Sciencemadness Discussion Board

α,β-dichlorovinyl ethyl ether

Sciocrat - 7-7-2010 at 11:40

Quote: Originally posted by Polverone  
I was able to retrieve the requested article on microfilm. Here's most of the article:

The production of ethyl chloroacetate, and eventually of choroacetic acid, by the action of water on aB (these should be alpha and beta, but I don't recall how to make greek symbols)-dichlorovinyl ethyl ether has been the subject of a large number of patents. By using dry hydrogen chloride in place of water, chloroacetyl chloride is obtained (<A HREF="">DE222194</A>;), and Imbert found (<A HREF="">DE212592</A>;) that dichlorovinyl ethyl ether and ethyl alcohol react, with the production of ethyl chloroacetate and ethyl chloride.

We find that aB-dichlorovinyl ether enters into a large number of reactions of the above type. It is attacked, and usually with great readiness, when heated with alcohols, phenols, or acids. Action is of two kinds:

CHCl:CCl-OEt + ROH ->
1) CH<sub>2</sub>Cl-CO<sub>2</sub>R + EtCl
2) CH<sub>2</sub>Cl-CO<sub>2</sub>Et + RCl

and it seems likely that an additive compounnd, CH<sub>2</sub>Cl-CCl(OEt)-OR, is first formed, which decomposes into the products 1 and 2. Our experience is that alcohols give the products of both reactions, but that 1 predominates, except in the case of methyl alcohol. Phenols give the products of 1 only, and usually in excellent yield. Acids react mainly in accordance with 2, the products being ethyl chloroacetate and an acid chloride. The yields are variable, but it would appear that reactions of the above type could be used in certain cases for the production of chloroacetates or acid chlorides.

To prepare aB-dichlorovinyl ether, sodium is dissolved in dry alcohol in sufficient quantity to form a saturated solution of sodium ethoxide. Trichloroethylene is then added in the proportion of one molecule of trichloroethylene to one and a half atoms of sodium. Heat is applied until action commences, when further heating is unnecessary. The product, when cold, is mixed with a large volume of distilled water, and the oil which separates is washed, dried with calcium chloride, and rectified. The main portion distills at 122-126 degrees C, and this is nearly pure dichlorovinyl ethyl ether. The yield is about 70 percent of the theoretical.

For the action on alcohols or phenols, the substance was employed in as dry a state as possible and mixed with the ether in equivalent quantity. Heat was applied to start the reaction, but further heating was often unnecessary, except toward the end of the process. In other cases, however, head had to be applied throughout to maintain the reaction. The products were separated by fractional distillation, or, where possible, by crystallization.

The results with methyl alcohol were not in accordance with Imbert's statement. Ethyl chloroacetate was the main product and methyl chloroacetate was only produced in relatively small quantity. Ethyl alcohol gave the expected excellent yield of ethyl chloroacetate. iso-Amyl, heptyl, allyl, and menthyl alcohols were each found to yield the chloroacetate of the acid radicle, but ethyl chloroacetate was also formed in these cases.

All the phenols examined gave good yields of the aryl chloroacetate, but in no case was ethyl chloroacetate detected. The compounds dealt with were phenol, o-cresol, guaiacol, alpha and beta-naphthol, resorcinol, and quinol. The two latter compounds gave the bischloroacetates.

The monobasic acids, the behavior of which with dichlorovinyl ethyl ether was examined, were acetic, chloroacetic, phenylacetic, benzoic, anisic, and alpha-naphthoic. In most cases action occurred readily on heating, but it was necessary to apply heat continuously throughout the process. Some hydrogen chloride was evolved in each case, but ethyl chloride was only observed in the case of anisic acid and of naphthoic acid. Ethyl chloroacetate was always present as the chief product of the reaction. The acid chloride formed at the same time was isolated in a pure state in the reactions with acetic, chloroacetic, and benzoic acids. In the other cases, the acid chloride was not obtained pure, but its presence was indicated by the immediate production of the corresponding amide on treating the appropriate fraction with ammonia.

Oooh, making acetyl chloride and ethyl chloroacetate - what interesting products to obtain from a cheap solvent chemical! Now if only sodium ethoxide were a little easier for an amateur of limited means to prepare in a clean and concentrated state.

I find this compound very interesting, and it probably deserves a thread of its own. :)

Recently I was able to synthesize some sodium ethoxide, and decided to try this method. I followed the procedure that Polverone mentioned. After trichloroethylene and sodium ethoxide in ethanol were mixed together in a lab beaker, I started to heat the solution and at about 50-60°C, the reaction began, and the heating was turned off after that moment. The solution was left to cool down, and upon cooling, I got a crystalline product. This I didn't expect, but the process was continued anyway. When the solution reached room temperature, it was dumped into cold distilled water, and the solution turned cloudy instantly. After a few minutes, a heavy and dense orange colored liquid settled at the bottom. This was removed from the solution and now sits in a test tube, waiting to be further reacted with ethanol.

Did anyone else try this method? If yes, it would be very useful if someone mentioned some useful properties of this compound, since so far I didn't find enough data to actually be able to determine whether α,β-dichlorovinyl ethyl ether is really what I have. :(

There is also a possiblity that I actually got dichloroacetylene (if my ethoxide solution contained some NaOH). Sodium hydroxide and trichloroethylene could produce this compound, but I would have probably noticed at least some of the dangerous properties of this compound if it was really present in the reaction :o

Polverone - 7-7-2010 at 12:24

I recall that I tried an unproven alternative procedure soon after I retrieved that article: instead of trichloroethylene in alcoholic sodium ethoxide, I tried it in a DMSO solution of sodium hydroxide. The mixture warmed so I presumed there was some sort of reaction... but when I added water bubbles evolved which spontaneously burst into smoky orange flames. Obviously I had produced dichloroacetylene. I think you would notice if you had done the same :P

Since I did not have a reliable way to produce alkoxides, and there was obviously a risk of making very hazardous products as I tried to explore alternatives, I abandoned further experiments with alkaline treatment of trichloroethylene shortly after.

