Sciencemadness Discussion Board

Chloroacetic Acid from TCCA and S/I2 Catalyst?

kclo4 - 12-7-2008 at 01:26

I've been wondering if Chloroacetic acid could be produced from Acetic acid, Trichlorocyanuric acid along with a catalyst such as Sulfur or Iodine, along with a small amount of hydrochloric acid to get the reaction started.

"Chloroacetic acid is synthesized by chlorinating of acetic acid in the presence of red phosphorus, sulfur, or iodine as a catalyst:

CH3CO2H + Cl2 → ClCH2CO2H + HCl" - wikipedia

But, I don't particularly enjoy messing around with chlorine gas, and would prefer to have HCl gas to deal with instead. :P

I think this would work, unless for some reason an iodine or sulfur catalyst isn't all that effective, or i am missing something serious about the reaction, but it seems the reaction from wikipedia and my reaction which would use TCCA, could easily be done in a flask.

Does acetic acid and TCCA have other reactions? other then the one i suggested, which would likley be slow with out S/I2?


And, off topic, would it be better to make chloroacetamide from acetamide doing something similar to the reaction on rhodium to produce methylamine from acetamide? http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/m...

Or to make chloroacetamide somehow from chloroacetic acid?

Thanks in advance :D

[Edited on 12-7-2008 by kclo4]

Sauron - 12-7-2008 at 03:14

There are existing threads on this reaction, and specific literature cited for the preparation of chloroacetyl chloride using TCCA.

The alpha-chlorination of a carboxylic acid using a halogen carrier (classically PCl3 or red P and Cl2) is the Hell-Volhard-Zelinsky reaction. It proceeds via formation of the acid halide in situ and then an enolization mechanism.

TCCA has been used as have NCS etc.

You are better off preforming acetyl chloride and reacting that with TCCA.

Note that chloroacetyl chloride is rather nasty stuff.

Quite a bit nastier than Cl2 actually.

I will dig up the article I have on TCCA and acetyl chloride.

Here it is.

[Edited on 13-7-2008 by Sauron]

Attachment: a-Chlorination of Carboxylic Acids Using Trichloroisocyanuric Acid.pdf (80kB)
This file has been downloaded 3999 times

kclo4 - 12-7-2008 at 11:55

I see, thank you very much Sauron, it was an interesting article, I'm kinda confused as to why the turned off the lights, surely they wouldn't effect the reaction significantly.
they also made a typo for the preparation of 2-Chloropropanoic Acid. :P

So, it seems like my reaction won't work, unless i add PCl3 or something like that to first get a small amount of acetyl chloride. Neither of those are easy to get or make so, thats to bad! I thought that i might be on to something.

Sauron - 12-7-2008 at 19:25

I suppose they wanted to demonstrate that the reaction is not photolytic, or to preclude a photolytic side reaction. The usual chlorination of GAA by the element, in presence of a halogen carrier, is photolytic.

So you want to use TCCA and you want to use S and/or I2 rather than the mostly unobtainable PCl3.

My suggestion is, prepare acetyl chloride, and skip the catalytic halogen carrier.

The only role of the PCl3 or sulfur halide formed in situ is to convert a small amount of AcOH to AcCl. It is the AcCl that then reacts with TCCA, and in the process, the PCl3 is regenerated, and the process starts all over till there is no more AcOH (or TCCA).

So, if you use stoichiometric AcCl, you don't need any halogen carrier. The alpha chlorination will proceed faster and under less forcing conditions than the usual H-V-Z. For an example of this approach see Org.Syn. Caproic acid (hexanoic acid) is converted to acid halide, then reacted with N-bromosuccinimide to give a-bromocaproyl halide, and that is then hydrolyzed to the a-bromo acid.

NBS is a N-halocycloimide just like TCCA. You could in fact use NCS but TCCA is cheaper and OTC.

kclo4 - 13-7-2008 at 00:46

Well, since i guess the mechanism of action for sulfur to work as a catalyst is that it forms a halide.
So, by adding a small amount of Sulfur dichloride or disulfur dichloride, that would start the reaction, correct?

And, for some reason, i can't ever find anything i look for on org syn. Is there some trick to it? When i search keywords, tons of other things always seem to pop up except what i want, and know is located their.

Sauron - 13-7-2008 at 01:14

See the attached monograph from Org.Syn.

