Sciencemadness Discussion Board - Terephthalic acid from PET

Terephthalic acid from PET

LearnedAmateur - 13-10-2017 at 05:58

So I have a few empty PET bottles lying around, and I was thinking of recycling them into relatively pure TPA. I have both sulphuric acid and sodium hydroxide so I can choose either route for hydrolysis. Does anyone have any experience with this reaction? What temperature should I run the reaction at and how long for? How can I separate out any copolymers and other additives? What solvent should I use, if any work better in conjunction with water. I don't mind so much if there are any phthalic acid isomers in the final product. Thanks for your help.

NEMO-Chemistry - 13-10-2017 at 06:23

no experience myself nut maybe these may help you.

https://www.youtube.com/watch?v=iTfQRWn7yEo

interesting reaction so i have added it near the bottom of my to do list!

http://www.sciencemadness.org/member_publications/terephthal...

https://www.sciencemadness.org/whisper/viewthread.php?tid=49...

I understand your looking for tips from those have done it, however i posted the links to give you something to look at, while you wait for someone with brains to reply.

HTH

Oh and by the way the SM links are not a dig like UTFSE, the search engine on the site is awful!! site is full of info but without some serious google ninja skills its hard to find.

http://dl.uctm.edu/journal/node/j2010-4/2_Spaseska_379-384.p...

[Edited on 13-10-2017 by NEMO-Chemistry]
included a patent, no idea if it helps, patents tend to do my head in! but posted it in case, let us know how it works out. Once i have better skills I want to try this experiment

https://www.google.com/patents/US7893122

[Edited on 13-10-2017 by NEMO-Chemistry]

LearnedAmateur - 13-10-2017 at 07:13

Thanks, I'll check them out. It's strange because I did a search before posting but that thread by Chromium didn't pop up. I was expecting at least one procedure, the closest I could find was this one:
https://www.sciencemadness.org/whisper/viewthread.php?tid=63...

NEMO-Chemistry - 13-10-2017 at 08:07

Quote: Originally posted by LearnedAmateur

Thanks, I'll check them out. It's strange because I did a search before posting but that thread by Chromium didn't pop up. I was expecting at least one procedure, the closest I could find was this one:
https://www.sciencemadness.org/whisper/viewthread.php?tid=63...

Its a open secret that the site search engine is junk, you have to site search via google. I am not too good at that, but a bit of google foo normally brings up what I am looking for.

I figured there might be some stuff in the links i posted, to occupy you while one of the brains turns up with experience in the reaction.

Once you done this one, look on nile reds you tube channel, he does some cool stuff with a similar reaction, but he uses pvc gloves.

Actually i was expecting alot more to pop on SM about this reaction, i remember a while alot of people where interested in it, but I cant find many of threads I remember seeing.

Boffis - 13-10-2017 at 08:54

I did a lot of work on this process and developed a semi-continuous repeating batch process where the liquid residue from one batch is recycled into the next batch. This process used sodium hydroxide and ethylene glycol as the decomposition medium and yields about 95% of theory. So I can vouch for this process. It was not possible to recover the glycol.

I also investigated the direct ammoniolysis of PET with conc ammonia fumes to give terephthalamide. This process is slow but effective.

Both of these processes are described on various threads on SM though I haven't posted some of my own experiments as other have already done this. Just search for the "terephthalic acid" with the search engine and you will get many hits.

NEMO-Chemistry - 13-10-2017 at 13:38

Boffis, this is where the search engine falls down, i searched for it on here, the pic is all the results I got. only 1 maybe 2 are relevant for what he wants. Google site search sometimes works better, but lately for me at least, it just throws up alot of non relevant stuff...

I suspect the OP, like myself is doing something incorrectly when searching. Others seem to have zero problem getting thread after thread come up for different topics, while some like me dont have so much luck.

So i think its safe to assume some of us (definitely me) are missing something out when UTFSE.

Most bizarre part is google always rescued me, lately my google foo has diminished. soon i fear i will have to hand back my google ninja black belt at this rate.

j_sum1 - 13-10-2017 at 15:19

Tdep (e tractions and ire) did ayt video on this. Low yield but instructive.

