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ketel-one
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I don't think S2Cl2 will work, it doesn't have S to Cl atoms in right proportion.
I think SO2Cl2 (SO2 + Cl2 in activated carbon) will take you to acetic anhydride though.
3NaOAc + SO2Cl2 = Na2SO4 + NaCl + Ac2O
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DJF90
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You can't do 2+2 chemistry when it comes to organic. S2Cl2 works great - theres a method posted here using the bromide instead, and that works fine
too.
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entropy51
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Since none of the reactions you have posted so far is feasible, I doubt anyone is surprised that you are out in left field once again.
See this thread for some much-needed enlightenment:
https://www.sciencemadness.org/whisper/viewthread.php?tid=90...
Better to remain silent and appear a fool than to open your mouth and remove all doubt.
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entropy51
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Quote: Originally posted by ketel-one  | My mistake then, I thought S2Cl2 was an idea no-one's tested yet.
You can always use AlCl3
anhydrous AlCl3 + acetic acid = hydrous AlCl3 + acetic anhydride. |
Please feel free to read a few of the posts on the forum and educate yourself on what some of the competent chemist members have done. That will help
keep you from looking, shall we say, uninformed.
Better to remain silent and appear a fool than to open your mouth and remove all doubt.
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ketel-one
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Ok I see, only compounds that hydrolyze in water would work, dehydration by itself won't.
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woelen
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Your rule is not correct, AlCl3 also hydrolyzes in water (to a mix of chloride/hydroxide and HCl) and yet it cannot make Ac2O. If you open a container
of anhydrous AlCl3 then you are welcomed by dense fumes of HCl. If you put a single drop of water on a heap of anhydrous AlCl3 then you hear a
hissing noise and HCl, mixed with waper vapor, is released.
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JohnWW
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Other possible alternatives to S2Cl2 and AlCl3 for anhydride preparation in that way should be PCl3, POCl3, PCl5, AsCl3, SCl2, SOCl2, SiCl4, SnCl4,
BCl3, and possibly TiCl4. The corresponding bromides may be usable insofar as they may be sufficiently stable.
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quarterfinal
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hi everyone.
I have been using the Vinyl Acetate , HCl acetic acid method proposed earlier. I have been constantly getting Ac anhydride. the yields are ok but the
purity is somewhat average. its probably because i am not a chemist and my fractionating column or my procedure might be crude. anyways i wanted to
thank this forum and a few people here. i have stopped making the anhydride as my purpose for doing it has been achieved. thanks again
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franklyn
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One pot synthesis of Ac2O from Trichloroethane
So claims this patent from 1932 - US 1870601
Which details hydrolysis of Methylchloroform in reflux with water catalysed by H2SO4.
On its own it hydrolyzes with water over years forming Hydrochloric and Acetic acid.
Accordingly it seems much more sensible to just heat together stoichiometric
amounts of 1,1,1-Trichloroethane and caustic soda , Na2O.
1,1,1-Trichloroethane is known to be incompatible with caustic soda.
2 CH3CCl3 + 3 Na2O -> (CH3CO)2O + 6 NaCl
See " Reactivity Profile " here _
http://cameochemicals.noaa.gov/chemical/1629
See " Incompatibilities & Reactivities " here _
http://www.osha.gov/web/dep/chemicaldata/ChemicalResult.asp?...
See " Reactivity Data " here _
http://www.relton.com/pdf/rapidtap.pdf
Availability of 1,1,1-Trichloroethane is extremely limited , this is a cheap source here
Carbo-Sol was discontinued in January, 2006 , get while it lasts.
http://www.retcoalloy.com/store/product.php?productid=182773...
.
Attachment: Ac2O by CH3CCl3 pat1870601.pdf (171kB)
This file has been downloaded 1065 times
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JohnWW
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1,1,1-Trichloroethane, technical grade, is widely used as a solvent by commercial dry-cleaners. Ask a local dry-cleaning firm if they will let let you
have some. (Bring along your own bottle). I was able to get about 500 ml of it from a local dry-cleaner a couple of years ago. However, it may contain
other chlorocarbon impurities of similar molecular weight. It can also be used as a thinner in correction fluid, which was the main reason I wanted
it.
