downloading the same and looking on the desktop - I have had 4 or 5 goes at downloading this particular book, all of which have been interupted as a result of the idiotic slow transfer rate.

Sauron - 27-2-2008 at 22:50

For silicon tetraacetate, the Brauer pages start at 701 and the original reference is to Inorg.Syn. IV P.45 for the prep from Ac2O, which is circular and therefore useless for purposes of this thread. The reference for the alternative prep from GAA is (I think) Z.Anorg.Allg.Chem. 272, p.313 (1953) the title of which is ON TRICHLOROSILICON ACETATE.

What we normally do when lifting a prep from a pdf is to use Acrobat to make a new pdf from the specific page range and then post that, the new relatively tiny pdf comes complete with the illustrations. For example, here's the SiCl4 section.

Brauer, and his references, also suggest that SiCl4 reacts with heavy metal acetates, such as thallium (I) acetate to give the silicon tetraacetate. Now, kiddies, don't muck around with thallium compounds. I am merely speculating that perhaps some less dramatically toxic heavy metal acetates such as those of Hg or Pb etc, might be more cost effective in this capacity and less likely to result in premature termination of life functions.

[Edited on 28-2-2008 by Sauron]

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S.C. Wack - 28-2-2008 at 04:12

When it was asked in the acetaldehyde synthesis thread lately what exactly acetaldehyde was good for, my first thought was of acetic anhydride. This was mentioned earlier this month in this thread, some patents are cited, and I just thought that I'd toss out three more patents for the hell of it.
DE699709
DE708822
US2259895
I don't look up many DE patents from 1933-1945, so just now noticed that the swastika on the documents is blotted out. Oh please.

LSD25 - 28-2-2008 at 04:56

I remember reading an article on the production of acetic anhydride from acetaldehyde via peracetic acid somewhere once before.

I thought I had saved the article, but I cannot find it - although I can find references to it. Anyway, here is the stuff I do have:

Zeyer, et al, 'The behavior of the iron(III)-catalyzed oxidation of ethanol by hydrogen peroxide in a fed-batch reactor' (2000) 2 Phys. Chem. 3605: http://tinyurl.com/3cvbkq

Acetic Acid by oxidation with Peroxide over Iron Hydroxide: http://tinyurl.com/32zgq6 (this like the preceding article, gives a mixture of acetaldehyde and acetic acid)

Chemicals from Acetaldehyde (1959) 51(12) Ind Eng Chem: http://tinyurl.com/2rvhh9 (a quick overview of the chemicals produced from acetaldehyde)

Philips, et al, 'A New Synthesis of Peracetic Acid' (1957) 79(22) JACS 5982: http://tinyurl.com/2nabdc

Here is an overview of the industrial synthesis:

Klaus Weissermel & Hans-Jürgen Arpe, Industrial Organic Chemistry: http://tinyurl.com/363tty

Now, I suspect that I have lost (or at least cannot find - same thing) the article I was thinking of, although this one looks something like it:

C. E. H. Bawn, T. P. Hobin & L. Raphael, 'The Metal-Salt-Catalyzed Oxidation of Acetaldehyde' Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, Vol. 237, No. 1210 (Nov. 6, 1956), pp. 313-324: JSTOR abstract is here: http://tinyurl.com/3528f6 (they also cite another article to a similar effect).

I have wondered about whether this was something that could be harnessed before, but it appears to have been ignored.

Oh, here is the article I was thinking of:

Carpenter, 'Oxidation of Acetaldehyde to Acetic Anhydride' (1965) 4(1) J. Industrial Engineering & Process Design 105: http://tinyurl.com/2atk64 [Thanks due to Solo for this article]

[Edited on 28-2-2008 by LSD25]

[Edited on 28-2-2008 by LSD25]

Sauron - 28-2-2008 at 04:56

Ullmann's on SiCl4 is interesting. Anyone contemplating running this prep should have a look.

To recap this section on SiCl4 and its utility in making AcCl or Ac2O directly, SiCl4 is very efficient at chlorination of anhydrous acetic acid in high yield and almost as efficient in the preparation of acetic anhydride from anhydrous sodium acetate (or potassium acetate).

The best price I found for SiCl4 was from Alfa, who sell a liter for $70; a liter weights about 1500 g so this is somewhat less than $50 a Kg. That is about 9 mols SiCl4.

