ning (acetaminophanatic)
04-19-04 01:55
No 501593
      OTC oxalyl chloride from ethylene glycol     

OTC preparation of oxalyl chloride: a idea worth trying

Here's a little bit of fluff that's been tickling the back of my neck for some time now...finally I got around to typing it up and bringing it around to you, the HIVE at LARGE, to beat, bash, and abuse at your leisure. With a little luck, this idea may even work.

Rationale:

You know why you want oxalyl chloride, or you wouldn't bee reading this. wink

Basic Idea:

Dry ethylene glycol is exhaustively chlorinated to yield oxalyl chloride. The reaction proceeds in two steps:

(CH2OH)2 + 2 Cl2 --> (CH=O)2 + 4 HCl

(CH=O)2 + 2 Cl2 --> (COCl)2 + 2 HCl

With no water available to hydrate the formed glyoxal intermediate or react with the product oxalyl chloride, what the reaction amounts to is the use of chlorine to carry all the hydrogens away. And therein lies the beauty of it all -- in most reactions of this type, oxidation and chlorination are competing with each other, making yield not so good. But this glycol is the perfect substrate--no alpha hydrogens to be preserved, no unsaturated bonds to screw up, nothing. Just chlorinate the hell out of it, and whatever sequence the reactions happen in, at the end, you will have oxalyl chloride.

I think the use of chlorine to oxidized alcohols to aldehydes is pretty well known since ye olde days, when the only chemists spoke german. So I won't go looking for refs on that unless requested. I probably couldn't get them even if I found them--they'd all bee back in the 1800s, in Chemische Berichte and Liebig's Annalen. So just trust ole' ning on this one, chlorine will oxidize alcohols to aldehydes, and no further without water present.

The second step needs more documentation. Luckily, I'm in a typing mood today, so here is a prime source--a patent that does just what we need:

US patent 5,872,290 : Preparation of acid chlorides

Abstract:

Disclosed is a method of making an acid chloride having the general formula R3C.COCl, where R is saturated aliphatic or aryl. A solution is formed in an inert solvent of an aldehyde having the general formula R3C.CHO and chlorine gas is sparged into said solution. The reaction between the aldehyde and the chlorine gas to produce the acid chloride is performed in the absence of a catalyst, an initiator, and UV light.

...

In the first step of the process of this invention, the aldehyde is reacted with chlorine gas to produce the corresponding acid chloride: R3.COCl
  To avoid the production of unwanted byproducts such as the t-alkyl chloride, an inert solvent is used in this first reaction. The aldehyde is dissolved in the solvent and chlorine gas is sparged into the resulting solution. The solvent should be a liquid between about 80 C and about 250 C. In general, the choice of a solvent depends on the boiling point of the acyl chloride to be prepared, the solvent being selected so that it can easily be separated from the acyl chloride by distillation. Chlorinated benzenes, such as mono, di, and trichlorobenzenes, and particularly o-dichlorobenzene are the preferred solvents. Other aromatic solvents that lack active hydrogens and also lack ether linkages can also be used.
  No initiator, catalyst, or UV light is used in this reaction as they not only add to the cost of the reaction, but also reduce the yield and selectivity. Since the reaction proceeds in the absence of light, the process can be carried out industrially in glass-lined steel reactors.
  The reaction is complete when chlorine breakthrough is observed. The reaction can be followed by GC.

...

In the following experiments an aldehyde was reacted with chlorine gas in a three-necked flask under various conditions in the absence of an initiator or a catalyst, with and without ambient light. The following table gives the conditions and a GC analysis of the product mixture.

Aldehyde  PA wt% / solvent   initiator   temp (C)  RHCO  RCOCl  RCl  other    Light

 PA       20 %    o-PhCl2     426 ppm    65-70     15     50    12    22      ambient
 PA       20 %    o-PhCl2     426 ppm    30-35     12     68     5    14      ambient
 PA       20 %    o-PhCl2      none      30-35     <1     85     2    10      ambient
 PA      100 %     none        none      35-45      5     25    44    24      ambient
CPA       20 %    o-PhCl2      none      40-50     <1     94     0     5      ambient
 PA       20 %    o-PhCl2      none      30-40      1     60     2    38      none



The experiments show that the presence of the initiator reduced the yield of acid chloride product, that the yield was higher at lower reaction temperature, and that the solvent significantly enhanced the yield. The last run shows the reaction proceeds even in the dark.