The first step is to prepare the acid chloride. This prep uses thionyl chloride which these days might be trouble to obtain. There are many alternatives, and which one you use is up to you.

The second step is what counts. NBS in CCl4. That gives you the a-bromoacyl chloride.

Now, it ought to be clear from the paper I posted abovethread that TCCA will a-chlorinate the acyl chloride just as well.

Afterwards you need to mildly hydrolyze the acyl chloride to acid but wthout cleaving the a-chlorine group.

As to doing a HVZ with SCl2 or S2Cl2, the answer is "maybe". But can you buy one or both of those> No, probably not for same reason as you probably will run up against with SOCl2.

You can make them of course but you need to use Cl2. If you are going to generate Cl2 then why not use it in the HVZ with sulfur?

That is I think more likely that TCCA, sulfur and your acid. If sulfur and TCCA will form a sulfur chloride it is news to me. Not impossible, but I have never heard of it being done. If it can be done I'd like to hear about it.

[Edited on 13-7-2008 by Sauron]

Attachment: CV6P0190.pdf (145kB)
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kclo4 - 13-7-2008 at 12:07

It can be done, or at least it appeares to have been done.
I've mixed a small amount of powerdered sulfur and TCCA in a test tube, and left it for a day. Small yellow droplets formed. However, that could be something other then SxCl2.

Also found this on SM, in a thread about S2Cl2

" I once tried to oxidize sulphur in acetic acid with TCCA in order to get acetic anhydride trough in situ SOCl2 formation. Well, it did not yield any dehydrating species able to form the anhydride but the reaction was extremely exothermic and TCCA had to be added very carefully trough the reflux condenser in very small portions (a lot of nasty fumes evolved). Besides the usual cyanuric acid precipitate the acetic acid contained an intensively yellow product, probably some undefined mixture of nasty stuff that might have been anything from various sulphur chlorides to something like ClSCN which decomposes further."

[Edited on 13-7-2008 by kclo4]

Nicodem - 14-7-2008 at 01:49

If you just insist on preparing chloroacetic acid via the Hell–Volhard–Zelinsky reaction, then there is also its modification using TCCA (Synth. Commun., 34, 889–893; uploaded already a few times on this forum). It uses PCl3 as a source for in situ AcCl formation. Sulfur will not work instead of phosphorous, but you could try with SOCl2, Ac2O or AcCl itself. I2 is a Lewis acid with interesting properties and might actually work (try and see). Bubbling HCl into TCCA/AcOH will do nothing to AcOH since TCCA gets reduced by HCl forming Cl2 which itself can not chlorinate AcOH (except under radical conditions like in the following...). You could try with ~10mol% dry paraformaldehyde for in situ AcCl formation (via oxidation to phosgene with TCCA).
There is also the radical chlorination of acetic acid which however requires intense light (like sunlight or an UV source) and heating but it does not require any AcCl intermediary (so no P or PCl3 is required).
The most OTC precursor to chloroacetic acid is 1,1,2-trichloroethene (aka "trichloroethylene") which can be hydrated in the presence of H2SO4 or FeCl3 at 100°C or higher directly to chloroacetic acid (however, it requires a pressure bottle withstanding at least 2 bars).

Sauron - 14-7-2008 at 02:34

I posted that article 6 posts upthread, but never mind. I think it was you I got it from anyway, Nicodem.

I would like to react sulfur and TCCA and see if I can get any sulfur chloride(s) to distill off. They are cheap enough so nothing to lose.

Nicodem - 14-7-2008 at 03:25

Sorry, in the hurry I read only the first and the last post.
Quote:
Originally posted by kclo4
So, it seems like my reaction won't work, unless i add PCl3 or something like that to first get a small amount of acetyl chloride. Neither of those are easy to get or make so, thats to bad! I thought that i might be on to something.

You can use other reagents that will similarly activate the alpha-methylene groups of the carboxylic acids. I already mentioned the possibility the reaction could work with the addition of paraformaldehyde (or benzaldehyde), but it could also work with P2O5 (which can be bought with less paper work compared to P or PCl3) or even B2O3. Even AlCl3 could potentially work. All it takes is some experimentation. Anything that can form AcCl, Ac2O or AcOX (any X which is considerably more electron withdrawing than H is potentially useful). So you can try first with I2 or dry paraformaldehyde. Though, if you have benzaldehyde I think it is more full proof since the paraformaldehyde could get oxidized to CO and HCl and stop right there instead of being oxidized to COCl2. Instead benzaldehyde gets oxidized to PhCOCl (which on turn is in AcOH + PhCOCl <=> AcCl + PhCOOH equilibrium required for the HVZ reaction).

