Sciencemadness Discussion Board

Modified Patent Route to Oxalyl Chloride

tupence_hapeny - 10-4-2007 at 09:52

Oxalyl Chloride

Oxalyl chloride can be made, but not perhaps in the way one would think, it is not possible to directly chlorinate oxalic acid with anything less than potassium trichloride, and even then the yields are low (30-50%).

It can be made however by photo-degradation of tetrachloroethylene glycol bis-trichloroacetate

The output of which is oxalyl chloride and trichloroactyl chloride (the greatest loss of this chemical noted in the patent was ~8-10%). The reaction is carried out in glass or enameled reaction vessels between 80-160C

Great I hear you mutter, but how in fucks name do I get that tetrachloroethylene glycol bis-trichloroacetate stuff?

Well, that is rather the point of this post, as it appears that it can be made rather simply, by condensing ethylene glycol with trichloroactetyl chloride, and then photo-chlorinating the same to get the tetrachloroethylene glycol bis-trichloroacetate and hydrochloric acid.

Fucking wundaful, I hear… But – wait, there’s more….

Trichloroacetyl chloride is made by the following process – in which the various lower chlorinated acetyl chlorides or even acetaldehyde (which is where this becomes interesting) are exhaustively chlorinated in the presence of activated charcoal as a catalyst:

The exhaustive chlorination of acetaldehyde is of course a rather slow process, so I include this one, which provides dichloroacetyl Chloride from the epoxidation and isomerization of trichloroethylene:

This one provides a mixture of dichloroacetyl chloride and the trichloroethylene oxide, and requires DMF or similar as a catalyst, in addition to chlorine or bromine (Note: dimethylamine is stated to work well)

This one uses a thin film (ie. the mix is ed through a tube by air, coating the inside of the tube, which is subjected to UV) and oxygen at around 200-250C to turn 80% of the TCE to DCAC:

So, where does one get the chemicals with which to do this? Well, in this neck of the woods trichloroethylene is sold as a cleaning chemical, particularly for cleaning electrical equipment (ie. look for electrical cleaning fluid). Ethylene Glycol is in anti-freeze, they all contain differing amounts, so if the ingredients are listed read them, if not, check the website of the manufacturer’s – especially look to see if the MSDS’ are available online.

The production of both chlorine gas and acetaldehyde have been covered exhaustively, on this board and elsewhere, and I shan’t even try to get into that here.

BTW it is possible to get ethylene glycol from PET, however, this would require anhydrous ammonia – not the best thing for an amateur chemist to be playing with in the current climate, DO NOT attempt to purchase it if you don’t feel like getting a visit in the near future (unless of course you are Sauron, Nicodem, et al).

I have also attached the oldest patent I have for the production of oxalyl chloride.

Attachment: Process for the Production of Oxalyl Chloride (US Patent 2816140).pdf (296kB)
This file has been downloaded 1814 times

Nicodem - 10-4-2007 at 10:12

Originally posted by tupence_hapeny
BTW it is possible to get ethylene glycol from PET, however, this would require anhydrous ammonia – not the best thing for an amateur chemist to be playing with in the current climate, DO NOT attempt to purchase it if you don’t feel like getting a visit in the near future (unless of course you are Sauron, Nicodem, et al).

WTF? Ethylene glycol can be bought on just about any gas station as well as in several shops all over the world!

PS1: It would be nice to explain what is the point of your post besides being one of the craziest routes to a two carbon compound ever.
PS2: I assume that by "potassium trichloride" you confused phosphorous trichloride.

Sandmeyer - 10-4-2007 at 10:19

He reminds me of someone who one posted idea that DXM.HBr would be a source of Br- which could be oxidized to Br2 which in turn would be used to brominate 2C-H... Now THAT's OTC! :D

tupence_hapeny - 10-4-2007 at 10:51

I saw it coming,


PS1: I make things because I like making things, I actually prefer making things to buying things. I have a feeling other people do too...

as to PS2: Yes, I did upfuck

As to the craziest way to a two carbon, why so?

I kinda think that the person who used phosphorus trichloride to make this same compound takes that particular cake, wouldn't you agree?