See also US patent 2,490,386 : Production of unsaturated acid halides, for more information on this, as well as Organic Syntheses CV 1, 155 (http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0155): o-benzoyl chloride.
-----

So, to make oxalyl chloride from antifreeze, you would dry it, probably with CaCl2 or MgSO4, then put it in a big flask on a scale with a stirbar and a stink-pipe going to a water tank to absorb the generated HCl gas. Chlorine would then bee passed through a wash-bottle of H2SO4 or a CaCl2 drying tube and into the flask until a certain amount of weight gain had occurred, indicating complete conversion. One would have to see whether a dilutive solvent was needed or if the reaction could bee run neat.

The chlorine could bee generated by electrolyzing concentrated HCl, probably the most convenient way to make several moles of it.

Unfortunately, most of our favorite solid chlorinating agents like NaOCl and Ca(OCl)2 will not work as replacements for the chlorine gas, due to the reactivity of the formed oxalyl chloride. However, it may bee possible that the chloramines (NBS, DCDMH, TCCA) will not react with the formed oxalyl chloride. If this bee the case, the whole synth would beecome a great deal easier. However, I would await the word of a real hive chemist, and not a mere wannabee like myself before getting my hopes up.

Chemists: Will (COCl)2 react with (RCO)2.NH? Or is it too deactivated?

Well, whatcha think?

I've been chased by both cops and robbers. So what does that make me?
 
 
 
 
    ning
(acetaminophanatic)
04-25-04 21:28
No 503044
      No comments?     

This is surprising--no takers on this idea? Not even to shoot it down? Oxalyl chloride is a very useful chem. Or has someone tried this? Not according to my searching...

BTW, the aforementioned chlorination technique should also work to turn other aliphatic aldehydes into acyl chlorides too...i.e. acetaldehyde --> acetyl chloride, propionaldehyde --> propionyl chloride. Yummy!

Also, a beilstein search shows that it's very possible for oxalyl chloride to attack dicarbonylamines. Whether this is only the case under basic conditions or whether it can be prevented by enough acidity remains to bee seen.

I've been chased by both cops and robbers. So what does that make me?
 
 
 
 
    Osmium
(Stoni's sexual toy)
04-26-04 00:48
No 503076
      > BTW, the aforementioned chlorination...     

> BTW, the aforementioned chlorination technique should also work to turn
> other aliphatic aldehydes into acyl chlorides too...i.e.
> acetaldehyde --> acetyl chloride, propionaldehyde --> propionyl chloride.

No it won't.

BUSH/CHENEY 2004! After all, it ain't my country!
 
 
 
 
    Organikum
(Wonderful Personality)
04-26-04 03:00
No 503092
      Great find ning! But.....     

Great find ning!
But.....

The chlorine could bee generated by electrolyzing concentrated HCl, probably the most convenient way to make several moles of it


If you want to electrolyze something to get chlorine I would suggest to use zincchloride or ironchloride - this is much better than electrolyzing HCl. To be true though electrolysis is a pain in the ass.
I tried it mad
Dropping dil. H2SO4 (battery acid) onto calcium hypochlorite (poolshock) is a much better way, dont forget to dry the gas by passing it through a washbottle with conc. H2SO4 - a simple CaCl2 drying tube wont get the chlorine real anhydrous. Passing the chlorine first through a CaCl2 drying tower and then through conc. H2SO4 is a good idea if one wants to make bigger amounts of Cl2 and does not want to change the sulfuric acid often. Staging two or more washbottles with H2SO4 is another possibility - bottles staged in line are better than a single, big one.

thats just a sidenote of course.
ORG


Shareholder of Paranoid Fucks inc.
 
