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Author: Subject: Reagents for the preparation of acid chlorides: pros and cons
Melgar
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[*] posted on 22-6-2016 at 11:45
Reagents for the preparation of acid chlorides: pros and cons


I've done a large amount of research on what reagents are used to prepare acid chlorides, and they mostly seem to be:


  • Phosphorus chlorides
  • Thionyl chloride
  • Phosgene and derivatives


All of these chemicals are somewhat dangerous to synthesize, and phosphorus chlorides are pretty much out of the question. However, diphosgene seems to have some really interesting properties that make it seem like an incredibly useful reagent, while being somewhat less dangerous and easier to store than regular phosgene. Thionyl chloride seems to be the gold standard, and I've made an impure form of it before (that I never got to use) so I know what the process is like. But I'm not sure what, if any advantages there are to thionyl chloride over diphosgene. Obviously, both would necessitate the use of a fume hood. My guess is that thionyl chloride is more selective, and so is used more, which would make sense.

As far as syntheses, the reactions I would use to obtain them are both similar to other reactions I have extensive experience with, and I'd estimate them to be similarly difficult and dangerous. Any reasons I should attempt one over the other?

Thionyl chloride synthesis I used:
Gas elemental sulfur with chlorine gas until enough of it is liquid to allow bubbling. Keep doing this until the color changes to indicate presence of SCl2. Continue bubbling Cl2, but now also bubble SO2 by adding HCl to sodium metabisulfite. Alternately, use thermal decomposition of iron sulfate.

This was all done outdoors, the first time, incidentally, and any gases were bubbled into a solution of potassium iodide and sodium bicarbonate. (tests for acids and chlorine) Never got about to purifying it or determining yield, but it seemed to work.

Proposed solution for diphosgene:
Prepare methyl formate from calcium formate and HCl-saturated methanol. Distill to purify. Dissolve chlorine in methyl formate, and add a catalytic amount of bromide salt to generate bromine monochloride in situ. (Bromine monochloride will form radicals in visible light, as opposed to chlorine, which requires UV). Possibly run the HCl vapors into a hydrogen peroxide solution to generate more chlorine gas for the reaction. Again: fume hood not optional.

Another benefit of diphosgene is that it can be used to generate thionyl chloride, should I ever need it. Any major downsides I've overlooked?

[Edited on 6/22/16 by Melgar]
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[*] posted on 22-6-2016 at 15:58


Thionyl chloride is popular because it's cheap, relatively stable, fairly safe to handle, and gives only gaseous byproducts. As you note, it is pretty selective in what it reacts with, which is nice (it means you can really push the system - using neat thionyl chloride and heating it, if need be - to persuade unreactive functional groups to cooperate, without too much risk to the rest of your molecule).

Phosphorous chlorides certainly work, although they're rarely used in the literature - not least because other reagents are generally front of mind for the reaction (I reckon I could ask anyone in my lab, and phosphorous chlorides would be a long way down the list for making acid chlorides - and we use them every day for other purposes!).

The phosgenes are also effective, but they tend to be very expensive and thus little used. Also, the synthesis necessarily generates phosgene itself, which is of course a potentially significant hazard. They also decompose into phosgene, which can be a greater hazard - accidentally breathing in a lungful when you open your container! I've used di- and triphosgene a couple of times in in the past, for very specific purposes (to prepare unsymmetrical carbonates and carbamates), but have never turned to them for acid chlorides.