Anyhow, having noticed several dozen posts ruminating on how to get there, why not have a look at how industry does it, and then see if that method can be adapted?

As I can purchase 40L drums of trichloroethylene, that particular route to dichloroacetyl chloride (and on to trichoroacetyl chloride) appealed to me.

Once that is in hand, what is wrong with using (and reusing) the trichloroacetyl chloride to make oxalyl chloride from ethylene glycol?

I take it you did in fact read the examples given in the patent?

As photo-chlorination is fairly simple, as per the procedures for both acetic acid and toluene, what is wrong with that?

But by-the-way, I did state, in the header of this topic, that it was to end up as a modified patent route, did I not?

PS I put in the part about the recycling of PET as this is one of my favourite topics, as I believe that I have explained to you, both in other topics and by PM? Perhaps if I mention the fact that it can be done often enough, someone may become interested in looking into it?

PPS Yes, the epoxidation and isomerization looks complex, but what can be accomplished by running the shit through a thin tube - can be accomplished (although not as effectively, as mentioned in the description of the prior art) other ways, and I suggest even by putting a bottle 1/4 full of the shit in the sun. Then distilling the phosgene and tetrachloride off.

Chlorinate the DCAC to TCAC over carbon, mix with the ethylene glycol (distilled), photo-chlorinate it, and put it in the bottle in the sun again.

WTF is so frigging advanced about that?

In the immortal words of Chopper Read: 'whinge, whinge, fuckin' whinge.'


Sauron - 10-4-2007 at 10:57

Oxalyl chloride is classically made by chlorinating anhydrous oxalic acid with phosphorus pentachloride. PCl5 being expensive and these days mostly embargoed bue to CWC, this method is pretty much a writeoff for most of us.

There are two good and available methods for the efficient production of oxalyl chloride on bench scale

Both have been elucidated here before, some people appear to be unaware of this.

1. TCT in acetone with TEA and anhydrous oxalyl chloride, yield 52%. A variant of this, TCT/DMF complex with higher yields.

2. TCT and anhydrous sodium oxalate dry distillation.

A very likely third route esp for those who can't get TCT is phthaloyl chloride.

By the way the phthaloyl chloride method is also best way to prepare trichloroacetyl chloride per H.C.Brown, this has also been posted here, yields c.53% because the trichloroacetyl chloride tends to fall apart to CCl4 and CHCl3. I have been hunting a Rec.Trav.Chim. article about this reference from the Brown article for some time, in order to try to exploit this as a prep for those chlorinated hydrocarbons (more CCl4/CHCl3 less acid chloride.)

Over-reliance on patents is a sure way to waste money and time. Patents are like waltzing on quicksand. Let's see where that reaction is written up in a peer reviewed journal before we take it too seriously.

More often than not, patents do not tell you how industry is doing it. They tell you how someone tried to get industry to do it, but industry wasn't wearing it. Furthermore many many succesful industrial patents do not translate well to bench scale. Like I said, let's see the peer reviewed writeup.

Oxalyl chloride IS commercially available, I have no problem importing it in 1 L bottles. It is not cheap. So if you want to save money and don't mind some labor in a GOOD HOOD you make your own. TCT and phthaloyl chloride are cheap.

[Edited on 11-4-2007 by Sauron]

tupence_hapeny - 10-4-2007 at 11:28


I am unsure which part of which reaction you doubted would work, however, I have found a journal article which deals with the photo-catalyzed chlorine sensitized oxidation of trichloroethylene to dichloroacetyl chloride (albeit somewhat indirectly):

Please reply, if you wish for me to research further, it would be helpful if you could specify the relevant parts and I will conduct my research accordingly.


Sauron - 10-4-2007 at 12:02

You misunderstood me. I was making a general observation about chemical patents and not any particular request for articles. However, if I were to be interested in the process you have in mind, which I am not particularly, I would want to see a journal article from a peer reviewed journal on the photolysis of tetrachloroethyleneglycol bistrichloroacetate to oxalyl chloride.