According to the stoichiometry and yields presented in the 1927 JACS paper cited upthread, that is sufficient to prepare about 1200 g of AcCl.

Or, by direct reaction with anhydrous sodium acetate, sufficient to obtain 13.5 mols acetic anhydride. Roughly 2 Kg.

The over all reaction of SiCl4 and AcOH is

2 SiCl4 + 4 AcOH -> 4 AcCl + 4 HCl + 2 SiO2

and it proceeds in 85% yield on AcOH basis

The reaction of SiCl4 with anhydr. NaOAc is

SiCl4 + 4 NaOAc -> 4 NaCl + 2 Ac2O + SiO2

and proceeds in 75% yield. So for every mol SiCl4 used, we get 1.5 mols Ac2O, when Ac2O is used as diluent, or 1 mol Ac2O when benzene is used as diluent.

It is obvious that if Ac2O is your target, it is better to get there in one step.

Commercial silicon tetraacetate hovers around $1 a gram in 100 g packing for tech grade (Fluorochem) and so is out of range of economical utility.



[Edited on 29-2-2008 by Sauron]

Fashist - 29-2-2008 at 00:50

Merck SICL4 is 56$ per liter(cheap than Alfa)
If you order drum(190kg) it will be cheaper.

Sauron - 29-2-2008 at 04:25

Good news for you, then.

If you get a quote for the drum, let me know what it is.

It's also good news for me since Alfa has no representation here but I buy from Merck regularly.

SiCl4 is quite moisture sensitive. You had best plan to handle it in such a fashion that it does not come into contact with any atmospheric moisture. For Kg quantities a dry box (glove box) with dessicant and a N2 purge would be best.

[Edited on 29-2-2008 by Sauron]

Pulverulescent - 24-4-2008 at 07:58

http://v3.espacenet.com/origdoc?CY=gb&LG=en&DB=EPODOC&IDX=GB424573&DOC=ce973ee58c33eea7621edc965e05ac7c23&QPN=GB424573

Has anyone seen this?

It's basically acetic anhydride from sodium bi-sulphate and sodium acetate, via the pyrosulphate!

Na2S207 + 2Na0Ac = 2Na2S04 + Ac20

It looks kinda interesting!

P

Pulverulescent - 24-4-2008 at 08:53

'Sorry, I'll try another link!


]http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=GB424573&F=0&QPN=GB424573

P

Pulverulescent - 24-4-2008 at 12:45

Duh. . .I noticed the method above was discussed earlier. . . it is a long thread!
I think it was tried unsuccessfully by a couple of members!
'Pity, it looked good at first glance, and if it actually worked it'd be a simple route for Ac20.

This thread seems to contain all possible routes, and they're all awkward!

AA, so desirable, but, what a bitch!

P

Fleaker - 26-4-2008 at 09:47

Despite the hazards, I say ketene and GAA is the way to go for making Ac2O. It is something you can run all day.

If you have the equipment to do it, it works.

Pulverulescent - 26-4-2008 at 10:20

And you don't actually need GAA!
Ketene and water will work if you don't mind waiting a bit longer for the anhydride!

P

Fleaker - 26-4-2008 at 20:42

Yes, but I would just start with GAA as a time saver. When I attempted this, the water in my second absorber column was indeed acidic after the reaction (in fact, I titrated it to find out how much ketene made it into that bubbler, looking back, I should probably have done an iodoform test too!).

Pulverulescent - 27-4-2008 at 08:49

It'll be Autumn before I can attempt the ketene, or any other route (blasted major home-improvement project!).

I'll probably go with copper tubing, brazed or copper eutectic joints, and electrically heated, to see how well it works.

'Only problem seems to be the lifetime of repeatedly heated copper tubing.

It still should be easier than an Ace-type lamp, at any rate!

And since I have GAA I won't be using water either.

BTW, Fleaker, how well did your ketene synth go, and what method did you use?

P

Ephoton - 28-4-2008 at 22:29

I always found ketene to be a problem not due to its manufacture but just becouse
it does not fully react with the GAA. the problem being that it then bubbles out of the
acetic acid and either gets waisted in another wash bottle or goes into the enviroment.

I would think though it would react very quickly with HCl to form acetyl chloride.
this might be a way to make the whole ketene lamp a little safer.