NEMO-Chemistry - 13-10-2017 at 15:25

One the links I posted was a you tube one, not sure if its the same though

j_sum1 - 13-10-2017 at 17:17

Nah. Tdep's synth is rough and dirty and a lot of fun to watch.
I'd look it up if I was on my computer.

NEMO-Chemistry - 13-10-2017 at 18:35

Quote: Originally posted by j_sum1

Nah. Tdep's synth is rough and dirty and a lot of fun to watch.
I'd look it up if I was on my computer.

LOL ok you convinced me to go look for it now, rough and dirty is the clincher, i will be back with a link if I find it

https://www.youtube.com/watch?v=JuvczYeM3kk

found it. looks like he has a leaning to things that go bang lol, interesting channel, i should goto bed but might watch a couple

[Edited on 14-10-2017 by NEMO-Chemistry]

18thTimeLucky - 14-10-2017 at 14:14

That is unfortunate you only just found out about Extractions&Ire NEMO-Chemistry! He has some great videos going into detail of the synthesis of usually energetic materials for his main channel. On his main channel Explosions&Fire he would make funny videos on energetic materials. I said 'would' as his main channel was recently banned from YouTube for reasons you can imagine. It is a real shame he did some great chemistry videos there with a personal touch. He is trying to reupload some to his new channel Explosions&Fire2 but I doubt YouTube will let him get away with it.

NEMO-Chemistry - 14-10-2017 at 16:34

Quote: Originally posted by 18thTimeLucky?

That is unfortunate you only just found out about Extractions&Ire NEMO-Chemistry! He has some great videos going into detail of the synthesis of usually energetic materials for his main channel. On his main channel Explosions&Fire he would make funny videos on energetic materials. I said 'would' as his main channel was recently banned from YouTube for reasons you can imagine. It is a real shame he did some great chemistry videos there with a personal touch. He is trying to reupload some to his new channel Explosions&Fire2 but I doubt YouTube will let him get away with it.

I watched the video where he explains about the ban.

Have you noticed since google purchased you tube, NO other video channels appear in the searches for vids?

Is TDEP still active here? There is some open source software that kinda like a youtube clone. Shared hosting is pretty cheap, might be cool if we did our own SM video hosting for stuff like that.

I am not technical enough to know how feasible it is, but on my shared host i run the video software, i only have it as a test. Seems resource hungry, but maybe a VPS would be enough?

And yeah i do like his 'real' chemistry lab lol i love the fact its untidy like mine, burn marks like mine. Paint cans like mine

. No offense to anyone, but some channels are kinda too shiny

Tdep - 15-10-2017 at 18:12

Hello, Mr Rough and Dirty here (could be my stage name.... work in progress)

Yeah every option compared to Youtube just because of the lack of user base, also the fact that only Youtube videos really appear in Google searches too, good point NEMO. I like making videos, but I wont make them if no-one is watching them. If I was just making them for sciencemadness, i'm sure people would just prefer to read a nice writeup, rather than watch me over-produce a video of somebody else's work from a different thread. Plus, a lot less editing. So to other platforms we go for the moment. Hopefully something gives with youtube soon, there's a lot of pressure on them. For now though, selected 'decent' videos are on Vimeo: https://vimeo.com/explosionsandfire and I will dump all the videos + all Extract&Ire vids on Vid.me https://vid.me/ExplosionsAndFire soon, for your 200 video browsing pleasure.

Anyway, enough about my selfish ass, lets answer the question. I agree my method is rough, but this synthesis is particularity forgiving which is nice, mainly due to the insolubility of TPA. I did the hydrolysis in ethylene glycol just so the high temps made it proceed quickly, as per the CHROMIUM publication. I think it also helps soften the chunks of plastic so that you get complete hydrolysis completely through the pieces. You could likely reflux it in ethanol, it might just take a day and your pieces might have to be small. You can always isolate the Na-TP from the EG or EtOH mix first, or filter the water/solvent mix after dissolving the Na-TP if you're worried about left over plastic in the reaction mix.