What you are proposing overall is if I understand it, esterification of ethylene glycol with trichloroacetyl chloride (or trichloroacetyl anhydride), those are commercially available. Then perchlorination over AC of that ester w/Cl2. Then the photodegredation of that perchlorinated ester to oxalyl chloride.

Furthermore you propose to make your own trichloroacetyl chloride by chlorination of DCAC and you maker DCAC from trichloroethylene. Sorry, do you mean 111-trichloroethane or 1,2,2-trichloroethane or ?? Because the former is now mostly banned. Here a special permit is required for its use.

All of that strikes me as laborious and somewhat technologically risky as compared to the three methods from oxalic acid I enumerated (and not counting the somewhat obsolete one from PCl5. As you mentioned, PCl3 really does not work worth a damn, and anyway like PCl5 it is mostly out of reach of most of us due to the furshlugginah CWC.

We have previously studied chlorination of ethanol and acetaldehyde quite a bit for prepn of chloral, and if this is pushed at all it goes to trichloroacetic acid. That acid is therefore not hard to prepare starting with ethanol, IF you have a shitload of chlorine or are willing to generate it, and have a whole lot of time.

Which one strikes you as simpler? Chlorination of ethanol or photolysis of your chlorohydrocarbon followed by chlorination of DCAC? I'd opt for the ethanol chlorination, myself.

No worries getting glycol esterified. But then your route requires another perchlorination, and then UV treatment, before you get where you want to be. So you work hard putting lots of chlorines on, only to knock them all off, all but two.

Seems wasteful to me, of chlorine, time and energy.

Oxalyl chloride just isn't that hard to make through the front door (from oxalic acid) so why all the effort?

not_important - 10-4-2007 at 13:13

Originally posted by tupence_hapeny

BTW it is possible to get ethylene glycol from PET, however, this would require anhydrous ammonia – not the best thing for an amateur chemist to be playing with in the current climate,...

WTF - ammonia? There are numerous examples of hydrolysis of PET using NaOH, from industrial scale recycling down to teaching chem lab size experiments.

Simply mixing ground PET and 50% NaOH and heating under reflux for awhile will give you ethylene glycol and disodium TPA. Running under pressure, flowing air through or using O2, will convert much of the glycol to oxalic acid with about 60% recovery as the acid, and 95+% of the TPA as the sodium salt.

[Edited on 11-4-2007 by not_important]

tupence_hapeny - 10-4-2007 at 14:10

I thank you for that NI,

I had seen references to the same, however, I have not actually read the procedures (whereas I have the one from ammonia).

What I find funny, is that I get mangled from one side for even suggesting getting ethylene glycol from PET, and on the other I get hit again for not providing the easiest possible route to the same...

Am I perverse or is that amusing?


not_important - 10-4-2007 at 14:25

Just pointing out that you picked one of the least accessible methods for hydrolysing PET, currently it likely is easier to buy ethylene glycol antifreeze, possibly distilling out the glycol if the application would have problems with the additives.

I think you get flack for choosing complicated or difficult-for-home-lab routes over simpler ones. I like many of the hot tube methods around, but often they are fussy and cantankerous things that take equipment the amateur experimenter isn't likely to have. Or you make some rather large leaps from knowns to proposed reactions that don't have any similar proven reactions or that depend on some rather non-standard if not wholly unknown mechanisms.

tupence_hapeny - 10-4-2007 at 15:16

Yeah, I'm starting to get that too....

I am actually making some attempt to make my approaches a little more 'standard issue', and if you look you'll see that I am actually trying to work out how this could be done in the equipment that most people have.

BTW, I was actually not suggesting people hydrolyse PET to get to their glycol - I was mentioning that it WAS and IS possible. For mine, I don't think it would be any messier than distilling green goop - and it WOULD be a whole lot more interesting into the bargain (not to mention cheaper).

The only excuse I have for searching out non-standard reactions is quite simply that I have neither the money nor the inclination to invest in expensive starting materials, such as are almost always called for in order to carry out 'standard' reactions. I start looking for how to make the precursors, and before you know it, there are several routes to the same thing as I want to make, some of which are old commercial routes, which have been rendered obsolete by the latest, you beaut whatchumacallit....

