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Picric-A
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2-chloroethanol
I have read about many ways to produce this compound, some look more simple than others.
2-chloroethanol is very usefull in organic synthsis. My intended use of this compound is in the synthesis of tetracaine, a potent yet disused ester
type local anasthetic derived from 4-ABA.
Here i will list the methods i have found and if anyone has any comments to make on their reliability, yield ect. please comment.
1)2-Chloroethanol is produced by treating ethylene with hypochlorous acid:
CH2=CH2 + HOCl → HOCH2CH2Cl
(source- wikipedia)
2) bubbling a mixture of carbon dioxide and ethene through a suspension of bleaching powder (calcium hypochlorite) in water)
(source- 'Organic Chemistry' by P.J.DURRANT)
3) bubbling hydrogen chloride through ethylene glycol at 100deg.C. This formed water and 2-chloroethanol. at higher temps. ethane dichloride is
formed.
(source- 'Organic Chemistry' by P.J.DURRANT)
So as you can tell 1 and 2 both rely on the action of hypochlorous acid on ethene, number 2 is just one of the many methods of perfomring number one,
I am most interested in number two however. both reagents, HCl and glycol are cheap and the prodedure seems simple.
The book says that HCl should just be bubbled through the glycol at 100deg.C and doesnt mention anything else. Because this reaction produces water i
am guessing if conc sulphuric is added to this mix it will make it react quicker however my guess is the reason the reaction should be kept at
100deg.C is to boil off the water as it is formed. This however poses the problem of the 2-chloroethanol having a b.p. of around 120deg.C so msot of
your product will boil off with the water. Can this problem be solved by refluxing the mix and adding conc sulphuric? this reaction would then
resemble an esterification reaction between the glycol and HCl.
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not_important
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Adding H2SO4 will promote the formation of 1,4-dioxane with a boiling point of 101 C.
You should be able to distill both water and 2-chloroethanol off, they're both products so removing them from the reaction mix is not harmful to
yields. You can fractionate them later to get the 2-chloroethanol.
BTW - 2-chloroethanol is fairly toxic and considered a carcinogen.
Methods 1 & 3 work, no idea as to how well 2 does.
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Picric-A
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Well if you are saying 1 works, two must work. 2 is simply forming the HOCl in situe by the reaction between Ca(ClO) and CO2 according to;
CO2 + H2O --> H2CO3
H2CO3 + Ca(ClO) --> 2HClO + CaCO3
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garage chemist
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Ethene and HOCl (from bleaching powder and CO2) will give a dilute aqueous solution of 2-chloroethanol. Isolating the pure substance from this is
impossible via distillation, as it forms an azeotrope with water that also has a boiling point close to 100°C, IIRC.
The ethylene glycol/HCl method would be better suited to produce a relatively concentrated product.
One would bubble HCl gas into glycol at 100°C in a distillation setup until the glycol has disappeared. The distillate is then fractionated.
Don't add H2SO4 to this, it will make dioxane, as already said. The water of reaction will be found in the product, but it isn't much as you'll see if
you calculate the stochiometry.
There is another method described in Vanino, Handbuch der präparativen Chemie Band 2 from 1937, that is refluxing ethylene glycol with disulfur
dichloride for 3-4 days.
The reaction mix is diluted with ether, filtered from byproduct sulfur, shaken with moist K2CO3, dried with dry K2CO3 and fractionated to obtain the
ethylene chlorohydrin. 100g glycol and 250g S2Cl2 give about 100g chlorohydrin.
This procedure has the great advantage to give an anhydrous product in relatively good yield, which is worth the long refluxing IMO if one is after
the pure compound.
Another method is to simultaneously bubble chlorine and ethylene into stirred cold water.
Since chlorine in water dissociates to HOCl and HCl, this is similar to the bleach method.
Only dilute solutions of chlorohydrin can be obtained this way (maximum 14-15%) since already at 8% chlorohydrin, the side reaction of chlorine
addition to ethylene giving 1,2-dichloroethane becomes noticeable and becomes the main reaction once a separate phase of 1,2-dichloroethane has been
formed.