Personally, I've never prepared any of the above, but I'd lean towards thionyl chloride for a couple of reasons. 1) It's the more commonly used reagent, which means that you're more likely to find a procedure which uses it for the product you're looking to obtain (instead of having to adapt procedures which use other methods). 2) The synthesis is a marginally less unpleasant (no risk of phosgene - admittedly less of a concern given you're flowing large amounts of chlorine through the system either way!), but the storage is much less hazardous (HCl and SO2 vs. phosgene when you open the bottle). 3) To my memory, the preparation of thionyl chloride has been documented in a hobbyist environment and works pretty well, whilst I've not come seen a similar synthesis of diphosgene. That could be a sign of my ignorance, of course, but if not you'd potentially be breaking new ground. If that's your goal, great - new preparations of potentially useful reagents which are adapted to non-professional settings are great! But, if you just want to use it, you may not be interested in spending time to troubleshoot all the problems that could arise, when you can just go with a relatively tried-and-true method.
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[*] posted on 22-6-2016 at 17:34


I have never tried to make any of them, but have used all of them. You missed oxalyl chloride, which is one of the best as it often works at rooom temp, unlike POCl3 and thionyl chloride, which sometimes or often require refluxing. It is also fairly volatile, so most of the time, you can work up the reactions by merely evaporating them, which is also true of thionyl choride, but not true of POCl3, which can make a big mess upon workup. I don't know if there is a good OTC prep for oxalyl chloride, but at least oxalic acid is easy to find as wood bleach. Wikipedia claims that "It can be prepared by treating oxalic acid with phosphorus pentachloride.", so no worse to make than most other nasties.

The key to a good acid chloride synthesis is dissolve the acid in DCM, add the oxalyl chloride, and then one drop of a 1% soln. of DMF in DCM to it. That generates a catalytic cycle which makes the reaction go much faster at RT, but don't ad too much DMF or you can make too many by-products. This is a classic trick, but really works well.
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Melgar
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[*] posted on 22-6-2016 at 21:32


Quote: Originally posted by ziqquratu  
Thionyl chloride is popular because it's cheap, relatively stable, fairly safe to handle, and gives only gaseous byproducts. As you note, it is pretty selective in what it reacts with, which is nice (it means you can really push the system - using neat thionyl chloride and heating it, if need be - to persuade unreactive functional groups to cooperate, without too much risk to the rest of your molecule).

Phosphorous chlorides certainly work, although they're rarely used in the literature - not least because other reagents are generally front of mind for the reaction (I reckon I could ask anyone in my lab, and phosphorous chlorides would be a long way down the list for making acid chlorides - and we use them every day for other purposes!).


I've gassed S2Cl2 with chlorine, and I've gassed esters and hydrocarbons with chlorine. S2Cl2 was definitely worse. Not to mention, it's next to impossible to get out all of the S2Cl2 unless you add the nastiest of all the nasty chemicals to work with: OLEUM! That's right, to really do this synthesis right, you really need to decompose a sulfate salt, (preferably one that gives a mix of SO2 and SO3), and believe it or not, that's better than the alternative, which is overgassing with Cl2.

According to my research, in the presence of dissolved chlorine, SO3 reacts with S2Cl2 to give every sulfur its own oxygen, and would really cut down on the SCl2 and Cl2 vapors.


Quote:

The phosgenes are also effective, but they tend to be very expensive and thus little used.

Ironic, given that burning a mixture of methanol and chloroform/MeCl2 in the right proportions can generate it so easily.

Quote:
Also, the synthesis necessarily generates phosgene itself, which is of course a potentially significant hazard. They also decompose into phosgene, which can be a greater hazard - accidentally breathing in a lungful when you open your container! I've used di- and triphosgene a couple of times in in the past, for very specific purposes (to prepare unsymmetrical carbonates and carbamates), but have never turned to them for acid chlorides.

My plan is to chlorinate methyl formate as opposed to methyl chloroformate. If nothing else, then if I can't synthesize the ester properly, then I'll know I certainly have no business messing around with phosgene. Better to start with the least dangerous reaction and work up from there.

