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Author: Subject: How to extract DINP from vinyl & hydrolyze to phthalic acid
SuperOxide
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[*] posted on 16-8-2020 at 13:07
How to extract DINP from vinyl & hydrolyze to phthalic acid


Hello, first off - I'm still somewhat new to these forums so go easy on me if I accidentally break a rule or two out of naivety.

I'm working on extracting some phthalate based plasticizers from vinyl gloves following some extraction and synthesis procedures I found online, as well as some YT videos (listed in the sources below), which seem to focus on DEHP as the plasticizer. I was able to follow these procedures pretty well using some vinyl gloves purchased from Walgreens. I'd like to run the process a few more times, so I went to purchase some vinyl gloves again, but when I got home I realized that even though it was the same exact box of vinyl gloves, they now use DINP instead of DEHP. I went to a few different stores (Walmart, CVS, etc), and it seems that the gloves with DEHP are all of a sudden as rare as unicorns.

So, now I have a nice stock of vinyl gloves that use DINP for the plasticizer. I figured that since this is also a phthalate based plasticizer, maybe the procedure is similar, but when I gave it a go, after the base ester hydrolysis reflux step, nothing seemed to separate out. The gloves were much more brittle after a soxhlet extraction (with ~90% IPA), so that leads me to believe that I likely did get the DINP out, but the basic hydrolysis step failed... But I could be wrong about that.

I consulted the Google Gods, and searched the forums here (as well as a few others), but either my Google-Fu isn't what it use to be, or there isn't much out there about extracting DINP and converting it to phthalic acid.

Any help would be appreciated. Thanks in advance for any replies (unless they're making fun of me, then that's just mean).

P.S. I realize I could possibly just buy phthalic acid or phthalic anhydride on Amazon... But I'd like to do this myself. That's half the fun!

Sources

  1. How to make Phthalic acid and Phthalic Anhydride by NileRed
  2. Phthalic Acid and Fatty Alcohols from Vinyl Gloves: Part 1 by UC235


[Edited on 16-8-2020 by SuperOxide]

[Edited on 16-8-2020 by SuperOxide]
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Maurice VD 37
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[*] posted on 18-8-2020 at 03:28


What is the composition of both DEHP and DINP ?
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UC235
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[*] posted on 18-8-2020 at 14:25


Isononyl should be almost indistinguishable from 2-ethylhexyl as far as processing the gloves goes. I'm not sure which mine were made with, to be honest.
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macckone
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[*] posted on 18-8-2020 at 14:47


Due to the ramp up in PPE production corners are being cut and formulations are being changed.
The amount of plasticizer may have decreased considerably and the vinyl polymer may have changed as well.
Good luck in your endeavor.
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SuperOxide
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[*] posted on 24-8-2020 at 06:27


Quote: Originally posted by UC235  
Isononyl should be almost indistinguishable from 2-ethylhexyl as far as processing the gloves goes. I'm not sure which mine were made with, to be honest.

Interesting... I notice after I run the soxhlet extraction that the gloves containing DINP seem to leave a white powdery residue in the boiling flask that gets past the cotton, more so than the DEHP gloves did. I know DEHP is a clear viscous liquid, and you're saying DINP is as well? I was worried that maybe that powder looking stuff was DINP, but if not, then I can just filter it off :-)

Quote: Originally posted by macckone  
Due to the ramp up in PPE production corners are being cut and formulations are being changed.
The amount of plasticizer may have decreased considerably and the vinyl polymer may have changed as well.
Good luck in your endeavor.

Yeah, thats also something I worried about... The gloves I did this first extraction with that used DEHP were from walgreens, and when I went to purchase the exact same gloves again, I noticed the DINP allergy warning on the box, and the picture of the gloves even looked a little different, but everything else was the same.


Thanks for the replies!
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SuperOxide
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[*] posted on 24-8-2020 at 11:09


Oh man... I think I may know what my problem was... and it's making me feel pretty foolish.

The "powdery residue" that I mentioned in my last post is seen here:
20200824_095822.jpg - 232kB

I thought it was an extremely fine white powder that was so fine that it went right through the cotton at the bottom of the soxhlet extractor, as well as most of my filters and Buchner funnels -- it looks like it's not a powder at all, but an extremely fine emulsion...
After running the soxhlet extractor for some time, the "white powder" disappeared and turned into a much thicker clear layer that got pulled down to the bottom, as seen here:
20200824_115950.jpg - 206kB

This means that my dumb ass was likely decanting the mostly useless IPA solvent and moving forward with that, while the actual desired product was left behind...