I always found ketene very easy to make.
just a little expensive on equipment and hard on nichrome wire.

not_important - 28-4-2008 at 23:15

It need not be wasted. Set up a train of water filled wash bottles, perhaps with a drop of H2SO4 in them as well. Ever so oft check the concentration of AcOH in the first and second bottles. At some point the first bottle will be somewhere between nearly 100% GAA and GAA+Ac2O. Add a new bottle to the end of the train, remove the first as on the next run the now GAA bottle will be making anhydride.

Using something more effective than ordinary wash bottles really helps with the problem of unreacted ketene. There were several examples of such given earlier in this thread; basically use a packed fractionation column for the absorber.

Pulverulescent - 29-4-2008 at 03:35

Could someone please post pictures of their ketene-generator---I'd love to see them!

'Such a long thread, but no pics!

Fingers crossed, guys!

Thanks!

P

Foss_Jeane - 14-5-2008 at 16:45

I found a couple of ketene generators. The first is sort of an afro-tech method.

Ghetto Ketene Generator

This one is really dangerous, and I wouldn't fool with it under any circumstances.

Here's a "ketene lamp" without the associated glassware. I'd like to get ahold of one of these since I collect funky old electronics.

Ketene Lamp

The latter might be OK to operate if you could set it up way out in the boonies and operate it by remote control at least a quarter mile upwind of the thing.

It would be bad enough if ketene were simply a nasty chemical that made irritating acetic acid when it comes in contact with moist eyeballs and/or nasal pasages. A good fume hood would take care of that. However, this stuff is way more toxic than that. As if that weren't bad enough, this is also one of the few substances that are known cancer-causers. No maybe's about that. You don't want stray molecules of this stuff floating around your basement.

IDLH Doc.

Polverone - 14-5-2008 at 17:10

Can I get a literature reference on ketene being a known human carcinogen? Sauron mentioned this earlier, but a few minutes with Google doesn't turn up any references indicating that it is a known or probable human carcinogen. In fact some references (e.g. "Risk Management for Hazardous Chemicals" by Jeffrey Vincoli) explicitly state that ketene exposure has not demonstrated carcinogenic effects. Kirk-Othmer says the same thing about carcinogenic effects (none demonstrated). The Health Council of the Netherlands likewise reports no known carcinogenic effects in a 2001 report.

joeflsts - 14-5-2008 at 18:07

Quote:
Originally posted by Polverone
Can I get a literature reference on ketene being a known human carcinogen? Sauron mentioned this earlier, but a few minutes with Google doesn't turn up any references indicating that it is a known or probable human carcinogen. In fact some references (e.g. "Risk Management for Hazardous Chemicals" by Jeffrey Vincoli) explicitly state that ketene exposure has not demonstrated carcinogenic effects. Kirk-Othmer says the same thing about carcinogenic effects (none demonstrated). The Health Council of the Netherlands likewise reports no known carcinogenic effects in a 2001 report.


Agreed, in fact most literature claims longer term exposure to bring on pulmonary edema.

Joe

Foss_Jeane - 14-5-2008 at 18:24

^^^^

It looks like that may have come from Wikipedia. There are some mentions of possible links to non-Hodgkin's lymphoma, though the link to ketene specifically doesn't appear to be established. Looks like something that was once thought to be the case, but turned out it really wasn't after further consideration.

Still, it's pretty darned toxic, and I wouldn't want to try running that ketene lamp inside, even with a fume hood.

Here's a thought.

stygian - 14-5-2008 at 18:40

I'm not sure of their structure but could a carboxylic-carbonic anhydride be decarboxylated to yield a dicarboxylic anhydride?

Jome - 9-6-2008 at 08:56

What do you mean, like pyruvic anhydride?

12AX7 - 9-6-2008 at 10:42

Carbonic? Would that be R-C(=O)-O-C(=O)-OH (or -O(-))? That would surely decarboxylate instantly.

Tim

Sauron - 9-6-2008 at 11:14

I have not been able so far to locate the page in my limited number of Org.Syn. annual volume hard copies from the 60s and 70s that contained the listed of proven human carcinogens, encompassing ketene.

I believe this was an OSHA list but that is going by memory and may be mistaken. I am quite certain ketene was on the list because I made note of the fact within the last few years.

