Is it possible to obtain oxalic dichloride by mixing anhydrous acetic acid and oxalic acid, heat the mixture and then passing chlorine gas into it?
I read that anhydrous acids and carboxylic acids react in balance reactions and so the chlorine could maybe substitute the OH-group and acetic acid
and HCl could maybe be formed.
Could that be?
There´s one more question:
Oxalic acid should react with PCl5, but does it also react with PCl3?
Because PCl3 would be much less required, but also it´s not that strong as PCl5.
R-COOH + PCl5 -> R-COCl + POCl3 + HCl
3R-COOH + PCl3 -> 3R-COCl + H3PO3
Does the second works with oxalic acid?Nicodem - 30-6-2007 at 04:46
Quote:
Originally posted by Per
Is it possible to obtain oxalic dichloride by mixing anhydrous acetic acid and oxalic acid, heat the mixture and then passing chlorine gas into it?
Oxidation of oxalic acid gives CO<sub>2</sub>. In your case where you would oxidize it with Cl<sub>2</sub> you would get
2CO<sub>2</sub> and 2HCl from one HOOC-COOH.
Quote:
I read that anhydrous acids and carboxylic acids react in balance reactions and so the chlorine could maybe substitute the OH-group and acetic acid
and HCl could maybe be formed.
Could that be?
I don't know what you mean. Could you explain better? How can Cl<sub>2</sub> substitute the OH groups? Surely you do not imply the
reaction would be driven by hypochloric acid (HClO) formation or some other such weird stuff? You can not prepare acid chlorides from acids with
Cl<sub>2</sub> unless in the stoichiometric presence of a reducent (the oxidation number in Cl<sub>2</sub> is 0 and in acid
chlorides it is -1; meanwhile all atoms in the acid moiety retain their oxidation numbers so obviously something is terribly wrong in your
propositions as they break the redox rules).
Quote:
There´s one more question:
Oxalic acid should react with PCl5, but does it also react with PCl3?
Examples of oxalyl chloride from oxalic acid formation found in the literature include the usage of thionyl chloride (Revista Latinoamericana de
Quimica, 28, 2000, 65-71), mixture of PCl<sub>5</sub> with POCl<sub>3</sub> in tetrakloroethene (patent
SU1810328), PCl<sub>5</sub> (Chemistry in Britain, 29, 1993, 1046-1048 and Ber., 8, 1875, 299-309). No use of
PCl<sub>3</sub> is to be found, but I assume it would work as well.
Quote:
Because PCl3 would be much less required, but also it´s not that strong as PCl5.
R-COOH + PCl5 -> R-COCl + POCl3 + HCl
3R-COOH + PCl3 -> 3R-COCl + H3PO3
Does the second works with oxalic acid?
The first equation is incomplete as POCl<sub>3</sub> can still chlorinate 3 -COOH groups. PCl<sub>3</sub> can chlorinate only
three equivalents of carboxylic acid while PCl<sub>3</sub> can chlorinate five equivalents.Aqua-regia1 - 30-6-2007 at 05:21
Instead PCl3, PCl5 the best way with S2Cl2 or SOCl2 to make.Sauron - 30-6-2007 at 12:37
PCl5 is too expensive and too hard to get. Thionyl chloride and sulfuryl chloride are mostly banned as CW precursors.
The cheapest and most readily available reagent to make oxalyl chloride is TCT (cyanuric chloride) which gives oxalyl chloride in 52% yield when
reacted with equimolar qty of oxalic acid (anhydrous) and TEA (2 mols) in acetone as solvent. Stir at room tempe for 3 hrs till no more cyanuric acid
ppts out, filter, and fractionate.
Oxalyl chloride is low boiling, quite toxic and corrosive, so all this needs to be done in a good hood.
It is rather expensive to buy.
Oxalyl chloride is a great reagent for preparing acyn chlorides and arylalkyl anhydrides but not so efficient for lower alkyl carboxylic derivatives.
It has many other unique reactivities.Per - 1-7-2007 at 06:42
Thanks guys,
Quote:
I don't know what you mean. Could you explain better?
O=R=O-R=O (anhydrous acid) and OH-R´=O (carboxylic acid) should give positive and negative charges (+) and (-), the problem is that I can´t
fill in any pictures here, hope you understand explanation anyhow.