Quote:
Personally, I've never prepared any of the above, but I'd lean towards thionyl chloride for a couple of reasons. 1) It's the more commonly used reagent, which means that you're more likely to find a procedure which uses it for the product you're looking to obtain (instead of having to adapt procedures which use other methods). 2) The synthesis is a marginally less unpleasant (no risk of phosgene - admittedly less of a concern given you're flowing large amounts of chlorine through the system either way!), but the storage is much less hazardous (HCl and SO2 vs. phosgene when you open the bottle). 3) To my memory, the preparation of thionyl chloride has been documented in a hobbyist environment and works pretty well, whilst I've not come seen a similar synthesis of diphosgene. That could be a sign of my ignorance, of course, but if not you'd potentially be breaking new ground. If that's your goal, great - new preparations of potentially useful reagents which are adapted to non-professional settings are great! But, if you just want to use it, you may not be interested in spending time to troubleshoot all the problems that could arise, when you can just go with a relatively tried-and-true method.

Actually, I kinda want to break new ground. I actually discovered two reactions already that I posted here: bromide-catalyzed chlorination (of toluene to benzyl chloride at least) and the fact that erythritol tetranitrate will detonate when heated rapidly in the presence of aluminum. Both reactions were confirmed by other members, and I've seen both threads referenced extensively. That makes me really happy. I feel like I've contributed my part to overall scientific knowledge. :)

Sure, one of my threads explains how to make NPEDs, but I also proved that ETN can be reliably detonated in the presence of metal via thermal shock, something that anyone using ETN should DEFINITELY know. To my knowledge, this had not been documented before.

Quote:

I have never tried to make any of them, but have used all of them. You missed oxalyl chloride, which is one of the best as it often works at rooom temp, unlike POCl3 and thionyl chloride, which sometimes or often require refluxing. It is also fairly volatile, so most of the time, you can work up the reactions by merely evaporating them, which is also true of thionyl choride, but not true of POCl3, which can make a big mess upon workup. I don't know if there is a good OTC prep for oxalyl chloride, but at least oxalic acid is easy to find as wood bleach. Wikipedia claims that "It can be prepared by treating oxalic acid with phosphorus pentachloride.", so no worse to make than most other nasties.

You may be forgetting how hard it is for the amateur chemist to obtain elemental phosphorus.

One really nice thing about phosgene is that it can be used to MAKE thionyl chloride and oxalyl chloride. I'm half-tempted to make a methylene chloride burner, run it through a dryer, and bubble the vapors into liquid SO2 just to avoid combining all the nastiest chemicals I have experience together.

Incidentally, since you mention oxalyl chloride, I've read that the electron withdrawing effect of the benzene ring also makes benzoyl chloride a decent, mild reagent for making other acid chlorides. If this is the case, I could theoretically chlorinate toluene to benzotrichloride, then combine this with an equimolar amount of benzoic acid to generate two units of benzoyl chloride for each unit of benzotrichloride I painstakingly made; the benzoic acid could be obtained on eBay for a song.

I wonder if this could be done by chlorinating benzyl alcohol? The resulting hydrogen chloride would combine with more benzyl alcohol to make benzyl chloride, which could then be further chlorinated. I like the benzotrichloride + benzoic acid route though, if I'm going to generate an acid chloride from another acid chloride. It seems like it works on all the carboxylic acids I'm interested in, at least according to an organic chemistry text I read recently, which I'm unable to locate for some reason.

[Edited on 6/23/16 by Melgar]
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[*] posted on 22-6-2016 at 23:08


Quote: Originally posted by Melgar  

Gas elemental sulfur with chlorine gas until enough of it is liquid to allow bubbling. Keep doing this until the color changes to indicate presence of SCl2. Continue bubbling Cl2, but now also bubble SO2 by adding HCl to sodium metabisulfite. Alternately, use thermal decomposition of iron sulfate
I don't believe it works. The reaction is too slow at normal conditions to be usefull, and also gives a complex mixture of many different products.
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[*] posted on 22-6-2016 at 23:18


I know SO2Cl2/HOBt (benzotriazole) works for alcohols, but has it ever been tried for carboxylates? It seems like the mechanism would generalize: it forms a 1-benzotriazolesulfonate ester, which then attacks chloride to release a stable zwitterion.

https://www.researchgate.net/profile/Dr_Chandra_Azad/publica...