HOWEVER, even if I find it, it would certainly appear to be the case that 30-40 years later, expert opinion has shifted and ketene is no longer regarded as a proven or even suspected human carcinogen.

If you examine the record over that many decades the experts appear to dither and waffle about what is and is not carcinogenic quite a bit.

Frankly this does not inspire great confidence in such "expertise", does it?

It rather implies that there have been rushes to judgement, later backpeddling, and in some cases reversals of the backpeddling.

A further implication is that carcinogenesis is still far from being well understood, and that includes chemical carcinogenesis.

As to the operation of a traditional ketene lamp such as described in Org.Syn., and various references, and formerly sold commercially by Ace Glass, I would not hesitate to perate one in a very well ventilated location such as in a fume hood that has been tested and shown to be well designed and have adequate face velocity and an appropriate scrubber system. One simply needs to appreciate that this is a small scale generator and can't be scaled up. A tube furnace type generator is scalable but now you are talking about a lot more risk.

[Edited on 10-6-2008 by Sauron]

LSD25 - 12-6-2008 at 06:46

I take it most people here are at least aware of the proposed or cited synthesis of AA from methanesulfonyl chloride and triethylamine cited on Rhodium's site?

Well, here is a variant on the theme, toluenesulfonyl chloride (the bromide is reuseable and can be regenerated according to a procedure elsewhere, so what about the chloride?) in excess is added to sodium acetate (I suspect dry) and then heated to 180-200C for 30min. No need for amines, just the sulfonyl chloride...

http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3...

(It is on page 2 of the PDF)

Could something similar be done with methanesulfonyl chloride do you think?

Also, on another track, phthalic anhydride is mixed with GAA and sodium acetate in order to prepare cellulose acetate phthalate. Doesn't this suggest the formation of at least the mixed anhydride? So if one mixed GAA with phthalic anhydride and sodium acetate, is it possible to prepare AA comparatively simply (especially given that the phthalic anhydride is regenerable with heat)?

[Edited on 12-6-2008 by LSD25]

Sauron - 13-6-2008 at 00:47

There is no shortage of Ac2O preps involving anhydrous (fused) NaOAc.

The one you cite appears to employ tosyl chloride as a chlorinating agent to convert part of the GAA to acetyl chloride, which then reacts with the NaOAc to form Ac2O.

No surprises here.

The problem seems to be that many people simply cannot efficiently prepare properly anhydrous sodium acetate. The detailed instructions have been given here many times. The anhydrous sodium acetate is commercially available as well, from reliable vendors.

If starting from the hydrated salt, the fusion needs to be done twice, the second, higher temperature stage being the one that usually gets overdone, resulting in carbonization.

If you start with the freshly opened commercial anhydrous material, a single melt will suffice, and in the case of the Merck "super dry" grade may be superfluous.

LSD25 - 13-6-2008 at 03:33

I thought I'd add in some interesting details of the preparation of the MsCl - not because it is off-topic - but because of the by-product(s) of performing this reaction in different solvents

The attached material contains 4 separate articles which have been condensed down

So Sauron, you'd agree that the MsCl should also give the anhydride from the salt and the anhydrous acid? So some thought on the preparation of MsCl from such a ubiquitious solvent as DMSO should be of some interest? What about AcCl (a byproduct of performing the rxn in GAA) or CCl4 (doing the rxn in CH2Cl2)... The best route (in terms of lack of byproducts and yield) appears to be 1:1 AcOH:H2O, where the intermediate chlorosulfone is hydrolysed in-situ giving predominantly the MsCl as the product.

[Edited on 13-6-2008 by LSD25]

Attachment: MsClfromDMSO.pdf (2.3MB)
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Sauron - 13-6-2008 at 03:52

I believe there are serious toxicity issues with mesyl chloride that do not apply to tosyl chloride.

I see absolutely no advantage to using either one to obtain acetyl chloride (in situ, or isolated) as compared to the numerous other methods that have been elucidated for preparing that acyl chloride and other acyl chlorides.

My point in my last post above was that lots of people appear to come to no joy when trying to get anywhere with reactions of anhydrous sodium acetate. Therefore until that problem is solved, rehashing old stuff from rhodium that calls for anhydrous sodium acetate is just spinning of wheels, isn't it?

There are preps of Ac2O that do not rely on anhydrous NaOAc, and no I do not mean using ketene.