Or just go for the radical chlorination...

Example of preparation of chloroacetic acid by trichloroethylene hydration:
Quote:
Equal amounts of trichloroethylene and 75 % sulfuric acid are reacted at 130 – 140 °C in a continuous process so that with complete trichloroethylene conversion, the resultant reaction mixture contains about 50 % chloroacetic acid and 1 – 2 % water. This blend is vacuum distilled to give pure chloroacetic acid. During this process the vapors are washed with water, which is returned to the sulfuric acid as a diluent. The resultant hydrogen chloride gas is washed with the fresh trichloroethylene and then purified by freezing and absorbing in water.

I don't remember exactly where I copied this from. It could have been from US4172957 which describes partial hydration of trichloroethylene to chloroacetyl chloride (or some of these: DE2059597, US3829477, US3742047 which describe the preparation of AcCl by using the in situ formed chloroacetyl chloride from trichloroethlyene). Or maybe from this forum since there already is an old thread on trichloroethylene hydration.

[Edited on 14/7/2008 by Nicodem]

Sauron - 14-7-2008 at 04:40

At the risk of repeating myself:

Any variation of the HVZ reaction is going to yield the chloroacetyl chloride or bromide and not chloroacetic acid. The acid will need to be liberated from the acyl halide.

Chloroacetic acid is a strong acid that will burn the skin but it is a solid. Chloroacetyl chloride is a liquid, and is highly lachrymatory and corrosive. Its preparation and handling must be carried out in a good hood with proper protective equipment and apparel in place.

It seems to me that going through chloroacetyl chloride to get to chloroacetic acid therefore makes no sense if the only reason is to avoid setting up a Cl2 generator and preparing the acid itself from GAA via photolysis.

Failing that, Nicodem is right, trichloroethylene is a good way to go.

Chloroacetic acid is a very cheap chemical commodity. The path of least resistance is to buy it.

Nicodem - 15-7-2008 at 01:34

The Hell-Volhard-Zelinsky reaction always yields the alpha-haloacid directly since the P, PCl3 or whatever else is used only a couple mol% amounts and therefore it can not quantitatively produce the alpha-haloacid halide. You can check the reaction mechanism and cycle here. The acid halide is only an intermediary since the alpha-methylene group needs to be activated for halogenation (the carbonyl needs to be enolizable enough). Once it gets alpha-halogenated the acid halide thermodynamically equilibrate yielding the alpha-haloacid.
You seem to be talking about alpha-halogenation of acid halides which does indeed yield alpha-haloacid halides, but is not formally a Hell-Volhard-Zelinsky reaction since it does not use its reaction cycle. It is just a normal alpha-halogenation of an enolizable carbonyl compound (just like ketones or aldehydes) and as far as I know it does not have a reaction name. This approach is obviously unnecessary when the desired product is chloroacetic acid which can be obtained directly using the classical Hell-Volhard-Zelinsky reaction conditions (for examples, like the ones used in the Synth. Commun. employing TCCA as oxidant uploaded by you above thread).

Sauron - 15-7-2008 at 02:11

Of course you are quite right that using ROCl or ROBr rather than ROOH + halogen carrier is not precisely HVZ. The dilemna is that red P or PCl3 are rather hard to come by these days for most of us in most places. The thread author is asking about using TCCA in conjunction with, not P and Cl2, not PCl3, but S, or I2. Or failing that, SCl2 or S2Cl2.

So my suggestion was to bypass the HVZ per se, prepare AcCl, and a-chlorinate that w/ TCCA which is a literature reaction.

I have not seen any lit. on using S or I2 with TCCA in a HVZ type procedure, and there is a post from a member who tried this and failed.

The authors of the Org.Syn paper I posted indicated that HVZ reactions can be quite sluggish, this was part of their rationale for the alternate.

It would be nice to find a review article covering the early lit. on HVZ to see if there is anything on use of S or I2 explicitly in chlorination of GAA using Cl2, or in the later lit., NCS or TCCA or maybe a halohydantoin (the usual suspects.) So far no such review has surgaced.