I am actually really starting to enjoy the reaction that this gets from some participants on this board.:D

Anyhow, I can see that I'll have to start spending time amongst the 'old' chem texts in the library, as these reactions appear to have been bog-standard once...

till then


Sauron - 10-4-2007 at 21:17

As for ethylene glycol, I just buy the anhydrous reagent grade and be done with it. The stuff is very hygroscopic and forms a variety of binary azeotropes and more complex azeotropic systems with other organics. Mostly I use it to prepare ethylene bromide and ethylene chloride and the halohydrins which I can no longer buy and all of those reactions require it to be dry.

Apart from my prior remarks about the pitfalls of chem patents, I see chemical problems in two categories:

Basic research: highly exploratory and experimental, breaking new ground. Given to fits, starts, hard knocks and setbacks.

Routine preps of needed reagents and building blocks: no real "research" involved, just paper chase through the lit. and then cookbook devotion to following orders like a good feldwebel. You need technique, and you need experience to sort out the wheat from the chaff in the literature, but really you are retracing the footsteps of others and often you have reliable, detailed methodology to employ.

It's just a matter of picking your fights. Oxalyl chloride (for example) is a commercially available, simple reagent and there are a number of straightforward decent-yielding preps for it if you want to make your own. IMO turning oxalyl chloride into a basic research project only makes sense if you expect to come out at the other end with a oatent of your own. Combining 3-4-5 other people's patents into a "process" seems to me to have all the disadvantages of basic research, lots of technological risk (one link in the chain flops and the process fails) and no likelihood of becoming intellectual property. Just not worth it.

Of course, in pursuit of a habby, do as thou wilt. It's your hobby project. But, my two cents worth, pick your fights more carefully. This one looks like a chemical blivet. Blivet: old Army term. Means 5 lbs of shit in a 1 lb.bag. Often used to describe certain unpopular officers.

[Edited on 11-4-2007 by Sauron]

unionised - 11-4-2007 at 00:11

"The stuff is very hygroscopic and forms a variety of binary azeotropes with water "
Are you sure about that? I can't find anything about an azeotrope with water on the 'net (though I accept it's very hygroscopic).

Maya - 11-4-2007 at 03:00

Just because it is possible for a 5-6 step method to produce a compound doesn't mean that its a practicable route. Usually the simplest 1 step protocol is the most practical.
Oh yeah, getting your info from patents is not the best idea, sometimes these are not repeatable.......

S.C. Wack - 11-4-2007 at 04:16

Merck says nothing about azeotropes. I've found $6/gallon walmart antifreeze to simple distill well, even though it has some diethylene glycol and various crap in it. The only problem is typical of that boiling point, the Very Hot Condenser. 2 Wests in line as air condenser and a third with water works, but even so I won't be using ethylene glycol to make oxalyl chloride either. I'd be looking for an alternative route or an alternative to oxalyl chloride.

Sauron - 11-4-2007 at 06:29

Two out of Three Ain't Bad

1. Ethylene glycol is hygroscopic (this was concede so I did not bother to verify

2. Ethylene glycol forms a variety of binary of azeotropes with other solvents

See attached Me Global PDF

3. I could not immediately verify my recollection that ethylene glycol forms multiple azeotropes with water. So this appears to be an error. Mea maxima culpa. I guess I was thinking of ethylene chlorohydrin.

I offer this nice long data file as reperation for my faulty aging memory. I have edited the earlier posts so as not to mislead anyone else. I go now to do penance after the fashion of albino monks in Opus Dei for my sins,

"Mea maxima culpa: is Latin for "Me very bad" (loose translation.)

[Edited on 11-4-2007 by Sauron]

Attachment: MEGlobal_MEG[1].pdf (1.8MB)
This file has been downloaded 1153 times

mackolol - 9-4-2018 at 03:15

What about making it by Example III described in this patent. Firstly esterification of ethylene glycol with oxalic acid. Then chlorinating formed ester and following method described?

Attachment: Process for the Production of Oxalyl Chloride (US Patent 2816140) (1).pdf (296kB)
This file has been downloaded 493 times

clearly_not_atara - 9-4-2018 at 14:17

Quote: Originally posted by mackolol  
What about making it by Example III described in this patent. Firstly esterification of ethylene glycol with oxalic acid. Then chlorinating formed ester and following method described?

