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Topic: experience with HCl reaction with alkyne  (Read 15569 times)

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Offline discodermolide

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Re: experience with HCl reaction with alkyne
« Reply #15 on: August 25, 2012, 11:00:52 AM »
How would the presence of HCl and SOCl2 explain the IR peaks that I see?

That looks like the acid chloride is no longer an acid chloride. Why did you make a KBr pellet? It exposes everything to moisture. Run an IR in a solvent like toluene, with a toluene blank. Then you could actually follow your reaction by IR.
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Offline ecnerwalc3321

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Re: experience with HCl reaction with alkyne
« Reply #16 on: August 25, 2012, 11:28:58 AM »
i made the KBr pellet because I thought that the product wouldn't be enormously affected by moisture during the brief time that I was making it (why else would people make KBr pellets?).  Are the chlorides really that moisture sensitive?  As far as solution IRs go, I'm not sure where to get a solution cell; we do have ATR capabilities, though I'm not sure how well that will work since it turns out that pyrene butyric acid/chloride does not dissolve in toluene. 


Offline discodermolide

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Re: experience with HCl reaction with alkyne
« Reply #17 on: August 25, 2012, 11:36:15 AM »
i made the KBr pellet because I thought that the product wouldn't be enormously affected by moisture during the brief time that I was making it (why else would people make KBr pellets?).  Are the chlorides really that moisture sensitive?  As far as solution IRs go, I'm not sure where to get a solution cell; we do have ATR capabilities, though I'm not sure how well that will work since it turns out that pyrene butyric acid/chloride does not dissolve in toluene.  



How do you know the acid chloride does not dissolve in toluene? Is this literature information?
Some acid chlorides are very sensitive toward moisture.
The acid is insoluble, as it reacts, if the acid chloride is soluble, you will end up with a solution.
If that does not work use neat thionyl chloride.
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Offline orgopete

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Re: experience with HCl reaction with alkyne
« Reply #18 on: August 25, 2012, 11:45:05 AM »
I still say it is a literature compound. If all else fails, prepare it the same way someone else has succeeded in preparing it (or just buy, it is commercially available). I see it was reported here, J. Org. Chem., 1984, 49 (1), pp 207–209
DOI: 10.1021/jo00175a055.

By the way, it is an aliphatic acid chloride. They are a lot more reactive than an aryl acid chloride. Acetyl chloride will react virtually explosively with water. It is very reactive. Use that as a guide to how to handle your acid chloride.
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Offline discodermolide

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Re: experience with HCl reaction with alkyne
« Reply #19 on: August 25, 2012, 11:51:08 AM »
I still say it is a literature compound. If all else fails, prepare it the same way someone else has succeeded in preparing it (or just buy, it is commercially available). I see it was reported here, J. Org. Chem., 1984, 49 (1), pp 207–209
DOI: 10.1021/jo00175a055.

By the way, it is an aliphatic acid chloride. They are a lot more reactive than an aryl acid chloride. Acetyl chloride will react virtually explosively with water. It is very reactive. Use that as a guide to how to handle your acid chloride.

What is worse is that there is an onset time of a couple of seconds or a bit less before the reaction starts. This causes accumulation and then almost a runaway situation. Very nasty.
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Offline discodermolide

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Re: experience with HCl reaction with alkyne
« Reply #20 on: August 25, 2012, 11:52:36 AM »
i made the KBr pellet because I thought that the product wouldn't be enormously affected by moisture during the brief time that I was making it (why else would people make KBr pellets?).  Are the chlorides really that moisture sensitive?  As far as solution IRs go, I'm not sure where to get a solution cell; we do have ATR capabilities, though I'm not sure how well that will work since it turns out that pyrene butyric acid/chloride does not dissolve in toluene.  



Orgopete says a) it is a known compound and b) it is commercially available. Why not just buy it?

Have a look here, using oxalyl chloride. http://cssp.chemspider.com/Article.aspx?id=206
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Offline ecnerwalc3321

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Re: experience with HCl reaction with alkyne
« Reply #21 on: September 10, 2012, 11:56:05 PM »
Thanks to all who replied to this thread. I finally was able to get a reaction to occur as evidenced by the ester peak (~1200 cm-1) in the IR shown below.  However, there is now the problem of purification.  The solid is dry (not sticky) so I'm pretty sure there is not much of the propargyl alcohol, SOCl2, toluene, hcl, or any liquid remaining.  Therefore, the two compounds are pyrenebutyric acid and the ester.  Both are solids that don't appear to crystallize (I wasn't able to get them to crystallize.  but then again, you can't use recrystallization to separate two solids, can you?). The solids were precipitated using hexane.  I've looked through a common list of purification methods but can't pinpoint which one to use as it seems that most are not applicable for the separation of two solids.  Does anyone have ideas? 