Oxalyl chloride, for example.

not_important - 13-6-2008 at 05:44

Quote:
Originally posted by LSD25
Well, what is the problem with anhydrous sodium acetate?

Here is a decent step-by-step: http://www.instructables.com/id/S1HFXYZFA190FOL/


Which makes the tri-hydrate, not the anhydrous acetate.

LSD25 - 13-6-2008 at 06:05

not_important, I do realise that but I was actually in the middle of the post - I'd posted what I had cos my connection is utter crap at present and was in the middle of editing the same in order to add in the additional ref's. Unfortunately your post tried to quote part of a post which was in the process of being edited and the database/server didn't like it:P

I will now paraphrase what I had above
Quote:
Here is a decent step-by-step: http://www.instructables.com/id/S1HFXYZFA190FOL/

Here is possibly the most complex method I have yet seen for doing so: http://www.jbc.org/cgi/reprint/173/1/205.pdf

PS The point in those papers (there are now 7 in the collection) is that the CCl4 or the AcCl are produced as byproducts (the AcCl comes about becuase of the formation of the methanesulfonyl anhydride which forms a mixed anhydride with the acetic/propionic acid, which then reacts with the chlorine(g) according to the author's). Now I don't know about you, but a simple 1 or 2 step from cheap as shit DMSO using only chlorine in aqueous AcOH is about as simple as this is ever going to get.

Check this monograph (http://www.fao.org/ag/agn/jecfa-additives/specs/Monograph1/A...) - the anhydrous form fuses then decomposes with additional heat to form acetone - the trihydrate melts, then with extra heat becomes a powder which then fuses and if more heat is applied decomposes to form acetone.

Now where do you think the dehydration is complete? As soon as it dries out again after the trihydrate 'melts'? This is simple stuff, why is it being dealt with again?

Then again, here is a detailed synthesis of both glacial acetic acid from sodium acetate:

Quote:
89. Preparation of Glacial Acetic Acid (Section 83). - Melt cautiously in an iron dish about 50 grams of anhydrous sodium acetate[1]. Grind the salt to a coarse powder in a mortar; weigh 40 grams of the salt and place it in a 200 cc. distilling flask. Add cautiously through a funnel, keeping the flask cold by immersion in water, 25 cc. of concentrated sulphuric acid. Place a thermometer in the flask in order to determine the temperature of the vapor. Connect with a condenser and receiver, and distil off the acetic acid. Weigh the acid obtained. Calculate the theoretical amount which can be obtained from 40 grams of sodium acetate, and the percentage yield of the experiment. Caution. - Glacial acetic acid causes painful blisters when left in contact with the skin.

from here: http://www.books-about-california.com/Pages/Experimental_Org...

Here is the synthesis of anhydrous sodium acetate:

Quote:
[1] Commercial fused sodium acetate is generally not anhydrous; it is well to fuse it before use. If the compound is to be prepared from the hydrated salt (CH3COONa.3H20) proceed as follows: Heat cautiously about 15 grams of the crystalline salt contained in an iron pan over a small flame. Stir continuously with a glass rod. The salt melts at first in its water of crystallization; as the dehydration proceeds it solidifies, and, finally, when anhydrous, melts a second time. Care should be taken to avoid heating the dehydrated salt much above its melting-point, as it undergoes decomposition when strongly heated.

from here: http://www.books-about-california.com/Pages/Experimental_Org...

For those who REALLY want to look at the Ketene route, here is a rather more detailed than normal article on the same:

http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3...

What in god's name is going on the with the fucked up format?



The sulfuric acid apparently causes some charring and I want to try phosphoric acid for this, but it apparently still does work (plus, I don't like wasting H2SO4).

[Edited on 13-6-2008 by LSD25]

Sauron - 13-6-2008 at 15:22

We are going around in a circle regarding anhydrous NaOAc.

The procedure for drying NaOAc.3H2O by fusion has been posted previously, in far more detail than that little clip from Feiser, and with illustrations, the source having been Gattermann. The problem is not reading about doing it. The problem IS doing it, on a decent scale and not charring it.

Gattermann states that a single fusion suffices for the comml anhydrous salt which might have readsorbed some moisture in storage. This sounds more productive to me, but people still seem to try to go from the trihydrtae for reasons of (false) economy, and they upgefuck.

I have yet to see anyone post success with this step.

