Sciencemadness Discussion Board

Useful aromatics from styrofoam

Hunterman2244 - 19-8-2018 at 11:40

How could one produce aromatic compounds like benzene, phenol, toluene etc from polystyrene? I have scoured the internet, and only seen ways of production of polystyrene. I was thinking conversion to benzyl cyanide somehow, but that really doesn't help.

unionised - 19-8-2018 at 11:50

It's fairly easy to convert it to styrene
https://www.thevespiary.org/library/Files_Uploaded_by_Users/...

Reaction with potassium permanganate turns styrene to benzoic acid (and CO2).
Styrene is quite reactive so there are lots of options.

wg48 - 19-8-2018 at 11:52

Quote: Originally posted by Hunterman2244  
How could one produce aromatic compounds like benzene, phenol, toluene etc from polystyrene? I have scoured the internet, and only seen ways of production of polystyrene. I was thinking conversion to benzyl cyanide somehow, but that really doesn't help.


I suggest you search the forum and the net using terms like polystyrene thermal degradation, recycling.


Hunterman2244 - 19-8-2018 at 12:02

Quote: Originally posted by unionised  
It's fairly easy to convert it to styrene
https://www.thevespiary.org/library/Files_Uploaded_by_Users/...

Reaction with potassium permanganate turns styrene to benzoic acid (and CO2).
Styrene is quite reactive so there are lots of options.

Thanks!

Hunterman2244 - 19-8-2018 at 12:32

Quote: Originally posted by wg48  
Quote: Originally posted by Hunterman2244  
How could one produce aromatic compounds like benzene, phenol, toluene etc from polystyrene? I have scoured the internet, and only seen ways of production of polystyrene. I was thinking conversion to benzyl cyanide somehow, but that really doesn't help.


I suggest you search the forum and the net using terms like polystyrene thermal degradation, recycling.



All I could find was converting it to p2p, and I have no interest in making drugs.

JJay - 19-8-2018 at 12:35

Quote: Originally posted by Hunterman2244  
Quote: Originally posted by wg48  
Quote: Originally posted by Hunterman2244  
How could one produce aromatic compounds like benzene, phenol, toluene etc from polystyrene? I have scoured the internet, and only seen ways of production of polystyrene. I was thinking conversion to benzyl cyanide somehow, but that really doesn't help.


I suggest you search the forum and the net using terms like polystyrene thermal degradation, recycling.



All I could find was converting it to p2p, and I have no interest in making drugs.


What?? You can make P2P from styrene?? I actually don't think that's easy to do.

Hunterman2244 - 19-8-2018 at 14:41

Quote: Originally posted by JJay  
Quote: Originally posted by Hunterman2244  
Quote: Originally posted by wg48  
Quote: Originally posted by Hunterman2244  
How could one produce aromatic compounds like benzene, phenol, toluene etc from polystyrene? I have scoured the internet, and only seen ways of production of polystyrene. I was thinking conversion to benzyl cyanide somehow, but that really doesn't help.


I suggest you search the forum and the net using terms like polystyrene thermal degradation, recycling.



All I could find was converting it to p2p, and I have no interest in making drugs.


What?? You can make P2P from styrene?? I actually don't think that's easy to do.

Doesn't seem too hard: https://www.sciencemadness.org/whisper/viewthread.php?tid=76...

JJay - 19-8-2018 at 15:39

Eh, I'm pretty sure that won't work exactly that way, and while a competent chemist could get something like that to function, the procedure is rather lengthy. I don't see why anyone would bother.

Hunterman2244 - 19-8-2018 at 17:31

Quote: Originally posted by JJay  
Eh, I'm pretty sure that won't work exactly that way, and while a competent chemist could get something like that to function, the procedure is rather lengthy. I don't see why anyone would bother.


Yeah, that was just what came up.

JJay - 20-8-2018 at 02:13

I would consider styrene itself a useful aromatic. I'm personally interested in it mainly because it is a terminal olefin that is cheap and easy to obtain, and I would like to explore the chemistry.

Hunterman2244 - 20-8-2018 at 02:50

Quote: Originally posted by JJay  
I would consider styrene itself a useful aromatic. I'm personally interested in it mainly because it is a terminal olefin that is cheap and easy to obtain, and I would like to explore the chemistry.


You could say that. I only meant making things that were in themselves useful, rather than like copolymers etc.

