Sciencemadness Discussion Board

Propionyl chloride with cyanuric chloride and anger

mr_bovinejony - 21-1-2021 at 18:41

OK here goes another acid chloride thread. But this one I know for sure works. I've looked at every single comment a user called Sauron has made mentioning cyanuric chloride, and not a single fucking one has a write up of how to use this shit. But one thing I found was the synthesis of acid chlorides when the acid is a liquid. Sauron says a strong excess of acid to cyanuric chloride. So here it goes.

In the flask is put 20 grams of cyanuric chloride. Be careful with this crap, it is awful. Propionic acid is added until about a centimeter of liquid is seen above the level of powder. Refluxed for 3 hours and a distillate of 17 mls is collected at 75 to 80c. Very strong fuming in air, the addition of water is very exothermic and kills my lungs.

And that's it. No molar measurements, no doi numbers, not a single fucking write up on this forum explaining the use of cyanuric chloride. But I have every paper I could find on this crap, and this is the only method I have found that has worked. The acetone and triethylamine method didn't work for me. The dmf method didn't work either. If you want I can explain about these, just ask.

If you couldn't tell by now, I am extremely salty about this compound and the posts made by Sauron that glorify this compound. But come on, not a single write up by this dude? I'll use the rest I have for further experiments but after this I think it's safe to say that phosphorous trichloride is the easiest way to acid chlorides.

Edit: this stuff fumes horribly. Even with the blue cap fancy bottles and like 7 layers of teflon tape I can still see the fumes escape. Any tips?

[Edited on 22-1-2021 by mr_bovinejony]

[Edited on 22-1-2021 by mr_bovinejony]

clearly_not_atara - 21-1-2021 at 20:41

I'm not sure PCl3 is so great for acid chlorides either. Usually PCl5 IIRC.

For acid chlorides from cyanuric chloride I think the most efficient method for other than oxalic acid (which I'm not convinced works at all) would be to use a propionate salt, reflux etc to generate anhydride, should be low/no gas evolution, then gas HCl and distill propionyl chloride. Of course this last step can still get a little nasty :D

The rxn of C3N3Cl3 with RCO2H is catalyzed by base but the formation of RCOCl is catalyzed by acid. A tricky reagent.

mr_bovinejony - 21-1-2021 at 21:05

Well the catalysis isn't described anywhere in the posts or papers I've read, which is where my anger is coming from. Why would I bother bubbling hcl gas into this shit when I could bubble chlorine into a slurry of red phosphorus and get the same result? Eh it doesn't matter now. I hope future people learning from sauron realize that this cyanuric chloride isn't the "cure-all" to your acid chloride woes

clearly_not_atara - 22-1-2021 at 08:05

Quote: Originally posted by mr_bovinejony  
Why would I bother bubbling hcl gas into this shit when I could bubble chlorine into a slurry of red phosphorus and get the same result?

Principally because HCl is less dangerous than Cl2 and rP is not always available. Of course, in your situation, this may all be irrelevant.

Also, I'm pretty sure you want to try to convert that PCl3 to POCl3. Not only does this increase yields, it prevents the production of phosphine by decomposition of the phosphorous acid byproduct.

Volatile acid chlorides are always unpleasant chemicals to be around. Keep that in mind.

[Edited on 22-1-2021 by clearly_not_atara]

Bubbles - 22-1-2021 at 15:25

I recently made some propionyl chloride using benzoyl chloride in a 3:2 ratio to propionic acid with a 62% yield.
A lot of HCl gas is evolved, which burned a hole in the tubing to the gas washer, which I could have anticipated.. Use good tubing.
The leftovers in the reaction flask form a smelly gel that takes some effort to remove. I ended up just putting it under a running tap for a while, benzoic acid is weakly soluble in water.

These are minor issues and I certainly recommend this route.

I use red teflon-lined GL45 caps for storing alkyl halides and now propionyl chloride. Second-hand they aren't too expensive.