Oh! Also, I should point out, that during the last thread where someone was dumb enough to make phosgene, IIRC we found a reference saying something to the effect that if you want to make diphosgene from methyl formate you have to do the first chlorination selectively to methyl chloroformate; apparently just replacing methyl chloroformate with the formate in the OrgSyn tek can cause a "boom". Also, IIRC, the OP of that thread was never heard from again.

[Edited on 23-6-2016 by clearly_not_atara]

[Edited on 23-6-2016 by clearly_not_atara]
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[*] posted on 23-6-2016 at 00:05


As others have already clearly stated, thionyl chloride is the way to go: safer than the alternatives, more commonly used, etc.



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[*] posted on 23-6-2016 at 04:44


Cyanuric trichloride is a good one that nobody has mentioned. It is almost as versatile as oxalyl chloride, as long as you don't mind filtering cyanuric acid.

Thionyl chloride isn't too hard to make if you can get your hands on P2O5. Some pyrotechnic suppliers are selling it now, and I can attest that it is the legitimate stuff.

Here is my video on S2Cl2:
https://www.youtube.com/watch?v=oYw89ieffa4

After this, just gas it with more Cl2 until a prescribed weight gain. Set up a short-path distillation rig with a 2 neck boiling flask that you no longer like, as it will be etched. Drip cold concentrated H2SO4 onto powdered P2O5 in the boiling flask and then gently heat, making sure the distilling SO3 doesn't clog the short path. Once the SO3 is collected and weighed, the correct (excess SO3) amount of SCl2 is weighed out and the two flasks are connected with a 105-deg double male elbow and a claisen adapter with a condenser attached vertically. The SO3 is heated gently to drive it over to the SCl2 flask, forming thionyl chloride. The excess SO3 prevents S2Cl2/SCl2 contamination in the final SOCl2, because their close BPs make them hard to separate. After driving the SO3 over, the SO3 flask is removed and its claisen port is stoppered, leaving only the condenser. After bringing to reflux briefly, the mix is cooled and the vertical condenser is replaced by a vigreux column and the SOCl2 is fractionated at its BP.

Surprisingly simple, not to mention that pretty much all the popular carboxylic acid chlorides (incl. oxalyl-, acetyl-) can be made from SOCl2.

EDIT: Of course, in practice the "simple" method I describe is really a pain in the ass - it's a shitstorm of drying tubes made incredibly corrosive by nearby reactions and small burns from flame-drying glassware, followed by the nightmare-inducing reek of sulfur chlorides and the suffocating process of tearing down two massive chlorine generators, topped by billowing, acrid clouds of sulfuric acid mist and the inevitable fine coating of powdered sulfur and SO3-scorched grease all over everything... your keck clips will be destroyed, your lab stands will be corroded. Your gas scrubbers will have sulfur stuck in them and something you didn't know was there will probably burn you through a nitrile glove at some point. The SO3 generation flask will be etched, and the lab will have a lingering stench for weeks... and all for 150ml of a rotten liquid that doesn't store well.

To put it simply, it's fun as hell.

[Edited on 23-6-2016 by Praxichys]




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Melgar
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[*] posted on 23-6-2016 at 05:54


Quote: Originally posted by byko3y  
I don't believe it works. The reaction is too slow at normal conditions to be usefull, and also gives a complex mixture of many different products.

It certainly did something, although now I suspect I probably made SO2Cl2. I was never able to purify it, because I cracked the glass cylinder when I was moving it indoors when it started to rain. I suppose it would have worked if I had used sulfur trioxide instead of dioxide. And this is supposed to be the SAFE route!

Quote: Originally posted by clearly_not_atara  
Oh! Also, I should point out, that during the last thread where someone was dumb enough to make phosgene, IIRC we found a reference saying something to the effect that if you want to make diphosgene from methyl formate you have to do the first chlorination selectively to methyl chloroformate; apparently just replacing methyl chloroformate with the formate in the OrgSyn tek can cause a "boom". Also, IIRC, the OP of that thread was never heard from again.