As to the chlorination of DMSO, I will take another look at this reaction. I note that the reaction is said to be closely akin to the chlorination of (among other things) MeSCN, which I have posted about elsewhere. Also one reported product is trichloromethyl methyl sulfide. It is easy to see how this can fragment to CCl4 via the well known trichloromethyl radical; IMO it would be a mistake to assume that CCl4 was only forming from chlorination of DCM solvent, particularly as no CHCl3 is mentioned as being formed as well.

Another feedstock for prep of MsCl is S-methylthiouronium sulfate, the methylated derivative of thiourea. The relationship to methyl thiocyanate is again obvious.

Another starting material is sodium methyl thiosulfate. This is from methylation of the ubiquitous sodium thiosulfate, readily available OTC from photographic suppliers. ("Hypo")



[Edited on 14-6-2008 by Sauron]

Sauron - 13-6-2008 at 19:03

Quote:
Originally posted by LSD25
I take it most people here are at least aware of the proposed or cited synthesis of AA from methanesulfonyl chloride and triethylamine cited on Rhodium's site?




I saw a couple preps of mesyl esters on Rhodium but nothing about MsCl, TEA and GAA/NaOAc to make Ac2O.

Kindly provide URL or attach the pdf here.

I just spent more time than I really cared to reading four papers you posted, which generally had little to do with chlorination of DMSO (save for the first.) They had a lot to do with chlorination of sym-trithiane, chlorination of dialkyl sulfides, etc. The yields of mesyl chloride were at best only fair and nowhere did I see a viable preparative path to CHCl3/CCl4 or AcCl, which were side products.

Interesting chemistry but mostly off target if not off topic. Other processes are more straightforward, simpler, with less elaborate workups and much higher yields.

Now I will have a closer look at the tosyl chloride article. I have a kilo of tosyl chloride on hand, something I can't say presently for mesyl chloride. The latter is readily enough available, without any DMSO having to die for it.]

The tosyl chloride prep of Ac2O from anhydrous NaOAc, which does not require GAA, is in the paper cited by LSD25 and in irs Reference 4 (JACS 68, 2019, attached below) conducted on a very very small scale (< 1 ml product). The TsCl and dry NaOAc are admixed as solids, then heated 30 min at 180-200 C, at which temp they are most certainly a melt. Ac2O distills off. IF this process scales up, it will indeed be both simple and useful.

I'd think that an oil bath preheated to 190 C would be ideal. Minimize the time to get the pot to temp.

I think I have a bottle of anhydrous NaOAc, unopened, around. This rxn does not really need a hood. Let me see what I can do about trying this one out on a 100 g basis. Maybe not today or tomorrow but hopefully this month.

I just crunched the numbers from the Ac2O prep LSD cited and from the reference I pulled up.

The original prep used equimolar amounts of sodium acetate and tosyl chloride, and got a 90% yield of Ac2O. LSD25's paper employed about a 15% excess of tosyl chloride, and did not indicate their product amount. They were operating at a fraction of the already small scale of the original (7.5 mmols vs 22.3 mmols.)

Tosyl chloride melts at 65-69 C and boils at 134 C/10 mm Hg. Sodium acetate (anhydrous) melts with decomp. above 300 C. So the salt will either dissolve or be suspended in molten tosyl chloride at 180-200 C, and Ac2O will flash off as it forms. Sounds like a 1 liter pot will suffice for about a 2.2 mol run that ought to produce c.100 ml Ac2O. That is from 162 g sodium acetate and 425 g tosyl chloride.

ANyone care to work out the stoichiometry? Or even what the reaction looks like? Obviously two equivalents of acetate are needed to produce one of anhydride. But does AcCl form in situ and react with the acetate to form the anhydride? Or what? Is HCl going to evolve? TsOH left behind? Anyone have a clue?


[Edited on 14-6-2008 by Sauron]

Attachment: Ac2OfromTosylchloride.pdf (301kB)
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LSD25 - 14-6-2008 at 02:54

Yeah, whoops - I think the auto-condense procedure in Acrobat is to blame for part of that, I have accidentally condensed part of the collection with itself and other papers did not get added to the collection at all (write-protected).

Sauron, yeah the reaction is nowhere near as simple as could otherwise be suggested, in fact it is more than a little interesting. I note in fact that you advanced some varied hypotheses above for what was going on, so I thought you might have appreciated the author's of those papers views on the same.