O=R-O-R-O(-)OH(+)-R´=O <> O=R-OH(+)-R-O(-)O-R´=O <> O=R-OH(+)-R´-O(-)O-R´=O and so on. I hoped the chlorine as a
nucleophile reagent could react because of the charges anyhow to the chloride. (sorry for bad explanation)
@Aqua-regia1
Couldn´t follow you
Sauron, thanks a lot,
I wanted to get the PCl5 from red P and chlorine, also I heared that thionyl chloride wouldn´t work with oxalic acid.
But now to the more important things:
TCCS is already available, no problem, but what´s with anhydrous oxalic acid, do you mean that it should be free of water or do you realy mean the
anhydride?
I heared that it should be almost impossible to produce it in a home laboratory, also I don´t know even the structure of this curious stuff.
Triethylamine is no problem, have it already.
Suggestion:
Does ether also work as solvent because of its lower boiling point and lower poisonous?
Fuming hood isn´t a problem too.
Quote:
It is rather expensive to buy.
That and the fact that it is ranked as "T" is the reason I´m asking for.
Sounds like this stuff is really amazing, until now I would just prepare DNPO and TCPO with it, the chemiluminescence stuff you know and the oxalyl
chloride is the only thing still lacks.
But now I´m very confident
[Bearbeitet am 1-7-2007 von Per]garage chemist - 1-7-2007 at 07:00
Nicodem, I think you are wrong with the statement that PCl5 can chlorinate five equivalents of carboxylic acid.
The Organikum describes the reaction of PCl5 with COOH groups just like Per wrote it, and says that POCl3 is unable to further react with COOH groups.
With the one molecule of HCl formed in the first reaction, one mole of PCl5 can only produce one mole of acyl chloride, making it much inferior to
PCl3 which can procidPCl5).
Per, are you still confusing TCT with TCCS?
TCT (trichlorotriazine) is a T+ substance, the trichloride of cyanuric acid.
And TCCS (trichlorotriazinetrione) is NOT an acyl chloride.
Chlorine can not be used to prepare oxalyl chloride, because oxalic acid and its derivatives are reducing agents, being immediately oxidised to CO2
when chlorine is around.
TCT, the highly reactive chlorinating agent that Sauron promotes is prepared by reacting hydrogen cyanide with chlorine and trimerising the resulting
cyanogen chloride. I am planning to prepare this substance myself, but I first need a good gas mask and at least one kilogram of potassium
ferrocyanide from which I can prepare HCN in large amounts.
Here is how to make TCT: https://sciencemadness.org/talk/viewthread.php?goto=lastpost...
Using TCT is the only good way to make oxalyl chloride that doesnt involve PCl5!Sauron - 1-7-2007 at 09:10
GC is correct.
PCl5 according to his experience can't be made from red P and Cl2, only from WP and Cl2.
That rendres it difficult and costly.
AFAIK TCT (cyanuric chloride) is the only other reagent to make oxalyl chloride. And TCT is not same as the swimming pool chemical TCCA which is a
chloramine not an acid chloride, see the structures.
And TCT unfortunately is also rated T in Europe.
Although I have no trouble buying it where I am (Asia) and have lots, I find it very useful. I can't help it is it is unobtainium in parts of Europe.
I suspect that the H.C.Brown benzoyl chloride method MIGHT work for oxalyl chloride, this would require three mols benzoyl chloride to one mol
anhydrous oxalic acid. By anhydrous oxalic acid I mean oxalic acid which has been oven dried above 100 C to give up its water of crystallization. You
can buy anhydrous oxalic acid, or buy the cheaper hydrated oxalic acid and dry it yourself. If you do that use it immediately. The very best results
will be had if you start with the commercial anhydrous acid and submit it to further drying in a temperature regulated and ventilated drying oven, or
a vacuum desicattor over a suitable dessicant. Using 4 mols to 1 of benzoyl chloride will slightly improve the yield.
There is no such thing as oxalic anhydride. Any attempt to prepare it just gets you CO and CO2.
It is also possible that the phthaloyl chloride method of Kyrides might work for oxalyl chloride. While Brown's paper dealt only with monocarboxylic
acids, Kyrides' paper did discuss dicarboxylic acids, particularly the propensity for phthaloyl chloride to yield not the acyl dichlorides but the
cyclic anhydrides in the cases of succinic and glutaric acids. So this is another reagent worth a try, although it is costlier than benzoyl chloride,
it is a lot cheaper than oxalyl chloride.
You can make phthaloyl chloride yourself (per Kyrides) and achieve some economy, from inexpensive phthalic anhydride, and not so expensive
benzotrichloride.