[Edited on 22-1-2021 by Bubbles]

Fyndium - 22-1-2021 at 21:24

Interesting. Could you detail the process a little?

mr_bovinejony - 24-1-2021 at 05:26

Well I tried a couple dry distillations that both failed with anhydrous oxalic acid. The cyanuric chloride has an amazing ability to sublime all throughout the apparatus. So I'm quite amazed that dry distillation of this stuff is even mentioned. I also tried with xylene as a helper solvent which didn't work.

Refluxing propionic acid and cc led to no sublimation. I'm going to try acetyl chloride today but I expect more of the same, with a great excess of acid I think it should go pretty smooth. I'm also wondering if benzyol chloride could be made with benzoic acid. We really need a solvent to avoid this dry distillation stuff...

[Edited on 24-1-2021 by mr_bovinejony]

dicyanin - 27-1-2021 at 01:48

I remember Sauron's time here, I agree it was mostly arm-chair chemist masturbation :D.

dicyanin - 27-1-2021 at 01:53

Quote: Originally posted by clearly_not_atara  
rP is not always available. Of course, in your situation, this may all be irrelevant.

depends on how much is needed, scratching tons of matchbook striker pad wetted with acetone is always an option for a few grams. Problem is cellulose contamination, and I assume also ground glass or a similar abrasive.

mr_bovinejony - 27-1-2021 at 15:52

Well at least I'm not the only one who thinks this about sauron.

I've been sitting on some phosphorous until I get the courage to make pcl5, still haven't worked up to it yet and my chloroform keeps going to other projects

FrenchChemist - 27-1-2021 at 21:39

I synthesized PCL5 from red phosphorus several times.

You have to cool the chloroform well because it gets very hot when you introduce chlorine, good mixing also makes things easier. The key thing with the chlorine introducing tube is that the end is quite wide because it clogs with the PCl5 formed several times. The reaction yield is very good, washing PCL5 on the filter once gives a practically colorless - very slightly greenish product.
As a container I recommend a glass bottle with a PTFE stopper. Otherwise, you will have to change stopper frequently or pour the product into new containers, which can be troublesome.

mr_bovinejony - 3-2-2021 at 00:23

How's the yield of that procedure? I would most likely be using the pcl5 right away so storage wouldn't be an issue

FrenchChemist - 3-2-2021 at 02:09

10g red P + 120-130 ml chloroform (some can evaporate so please have a little more on hand) ----> +-50g PCl5

good condenser should do the job

Fyndium - 4-2-2021 at 00:43

Red P could or could not be more easily available than PCl5. A very good detail, though, might come in handy if needed.

I suppose that best storage method for PCl5 would be to seal it into ampoules.

Benignium - 4-2-2021 at 02:19

mr_bovinejony, Can you provide details of the triethylamine procedure you tried and why you think it failed for you? This was the only detailed description of Sauron's that I've encountered, and otherwise a prominent one.

clearly_not_atara, NurdRage mentions the apparent ease of preparing oxalyl chloride using cyanuric chloride in this video. Is this what you referred to? Surely NurdRage wouldn't be so careless as to lie?

That said, I've ordered some cyanuric chloride and intend to use it to make acid chlorides so this is relevant to my interests.

[Edited on 4-2-2021 by Benignium]

clearly_not_atara - 4-2-2021 at 06:03

Quote: Originally posted by Benignium  
clearly_not_atara, NurdRage mentions the apparent ease of preparing oxalyl chloride using cyanuric chloride in this video. Is this what you referred to? Surely NurdRage wouldn't be so careless as to lie?

I don't think he lied, I think he learned it from us. Our communities are as susceptible as any others to the game of telephone and citogenesis. I myself may have caused such misconceptions in the past (practically nobody can be totally innocent here; most of us learned to speak cautiously by trial and error). Similar effects have been found in the "professional" scientific literature!