I was going to attempt to use a chlorination method I've used before, in which a small amount of bromide salt is introduced, which generates bromine monochloride in situ. Bromine monochloride can then be selectively activated by incandescent light, producing the halogenation at lower temperatures, and without any significant risk of a runaway reaction. The danger you speak of, is that the heat generated will raise the temperature to the point where chlorine radical generation is spontaneous, which is of course, quite... exothermically unfavorable.

If that doesn't work, then no loss on my part. I'll try making benzoyl chloride instead.
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[*] posted on 23-6-2016 at 09:18


Actually, you could make cyanuric chloride. It's a little more dangerous than making SOCl2, but the final product is much safer to work with (and NCCl is still less scary than phosgene). You essentially make cyanogen chloride by passing Cl2 over sodium cyanide, although maybe ferricyanide would work (chlorine is pretty reactive after all). Then NCCl trimerizes to trichlorotriazine.

You may be able to make use of this:

http://www.sciencedirect.com/science/article/pii/S0043135498...

[Edited on 23-6-2016 by clearly_not_atara]
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Melgar
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[*] posted on 23-6-2016 at 13:03


Quote: Originally posted by clearly_not_atara  
Actually, you could make cyanuric chloride. It's a little more dangerous than making SOCl2, but the final product is much safer to work with (and NCCl is still less scary than phosgene). You essentially make cyanogen chloride by passing Cl2 over sodium cyanide, although maybe ferricyanide would work (chlorine is pretty reactive after all). Then NCCl trimerizes to trichlorotriazine.

You may be able to make use of this:

http://www.sciencedirect.com/science/article/pii/S0043135498...

[Edited on 23-6-2016 by clearly_not_atara]


Nice. I can get potassium and sodium cyanide for less than $20 a pound at the jewelers' supply store. I don't suppose TCT substitutes for cyanogen halides in reactions that call for it very frequently though? I'm still kind of interested in trying the diphosgene synthesis, even if it's just a few grams, just to test out my theory. After I stumbled on that milder free-radical chlorination reaction a few years back, I never really attempted any of the other syntheses that this reaction could potentially be used for.
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[*] posted on 23-6-2016 at 23:51


Just make sure you do your research before making cyanogen chloride. It can be done safely, but it is still a deadly war gas. Trimerization occurs by passing NCCl over a catalyst.

TCT can be used to make most acyl halides, I'm not sure if it'll convert amides to chlorimines but I think it will convert phthalic acid to phthaloyl chloride, and phthaloyl chloride will totally convert amides to chlorimines. It might even convert oxalic acid to its halide, but I'm less sure of that. I also don't know what the reaction products with sulfonic acids look like.

I think TCT is a pretty good replacement for SOCl2 overall. However, NCCl itself is a different beast: it dealkylates amines and undergoes various complex condensation reactions, as it is a very reactive electrophile and the reaction products tend to be unstable.
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[*] posted on 24-6-2016 at 09:03


Acetyl chloride can be made from acetic anhydride and HCl. What specific acid chloride do you need?

[Edited on 24-6-2016 by Magpie]




The single most important condition for a successful synthesis is good mixing - Nicodem
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[*] posted on 24-6-2016 at 09:52


Magpie,

Acetic anhydride and CL2 does not make acetyl chloride, but a mixture of Chloroacetyl chloride and Chloroacetic acid. See the patent below:

To the other guys, specifically "Praxichys" or Doug's Lab at you tube: I sent you a long time ago, at you tube discussion board, a patent to make thionyl chloride from your S2CL2 pre made, but it seems you didn't pay enough attencion.

Of course it's possible to sinthesize thionyl chloride from SCL2 (or S2Cl2), Chlorine and SO2, using ferric chloride as a catalist, withouth the use of nasty, corrosive and lethal SO3. Even wikypedia say the same.

When my Lab get plenty ready, what i hope be soon, it will be my first great movie demonstration, and it will be posted here and at You Tube.