However the suggestion that the majority of the papers don't actually deal with the chlorination of DMSO in aqueous acetic acid, misses the point somewhat:
Quote:
The complication involved in chlorinating more nucleophilic sulfides and sulfoxides is that the product is often nearly as reactive as the starting material. For example,
chlorination of DMSO in aqueous acetic acid, at room temperature, leads to the formation of 1-chloro-2-thiapropane-2-oxide, 1, which is seriously
contaminated with 1,l-dichloro-2-thiapropane-2-oxide. 2.

This was taken from page 24/45 of the attached material (actually the study on the intermediate stages of the 'sulfohaloform reaction).


With that in mind, the repeated references to starting from this intermediate begin to make some sense, don't they? As to the remainder of the articles, particularly those which deal more with the specifics of the reaction than the product thereof, I have found it is important to at least make the effort to provide additional material (on this board and others) in order that other people can see where the idea comes from (and more especially, the concept underlying such ideas) - such left-field suggestions generally get pooh-poohed rather quickly otherwise:P

There are numerous studies on this reaction, apparently there was quite a bit of work carried out on the subject, for example:
Quote:
Mechanism of the photochemical chlorination of sulfones, Russian Chemical Bulletin, Springer New York (ISSN 1066-5285 (Print) 1573-9171 (Online): Volume 19, Number 9 / September, 1970: DOI 10.1007/BF00849770)

Conclusions
1. The photochlorination of dimethylsulfone proceeds according to a radical-chain mechanism with cleavage of a C-H bond and formation of trichloromethylmethylsulfone as the only product.
2. Photochlorination of diethylsulfone at the first step also proceeds with cleavage of a C-H bond, but the radical C2H5SO2CH2CH2 formed in this case is stabilized by cleavage of a C-S bond, forming ethylene and the radical C2H5SO2.
3. Photochlorination of methylphenylsulfone proceeds according to a mechanism analogous to that for diphenyl- and dimethylsulfones.
4. Photochlorination of sulfolane proceeds according to a radical-chain mechanism with cleavage of the C-H bond at thebeta-carbon atom, forming 3,3,4,4-tetrachlorosulfolane as the final product.
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2029–2032, September, 1970.


Now that would be interesting as I think that is one of the intermediates in the MsCl synthesis and MSM is cheap as shit.

As to the Rhodium.ws reference, it is a page I know you are familiar with (at the bottom).
Quote:
A Mild Method for the Synthesis of Carboxylic Anhydrides
General Procedure, exemplified for Propionic Anhydride:

Propionic Acid + Methanesulfonyl chloride --Et3N--> Propionic Anhydride

To a stirred solution of propionic acid (2 mmol) and methanesulphonyl chloride (1.05 mmol) in dry THF (10 ml) at -15°C under nitrogen was added triethylamine (3.5 mmol) in THF (5 ml) slowly over 20 minutes. After stirring 1 hour at -15°C the reaction mixture was allowed to warm to room temperature. The reaction mixture was filtered through Celite and the solvent was evaporated off under reduced pressure. The anhydride was isolated by short-path distillation (yield: 85 %, bp: 70-72°C / 20 Torr (lit. bp: 67.5°C / 18 Torr)).

Reference:
"A mild method for carboxy-group activation and synthesis of carboxylic anhydrides", J. Chem. Research 100 (1984)

This method is fairly general. The authors prepared several anhydrides, in good to excellent yield. There are two methods of isolation (used depending on the anhydride made).

Method of isolation A

The solvent was evaporated under reduced pressure and the residue was partitioned between ether or ethyl acetate (50 ml) and a cold saturated solution of sodium hydrogen carbonate (50 ml). The organic phase was washed successively with saturated sodium hydrogen carbonate solution and brine, dried (MgSO4), and concentrated in vacuo to afford the anhydride.