It seems reasonable to me that with a good technique you could probably make oxalyl chloride via cyanuric chloride. But the idea that it's "easy" or "proven" because NurdRage said it, is dubious at best.

mr_bovinejony - 4-2-2021 at 08:50

@Ben I pretty much followed the procedure sauron posted about so many times word for word. I think the issue was not enough acetone, it was always a slurry which was hard to stir. Also the addition of triethylamine let off a good amount of some kind of vapor, I'm not sure if it was exothermic and it boiled away or if it was some kind of reaction that wasn't mentioned in the paper. Either way, that method isn't the greatest. I've recently learned that it's better to use chemplayers method to make acetyl chloride or propionyl chloride but bubble in way more hcl than he did to get more than a 30% yield. Benzoyl chloride can also be made this way apparently, depending on how soluble benzoic acid or sodium benzoate is in the acetonitrile

If you are going to try it anyway, I recommend making sure that everything is completely dissolved in the acetone before adding triethylamine. The cyanuric acid should precipitate out as the acid chloride is formed

[Edited on 4-2-2021 by mr_bovinejony]

Newton2.0 - 4-2-2021 at 09:21

I have some cyanuric chloride and PCl5. I'm so hesitant to use the PCl5 because it is so scarce. I'm planningon making some butyryl chloride from butyric acid. I also have some propionic acid, so I intend to use the cyanuric chloride method if I can.

Now, if there's a way to catalyze the reaction to increase yields, that would be great!

mr_bovinejony - 4-2-2021 at 22:00

Use your pcl5 for the compounds that can't be made with acetonitrile and hcl. Oxalyl chloride is the main one, cinnamyl chloride is another. Things like acetyl, propionyl, butryl, and benzoyl can be made by chemplayers method

NaK - 6-2-2021 at 05:18

For future reference, here is the Versuchschemie procedure by Stefan aka garage_chemist machine-translated from german:

Stefan - 14/12/2006, 00:29
Title: Phosphorus pentachloride
This method of making phosphorus pentachloride, invented by me, uses a new approach to solve the problems in the
unification of the elements.
The problems with conventional reaction control (conducting chlorine onto red phosphorus) are, first, the extreme heat generated during
reaction, which must be dissipated, and second, the formation of the phosphorus pentachloride as a hard sublimate crust in the flask which must be
must be scraped off, with atmospheric moisture reducing the quality of the product by partial hydrolysis to phosphorus oxychloride.
My approach circumvents these problems by performing the reaction in an inert medium (solvent) in which chlorine is good and
Phosphorus pentachloride moderately soluble. The medium boils under reflux due to the heat of reaction, which eliminates the problem of
temperature limitation and heat dissipation is elegantly solved in one.
I used specially purified (dry and alcohol-free) chloroform as the inert medium. Unsuitable are all solvents which
react with the reactants and products.

Chloroform reacts with chlorine to a small extent to form carbon tetrachloride, but this reaction takes place only to a small extent,
which is why chloroform is suitable as a reaction medium.
Carbon tetrachloride would be the ideal choice. Dichloromethane will probably work as well, possibly taking place the
chlorination of dichloromethane occurs more readily than that of chloroform, however, so increased chlorine consumption may be detectable.

Chlorine (from TCCS and HCl).
phosphorus pentoxide
conc. sulfuric acid
red phosphorus