These two methods are a bit speculative but seem promising to me and I think you can at least get benzoyl chloride in Europe.garage chemist - 1-7-2007 at 09:14
PCl5 is easy to prepare from red P and chlorine, in chloroform as a diluent to remove the enormous heat of reaction.
Its PCl3 that cant be made from red P, only from WP.
The red P preparation of PCl5 is still far from ideal though, requiring good solvent removal to obtain a pure product. The procedure is also lengthy.Sauron - 1-7-2007 at 10:49
Thanks for correction.
I misstated Kyrides' findings a little. It is possible to obtain succinyl or fumaryl chlorides, or the cyclic anhydrides (succinic or maleic)
depending on conditions.
The interesting thing about the prep of phthaloyl chloride is that benzoyl chloride is a major byproduct and that therefore you get almost quant
yields of two useful reagents not just one.
Catalytic amount of ZNCl2 (or Zinc oxide, or Zn powder) are required.
The reaction is run overnight (20 hrs) at 120-130 C under reflux.Per - 2-7-2007 at 05:49
Yes, I confused C3Cl3O3N3 and C3Cl3N3, the missing oxigen atomes are the difference.
Isn´t it possible to synthesice PCl3 from PCl5 and red P?
In the TCT prep. instruction liquid anhydrous hydrogen cyanide is mentioned, I didn´t found any information about that stuff, is it easy to get from
cyanides?
Maybe I try to prepare TCT but firstly I have to buy some ferrocyanide from ebay, think a good fuming hood should be enought to avoid critical
situations with hydrogen cyanide gas.
Could NH3 be used to make HCN visible like Cl2, to find out if the apparature´s leaky?
Quote:
By anhydrous oxalic acid I mean oxalic acid which has been oven dried above 100 C to give up its water of crystallization.
That´s what I thought. Hydrated oxalic acid isn´t a problem, could be also bought from ebay as beekeeper stuff, drying is easy but take care of the
sublimate, don´t breath it.not_important - 2-7-2007 at 07:57
If you're concerned about breathing oxalic acid sublimate, you do not want to get yourself within a km of liquid HCN. I've made small amounts of
anhydrous HCN for researchers at university, but it was always less than a ml so a fume hood and good gloves were enough protection. I wouldn't want
to make enough to prepare a useful amount of TCT; if you can't buy TCT find another method that doesn't need it.Per - 4-7-2007 at 05:02
I´m afraid that the only way to get oxalic chloride convenientliy is by using PCl5 or TCT, and TCT should be much cheaper.
Think the best way to prepare it is by using a satured solution of Cl2 in CCl3H and then bubbling HCN gas in it, so it could be reached to have always
just a small amount of HCN gas.
Does anybody know how many chlorine could be dissolved in CHCl3?garage chemist - 4-7-2007 at 05:11
That depends on the temperature. With good cooling, I am sure a large amount of chlorine can be dissolved.
But read the instructions in the TCT thread, they specify the amounts of chloroform to use for reacting a given amount of HCN.
Remember that the chloroform must contain ethanol, otherwise you will get monomeric ClCN only, which is a really nasty substance.Per - 4-7-2007 at 12:03
Thanks, may it´s the best way to prep. an at room temp. saturated solution of dissolved chlorine and cooled this for reaction, otherwise chlorine
would escape if the solution get´s hot by the reaction with HCN.
Reading the TCT thread is necessary of course, but until now I hadn´t the time for reading it properly.garage chemist - 4-7-2007 at 12:27
The chlorine solution should be made while already cooling, because the solubility of gases in liquids increases with sinking temperature. You will be
able to dissolve more chlorine if you cool the solution from the beginning.
[Edited on 4-7-2007 by garage chemist]dhamini - 3-8-2013 at 07:33
[Edited on 3.8.13 by bfesser]plastics - 4-8-2013 at 02:58
I know you sometimes have to take patents with a pinch of salt but these were on my 'to do' list until I managed to get hold of a reasonable quantity
of oxalyl chloride
Attachment: OxalylChloride.pdf (209kB) This file has been downloaded 796 times
I don't have ethylene oxalate so I decided to make it via a method I found in Shirley, Preparation of Organic Intermediates. An old but good read;
courtesy of the used book seller.
The method is as follows:
90 g of anhydrous acid and 400 g of PCl5 are ground together, placed in an ice bath and allowed to come to room temp until all is liquid (2-3 days).
Several distillations will be needed to get rid of all the P.
D1 collect 60-100*C
D2 collect 60-75
D3 collect 63-64 (snyder column, cold-finger or partial take-off head. (or run more distillations)
45-50% yield