An interesting method of isolating the chlorohydrin from its aqueous solution is given: the solution is saturated with anhydrous sodium sulfate at
32°C, decanted from any indissolved solid, left to cool without disturbing it and then a seed crystal of sodium sulfate decahydrate is added. The
supersaturated sodium sulfate solution crystallizes and the chlorohydrin separates as an oily phase on top of it. It is decanted, dried with Na2SO4
and rectified to give pure chlorohydrin.
Ethylene chlorohydrin is of special interest because of its use as a lab precursor to ethylene oxide- just add it to cold concentrated KOH solution.
[Edited on 31-7-2009 by garage chemist]
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ammonium isocyanate
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The classic synthesis of propylene oxide proceeds via a propylene chlorohydrin intermediate. It can be produced by bubbling chlorine and propylene
gas through an aqeous solution of a metal hydroxide. I'm not sure what the reaction conditions or yields are, but I plan on trying it soon. The
yeilds I assume are relatively high since it is the main method used in industry. According to garage chemist, the same method would produce the
ethylene chlorohydrin intermediate. I imagine that performing an analogous reaction to the one I plan on attempting, using instead ethylene at
elevated temperature, and collecting the epoxide as it boils over (which would probably be pretty concentrated, even if it does form a low-boiling
allotrope with water, due to the large differences in polarity and boiling points) would allow for the production of relatively concentrated ethylene
chlorohydrin by gassing with HCl.
It would be a roundabout method of production, but it might be worth a try.
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Nicodem
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Thread Moved
31-7-2009 at 08:23 |
Filemon
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The reduction chloroacetaldehyde with Fe + HCl, 1:2 (chloroacetaldehyde: Fe). The iron proportion should be minimum because it also reduces halogens.
Although it may reduce selective because the aldehydes or ketones are much more reactive.
http://www.orgsyn.org/orgsyn/pdfs/CV1P0304.pdf
[Edited on 31-7-2009 by Filemon]
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Picric-A
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@GC- your method of refluxing disulphur dichloride and glycol looks extremly tempting!
should you be refluxing the DSDC or the glycol for this?
Also, yes this is rather cheapskateish but do you rekon leaving a mix of DSDC and glycol to stand for a week will still work? the only thing i dont
like about this procedure is the fact i would be wasting a hell of a lot of electricity/gas doing this. the reflux water isnt a problem becuase i have
a recirculating pump.
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DJF90
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You would heat to reflux. It doesnt matter which component is boiling; if you heat it to the higher bp then the lower bp component will escape through
the top of the condensor
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Magpie
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In refluxing you are just boiling the mixture and condensing the vapors. The boiling point will be whatever it is for the system you have and depend
on the proportions of the mutually soluble components. The vapor will also be a mix of these mutually soluble components and condense completely
assuming the condenser temp and residence time in the condenser are adequate.
The single most important condition for a successful synthesis is good mixing - Nicodem
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len1
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@entropy - do you have a full version of that article - I dont seem to be able to get it? thanks
[Edited on 1-8-2009 by len1]
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entropy51
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Quote: Originally posted by len1  | @entropy - do you have a full version of that article - I dont seem to be able to get it? thanks
[Edited on 1-8-2009 by len1] |
Well, I'm getting a little reluctant to post articles due to the animosity here, but for you, OK.
On second thought, since you have downloaded the article, I am removing it because of the sulfur mustard prep it contains.
[Edited on 1-8-2009 by entropy51]
[Edited on 1-8-2009 by entropy51]
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len1
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Thank you very much. I must admit I have been feeling the same way.
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setback
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| Quote: Originally posted by entropy51 | | Quote: Originally posted by len1 | @entropy - do you have a full version of that article - I dont seem to be able to get it? thanks
[Edited on 1-8-2009 by len1] |
Well, I'm getting a little reluctant to post articles due to the animosity here, but for you, OK.
On second thought, since you have downloaded the article, I am removing it because of the sulfur mustard prep it contains.