Also, I find HCl works better in these types of synths because it leaves when you dry it, but sulfuric acid hangs around and makes it hard to get so dry.

NEMO-Chemistry - 16-10-2017 at 06:51

You tube only wants kids putting on make up or talking shite.

Alot of other tech channels are being hounded off. The correlation to look at is patreon. Until google buys patreon it will give preference to tubes that use its advertising.

Kind of makes you choke when you read do no evil!

Vimeo dosnt come up on video searches for me, so i will go hunt your channels down, no idea why google are allowed to get away with so many outrageous business practices

18thTimeLucky - 16-10-2017 at 10:03

Legend has it that if you repeat Tdep 3 times in a forum, Mr Rough and Dirty appears himself. In a perfect world SM video hosting would be pretty neat but I have to agree a write-up is just way more practical and easy to follow.
Videos are really more for entertainment, and pictures cover the visuals of an experiment with a fraction of the upload size. Kind of the reason why I started a blog rather than a YouTube (or another platform) channel, along with all that editing...

Melgar - 16-10-2017 at 14:17

Has anyone tried LiOH? Anecdotal reports seem to indicate that Li is better than Na or K at overcoming steric effects that inhibit reactions, due to its small size. And PETE hydrolysis is one of the most sterically hindered reactions I know of. Even a catalytic amount of lithium could theoretically help, since it's a slightly weaker base and could be activated again by sodium or potassium hydroxide. Propylene glycol + water + Li (metal or hydroxide) + NaOH would be the first thing I'd try. I'm probably wrong, but it's always good to try new ways of doing things, to test your theories vs. reality.

j_sum1 - 16-10-2017 at 14:41

Quote: Originally posted by Melgar

Has anyone tried LiOH? Anecdotal reports seem to indicate that Li is better than Na or K at overcoming steric effects that inhibit reactions, due to its small size. And PETE hydrolysis is one of the most sterically hindered reactions I know of. Even a catalytic amount of lithium could theoretically help, since it's a slightly weaker base and could be activated again by sodium or potassium hydroxide. Propylene glycol + water + Li (metal or hydroxide) + NaOH would be the first thing I'd try. I'm probably wrong, but it's always good to try new ways of doing things, to test your theories vs. reality.

That is a really cool idea.
I want to try this.

JJay - 16-10-2017 at 15:11

I've been wanting to give this a try... I have some lithium chloride. I guess that would probably work almost as well as lithium hydroxide?

NEMO-Chemistry - 16-10-2017 at 15:54

There are some references and a patent that mention Lithium Hydroxide being used. The patent is US 20100133088 A1
But the paper i scanned through quick and couldnt find the useful bit.

[Edited on 16-10-2017 by NEMO-Chemistry]

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Melgar - 16-10-2017 at 22:07

I figured I should give it a shot since I had all that stuff. For the lithium, I just used the white crap that's been flaking off my lithium metal, and collecting at the bottom of the vial. I think it's mostly carbonate, with a few flecks of Li metal here and there that'd react suddenly. I used PETE from a piece of blister wrap, though I should have used polyester cloth, as it's more uniform and it'd be easier to see dissolve. I had some sodium hydroxide that was sitting out from earlier (barely any) and so used that, although now I think KOH would be better since it's less hard on glass and a stronger base. I don't know if its low solubility in solvents other than water would help or hurt the reaction. Perhaps it could force lithium ions into nonpolar phases? Or maybe it'd just interact less with everything? It formed a cloudy solution on heating, and the PETE softened. I guess I don't know what I was expecting. Maybe n-butanol would be a better solvent? It's miscible with plenty of nonpolar solvents after all.

Eh, it's too hot to touch now, and I can't really do anything with it anyway, so I guess I'll just add some of my thoughts and observations.

LearnedAmateur - 17-10-2017 at 02:09

Some great tips, you've all been a great help, just have to order myself some EG since I don't have antifreeze lying around. Thinking of experimenting with some other TPA based polymers, or even just some esters to see if anything funky comes up.

Tdep - only watched a few of your videos so far but I love them, I'll be stuck in for a while - thanks for taking the time to produce them!