Nicodem - 15-7-2008 at 03:01

The comment Kclo4 copy/pasted and for reasons unknown didn’t cite was from one my post where I described an experiment I did years ago. As is obvious from the description it had nothing to do with alpha-chlorination of acetic acid, I was just curious if it was possible to prepare acetic anhydride or acetyl chloride with the use of TCCA/sulfur combination.

I already gave a few possible alternatives for P or PCl3 to be used in the HVZ halogenation (personally I find benzaldehyde to have good chances). It is highly unlikely you will find many (if any) alternatives to P and the likes in the literature since nobody cares if red P, PCl3 or POCl3 are unavailable to amateurs. As long as even the most pathetic organic lab will have them available there will be no motivation to research alternatives. There could however be something on sulfur being used in the literature, and then there is one or two papers on I2/Cu(II) for the alpha-iodination of carboxylic acids.

Sauron - 15-7-2008 at 03:27

Amen to that. Nobody cares about the obstacles in the path of hobbyists except of course, other hobbyists (the reason this thread exists), and of course, on the negative side, those who would cheerfully pile more hurdles in our path (viz., the recent unpleasantness in Germany, Switzerland and Austria.)

S.C. Wack - 15-7-2008 at 04:26

Of course the use of sulfur or iodine is in the literature. Just with chlorine, not with TCCA; someone will have to get busy and experiment themselves.

Sauron - 15-7-2008 at 04:48

(stunned Silence)

Experiment?

What an original idea!

Get out from in front of the box and DO something?

Nah. Too radical. It'll never catch on.

AndersHoveland - 30-11-2011 at 13:57

I thought I read somewhere that chlorine will react with a mix of acetic anhydride and glacial acetic acid alone [without any other catalyst]. And that sulfur can also catalyse the reaction between glacial acetic acid [probably there cannot be water, best to dissolve in chloroform] and chlorine.

I found this in a quick online search:
Quote:

...chloroacetate production processes, from glacial acetic acid in the presence of sulfur catalyst with chlorine...


In the case of phosphorous or sulfur as a catalyst, I think the chlorine initially reacts with the P or S, to form PCl3 or SCl2, which are both act as acid anhydride dehydrating agents, which can shift the equilibrium of acetic acid into an unsaturated tautomer derivitive [in which there is a carbon-carbon double bond], through which the chlorine can then directly attack.

organichem - 31-7-2014 at 23:26

Well - I'm interested in the TCCA method and was asking myself as I read through the paper:
Quote:

Excess 1 [TCCA] was destroyed by the slow addition of solid NaHSO3 until a wet iodide-starch


Well as far as I know NaHSO3 only exists in aqueous solutions - so they rather used sodium disulfite?
What does the equation look like? I came up with the need of water... (3 mol H2O per mol disulfite that's capable of reducing 2/3 mol TCCA)

TCCA + 3 H+ + 6 e- --> cyanuric acid + 3 Cl-...| *2
3 H2O + S2O52- --> 2 SO42- + 4 e- + 6 H+........| *3
-----------------------------------------------------------------------
9 H2O + 3 Na2S2O5 + 2 TCCA --> 2 cyanuric acid + 6 NaHSO4 + 6 HCl

AJKOER - 1-8-2014 at 12:05

OK, a point that I find annoying in my so called bleach battery that employs HOCl (that I prepare from vinegar and NaOCl), Aluminum source and copper metal with NaCl as the electrolyte. Namely, a sickening smell on letting the galvanic cell stand for a few days in diffused sunlight. I am not referring to Cl2, which the cell in its early life can produce liberally. I actual find the smell of chlorine tolerable in comparison.

My guess is a some chloro acetyl compound perhaps formed in the presence of sodium acetate, HCl, HOCl, chlorine, copper, cupric chloride or the oxychloride, Al2O3 or Aluminum oxychloride. In other words, one of these could constitute a possible catalyst in conjunction with photolysis.

My speculation on the formation of the chloro acetyl compound is weakly based not only on the powerful sickening fumes, readily attacks ordinary rubber gloves, and also readily kills any weed I pour it on, no matter how large.

[Edited] I have decided to re-examine other convenience paths to HOCl other than by the action of acetic acid on NaOCl , as whatever this compound is, it apparently falls into 'should avoid' category. Previous efforts with CO2 and Boric acid demonstrate short comings (slow reaction rate for one).

[Edited on 1-8-2014 by AJKOER]