[Edited on 1-8-2009 by entropy51]
[Edited on 1-8-2009 by entropy51] |
I don't blame people for not liking you.
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len1
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Why this attack? Entropy did me a favour by posting an article. This is what he and I were talking about, I guess nothing you can do, this thing
will happen its a public place.
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ergoamide
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The reaction between ethylene oxide and HCl is a very quick and complete reaction by all accounts in organic chemistry books. It proceeds very rapidly
even at -30C.
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Polverone
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Good grief, the Gomberg paper is in the public domain by now. Here's a copy from Google Books, in case anyone following this thread was disappointed
by the ninja editing:
http://www.sciencemadness.org/scipics/refs/gomberg_chlorohyd...
PGP Key and corresponding e-mail address
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garuda
a.k.a. Sauron
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Notwithstanding the public domain ststus of the Gomberg paper, the fact remains that the topic is not mustard gas but 2-chloroethanol (ethylene
chlorohydrin).
When Saddam Hussein was prevented from importing thiodiglycol to feed Chemical Ali's mustard plants, they switched to 2-chloroethanol and made their
own thiodiglycol a la Gomberg.
A lot of people were injured, blinded, killed and who knows how many more will suffer delayed carcinomas because sulfur mustard is a potent
carcinogen.
So do not call entropy's actions "mimja editing". instead consider the abject irresponsility of your own actions, polverone, and allow entropy51 to
see to his own karma as best he can. I applaud his self-restrainst. What does the preparation of a compound that crosslinks the strands of DNA and
prevents replication and repair, have to do with amateur chemistry?
It would have been better to extract the chlorohydrin info from the paper and publish only that.
Anyway Gomberg is obsolete for either product.
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entropy51
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Fine, Polverone. Now if some young kid actually manages to make a gram of sulfur mustard and blind himself it will not be on my conscience. Any
member of the public can now easily access a fairly explicit recipe, as I realized after I posted. I was focused on the chloroethanol aspect and
didn't think about the rest of the paper. My mistake, and I admit it. Once I realized my mistake I tried to mitigate my error.
Being in the public domain is not the same as easily located.
See hubris.
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Polverone
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I have edited the paper to omit the last 4 pages which detail the mustard preparation. The bulk of the paper does deal with chlorohydrin preparation,
and in detail that is likely to be useful to amateurs such as the thread starter who may not have ready access to ethylene oxide or modern
chlorination reagents. The halogenohydrins are hazardous but versatile synthetic intermediates. The Gomberg reference was a fine addition to the
thread as it illustrates how to produce ethylene chlorohydrin and gives a template for experimentation that would be useful as a starting point for
working with other alkenes. The same paper is referenced by numerous later academics and the Kirk-Othmer encyclopedia of chemical technology on the
topic of chlorohydrins so you were in more than respectable company to suggest it.
If your conscience will bother you when you share information about potentially hazardous reactions, please think twice before posting.
Sharing and then withdrawing valuable information really rubs me the wrong way. It's the reason we have a time limit on editing posts.
PGP Key and corresponding e-mail address
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JohnWW
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But what is the point of such censorship, when any fool bent on death and destruction could simply Google for the phrase "sulfur OR sulphur mustard",
and get the same information that way? This search string throws up 79,200 results to choose from, including (on refining by adding Gomberg to the
search string, which reduces the number of results to only 38) the entire 1919 JACS paper (and what appears to be a patent by him) by Moses Gomberg
(which fortunately came out a few months too late for the stuff to be used in the Great War/Whore)? As with its analog "nitrogen mustard" (249,000
Google results, but also of use as a chemotherapy drug for cancer), the structural relationship to 2-chloroethanol and the consequent synthetic
possibilities would be obvious to any competent organic chemist.
