Sciencemadness Discussion Board - plasticisers from vinyl & green saponification!

plasticisers from vinyl & green saponification!

hydride_shift - 4-2-2015 at 20:18

There is much discussion on alcoholic extraction of phthalate esters from PVC products; and ester cleavage via NaOH for purposes of attaining phthalic acid. The major limitation with such a procedure is finding the right product.

Today, I trialed a small extraction/saponification on some "food grade" vinyl tubing i had handy using;
- 40g chopped vinyl tubing
- 60mL 95% ethanol
- ~10g NaOH in 50ml H2O

The extraction was performed by gently refluxing vinyl and ethanol until it became noticeably yellow. To the warm yellow liquid, 50mL of NaOH solution was added immediately precipitating a milky solid which transformed to a teal green emulsion before my eyes! Over time this progressed from a tan brown, to a reddish brown characteristic of contaminated aromatic compounds. The solution has formed small droplets of oily liquid on the surface, and a strange unfamiliar alcohol like scent.

Thought this was quite interesting and worth sharing, any wild stabs in the dark on the ID of the plasticiser or any further tests would be much appreciated. Constructive criticism on write-up style is also welcome.

Zombie - 4-2-2015 at 20:59

Most likely DEPH. (2-ethylhexyl) phthalate (di-2-ethylhexyl phthalate, diethylhexyl phthalate

It's the most common plasticizer found in vinyl (PVC) tubing, and something to be avoided in the distillation of ETOH. (drinking purposes)
It;s those few key words that tipped me off... ETOH , Vinyl , heat

I looked up the Wiki on it for you... While I could never produce the compound I do know that ETOH will pull it out of PVC/Vinyl

"Bis(2-ethylhexyl) phthalate (di-2-ethylhexyl phthalate, diethylhexyl phthalate, DEHP; dioctyl phthalate, DOP), is an organic compound with the formula C6H4(C8H17COO)2. DEHP is the most common of the class of phthalates which are used as plasticizers, accounting for an almost 54% market share in 2010.[2] It is the diester of phthalic acid and the branched-chain 2-ethylhexanol. This colorless viscous liquid is soluble in oil, but not in water. DEHP is a High Production Volume Chemical.

http://en.wikipedia.org/wiki/Bis%282-ethylhexyl%29_phthalate

[Edited on 5-2-2015 by Zombie]

blogfast25 - 5-2-2015 at 11:11

Quote: Originally posted by Zombie

Most likely DEPH. (2-ethylhexyl) phthalate (di-2-ethylhexyl phthalate, diethylhexyl phthalate

It's the most common plasticizer found in vinyl (PVC) tubing, and something to be avoided in the distillation of ETOH. (drinking purposes)
It;s those few key words that tipped me off... ETOH , Vinyl , heat

I looked up the Wiki on it for you... While I could never produce the compound I do know that ETOH will pull it out of PVC/Vinyl

All true and the OP already knows it.

His question is why the extracted plasticiser doesn't chemically seem to behave like DOP should.

My advice: repeat the extraction, evaporate the ethanol and try and characterise the resulting residue: density, MP or such like.

Antioxydants co-leached from the vinyl, may also be f*cking up the de-esterification (but it's not very likely).

Did you calculate the amount of NaOH used for the de-esterification?

Adding the NaOH as a watery solution may not be a great idea here because the water may cause the DOP out of solution. NaOH is soluble in EtOH, so can be added as such (pure). 50 ml water to 60 ml of EtOH/DOP would almost certainly force the DOP out of solution, causing an emulsion to form.

[Edited on 5-2-2015 by blogfast25]

Hellafunt - 5-2-2015 at 11:30

ive tried twice to extract the DEPH from vinyl gloves, and failed both times. Im pretty sure my technique was sound and that the problem was the gloves didnt contain any DEPH.
i was wondering if anyone can suggest a brand of gloves or pvc item that definitely has the target compound. I am in the pacific northwest of the good ol' USofA. thanks, hellafunt

Zombie - 5-2-2015 at 11:42

In distilling I can tell by the smell "unfamiliar alcohol like scent." what hose/tubing NOT to use.

Sort of a sweet smell that makes a sour face... Bear with me... Rubber bathtub ducks. They have more of that smell than anything I can think of, and it makes sense that your plasticize-r will be there in higher amounts due to the (bear with me) Squeezy nature>

Shoot me now Blogfat. It's the best I could do, for now. Just throwing food for thought.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&...

Key findings
Nearly half of the toys tested contained phthalates.
Most of the toys testing positive for phthalates had high levels of the chemicals, including a rubber ducky from Fred Meyer, a green ball purchased at Toys "R" Us, Target-brand penguin and "Baby I'm Yours" doll, and a dinosaur figurine from Wal-Mart.

http://www.watoxics.org/news/pressroom/press-releases/danger...