See everybody the patent below:



Attachment: thionyl chloride.pdf (707kB)
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Attachment: CHLOROACETYL CHLORIDE.pdf (380kB)
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[*] posted on 24-6-2016 at 10:25


Quote: Originally posted by Chemi Pharma  
Magpie,

Acetic anhydride and CL2 does not make acetyl chloride...


I meant to say HCl instead of Cl2. I corrected the post. Thanks for the note.




The single most important condition for a successful synthesis is good mixing - Nicodem
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[*] posted on 24-6-2016 at 11:35


@Chemi Pharma - I am very interested to see your results. I abandoned this method early on since I lacked a good way to regulate the two gases. It makes me wonder if dripping H2SO4 onto a mixture of powderd Ca(OCl)2 and Na2S2O5 would generate the gases in the proportion in which the powders were mixed...

With your permission, I can reexamine this with better glassware and methods. I will not make a video about it if you would like to do that first.

My biggest problem is that any SO2Cl2 contamination is basically impossible to remove since its BP is so close to SOCl2.




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[*] posted on 24-6-2016 at 12:11


Of course i want to see you trying that first.

Science first, the father of the child goes further.

Read all the patent and you will see it's easy avoid SO2CL2 formation, in favor of SOCL2 just keeping the temperature of the reflux solution above 200ºC.

Your experiment at You Tube went very well. Improving your experience, I think we can produce Thionyl Chloride in one pot instead destilating the S2CL2/SCL2 mixture, as you did, just keeping refluxing it, adding more Chlorine at one side and also dry SO2 toghether at the other side of a three neck baloon, inside the mixture on refluxing.

The SO2 could be generated almost dry dripping conc. H2SO4 over sodium thiosulfate or bisulfite.

I Thought use a gas meter to measure the volume of chlorine and SO2 bubbled into the refluxing mixture.

You know: 22,4 liters of a gas is equal an one mol of the gas. One mol of Chlorine weight 71 grs and one mol of SO2 weight 64 grs.

It's just a stechiometry matter, but i believe an excess of gases will increase the yield.

When the reaction has done, cease the gas inlet, diminish the temperature, add a few grams of ANHNIDROUS ferric chloride as a catalizer and distill the thionyl chloride with a fracionated column, cause the boiling point of SCL2 and SOCL2 are too close.

Try this experiment Praxichys. I trust in your knowledgment cause iI saw everithing what you did as experiments at You Tube. If not I will do it soon.

Everybody here at sciencemadness is waiting for an OTC way to sinthesize Thionyl Chloride, using just raw materials, cause it's a hard to get chemical to buy on the market, although so useful in organic chemistry, thanks the creators of the mustard gas.

lucky!
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clearly_not_atara
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[*] posted on 24-6-2016 at 12:22


Since we already know that SO2 + Cl2 makes SO2Cl2 in the presence of a catalyst -- and it's famous as a reaction that almost anything will catalyse, including carbon, water, and visible light -- so it stands to reason that ferric chloride will do this as well. The equilibrium must therefore involve the comproportionation of SO2Cl2 and SCl2, and because the reaction succeeds, we know that this comproportionation must be kinetically viable and thermodynamically favorable under the reaction conditions.

So the direct comproportionation of SCl2 and SO2Cl2 is another way to carry out this reaction, most likely, and the instability of SCl2 explains where the free energy comes from. This is useful because the reactants are now both condensed at STP, and it's a dangerous reaction so it doesn't need to be any harder to contain than it already is...

Also, using excess SCl2 may be a way to avoid any SO2Cl2 in the reaction yield.

