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franklyn
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Now T H I S is an explanation
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]
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lester
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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 )
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Fashist
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POCL3+4ACONA->2AC2O+3NACL+NAPO3
Good idea
any body has idea?
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Sauron
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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.
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Fashist
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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)
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Sauron
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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.
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franklyn
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| 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.
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Sauron
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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]
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Fashist
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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
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Sauron
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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]
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Fashist
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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]
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Fashist
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I will try
K2S207+ACONA->AC2O+na2so4+k2so4
i just find pottasium pyrosulphate(old merck product)
anybody has idea?
thx
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lester
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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
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Sauron
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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.
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Fashist
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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
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Sauron
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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.
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Fashist
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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?
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JohnWW
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| 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?
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S.C. Wack
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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.
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Sauron
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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]
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DJF90
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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.
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Sauron
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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]
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-jeffB
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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.
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garage chemist
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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.
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JohnWW
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| 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".
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That article has been posted in the References section, under the wanted references thread.
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