[Edited on 5-2-2015 by Zombie]

blogfast25 - 5-2-2015 at 11:42

Quote: Originally posted by Hellafunt

ive tried twice to extract the DEPH from vinyl gloves, and failed both times. Im pretty sure my technique was sound and that the problem was the gloves didnt contain any DEPH.
i was wondering if anyone can suggest a brand of gloves or pvc item that definitely has the target compound. I am in the pacific northwest of the good ol' USofA. thanks, hellafunt

Besides gloves there's ton of p-PVC made items out there that almost certainly contain DEHP (DOP) like shower curtains, vinyl flooring, garden hose, automotive upholstery etc. DOP has far from been phased out, as least as far as I know.

PVC is easy to identify: hold a very hot clean copper wire against the item, then hold the wire in a Bunsen flame: green flame indicates chlorine (CuCl2). That's a good test if you already suspect something is made of PVC.

[Edited on 5-2-2015 by blogfast25]

Hellafunt - 5-2-2015 at 13:09

great info , thanks!

hydride_shift - 5-2-2015 at 18:23

Got some new "latex free" gloves today, alot of other synthetic latex alternatives are out there and where i live there is no requirement to label ingredients of non-food products.

Quote: Originally posted by blogfast25

PVC is easy to identify: hold a very hot clean copper wire against the item, then hold the wire in a Bunsen flame: green flame indicates chlorine (CuCl2). That's a good test if you already suspect something is made of PVC.

Looking good!

I will repeat yesterdays alcohol extraction with both the tubing and the gloves and evaporate to dryness, and come back with results and report on any noteworthy differences. Sadly i don't have accurate MP or TLC hardware.

blogfast25 - 5-2-2015 at 19:50

Quote: Originally posted by hydride_shift

Sadly i don't have accurate MP or TLC hardware.

TLC wouldn't help much w/o a DOP standard to compare with.

I'm now pretty convinced that if you add the NaOH as pure NaOH or as an ethanolic solution to your lixiviate, the sodium phthalate (as crystals) and the relevant alcohol (2-ethyl hexan-1-ol, as a supernatant liquid) will be yours. You may want to heat moderately to help things along. Steam bath, for instance, 30 mins.

Any leached out anti-oxidants may cause irrelevant discolouration.

Why not split your leachate into two parts? Use one to evaporate the solvent and isolate the plasticiser, use the second part to add the NaOH too?

Keep us posted.

[Edited on 6-2-2015 by blogfast25]

Oscilllator - 5-2-2015 at 20:15

Quote: Originally posted by blogfast25

I'm now pretty convinced that if you add the NaOH as pure NaOH or as an ethanolic solution to your lixiviate, the sodium phthalate (as crystals) and the relevant alcohol (2-ethyl hexan-1-ol, as a supernatant liquid) will be yours. You may want to heat moderately to help things along. Steam bath, for instance, 30 mins.
[Edited on 6-2-2015 by blogfast25]

I suggest you watch UC235's video on phlalic acid from vinyl gloves. I believe in that video he encounters troubles as a result of using solid sodium hydroxide. Perhaps he can weigh in on the issue?

Hawkguy - 5-2-2015 at 21:58

PVC is easy to identify: hold a very hot clean copper wire against the item, then hold the wire in a Bunsen flame: green flame indicates chlorine (CuCl2). That's a good test if you already suspect something is made of PVC.

[Edited on 5-2-2015 by blogfast25][/rquote]

Dude... Won't hot copper produce the green flame?

Hawkguy - 5-2-2015 at 22:00

Dude I know PVC does produce those flames, but it might not be a great test using copper.. Maybe plain old iron would do fine so you could distinguish the threads of colour...

UC235 - 5-2-2015 at 22:17

Are you sure that the initial "precipitate" is indeed a solid? If you had alcoholic DEHP and added aqueous NaOH, you'd immediately get a milky solution since the aq. NaOH is going to bring the polarity of the solvent way up, dropping the solubility of the DEHP which oils oil. This should split out into a second phase. To get proper reaction, you'll want to heat with vigorous stirring for several hours. The produced 2-ethylhexanol (a slightly fruity, unpleasant scent), unfortunately, is also immiscible and will preferentially retain unreacted ester, necessitating the stirring to bring it in contact with the NaOH solution.

If I were to extract DEHP from vinyl tubing, I think I'd take a cheese grater to it to increase surface area and thus rate of extraction. A "yellow" solution doesn't necessarily indicate anything (other than contamination), as DEHP is colorless, as is sodium 2-ethylhexylphthalate, 2-ethylhexanol, and disodium phthalate. If the tubing is well extracted, it should be white, opaque, and brittle.

Unfortunately, there are also other plasticizers on the market, although DEHP is still the major one. Fatty alcohol succinates and adipates are not entirely uncommon (and non-estrogenic) There are also other alcohols, such as "isononyl (mixed branched chain nonyl alcohols)" available to make esters, including those from phthalic acid.

If you can pick a brand of vinyl gloves (unpowdered) that has DEHP, you're looking at a 30-35% plasticizer content (and already in readily extractable thin sheets). Shower curtains seem to be far lower at 10-15%. I have no experience with vinyl tubing, but would assume it's somewhere between those two.