[Edited on 7-11-09 by JohnWW]
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not_important
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Um, 1,1,1-Trichloroethane is regulated by the Montreal Protocol as an ozone depleting substance and is being rapidly phased out. In many countries
its sale is heavily taxed to discourage its usage. In some countries the manufacture of TCE has stopped, and it is only available from the remaining
stocks until they are exhausted.
It's also fairly toxic, in California it was so listed back in the late 1980s and its use in products such as correction fluid was quickly phased out.
Tech or solvent grade TCE contains various stabilisers, as it slowly decomposes to 1,1-dichloroethylene and HCl; the stabilisers can make up over 5%
of the product as sold. It's likely that you would need to determine what the additives are and devise a purification process. Note that simple
distillation is not likely to work, as the majority of uses for TCE are as a cleaning solvent it was typically recovered by distillation; the
stabilisers would need to not segregate from the TCE itself and so either boil near TCE's BP or form azeotropes with it.
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franklyn
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It's not toxic at all. After a lifetime of inhaling the fumes I
would not be here , and in the best of health.
Just don't drink too much of it.
.
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Plasmapyrobattics
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Na2O (Sodium monoxide) might be a problem to procure.
What about Calcium oxide ?
2 mol 1,1,1-Trichloroethane reacted with 3 mol CaO :
3 CaO + 2 CH3C.Cl3 --> (CH3CO)2O + 3 CaCl2
168 g CaO (3 mol) with 267 g / 202 ml (2 mol) Trichloroethane.
Any thoughts ?
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hector2000
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| Quote: Originally posted by franklyn |
So claims this patent from 1932 - US 1870601
Which details hydrolysis of Methylchloroform in reflux with water catalysed by H2SO4.
On its own it hydrolyzes with water over years forming Hydrochloric and Acetic acid.
Accordingly it seems much more sensible to just heat together stoichiometric
amounts of 1,1,1-Trichloroethane and caustic soda , Na2O.
1,1,1-Trichloroethane is known to be incompatible with caustic soda.
2 CH3CCl3 + 3 Na2O -> (CH3CO)2O + 6 NaCl
. |
This Reaction need pressure?(like patent reaction?)
Chemistry=Chem+ is+ Try
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unome
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For the other devotees of Tarbutton, et al's work, here is one of the papers they actually disproved the essence of, but what is important is the fact
that it is not run in a pressure vessel of ANY description, nor does it use anything more than scrupulously dry reagents in a steel pipe which is then
heated to give "reportedly" PF5 (but which Tarbutton, et al, showed to be far more likely to be a mixture of POF3 and PF5) through the use of their
far more elaborate apparatus - which was designed solely to ensure that they could quantify, isolate and identify the gasses evolved, not because such
apparatus was needed per se...
A New Method of Preparing Phosphorus Pentafluoride
Howard J. Lucas, Fred J. Ewing
J. Am. Chem. Soc., 1927, 49 (5), p 1270
DOI: 10.1021/ja01404a501
| Quote: | Excerpt from start of Note... (it is one page, if you want to read the whole thing, follow the link above to the JACS site)
It has been found that when a mixture of calcium fluoride and phosphorus pentoxide is heated, a gas is evolved, composed largely of phosphorus
pentafluoride. The details of the method are as follows. A mixture of 25g. of phosphorus pentoxide with approximately 55g. of pure calcium fluoride
(previously dried by heating in an iron crucible over a flame) was heated in a 2cm. iron pipe about 30cm. long, capped at one end and connect to a 1
cm. pipe at the other. Glass cannot be used. In order to reduce to a minimum the formation of hydrogen fluoride, the apparatus and materials had to be
free from moisture. It was found necessary to bake out the apparatus, to use the best phosphorus pentoxide, to ignite the fluoride, to transfer it
while still hot to the hot apparatus, and to measure out the materials rapidly (about 50cc. of each) instead of weighing. The ingredients were mixed
by shaking. The rate of gas evolution depended upon the temperature and was quite rapid when a large flame was used. The gas fumed in moist air....
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PS Before I get asked why this is here, it is in response to Sauron's claim somewhere in the last few pages (IIRC) that a pressure vessel/other
expensive equipment was necessary to replicate the procedure of Tarbutton, et al. It is not. I'll throw Tarbutton, et al's paper here so people know
what I mean anyhow... Seems to me that fused NaCl and P4O10 should be able to do the trick at a reasonable temperature (didn't Brauer or one of the
inorganic books have a route to drying P2O5/Polyphosphoric acid (if it ain't completely dry it is not the pentoxide anymore is it?) by sublimating it
in a tube?