[Edited on 24-6-2016 by clearly_not_atara]
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[*] posted on 24-6-2016 at 12:35


Clearly,

I would like you read first the entire arguments contained at the patent i had post. The patent seems to bring too many solid arguments, enough to make me feel it's realible;

Posting again to everybody download and read:

Attachment: thionyl chloride.pdf (707kB)
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[*] posted on 24-6-2016 at 12:41


Chemi, I think you misunderstand. I assumed the patent was correct; I just suggested on mechanistic grounds an easier way to perform the same reaction. In particular, we know that SCl2 does not react with Cl2 above 250 K or so, because SCl4 is unstable at these temperatures. SCl2 also does not react with SO2. But SO2 reacts rapidly with Cl2.

Note that S2Cl2 does not work in my modification, because we have no reason to believe it will react with SO2Cl2. In this case we know that it does react with Cl2 directly.

[Edited on 24-6-2016 by clearly_not_atara]
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[*] posted on 24-6-2016 at 12:44


Sorry Clearly,

I read your comment too fast. It was a misunderstood.

I apologize.
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[*] posted on 24-6-2016 at 17:48


Quote: Originally posted by Melgar  
Incidentally, since you mention oxalyl chloride, I've read that the electron withdrawing effect of the benzene ring also makes benzoyl chloride a decent, mild reagent for making other acid chlorides. If this is the case, I could theoretically chlorinate toluene to benzotrichloride, then combine this with an equimolar amount of benzoic acid to generate two units of benzoyl chloride for each unit of benzotrichloride I painstakingly made; the benzoic acid could be obtained on eBay for a song.

I wonder if this could be done by chlorinating benzyl alcohol? The resulting hydrogen chloride would combine with more benzyl alcohol to make benzyl chloride, which could then be further chlorinated. I like the benzotrichloride + benzoic acid route though, if I'm going to generate an acid chloride from another acid chloride. It seems like it works on all the carboxylic acids I'm interested in, at least according to an organic chemistry text I read recently, which I'm unable to locate for some reason.


BTW...benzaldehyde is easily chlorinated if one wants to use it that way...actual reference, JACS 60, 1325 (1938) aka A Convenient Preparation of Volatile Acid Chlorides...and as noted there, phthalyl chloride came first (JACS 59, 206 (1937), also sort of a SOCl2 preparation), which that benzotrichloride will give with phthalic anhydride...




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[*] posted on 25-6-2016 at 09:52


Depending on what sort of acid chloride do you have in mind there may be another route which employs sulfuryl-chloride as chlorinating agent:
E.g.: 2 Sodium-benzoate + SO2Cl2 -> Na2SO4 + 2 benzoyl-chloride
(or something like that, depending on the exact reagents and stochiometry)

I faintly remember reading a paper about sulfuryl-chloride a few months ago and the above equation is from that paper. I also remember that water is a catalyst poison in making sulfuryl-chloride (at least when activated carbon (Norit) is used). Thoroughly dried carbon gives best results.
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[*] posted on 26-6-2016 at 11:46


What concerns PCl3, which no one cares about, since it is "impossible" to produce from red phosphorus, I know a guy, who is also interested in chemistry, and he claims, that it can be made (and he did made it) from red phosphorus, but:
-temperature must be kept low, even below 100C.
-chlorine must be diluted with inert gas, down to 10%-20%.
-silica should be added as a catalyst.
I'm not sure if that actually works, but that's what he said. I have no way to test this, but maybe somebody over here will do - eventually.

Also wikipedia mentions PCl3 can be oxidised with potassium chlorate:
PCl3 + KClO3 ---> 3POCl3 + KCl
I wonder, if simmilar thing works for SCl2:
3SCl2 + KClO3 ---> 3SOCl2 + KCl
Or:
3SCl2 +KClO3 ---> 3SO2Cl2 + 2KCl
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[*] posted on 26-6-2016 at 13:38


Well, one of you clever monkeys came up with this.....AcetylChloride from Acetonitrile, AceticAcid, and HCL gas. Even made a video demo!

https://www.youtube.com/watch?v=ExDI9KUW-9Q

Yield is about 30%. Not bad.... considering the cheapness of the starting materials, and the current difficulties with obtaining Acetyl Chloride.

[Edited on 26-6-2016 by zed]
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