 
 
 
    ning
(acetaminophanatic)
04-29-04 08:35
No 503762
      Hmmm. Backpressure has me worried     

How much backpressure would two sulfuric acid washbottles in series with the reaction vessel generate? It's starting to sound like I'd need to wire down the stopper....

Dropping funner --> Ca(OCl)2 --> Wash bottle --> Rxn vessel --> HCl catcher

One reason I thought of electrolyzing HCl is...look how much of it the stupid reaction generates!

(CH2OH)2 + 4 Cl2 ---> (COCl)2 + 6 HCl

in fact, 2 out of every 3 chlorines is lost! So if there was a way of catching the HCl gas and returning it to, say, an electrolysis vessel, it would make things better.

But for a first try, I suppose just the chemical way. Pyuuu.
Ca(OCl)2 seems hard to find where I live. Maybee use LiOCl instead. tongue


Osmium, I know what you're thinking. HCl generated by the chlorination induces alpha-chlorination too. But I'm telling you, it seems they had that problem solved in one of these patents. If you wish, I can look it up.

I've been chased by both cops and robbers. So what does that make me?
 
 
 
 
    Rhodium
(Chief Bee)
04-29-04 09:12
No 503767
      back-pressure calculation     

How much backpressure would two sulfuric acid washbottles in series with the reaction vessel generate?

It depends on how much the sulfuric acid level rises in the wash bottle when the acid inside the inlet tube is filled with gas.

Sulfuric acid density: 2.88

http://hyperphysics.phy-astr.gsu.edu/hbase/pman.html

The Hive - Clandestine Chemists Without Borders
 
 
 
 
    Osmium
(Stoni's sexual toy)
04-30-04 01:33
No 503950
      > Sulfuric acid density: 2.88 Make hat...     

> Sulfuric acid density: 2.88

Make hat 1.8something. wink

When drying gasses with sulfuric, the inlet tube only needs to be a few mililiters below the acid level, unless your gas is extremely wet or being produced at a very high rate.

BUSH/CHENEY 2004! After all, it ain't my country!
www.american-buddha.com/addict.war.1.htm
 
 
 
 
    Rhodium
(Chief Bee)
04-30-04 05:52
No 503985
      Typos happens so easy     

Make hat 1.8something.

Yes, naturally. My bad. It fluctuates between 1.83 and 1.88 depending on source.

When drying gasses with sulfuric, the inlet tube only needs to be a few mililiters below the acid level

That's odd - I assume you mean millimeters? wink

The Hive - Clandestine Chemists Without Borders
 
 
 
 
    Osmium
(Stoni's sexual toy)
04-30-04 06:45
No 503996
      :-o     

blush

BUSH/CHENEY 2004! After all, it ain't my country!
www.american-buddha.com/addict.war.1.htm
 
 
 
 
    ning
(acetaminophanatic)
05-09-04 22:42
No 506153
      TCCA and pKa     

According to the online pKa calculator
http://ibmlc2.chem.uga.edu/sparc/index.cfm
cyanuric acid is very easily deprotonated. It's aqueous pKa is around 7.

However, the more ning thinks about it, the more it seems possible to do this the TCCA way. As long as the ethylene glycol is pre-saturated with HCl to ensure the acidity is far below 7, to prevent the formation of deprotonated cyanurates that the oxalyl chloride could attack.

This also will make the reaction go as fast as the TCCA is added. In fact, this is at least a self-sustaining reaction, because only 1/3 of the chlorine is actually absorbed by the glycol:

HOEtOH + 4 Cl --> O=Et=O + 4 HCl, + 4 Cl --> ClOEtOCl + 2 HCl

Since this HCl reacts with TCCA to release more chlorine, the reaction may rapidly accelerate to a frightening and possibly explosive rate, like a snowball going down a mountain side. Yikes!

In this case, it would probably bee best to dissolve the TCCA in some inert solvent in a dropping funnel, and add it slowly to the well-stirred glycol. What sort of solvent would this bee? Chloroform, perhaps? What else can dissolve TCCA well and not beecome chlorinated easily?

Mmmm, OTC oxalyl chloride. Yummy.

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