Hellafunt - 5-2-2015 at 23:27

UC235, your first paragraph pretty much sums up my last attempt. Ugh,"slightly fruity, unpleasant scent", makes me queazy thinking about it. very cloying. after adding the aqueous NaOH, i refluxed with stirring for 2 hours. It became 2 phases, but when i acidified the aqueous layer with HCl, the whole solution instantly turned to what resembled cream. no crystals ever formed.
I guess its time to go rubber ducky hunting.

Zombie - 6-2-2015 at 01:59

It's Wabbit Season!

blogfast25 - 6-2-2015 at 03:42

Quote: Originally posted by Hawkguy

Dude I know PVC does produce those flames, but it might not be a great test using copper.. Maybe plain old iron would do fine so you could distinguish the threads of colour...

"Dude", copper works just fine. It would be better to include a Cl-free blank like PE or PP for comparative purposes, though... I should have specified that.

[Edited on 6-2-2015 by blogfast25]

blogfast25 - 6-2-2015 at 09:33

I suddenly remembered Magpie had successfully carried out and written up a post on DOP from pPVC, phthalic acid and 2-ethyl hexa-1-ol:

http://www.sciencemadness.org/talk/viewthread.php?tid=6573&a...

[Edited on 6-2-2015 by blogfast25]

hydride_shift - 9-2-2015 at 01:45

Had some success!

20g of freshly cut vinyl gloves were boiled in 150ml of ethanol in a hot water on an induction stove at 80*C. After 30 min additional 50ml of ethanol was added to replace lost solvent and boiled for an additional 30 min. The same procedure was repeated with the 20g of cut up vinyl tubing that had been used before.

The resulting solutions were both filtered separately to remove vinyl solids. When the solid material was WASHED with COLD water the solutions went milky. At this point the mixtures were halved, to one portion a few grams of solid NaOH were added. All FOUR solutions were boiled on a waterbath at 95-100*C for an hour. As the volume was reduced both alkali solutions oily droplets began to rise to the surface, most likely 2-ethylhexanol with unreacted ester. In the other solutions, a waxy clear liquid began to form both of which bore a striking resemblance.

It became apparent that both products very likely contain DEHP at the very least the same phthalate ester. The two alkali solutions were combined at this point, however upon cooling no obvious separation was seen. Approximately 20mL of hot saturated NaCl solution was then added
to the sep funnel and two phases became clear. The lower organic layer was removed and Hcl was added forming 0.5g of white needle-like crystals which are insoluble in water resembling Phthalic acid. The same method was repeated on the remaining extract, the final combined product was roughly ~5g.

In future I would perform this at the 100g scale with isopropanol on reflux. To further minimise DEHP separation I would avoid the use of cold water entirely and use a hot solution of NaOH (with more dilligence for stochiometry).
Also having some difficulty sublimating the product, I think the oil bath on my induction stove is not getting hot enough and dry heating a beaker with a naked flame was not practical. Do you need to heat +207*C to get it to start to sublimate?

Zombie - 9-2-2015 at 02:22

The Wiki page is showing a flash point of 216* C, and a boiling point of 385* C
So I assume that means you do need higher temps.

http://en.wikipedia.org/wiki/Bis%282-ethylhexyl%29_phthalate

blogfast25 - 9-2-2015 at 16:39

Quote: Originally posted by hydride_shift

Do you need to heat +207*C to get it to start to sublimate?

Good write up, thanks.

You won't sublime phthalic acid at an MP of 207 C!

For purification I would search for a decent solvent (I'm not sure which one but will have a look) and do a thermal recrystallization.

Ooopsie: memory flashback. Phthalic acid is actually well soluble in boiling water: 18 g/100 g of water at 100 C, 0.54 g/100 g of water at 14 C. Probably even less at 0 C.

Problem solved.

[Edited on 10-2-2015 by blogfast25]

Zombie - 9-2-2015 at 16:57

Quote: Originally posted by blogfast25

Quote: Originally posted by hydride_shift

Do you need to heat +207*C to get it to start to sublimate?

Is that a simple re-crystallization process you are describing?

blogfast25 - 9-2-2015 at 17:31

Yes, Sir. Dissolve 18 g of PA in 100 g of boiling water, allow to cool slowly to RT, then chill on ice. Most of it will crystallise out. Impurities that haven't reached their solubility limit stay in solution. Oldest trick in the book.

Repeat several times for extra purity. Crystals tend to become larger and more 'perfect' as purity goes up.

Quote: Originally posted by Zombie

The Wiki page is showing a flash point of 216* C, and a boiling point of 385* C
So I assume that means you do need higher temps.

http://en.wikipedia.org/wiki/Bis%282-ethylhexyl%29_phthalate

That's an entry on DOP (slang for Bis blahdiblah). The OP wants phthalic acid (PA). But he had to extract DOP from pPVC, then alkali de-esterify the DOP. Keep up!

[Edited on 10-2-2015 by blogfast25]

Zombie - 9-2-2015 at 18:31