(BTW Moses Gomberg was the same organic chemist who, around 1900, endeavored to prepare as many highly phenyl-substituted hydrocarbons as possible,
using especially Grignard reactions, along with metal reductions. When trying to prepare hexaphenylethane, he discovered the intensely yellow colored
triphenylmethyl carbocation and triphenylmethyl free radical instead, in which the positive charge and unpaired electron are resonance-delocalized
over the whole structure, see http://en.wikipedia.org/wiki/Triphenylmethyl_radical and http://en.wikipedia.org/wiki/Triphenylmethanol )
[Edited on 2-8-09 by JohnWW]
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entropy51
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| Quote: Originally posted by Polverone | | I have edited the paper to omit the last 4 pages which detail the mustard preparation. The bulk of the paper does deal with chlorohydrin preparation,
and in detail that is likely to be useful to amateurs such as the thread starter who may not have ready access to ethylene oxide or modern
chlorination reagents. The halogenohydrins are hazardous but versatile synthetic intermediates. The Gomberg reference was a fine addition to the
thread as it illustrates how to produce ethylene chlorohydrin and gives a template for experimentation that would be useful as a starting point for
working with other alkenes. The same paper is referenced by numerous later academics and the Kirk-Othmer encyclopedia of chemical technology on the
topic of chlorohydrins so you were in more than respectable company to suggest it.. |
Thank you for editing, I should have done that. I agree that it is a valuable paper with respect to the chlorohydrin part.
| Quote: Originally posted by Polverone | | If your conscience will bother you when you share information about potentially hazardous reactions, please think twice before posting.
Sharing and then withdrawing valuable information really rubs me the wrong way. It's the reason we have a time limit on editing posts.
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I will try to do better the next time. But I was within my rights to edit within your time limit.
I wish you would get so indignant when one of your moderators deletes one of my posts as when I delete one myself.
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entropy51
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| Quote: Originally posted by JohnWW | | 1919 JACS paper by Moses Gomberg (which fortunately came out a few months too late for the stuff to be used in the Great War/Whore)?
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I hope your knowledge of chemistry is better than your knowledge of history.
Mustard was the most used chem agent in the Great War, Gomberg just wasn't allowed to publish until after the war ended.
The Gomberg paper did not come up in the first 1000 hits when I googled those terms. EDIT: OK, so you modified it to search for Gomberg. Anybody who
knew about the Gomberg paper didn't learn anything new. But the kewls wouldn't have known about Gomberg's paper, would they? As I said, public
domain is not the same as easy to find.
[Edited on 1-8-2009 by entropy51]
[Edited on 1-8-2009 by entropy51]
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len1
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Does one really think that with the many examples of kewls doing complicated experiments here, we will soon have someone post a successful mustard
synthesis on a process that took the UK and France 18 months to get going, opearating in overdrive, without considering cost? I doubt anyone will
even get to the chlorohydrin. 99% of posts end with just an exchange of refereces (which is fine), but often theres a pretence that the poster
actually needs the ref for something practical, which never gets done.
| Quote: | I wish you would get so indignant when one of your moderators deletes one of my posts as when I delete one myself.
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Agree. Reminds me of the church in the 1800's, if the state takes your life, thats as it should be because nothing happens against God's will, but if
you take your own life, thats a crime against God.
PS Since the deleted method is completely unsuitable for kewls, and moreover would be very hard for them to understand, which is unfair, may I propose
this far simpler method which a dilitant can actually do (and pictures of what to aim for)
http://en.wikipedia.org/wiki/Mustard_gas
May I particularly recommend method 1? I know from my professional experience that anyone who is going to pass their second year organic can generate
the two immediate precursors. The last step, although I have not myself done, but have read on, generates lots of colloidal sulphur which was a
sticking point for the Allies. But who cares if you are going to maim yourself.
[Edited on 2-8-2009 by len1]
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Picric-A
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Slightly off topic but can one react 2-Aminoethanol with acylating agents like ethyl chloride to produce diethylaminoethanol?
thanks,
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Nicodem
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Ethyl chloride is not an acylating agent.
You can't just stop the alkylation of aminoethanol at the stage of diethylaminoethanol so the yield might be somewhat low, but in principle it is
preparatively possible. Though nobody would ever use ethyl chloride for that - using rational reagents you get rational results, but with irrational
reagents it's anyone's guess.
Check the literature for details.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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