Sciocrat - 6-1-2011 at 04:29

@ Polverone - thanks for your input. :)

I haven't done any more experiments involving sodium ethoxide, as I don't have any source of it nowadays. :(

However, I could obtain some lithium, so I was thinking about using it instead of sodium. The mass of the needed lithium would be considerably lower than the mass of sodium, since the Ar of lithium is much lower. Also, I've read in certain sources, that the solubility of lithium ethoxide seems to be a bit higher than the solubility of sodium ethoxide - this could also reduce the amount of the ethanol needed to dissolve the ethoxide.

Any thoughts on this? Also, I would appreciate any additional info about the mentioned synthesis.

btw. my main goal is to synthesize ethyl chloroacetate, and then chloroacetamide. First, I tried making chloroacetic acid by the reaction of trichloroethylene and sulphuric acid (by leading trichloroethylene into sulphuric acid heated at high temperatures (150°C+). That yielded strange results - basically I got some sort of black polymerized gunk. I tried to distill this material, but since I don't have a proper apparatus for distilling substances with a somewhat higher boiling point, I managed to get only a few drops of the product. I'm not sure what kind of smell does chloroacetic acid have, but the product had a specific stingy smell.

I was also thinking about making chloroacetyl chloride first, but that involves certain compounds (like ketene), which I would rather like to avoid.

Once again, any advice would be greatly appreciated :)

[Edited on 6-1-2011 by Sciocrat]

garage chemist - 6-1-2011 at 04:48

Now that potassium metal is easily available to anyone that is willing to do the synthesis from KOH and magnesium, you should be able to make your desired (potassium) ethoxide solution from this.
Also, sodium metal is more available from ebay or some sellers today than it was a few years ago.

Sciocrat - 6-1-2011 at 09:47

Quote: Originally posted by garage chemist  
Now that potassium metal is easily available to anyone that is willing to do the synthesis from KOH and magnesium, you should be able to make your desired (potassium) ethoxide solution from this.
Also, sodium metal is more available from ebay or some sellers today than it was a few years ago.

I will certainly look more into this. However, at the moment, it is much simpler (and cheaper) for me to obtain one mole of lithium (~7 grams), than to make 1 mole of potassium (~39 grams), via the Mg+KOH reaction. Also, I'll need a considerably smaller amount of ethanol to dissolve one mole of lithium ethoxide, compared to potassium ethoxide.

As for the sodium, it is listed as a hazardous chemical in my country, so it wouldn't get passed the customs, unless I had special permits, which I don't have unfortunately.

[Edited on 6-1-2011 by Sciocrat]

[Edited on 6-1-2011 by Sciocrat]

garage chemist - 6-1-2011 at 13:38

I do not know whether lithium will work here. I'd consider lithium too valuable for a simple alcoholate reaction- sodium is generally used here, and potassium will almost certainly work as well.
More importantly, how are you planning to obtain absolute ethanol? This is a task in itself and at least as important as getting the alkali metal.

Sodium is rightfully listed as a "hazardous chemical" in any civilized country. If it has to cross a border on the way to you, you're looking at the wrong supplier. Where do you live?

Finally, the reaction of sodium ethoxide solution with trichloroethylene will almost immediately give a crystalline product, namely sodium chloride, besides the desired product which stays in solution.

Sciocrat - 6-1-2011 at 14:16

Quote: Originally posted by garage chemist  
I do not know whether lithium will work here.

Could you elaborate on this?

I made absolute ethanol from the 96:4 ethanol:water azeotrope, by adding calcium oxide to the mentioned mixture. The oxide reacts with the water and forms calcium hydroxide which is insoluble in ethanol. After that, pure ethanol has been obtained via distillation.

I live in Croatia; few years ago, a new law related to the classification of substances has been introduced, and since then, it has become much more difficult to order/obtain chemicals, especially when they need to cross the border. If you have any advice/info regarding this problem, I would appreciate hearing it.

Basically, a relatively small quantity of chloroacetic acid would save me a lot of trouble, but this is even harder to obtain than alkali metals. Tried contacting the local Sigma-Aldrich reseller, as I've worked with them before, but pretty much anything related to chloroacetic acid is toxic (and/or hazardous in some other way) and thereby not available without special permits.

[Edited on 6-1-2011 by Sciocrat]

Sciocrat - 24-1-2011 at 02:54

A saturated solution of lithium ethoxide in ethanol was prepared by reacting lithium metal with the alcohol. After that, trichloroethylene was added to the solution and heat was applied. Again, at about 50°C the reaction started and the heating was a bit lowered. After about 15 minutes, the beaker was removed from the heat source and was left to cool down.

As soon as the solution cooled down, it was dumped into a larger amount of cold water. The solution became cloudy and after some time a dense orange liquid settled at the bottom (the same product that was obtained in the first experiment involving sodium (ethoxide)).

There was about 30 ml of this liquid. It was separated and added to another beaker. After that, ethanol was added and heating was applied once again. Upon heating some bubbling occured, but even after 20-30 minutes, a large portion of the orange liquid was still present (image below).

I stopped the experiment at that time, but I will try heating the mixture of the orange liquid and ethanol further. I am also thinking about adding more ethanol to the reaction.

The patent states that α,β-dichlorovinyl ethyl ether is pretty reactive and that it should readily react with ethanol (with heating being unnecessary after the temperature has been brought up a bit in the start), but that doesn't seem to be true in my case.