JJay - 20-8-2018 at 03:27

Oh... you can hydrobrominate styrene with hydrogen bromide and react with a strong base to make phenyl ethyl alcohols (one or both depending on reaction conditions)... aqueous bromine will react with styrene to form a bromohydrin that can be reacted with a strong base to make styrene oxide, which is pretty easy to isomerize to phenylacetaldehyde. There are some pretty easy routes to cinnamyl compounds from styrene. And of course, it can be used to make plastics.

Styrene is interesting mainly because it can be used in almost all of these reactions (as well as others):

8-Addition-to-alkenes_2015-1024x789-1.jpg - 171kB



[Edited on 20-8-2018 by JJay]

wg48 - 20-8-2018 at 05:22

Quote: Originally posted by Hunterman2244  
Quote: Originally posted by wg48  
Quote: Originally posted by Hunterman2244  
How could one produce aromatic compounds like benzene, phenol, toluene etc from polystyrene? I have scoured the internet, and only seen ways of production of polystyrene. I was thinking conversion to benzyl cyanide somehow, but that really doesn't help.


I suggest you search the forum and the net using terms like polystyrene thermal degradation, recycling.



All I could find was converting it to p2p, and I have no interest in making drugs.


Sorry Hunterman I was thinking of PET when I posted that.

Here are some links from googling "thermal decomposition products of polystyrene":
https://www.ncbi.nlm.nih.gov/pubmed/734408
https://core.ac.uk/download/pdf/82156634.pdf

There are many more, you may find a detailed home chemist procedure in there or in this forum.




[Edited on 20-8-2018 by wg48]

Hunterman2244 - 20-8-2018 at 06:14

Quote: Originally posted by wg48  
Quote: Originally posted by Hunterman2244  
Quote: Originally posted by wg48  
Quote: Originally posted by Hunterman2244  
How could one produce aromatic compounds like benzene, phenol, toluene etc from polystyrene? I have scoured the internet, and only seen ways of production of polystyrene. I was thinking conversion to benzyl cyanide somehow, but that really doesn't help.


I suggest you search the forum and the net using terms like polystyrene thermal degradation, recycling.



All I could find was converting it to p2p, and I have no interest in making drugs.


Sorry Hunterman I was thinking of PET when I posted that.

Here are some links from googling "thermal decomposition products of polystyrene":
https://www.ncbi.nlm.nih.gov/pubmed/734408
https://core.ac.uk/download/pdf/82156634.pdf

There are many more, you may find a detailed home chemist procedure in there or in this forum.




[Edited on 20-8-2018 by wg48]

Thanks, Using PET is an interesting route l, it just seems to have low yields.

wg48 - 20-8-2018 at 06:22

Quote: Originally posted by Hunterman2244  

Thanks, Using PET is an interesting route l, it just seems to have low yields.


The best method (good yield and simple) for PET uses ethylene glycol. I think there is a procedure for it in the PET thread.

Hunterman2244 - 20-8-2018 at 16:36

Quote: Originally posted by wg48  
Quote: Originally posted by Hunterman2244  

Thanks, Using PET is an interesting route l, it just seems to have low yields.


The best method (good yield and simple) for PET uses ethylene glycol. I think there is a procedure for it in the PET thread.

Yeah, thanks.

VSEPR_VOID - 21-8-2018 at 02:49

Does anyone have a procedure for preparing benzoic acid from styrene?

P2P would be easy to prepare from styrene in theory as it would only take a hydrolysis followed by controlled oxidation.

JJay - 21-8-2018 at 02:58

Quote: Originally posted by VSEPR_VOID  
Does anyone have a procedure for preparing benzoic acid from styrene?


Toluene would require less oxidizer.
Quote:

P2P would be easy to prepare from styrene in theory as it would only take a hydrolysis followed by controlled oxidation.


Bullshit. It doesn't have enough carbons.

Hunterman2244 - 21-8-2018 at 13:40

Quote: Originally posted by JJay  
Quote: Originally posted by VSEPR_VOID  
Does anyone have a procedure for preparing benzoic acid from styrene?


Toluene would require less oxidizer.

Any procedure for that then?

GrayGhost- - 21-8-2018 at 15:01

Quote: Originally posted by VSEPR_VOID  
Does anyone have a procedure for preparing benzoic acid from styrene?

P2P would be easy to prepare from styrene in theory as it would only take a hydrolysis followed by controlled oxidation.



