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Author: Subject: Acrylic acid
bmays
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[*] posted on 9-7-2016 at 20:41
Acrylic acid


I have found patents (US8252960) which show acrolein is oxidized by air via a large variety of catalysts, although i wish to avoid this. How about oxidation with dichromate or permanganate? Any ideas or tips how this might be done? I'm planning on simply adding potassium permanganate a small amount of water should facilitate the oxidation, then distill. This stuff is horrendously acrid, i'm hoping this goes smoothly.
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CuReUS
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[*] posted on 9-7-2016 at 22:32


Quote: Originally posted by bmays  
How about oxidation with dichromate or permanganate?

permanganate or dichromate will convert the double bond to a diol and may even cleave it
http://www.chemguide.co.uk/organicprops/alkenes/kmno4.html
better to do the pinnick oxidation instead - https://en.wikipedia.org/wiki/Pinnick_oxidation
also see this -http://pubs.acs.org/doi/abs/10.1021/jo00354a037


[Edited on 10-7-2016 by CuReUS]
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[*] posted on 10-7-2016 at 08:02


I should also warn you that acrolein is *nasty*. I've run into few lachrymators that are worse, and it can cause fatal pulmonary edema with very small doses. Sartori profiles it as a war gas for good reason.

If you are going to mess with it, I hope you have a serious hood and are prepared with adequate PPE. I don't usually engage in nanny-grade fear mongering, but I've worked with this one and...it was a memorable experience.

Good luck,

O3




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[*] posted on 10-7-2016 at 10:25


Acrolein is about as toxic as phosgene on brief exposure (3500 mg-min/m^3 Haber product), and causes cumulative injury as well on repeated exposure.

It made a terrible tear gas because although it is irritating, its toxic concentrations are the same as its lachrymatory concentrations (for most tear gases there is an effective ratio of intolerable irritant concentration/hazardous concentration in the thousands, for acrolein it is less than 1:1).

7 mg/m^3 is threshold irritating, but can poison you fatally in about 8 hours
50 mg/m^3 is intolerable, but lethal in a 70 minute exposure

Threshold lethality, for sensitive individuals, will be less than this even.

So if you encounter any irritation from acrolein at all, you have not just an irritating concentration, but a hazardous-to-health one as well.

I remember a kid's chemistry manual that had as an experiment the heating of potassium hydrogen sulfate and a small amount of glycerin in a test tube, and experiencing the irritating fumes produced. As conducted, no detectable harm would result, but still one cannot imagine such an experiment appearing today.


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bmays
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[*] posted on 10-7-2016 at 18:37


Thanks Cureus. i think i will keep a cork in it until i get an HOCl scavenger and do some further reading. Maybe a weak solution of hydrogen peroxide. Yes acrolein is atrocious. It gave my a headache yesterday. If i had known it was so bad i would have left it alone. How about potassium peroxymonosulfate in methanol, to avoid azeotropes. Will the methyl ester be formed? Maybe stick to water.
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[*] posted on 11-7-2016 at 22:33


Sorry Cureus your last link outlined the reaction conditions. I missed that yesterday.
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[*] posted on 12-7-2016 at 11:30


To avoid the use of accrolein...
Maybe start from CH2=CH-CO-CH3 (butenone) with NaOCl/NaOH (bleach)
CH2=CH-CO-CH3 + NaOCl/NaOH/H2O --> CH2=CH-CO2Na (aq) + HCCl3

Butenone could be done from aceton (propanone) and formaldehyde...via condensation crotonisation...
CH3-CO-CH3 + CH2=O -catalyst 1-> HO-CH2-CH2-CO-CH3 -catalyst 2-> CH2=CH-CO-CH3 + H2O
Formaldehyde must be in minority vs aceton otherwise you would get poly-hydroxymethylation ...
up to (HOCH2-)3C-CO-C(-CH2OH)3... and further reduction of the carbonyle into -CHOH- (thus yielding a nonane-heptol).




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[*] posted on 14-7-2016 at 06:17


Thinking about acrolein a bit more - it is classed in the CW literature as a "toxic lachrymator".

Upon considering its true toxic characteristics, it occurs to me that this is a very misleading way of classifying it.

It should be considered a lethal lung injurant agent, but with exposure warning irritation.
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bmays
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[*] posted on 16-7-2016 at 00:45


Thanks PH Z. That seems like it would be a good route, if only acrylic acid wasn't miscible in water. I wonder if it could be salted out. MVK is likely possible with a long reflux and excess of formaldehyde.

Hi careysub, yes pouring the acrolein from the flash into the bottle i got some fumes in my nose and eyes despite standing at arms length upwind and it had me staggering, stings as bad as the hottest hot pepper but passes in 10 seconds. It would be hard to poison yourself without being in severe pain. Turns out in the end most of what i made was somehow water anyways, thought i had everything sufficiently dry.... 5ml came over at about 140f, 40ml came over at 211f, and 15ml polymerized in the flask. I was experimenting with air in a hot copper tube and think i possibly made some acrylic acid. Either that or it was glycerin, it didn't smell actually so i think it was burnt glycerin which distilled over. Nightmare tar like goop, took me hours to clean and had to resort to chromic acid to finish it off. If i had $15 i would have thrown the china 250ml rbf in the garbage, but it has served me well so i guess it deserves my tlc haha.

I don't have any hydroquinone, i was under the impression it took sodium hydroxide so polymerize acrylic acid into sodium polyacrylate. I guess i better find some hydroquinone i might need it. I do believe what i was dealing with was polymerized glycerin though, not sure.

[Edited on 16-7-2016 by bmays]

[Edited on 16-7-2016 by bmays]
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[*] posted on 16-7-2016 at 04:46


Quote: Originally posted by PHILOU Zrealone  
To avoid the use of accrolein...
start from CH2=CH-CO-CH3 (butenone)

Quote: Originally posted by bmays  
Thanks PH Z. That seems like MVK would be a good route

MVK is as toxic as acrolein :o
Quote:
MVK is extremely hazardous upon inhalation causing coughing, wheezing and shortness of breath even at low concentrations. It will also readily cause irritation of the skin, eyes, and mucous membranes.

https://en.wikipedia.org/wiki/Methyl_vinyl_ketone#Safety
Quote:
I don't have any hydroquinone, i was under the impression it took sodium hydroxide so polymerize acrylic acid into sodium polyacrylate. I guess i better find some hydroquinone i might need it.

https://youtu.be/7oAcT4Duun4?t=677
as nile red's video showed,hydroquinone won't prevent polymerisation for very long.The best thing to do is to use the acrylic acid ASAP.
in case you still want to add an anti-oxidant,benzoquinone is a better choice (hydroquinone has to first convert to benzoquinone in the presence of O2,only then it can act as radical scavenger,so why not use benzoquinone directly instead ? ;) )




[Edited on 16-7-2016 by CuReUS]
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