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Re: experience with HCl reaction with alkyne
« Reply #22 on: September 11, 2012, 12:16:53 AM »
The ester peak in the IR is very weak. Was the sample dilute? Or did you just not have much material?
You can crystallise solids apart, you just need to find the correct solvent.
If you are sure one of the compounds is the acid you can dissolve the mixture in a solvent and wash with sodium bicarbonate solution. This makes the sodium salt of the acid which should remain in the water, the ester in the organic. Otherwise a maybe more convenient method is flash chromatography on silica-gel.
Here are a couple of links
http://www.youtube.com/watch?v=fF1gXUvyGb4
http://en.wikipedia.org/wiki/Column_chromatography
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Offline ecnerwalc3321

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Re: experience with HCl reaction with alkyne
« Reply #23 on: September 11, 2012, 12:36:01 PM »
Thanks for the suggestion, discodermolide.  I just tried using the separatory funnel method and am waiting for the product to dry. We don't have a column (not a chem lab) so chromatography would be a little bit more involved.  I did a little reading on the basics of extraction and have a couple questions. 

1. If you have two compounds A and B that are soluble in an organic solvent but A is also soluble in water, can you do an extraction of A from the organic to the aqueous phase?  If so, what is the driving force that makes this happen?  Is it determined by whether the aqueous phase is acidic or basic?

2.  If you have C and D (where C is an alkyl halide and D is an alcohol) which are both insoluble in water but soluble in organic, how would you go about extracting C from D?


discodermolide, how were you able to tell that the ester signal is weak?  I'm looking at the peak at ~1200 cm-1 and see that it's quite strong.  Is this the wrong peak?  Thanks.

Offline discodermolide

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Re: experience with HCl reaction with alkyne
« Reply #24 on: September 11, 2012, 01:03:03 PM »
First the IR, the ester peak is at 1737 cm-1. It should normally be much stronger. Unless you 1) used very little for the IR, or 2) if it is your reaction mixture then you don't have much ester.
Extractions:
Question 1: This is dependant upon the partition coefficient of A between the solvent and the water. Roughly if you have 100% of A in the organic with a coefficient of 50% then 1 extraction with water will remove 50%, the second extraction 50% 0f the 50%, i.e. 25% and so on. Ultimately with many extractions you will remove A.
Question 2: In this case you probably will not be able to extract them apart with any reasonable success. You could try acetonitrile/heptane, the alcohol will stay in the acetonitrile, the alkyl halide will go into the heptane. This depends very much upon the type of alcohol and alkyl halide you have.

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Offline orgopete

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Re: experience with HCl reaction with alkyne
« Reply #25 on: September 11, 2012, 01:37:28 PM »
These results do not seem as expected. Here is a prep and reaction of the acid chloride.
http://www.nanoscalereslett.com/content/pdf/1556-276X-7-296.pdf

Just repeat its preparation and react it the residue with methanol. I think you can skip everything else in this case. The residue should be the ester. Methanol will evaporate, any HCl will evaporate. It should give a reasonable amount of ester. Lets do the simple before we worry about what did or didn't happen in the propargyl alcohol case.
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Offline ecnerwalc3321

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Re: experience with HCl reaction with alkyne
« Reply #26 on: September 13, 2012, 05:39:49 PM »
I think I got it now.  First is the IR of your requested compound, orgopete.  Second is the IR of my product in question.   I feel that you should be able to see what I've made given all the help you have given me.  Definitely more convincing evidence that the reaction happened the way it's supposed to?

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Re: experience with HCl reaction with alkyne
« Reply #27 on: September 13, 2012, 08:25:46 PM »
That looks like a much better reaction and IR, nice strong ester peak and the triple bond CH at just above 2000cm-1. Congratulations.
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Offline orgopete

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Re: experience with HCl reaction with alkyne
« Reply #28 on: September 14, 2012, 09:09:13 AM »
I have been reading some experiments on radiant heat of John Tyndall from 1872. What is common to the experiment noted here is the need to ensure the quality of the experiment. Tyndall goes to length to test for alternate theories. One can find these tests in even the most basic of troubleshooting guides. 1. Plug it in.

I did not think it was a question of the reaction, but the poster had to determine which step was preventing the desired outcome. Is it the reaction, or is is it me? Been there, done that.
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