I read the first few posts and was about to suggest this very method but it's already got a patent!

Another alternative might be ethylene glycol dibenzoate or ethylene glycol phthalate.

S.C. Wack - 9-4-2018 at 14:56

Quote: Originally posted by mackolol  
What about making it by Example III described in this patent. Firstly esterification of ethylene glycol with oxalic acid

Is it so easily made, or do you have to make diethyl oxalate first? See one of the other threads. If some phosgene is OK (use for something else?), ethylene carbonate is cheap. More on the preparation and use of the carbonate here.

[Edited on 9-4-2018 by S.C. Wack]

byko3y - 10-4-2018 at 02:43

Is there any other way of making ethylene oxalate except by starting from oxalyl chloride?

clearly_not_atara - 10-4-2018 at 07:15

I would imagine transesterification of some lower alkyl oxalate should work fine. At a high enough temperature polymerization should be disfavored

[Edited on 10-4-2018 by clearly_not_atara]

S.C. Wack - 10-4-2018 at 15:31

The first link was for Sauron in the middle of the thread. He mentions a patent that sounds familiar. Then another one.

chemplayer... - 15-4-2018 at 23:03

Just for info we tried making oxalyl chloride using PCl3 + anhydrous oxalic acid and it doesn't work. No idea why or whether there's a special technique, but it didn't.

byko3y - 16-4-2018 at 06:26

Not only oxalyl chloride is a strong chlorinating agent, thus cannot be prepared from weak chlorination agents, but also it is not stable on heating, decomposing into carbon monooxide and phosgene. For those reasons phosphorus pentachloride (possible with oxychloride admixture) is exclusively used in laboratory practice for preparation of oxalyl chloride.

AJKOER - 27-8-2018 at 07:53

Those acquainted with photolysis will remember how hydrogen and chlorine can be easily radicalized with light at low temperatures. In the current case, we need to radicalize only some of the chlorine using a process referred to as photochlorination (see general reaction mechanics outlined in Wikipedia at ). An important comment per Wikipedia, to quote:

“The selectivity of photochlorination (with regard to substitution of primary, secondary or tertiary hydrogens) can be controlled by the interaction of the chlorine radical with the solvent, such as benzene, tert-butylbenzene or carbon disulfide.[14] The complex formation between benzene and the chloride radical reduces its reactivity which increases the selectivity.[15] By varying the solvent the ratio of primary to secondary hydrogens can be tailored to ratios between 1: 3 to 1: 31.[16] At higher temperatures, the reaction rates of primary, secondary and tertiary hydrogen atoms equallize. Therefore, photochlorination is usually carried out at lower temperatures.[13)“

So, an attempt at photolysis would be to apply light in the presence of dry chlorine and dry oxalic acid in an appropriate solvent (per above or none, just use less efficient gaseous nitrogen, since the net reaction implies only half of the Cl2 should be radicalized, so I would try to avoid over radicalization of the chlorine with a possible loss of yield). One of many speculated schemes includes:

Cl2 + hv → •Cl + •Cl

H2C2O4 + •Cl → HCl + •HC2O4

•HC2O4 + Cl2→ HCl + •C2O4Cl

•C2O4Cl + •Cl → (COCl)2 + O2 [or, possibly unsuccessfully, 2 CO + Cl2 + O2 ]

With an implied net:

2 Cl2 + H2C2O4 + hv → 2 HCl + O2 + (COCl)2

The literature cites the use of atomic chlorine on aqueous H2C2O4 and FeCl3, which I claim is different from the dry acid (no H+ + C2O4(2-) ions, see ).

[Edited on 27-8-2018 by AJKOER]

mackolol - 27-8-2018 at 08:59

Quote: Originally posted by Sauron  

A very likely third route esp for those who can't get TCT is phthaloyl chloride.

Does isomer matters? And does the procedure look the same as with TCT, simple distillation with sodium oxalate and phthaloyl chloride will work? And what are the yields?