Synthesis of benzaldehydes from toluene and its derivatives. (note that obviously substituded toluenes may bee used too)
...Synthesis of benzaldehyde and its derivatives by oxidation of the corresponding toluenes is an important industrial process in pharmaceutic drug synthesis.
Oxidation of -CH3 group to -CHO is carried w/MnO2 in presense of sulfuric acid. In case if MnO2 is present in excess, aqueous acid is used and if a stoichometric quantity of MnO2 is taken, conc. H2SO4 is emloyed.
If the rxn is carried out at temp's below 40 C, aldehydes are formed, however, if its temp's allowed to rise to 60-70 C, the main product is benzoic acid.


citated by Antoncho in the Hive

[Edited on 21-8-2018 by GrayGhost-]

JJay - 21-8-2018 at 15:56

Quote: Originally posted by Hunterman2244  
Quote: Originally posted by JJay  
Quote: Originally posted by VSEPR_VOID  
Does anyone have a procedure for preparing benzoic acid from styrene?


Toluene would require less oxidizer.

Any procedure for that then?


Since you asked: https://hobbychemistry.wordpress.com/2015/03/29/benzoic-acid...

Toluene from styrene may be possible but doesn't look trivial. Benzaldehyde from styrene... hmm... that might not be a terrible idea. Benzaldehyde will readily oxidize in air to benzoic acid.

I guess you could gas styrene dissolved in a fluorinated solvent with ozone to produce benzaldehyde, then heat the benzaldehyde in thin layer in an oven to make benzoic acid. I don't have a procedure for that, but I don't think it would be hard. While styrene would require more oxidizer to produce benzoic acid that way than toluene would, ozone and air are cheap and green oxidizers. Of course, you have to recycle the fluorinated solvent.

[Edited on 22-8-2018 by JJay]

Melgar - 22-8-2018 at 05:13

Unless you enjoy picking at globs of hard, charred plastic that have been fused to the inside of your glassware, I'd avoid attempting styrene pyrolysis as a way of obtaining styrene. Especially when you can just buy it OTC from boat supply places, or just buy it online:

http://www.carbonfiberglass.com/Resin-Systems/gelcoat-gel-co...

Ozonolysis isn't very practical for amateurs, due to how much solvent and product evaporates when you send those quantities of air through it. If your goal is to actually make benzoic acid from styrene, that just seems masochistic. Benzoic acid isn't very interesting, and it forms as a by-product of so many reactions where you're actually trying to make something else, that I'm not sure what you'd be able to learn from trying to synthesize it on purpose.

If you're going to try to use styrene in a more novel reaction, this reaction seems like an interesting one:

http://www.sciencemadness.org/talk/viewthread.php?tid=6513

[Edited on 8/22/18 by Melgar]

DavidJR - 22-8-2018 at 05:18

Quote: Originally posted by Melgar  
Unless you enjoy picking at globs of hard, charred plastic that have been fused to the inside of your glassware, I'd avoid attempting [poly]styrene pyrolysis as a way of obtaining styrene.


I can't imagine cleanup would be that difficult - there are numerous solvents which readily dissolve polystyrene. Have you actually attempted this?

Melgar - 22-8-2018 at 05:37

Quote: Originally posted by DavidJR  
I can't imagine cleanup would be that difficult - there are numerous solvents which readily dissolve polystyrene. Have you actually attempted this?

When its a partially-pyrolyzed semi-charred lump that probably has some cross-linking going on, it doesn't dissolve to anywhere near the same degree that pure polystyrene does.

DavidJR - 22-8-2018 at 06:05

From the link in the first reply to this thread:

" The still pot is difficult to clean but on soaking with a few mL of toluene the residual polystyrene will come away from the glass. Some black residue is formed and can be scrubbed out with soap and water. Because the flask is difficult to clean some instructors set aside enough flasks for this specific experiment. Continuing the thermolysis until the polystyrene is gone and then scrubbing the residual carbon out with soap and water may achieve cleaning. Because, as a general practice, it is dangerous to continue a distillation to dryness, we do not instruct students to clean their flasks in this way."

JJay - 22-8-2018 at 08:20

There are a few discussions on ozonolysis on this board by people who have actually done it, using the right equipment, who say it is easy.

While that quart of styrene may cost only $8, shipping styrene is expensive. Recycled polystyrene is free. Personally, I'd use some kind of cheap, disposable yet reusable steel container like a paint can to hold the polystyrene for thermolysis.