Safety Instructions:
Chlorine is toxic and hazardous to the environment.
Chloroform is harmful to health.
Phosphorus pentoxide and sulfuric acid are corrosive.
Red phoshor is highly flammable.
Phosphorus pentachloride is very toxic and corrosive.
Caution: purified and unstabilized chloroform poses a risk of phosgene formation during storage. Once the
stabilizing ethanol has been removed, the chloroform should be used as soon as possible (within 1-2 days).
tightly closed and protected from light. Handle only under the fume hood.
After the chloroform has been recovered and purified, it is stabilized again with 1% ethanol to keep it shelf stable. It
contains a small amount of carbon tetrachloride after the reaction and should therefore not be poured back into the storage bottle,
but should be stored separately.
Caution. Phosphorus pentachloride reacts violently with water! Inform yourself about the properties of the substance beforehand.
reacts with many substances, sometimes unexpectedly, e.g. phosgene is formed with sodium carbonate!
Purification of the chloroform for synthesis:
The chloroform (110 ml) is first mixed in the separating funnel with about half of its own volume of concentrated sulfuric acid.
several times vigorously and for a long time, leaving it to stand for some time in between.
The chloroform is then very carefully separated from the sulfuric acid (the chloroform forms the upper phase) and stored in a
(the chloroform forms the upper phase) and mixed with phosphorus pentoxide in portions in a sealable vessel (round-bottomed flask or similar) and shaken. Phosphorus pentoxide is added
phosphorus pentoxide is added until it remains powdery and no longer clumps together when added further. It is left to stand for a few hours
with occasional shaking.
Then the chloroform is decanted into a dried column flask, a little fresh phosphorus pentoxide is added and distilled off.
distilled off. The still should be protected against the ingress of moisture.
Work is to be carried out in the fume hood!
A gas generator is set up, followed by a frit washing bottle with concentrated sulfuric acid (for drying).
A 250 ml three-neck round bottom flask is fitted with gas inlet, reflux condenser and stopper and clamped over a magnetic stirrer.
clamped in place. A stirring fish is placed inside.
The gas generator is filled with trichloroisocyanuric acid (used: 84g, this was not sufficient as was shown later) and 23% hydrochloric acid (used: 150ml).
hydrochloric acid (used: 150ml, not sufficient), the reaction flask is filled with 10g red phosphorus and the purified chloroform.

The magnetic stirrer is set in motion at high speed and the chlorine introduction is started.
Due to the heat of reaction, the chloroform immediately becomes hot and soon begins to boil under reflux.
A small amount of hydrogen chloride escapes from the top of the cooler, which is due to reaction of chlorine with the chloroform.

In order to reduce this reaction somewhat, I have tried to cool the thing by water cooling:
But this turned out to be very disadvantageous, because then the inlet tube was clogged by crystallizing PCl5. Do not use
use external cooling!

Despite working at the boiling point, the inlet tube clogged several times due to PCl5 especially towards the end of the reaction. This is very
dangerous, since pressure then builds up and some component, usually the wash bottle head or the dropping funnel, can be catapulted out.
can be catapulted out. You have to keep a close eye on things and often pull out the inlet tube a little (but leave the gland
left in! No humidity should get in!) to see if it is still open. A sudden drop in the
a sudden drop in the gas injection rate, which can be seen in the wash bottle, is an alarm signal.
must be loosened.
One then pushes a rigid wire into the discharge pipe and pokes out the blockage.

The chlorine injection lasted three hours, with chloroform boiling continuously under reflux! This gives an impression
of the enormous amount of heat released by the reaction. Without a solvent, nothing really works, at least not on such a large scale.
large scale.

The chlorine developer had to be reloaded once in a while, since the frequent loosening of blockages caused a
a significant part of the chlorine escaped into the fume hood.
The feed pipe should definitely be flared at the bottom next time to avoid this!

When the reaction is complete, any red color has disappeared and the chloroform above the PCl5 takes on a green color due to dissolved excess chlorine.

chlorine (important to avoid PCl3 formation).

This is what it looks like (still hot, magnetic stirrer turned off):

The flask was left tightly closed until the next morning (it would be better to work up immediately, but it was already
late at night).

The still dissolved PCl5 crystallized out and filled the whole flask, no liquid was visible at all:

The flask was prepared for distillaton, heating must be done with water bath.
Chloroform was distilled on the sidende water bath until nothing remained. The contents of the flask liquefied

This is how it looked when nothing more passed over:

Then the mass was crushed a little with a spatula (the flask must only be opened very briefly, because of humidity), the
distilled chloroform/carbon tetrachloride mixture was removed and the template was replaced.

Then vacuum was applied and the whole mass was slowly heated with the water bath. Some solvent escaped again (through the water jet pump, recognizable by the smell). Heating was continued (up to almost 100°C) until the last residual solvent was removed and the PCl5 began to sublime.

Then the heating bath was removed, the vacuum was taken away and the
mass was coarsely crushed (in the flask, with the spatula) after cooling and immediately transferred to a tightly sealable glass vessel with a Teflon seal that had been weighed empty beforehand.
glass vessel with Teflon seal.