Boy oh boy.. don't I feel like an idiot >_<

Regardless, thanks for the replies! They did convince me to give the whole thing another go. And though I haven't finished turning the DINP into phthalic acid, this makes me pretty confident that it was just user error.

[Edited on 24-8-2020 by SuperOxide]

[Edited on 24-8-2020 by SuperOxide]
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SuperOxide
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[*] posted on 25-8-2020 at 16:47


Update... for anyone who cares, or is just incredibly bored.

After running everything through the centrifuge, I continued on following the same procedure that worked for me the first time (more or less). I've ran this procedure several times now and this is the first time I didn't exclude some of the "mysterious white powder" (which ended up being the important emulsified phthalate), which no doubt was reducing the amount of phthalates being processed in those runs. On the contrary, since I ran the mixture through a centrifuge this time, not only should there be much more phthalate being processed, but I also removed some of the IPA being used as a solvent after it separated out in the centrifuge.
So I expected the results to be quite different, and I wasn't let down! After adding some concentrated HCl to convert the soluble phthalic salt into insoluble phthalic acid, a nice white precipitate fell out of solution!..

20200825_165022-1.jpg - 37kB
20200825_165052-1.jpg - 40kB

.. which is in marked contrast from all the previous runs, where upon addition of the HCl the solution would just become slightly hazy (or not change at all) and the phthalic acid would only crystalize after sitting overnight in the refrigerator (which also didn't even happen on some failed runs).

This is definitely promising! I'm going to let it sit overnight in the refrigerator so more crystals can form and settle out.

If it turns out that I somehow still managed to screw this up, and this isn't phthalic acid, then I'm going to have some serious egg on my face, again >_<

Thanks!
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SuperOxide
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[*] posted on 4-9-2020 at 10:47


Since I know that some of you are likely losing sleep over this critically important matter... I thought I'd give an update.

Quote: Originally posted by SuperOxide  

If it turns out that I somehow still managed to screw this up, and this isn't phthalic acid, then I'm going to have some serious egg on my face, again >_<

Well, I have some egg on my face. When I added the HCl, a precipitate clearly fell out of solution (as seen in the above photos). It did eventually settle to the bottom and I was able to filter it off (forgot to get a photo of the precipitate settled to the bottom, sorry). But it was definitely not a crystalline solid... Here's what it looked like after it dried:
phthalate-attempt-result.png - 755kB

It's not soluble in water, and I thought I'd give sublimation an attempt, and I cranked my hotplate to as high as it would go, and it never melted at all.
The solution that it precipitated out of smelled very similar to the solutions of successful prior runs, not sure what that says, though.

However... Walgreens finally got the proper DEHP containing gloves back in stock. So I'll save the mysterious white precipitate in a vial for now, and perhaps I'll try to see what the hell it is sometime in the future. But for now, I'm giving up working with the gloves containing DINP, since I have the DEHP containing gloves now.

Thanks for the previous replies! Sorry I wasn't able to get this working, even with your help.

[Edited on 4-9-2020 by SuperOxide]
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[*] posted on 5-9-2020 at 10:59


Quote: Originally posted by UC235  
Isononyl should be almost indistinguishable from 2-ethylhexyl as far as processing the gloves goes. I'm not sure which mine were made with, to be honest.


I find this interesting... The gloves I've ran this experiment on are apparently the same thing with the exception of the plasticizer.
- These gloves work perfectly fine; while
- These gloves are the ones that I couldn't get to work.
They're both Walgreens brand vinyl exam gloves. The gloves in the 2nd pair contain a notice on the box that it contains DINP, while the box in the first link contain no such warnings.

Since they're the same brand and basically the same thing, I think it's somewhat ok to assume that the only real difference is the plasticizer they use. And I made sure that the extraction and processing steps are as identical as I can possibly make them (same reagents, same volume/quantity/concentration of reagents, same soxhlet extraction duration/cycles, same reflux time, same temperatures, etc). Yet the results are quite different. Very odd.

P.S. Sorry for the multiple posts - but it seems that I can't edit or even delete previous posts after a certain amount of time goes by.

Thanks again.

[Edited on 5-9-2020 by SuperOxide]

[Edited on 5-9-2020 by SuperOxide]
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