Method of isolation B

(implemented in the propionic anhydride synthesis)

The reaction mixture was filtered through Celite and the solvent was evaporated off under reduced pressure. The anhydride was isolated by short-path distillation.
Synthesis of internal anhydrides

To a stirred solution of phthalic acid (0.332 g, 2 mmol) in dry THF (12 ml) was added triethylamine (0.202 g, 2 mmol) under nitrogen. The reaction mixture was cooled to - 20 °C. After stirring for 15 minutes, methanesulphonyl chloride was added (0.24 g, 2.1 mmol) followed by triethylamine (0.404 g, 4 mmol) in THF (5 ml) over 15 minutes. The reaction mixture was stirred at -15°C for 2 hours. The product was isolated using method A (0.275 g,, 93 %, m.p. 130-131°C)

Other Examples

Acid: MeCH=CHCOOH
Yield anhydride: 87%
Method of isolation: B

Acid: PriCOOH
Yield anhydride: 89%
Method of isolation: A

Acid: Me(CH2)7CH=CHCOOH
Yield anhydride: 95%
Method of isolation: A

Acid: PhCOOH
Yield anhydride: 92%
Method of isolation: A

Acid: 4-O2N-C6H4COOH
Yield anhydride: 82%
Method of isolation: B

Acid: PhCH=CHCOOH
Yield anhydride: 85%
Method of isolation: B

Acid: 4-MeO-C6H4COOH
Yield anhydride: 94%
Method of isolation: B

Acid: 2-Cl-C6H4COOH
Yield anhydride: 93%
Method of isolation: A


[Edited on 14-6-2008 by LSD25]

Attachment: PreparationandmechanicsofMsClfromDMSO.pdf (2.7MB)
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Sauron - 14-6-2008 at 07:41

No, I did understand where Clayton was going with his chlorinations in various aqueous and nonaqueous solvents and divers substrates. One could hardly miss the significance.

Thanks for the ref from rhodium. Interesting that the MsCl reaction calls for TEA. On the other hand these are proceeding from the acids not the carboxylates.

Just as the chlorinations diverse with and without the presence of water in the cases of the sulfoxides, sulfides etc, they also differ with and without water in the case of alkyl thiocyanates.

Mesyl chloride being the major product when water is present.

See

1.

The Action of Chlorine on Thiocyanates
Treat B. Johnson and Irwin B. Douglass
JACS 61 pp 2548 - 2550 (1939);

DOI: 10.1021/ja01878a085

2.

Explosion Hazard in the Chlorination of Alkyl Isothioureas to Prepare Alkyl Sulfonyl Chlorides
Karl Folkers, Alfred Russell, and R. W. Bost
JACS 63 pp 3530 - 3532 (1041);

DOI: 10.1021/ja01857a510

Or just hang on a wee bit as I am requesting these in References.

The second is a reminder than these chlorinations can get nasty.

Mesyl chloride is also formed in the aqu chlorination of s-methyl thiouronium salts, but Merck had a nasty kaboom! while doing so.

At that time everyone was working on preps for these reagents because of the great interest in sulfa drugs at start of WWII.

While MeSCN can't compete with DMSO for economy, it is certainly a closely related reagent, you can regard it as a dehydrated methylsulfonic acid (almost). Traditionally mesyl chloride was prepared by brute force chlorination of methanesulfonic acid with PCl5, which was costly and inefficient. SOCl2 was also used with better results.

Sauron - 14-6-2008 at 07:55

I hate to be a spoilsport but, have a look at the relative complexity of the reaction conditions for the MsCl prep of anhydrides.

THF solvolysis
Cooling -15 C
N2 atmosphere

And all that for a measly 2 mmol scale. To operate on a mere 1 molar basis 500x volume of THF would be needed with requisitely larger vessel.

Now compare this to the elegant stark simplicity of the tosyl chloride procedure. (Also unearthed by you.)

No solvent
No inert atmosphere
No elaborate workup - anhydride distills off in case of acetic anhydride

Now, are we going to believe that someone who can't get tosyl chloride, can get a lot of THF?

The tosyl chloride procedure is clearly better, more amateur friendly.

This observations renders all the DMSO chlorination material academic. At least in my opinion.

Wouldn't you agree?



PS

For those of us who buy our reagents both tosyl chloride and mesyl chloride are cheap.

Acros prices:

Tosyl chloride 2 Kg $88 (about 10 mols)

Mesyl chloride 1 L (1500 g) $100 (13 mols)

The cost per mol is about same.

Obviously for those who must DIY, mesyl chloride will be easier to build, unless one has a surfeit of chlorosulfonic acid.



[Edited on 14-6-2008 by Sauron]

[Edited on 15-6-2008 by Sauron]
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