It is weighed to determine the amount of product.
I obtained 65g, an almost 100% yield. This must also be obtained, otherwise one has worked uncleanly (air humidity
was added).

The distilled off solvent is washed thoroughly with aqueous sodium carbonate solution (still contains some
phosphorus compounds, such as POCl3 and co-distilled PCl5) and then dried (e.g. with CaCl2 or sulfuric acid) and distilled
(observe boiling range to see how much CCl4 is in it).

It is mixed with 1% ethanol for stabilization and labeled and stored as recycled chloroform (contains carbon tetrachloride).

Phosphorus pentachloride is the strongest chlorinating agent and can generally convert almost all acids to their acid chlorides.
It can even be used to chlorinate sulfuric acid to chlorosulfonic acid! Neither PCl3 nor SOCl2 can do this.

However, only one chlorine atom is utilized. The by-product is always phosphorus oxychloride POCl3.
H2SO4 + PCl5 ---> ClSO3H + POCl3 + HCl

The acid chlorides can also be produced directly from the salts of oxygen acids by the action of PCl5. Example is
the preparation of phosgene from sodium carbonate:
Na2CO3 + 2 PCl5 ---> COCl2 + 2 POCl3 + 2 NaCl.

You can also make PCl3 from PCl5 by mixing it dry with an excess of red phosphorus and heating it. The
mixture liquefies and PCl3 can be distilled off.

[Edited on 6-2-2021 by NaK]

Attachment: pcl5.pdf (1MB)
This file has been downloaded 144 times

NaK - 6-2-2021 at 05:41

And here the continuation:

Echolot - 8/9/2009, 15:08
Title: Oxalyl chloride
Here oxalyl chloride is prepared starting from phosphorus pentachloride and anhydrous oxalic acid.

100ml round bottom flask
Reflux condenser
Fermentation tube
Distillation bridge
Stand material

Phosphorus pentachloride
anhydrous (!!) oxalic acid
conc. sulfuric acid
possibly dichloromethane or chloroform, rhodamine B and hydrogen peroxide 30%.

Safety instructions:
Phosphorus pentachloride is very toxic, oxalic acid is harmful to health, sulfuric acid is corrosive.
Caution: Oxalyl chloride formed is highly corrosive, toxic and reacts violently with water ! Please be very careful with this
substance and only work under a well-drawn fume hood !

In a 100ml round bottom flask place 25g of phosphorus pentachloride and 5g of anhydrous oxalic acid. Weighing and filling into the flask
flask as quickly as possible so that the substances get as little humidity as possible. Subsequently
the two substances are mixed thoroughly with a glass rod and crushed. For this purpose it is advisable to pass the glass rod through a balloon/rubber hand.

a balloon/rubber glove to prevent air circulation:

When both substances are well mixed, remove the glass rod and the "seal" and quickly put on a fermentation tube filled with
conc. sulfuric acid:

The purpose of the fermentation tube is to allow any excess pressure to escape, but still keep everything airtight. I advise
to use a tube with a ground core, the silicone seal of my Quickfit was after a short time completely

Now let the flask stand for 2-3 days, after this time, according to the literature, the contents of the flask should be completely liquefied.
have liquefied. However, this was not the case with me even after more than a week, which is why I finally installed a reflux cooler
(an air cooler is sufficient) and carefully heated the piston:

After some time, the first droplets formed on the piston wall, which a short time later condensed in the reflux condenser and dripped down.
dripped down. The reaction rate increased rapidly until almost everything had liquefied and boiled under reflux without further heating.
boiled under reflux without further heating. After the reaction was completed, only a few solid components (probably unreacted phosphorus pentachloride) remained in the solution.

phosphorus pentachloride) were present in the mixture:

A distillation bridge was now set up and the resulting oxalyl chloride-phosphorus oxychloride mixture distilled off:

After almost all of it had passed over, a white substance began to deposit on the flask walls and in the distillation bridge, probably indicating sub
which is probably due to subliming, unreacted PCl5.