[Edited on 3-12-2009 by unome]
Attachment: Tarbutton.POCl3.from.P2O5.NaCl.pdf (802kB)
This file has been downloaded 1013 times
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Waffles SS
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Does anyone tried Bromo Acetyl Bromide or Chloro Acetyl Chloride method for make Ethenone(ketene)?
BrCH2COBr +ZN(dust) ===> H2C=C=O +ZNBr2
or
ClCH2COCl +ZN(dust) ===> H2C=C=O +ZNCl2
H. Staudinger,
H. Klever, Ber. Dtsch. Chem.
Ges. 1908, 41, 594 – 600
as you know anhydrid acetic finally make from ketene
[Edited on 9-12-2009 by Waffen SS]
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bbartlog
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Zinc Nitride? What? No wait, you mean zinc.
Um, anyway, it seems like if you have acetyl chloride you can go straight to acetic anhydride (via reaction with NaOAc) rather than messing around
with ketene (which has to be bubbled through glacial acetic acid, is poisonous and so on). I suppose if I had chloro acetyl chloride but not plain old
acetyl chloride, and zinc dust and glacial acetic acid on hand, and a setup for handling the ketene, it might be tempting. But in general I think it's
not as good as other methods already described.
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Waffles SS
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Zn is Zinc my friend not Zinc Nitride.
If this reaction work ofcourse is easier than acetone Pyrolyze
[Edited on 9-12-2009 by Waffen SS]
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bbartlog
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Zn is zinc, yes. ZN on the other hand is... well, I guess it's also zinc, but since there can be ambiguities when you are sloppy with capitalization,
I thought I'd point it out. Hf versus HF, Co versus CO and so on.
| Quote: | | If this reaction work ofcourse is easier than acetone Pyrolyze |
Depends on what you have I guess. Chloroacetyl chloride and acetyl chloride aren't trivial to make. If you already have them, then sure.
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Waffles SS
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| Quote: |
NEW METHOD FOR PREPARATION OF ANHYDRIDES AND AMIDES OF
CARBOXYLIC ACIDS USING CARBON TETRACHLORIDE
The acid anhydrides were obtained in 48-97% yield by reacting either the Na or K salt of the carboxylic acid with CCI4 in the presence of CuCl, CuCI2,
FeCl2 or Cu at 18-20C and atmospheric pressure in either DMF or acetonitrile.
J. Weiss, F. Havelka,
and B. K. Nefedov
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Anybody tried this method?
Attachment: ccl4.pdf (335kB)
This file has been downloaded 2265 times
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entropy51
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Someone may have tried it by now. Solo posted that article three years ago in the references section. I suspect the difficulty getting CCl4 may have
hindered experimentation by many of us. Thanks, it's interesting nonetheless.
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Jor
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Interesting, I have some 350mL of CCl4 and access to more.
Not sure what anhydrides I will want to make though. Maybe later it will come at hand.
talking about anhydrides, a bit offtopic, but does anyone know what i could do with my 10mL of trifluoroacetic anhydride?
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DJF90
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TFAA mediated moffatt oxidation? I have some 900-1000mls of CCl4, but I do not find this an interest to myself as there are better ways of obtaining
anhydrides.
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Foss_Jeane
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Those reactions are only useful where you need your ketene with a high level of purity. For the most part, the byproducts of acetone pyrolysis
(methane, ethene, CO, CO2) don't interfere in most cases where ketene is used (e.g. acetic esters, amides, acetic anhydride). Unless you happen to
have come by the Cl-acetyl-chloride, it would be pretty pointless to do this if acetic anhydride is the goal.
Otherwise, just use a ketene "lamp", or heat the acetone vapors some other way to get your ketene.
If you're going to be working with ketene, make sure you have a good fume hood and ketene traps (dilute acetic acid works well for this, and you get
more concentrated acetic acid too). Definitely study up on the possible hazards of working with ketene.
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Waffles SS
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My main problem is unknown componet that produced in absorb flask.this componet is soluble in water and has ~100-105boiling point.
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Polverone
Now celebrating 21 years of madness
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Thread Split
10-2-2010 at 10:34 |
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