I obtained about 4ml of milky (because of the PCl5) liquid, which passed over at about 60-100°.
To separate the oxalyl chloride from the phosphorus oxychloride, distill it over a column, the part that passes between 60° and 65° contains the oxalyl chloride.

part contains the oxalyl chloride and is kept:

I obtained about 1.6ml, about 34%

Such a poor yield is unfortunately normal for this synthesis (the literature writes of 40%) and also explains the high price
of oxalyl chloride.

It is still contaminated with some phosphorus oxychloride and phosphorus trichloride, so a redistillation with a
column is recommended. The PCl3 can be removed by passing chlorine through the oxalyl chloride, which will cause PCl5 to precipitate and
precipitates. One then redistills and can remove dissolved chlorine by shaking out with a little mercury. Subsequently
one has to distill again from the HgCl/HgCl2 formed and obtains quite pure oxalyl chloride in this way. In view of my
low yield, however, I have dispensed with this purification.

The oxalyl chloride must be stored in a tightly sealed glass bottle with a Teflon insert in the lid !
In order to test whether oxalyl chloride has really been formed, one fills some sealable container (I took a small
half with dichloromethane or chloroform and add a few drops of oxalyl chloride and a spatula tip of rhodamine.
spatula tip of rhodamine B. In the dark, add 1-2 ml of 30% hydrogen peroxide to the solution, close the tube well and shake vigorously.
and shake vigorously. If oxalyl chloride is present, a very bright orange chemiluminescence is seen, which lasts up to about

There are essentially 3 reactions taking place:
(COOH)2 + PCl5 ----> 2CO2 + 2HCl + PCl3 (the oxalic acid is oxidized).
(COOH)2 + 2PCl5 ----> 2POCl3 + (COCl)2 + 2HCl (the desired reaction)
(COOH)2 + 2PCl5 ----> POCl3 + CO + CO2 + 2HCl (decomposition of the oxalic acid)

[Edited on 6-2-2021 by NaK]

Attachment: (COCl)2.pdf (709kB)
This file has been downloaded 138 times

Fery - 6-2-2021 at 06:56

NaK thx for sharing.
Texium (zts16) used similar approach (CHCl3 as solvent) to produce PBr3 - where no risk of clogging inlet gassing tube as it is not required.

NaK - 6-2-2021 at 12:19

Apparently you can improve the yield of oxalyl chloride significantly by performing the reaction with phosphorus oxychloride present. So you could do it once and then use the distilled off phosphorus oxychloride in subsequent runs

Benignium - 7-2-2021 at 08:35

clearly_not_atara, you're entirely correct. As skilled and knowledgeable as he is, NurdRage is by no means some perfect being and what I said is silly and unfair among other flavors of wrong.

mr_bovinejony, thank you. I will attempt the preparation using a sufficient amount of acetone. Perhaps there are even better options for a solvent.

solo - 8-2-2021 at 17:47

....over at Research gate forum i found this entry which may be of some assistance in the quest for the said acid chloride...solo

Gandhi K. Kar
Presidency University, Kolkata
You can use oxalyl chloride. It's very good reagent. We have used it several times. To avoid formation of HCl you can use the following procedure: Convert the acid (in solution of ethanol) into sodium salt with drop wise addition of ethanolic NaOH (phenolphthalein indicator can be used to avoid excess use of alkali) and then remove the solvent to get the solid acid salt. It is to be dried under vacuum. Now to the suspension of the acid salt in dry benzene or dry toluene containing catalytic amount of pyridine, the oxalyl chloride (about 1.1 equivalent) is to be added drop wise preventing from moisture (CaCl2 guard tube or inert atmosphere can be used). The solution is to be stirred for about 1.5 hours at r.t and then ~30 min at about 60 degree centigrade. The precipated Na-satl is to be filtered out. Removal of the solvent from the filtrate will furnish the crude acid chloride which is sufficiently pure for most of the purposes.
Prof. El-Emary also recommended the use of oxalyl chloride but it is to be used for Na-salt of the acid. Use of PCl3 or PCl5 again suffers from formation of hazardous HCl or POCl3 etc.