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Paddywhacker
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This worked like a charm, though I'm still purifying the volumenous terephthalic acid precipitate, so I don't yet know the actual yield.
Has anybody tried a similar hydrolysis of Nylon? I've had a scrounge around but cannot find any suitable.
But what to do with the terephthalic acid?
I was thinking of pyrolyze a salt of it to try and get benzophenone with two COOH groups.
1. Form the half salt... 5g TPA + 2.6 g NaHCO3
2. Pyrolyze
or
1. Form the half methyl ester:- 5 g TPA + 1.1 ml MeOH
2. Form the sodium, calcium or barium salt of that
3. Pyrolyze.
or maybe a cross-pyrolysis with excess Sodium Acetate to give para (CH3CO)2C6H4
Any other ideas?
Edit:- Was filtered on the Buchner, washed with 500 ml H2O and then 250ml ethanol from the freezer. The ethanol extracted some sort of pink pigment.
After drying on the Buchner for several hours, the yield was 27.3g of obviously damp product, pure white in the bulk but with a skin of slight pink.
I'm going to heat it up with ethanol to remove the pink, cool in the freezer, and then re-filter, but it was obviously a successful prep.
Edit:- The product was dispersed in 200 ml of boiling EtOH which was then chilled in the freezer and the slurry refiltered on buchner. The product,
after drying for 8 hours in a vacuum, weightd 20.85 g.
This is a yield of 110%. I wonder if there isn't some mono ethylene glycol ester of terephthalic acid in the product.
[Edited on 3-3-2009 by Paddywhacker]
[Edited on 4-3-2009 by Paddywhacker]
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sparkgap
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Nylon's an amide, so I'd think harsher conditions are needed for hydrolysis.
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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Picric-A
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Has anybody got access to this article? http://pubs.acs.org/doi/abs/10.1021/ie010563z
Seems a good way to anhydrous oxalic acid and (sodium) terephthalate.
On another note, does anybody know the solubility of sodium terephthalate in ethylene glycol? I intend on decarboxylating the acid so it seems a waste
acidifying, filtering then neutralizing again when I want the sodium salt anyway! Not to mention a pain!
thanks
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DJF90
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How did you figure that ANHYDROUS oxalic acid would be formed when the abstract mentions using concentrated NaOH solutions? The experimental section
uses an autoclave at 160-250C, and also they use 20ml of water with a prescribed amount of NaOH (appears ~37% gives best yield of oxalic acid) for
0.67g of PET... and oxygen gas at 1-10 MPa. Conditions that are slightly out the way for us amatuers and also it doesnt look very scalable.
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panziandi
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Anhydrous oxalic acid? Obtained from an aqueous alkaline solution? Picric-A I think you might have some wires crossed lol! Really it seems a bit
"idealistic green chemistry" kind of themed. You could always obtain your chemicals through your usual methods... 
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Picric-A
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@ DJF90 - I guessed one could substitute the conc NaOH soloution for the easier NaOH dissolved in ethylene glycol, thus creating anhydrous conditions.
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DJF90
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Generally such a swap may vastly affect the outcome of the reaction. You also forget that to get the free acid you need to acidify the sodium salt,
which again is aqueous (I think they used 2N sulfuric IIRC to ppt. the terephthalic acid, the oxalic acid was determined in solution).
For the amatuer the best method (IMO) is the one outlined, it could have some minor changes possibly but in general it is a food procedure. The oxalic
acid byproduct by doing the hydrolysis by this alternative method is not worth the additional hassle of reaction volume, use of autoclave etc etc,
especially as the oxalic acid produced will be anything but anhydrous and can be purcased very cheaply either from a chemical supplier, hardware
store, or even ebay.
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Polverone
Now celebrating 21 years of madness
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Thread Split
28-6-2009 at 11:25 |
UnintentionalChaos
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Quote: Originally posted by Paddywhacker  |
Edit:- The product was dispersed in 200 ml of boiling EtOH which was then chilled in the freezer and the slurry refiltered on buchner. The product,
after drying for 8 hours in a vacuum, weightd 20.85 g.
This is a yield of 110%. I wonder if there isn't some mono ethylene glycol ester of terephthalic acid in the product.
[Edited on 3-3-2009 by Paddywhacker]
[Edited on 4-3-2009 by Paddywhacker] |
What was the original mass of PETE that you used? I wonder if it's just a calculation error. The "molar mass" of the original PETE is 192.168g/"mol"
and the molar mass of terephthalic acid is 166.131g/mol.
[Edited on 6-29-09 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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bfesser
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Hey, guys, let's not be too harsh. It may not be accessible to most amateurs, but it's something to read.  Thanks, Picric-A.
Attachment: ie010563z.pdf (94kB)
This file has been downloaded 2047 times
[Edited on 6/29/09 by bfesser]
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DJF90
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I already read this before I told Picric-A its a useless article. The use of an autoclave to get terephthalic acid is pointless, especially when we
have this method that is much simpler and works, courtesy of chromium.
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panziandi
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I have to agree I took a read of it too and I think it is much more than what is realistic to an amateur...
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UnintentionalChaos
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I have a large beaker of disodium terephthalate solution awaiting further purification at the moment. I don't have my notes with me, but I'll add in
some details later when I have a yield.
I used diethylene glycol as solvent with dry NaOH prills in 25% excess of theoretical. Approximately 100mL of DEG, 25g NaOH (.625mol), and 48g of PET
(0.25mol) were used. Depolymerization proceeded smoothly with heating in a stainless steel reaction vessel under constant stirring. There was constant
evaporation of ethylene glycol from the reaction mix while heating for 20 minutes.The resultant off-white slurry dissolved in 400mL of water and about
4g of PET had not reacted after becoming encased in disodium terephthalate. Either longer heating or more vigorous stirring is required.
90g of 92% NaHSO4 dissolved in about 200mL of water was used to precipitate the free acid from solution as flocculent, white material. This was
collected by vacuum filtration and redissolved in 22.62g of NaOH and an arbitrary amount of water (@400mL). I will reacidify and boil to form a more
compact precipitate later on.
The diethylene glycol was from this product, which is sold as a chafing dish fuel:
http://www.candlefuel.com/pdf/CLC_Deg.pdf
As the MSDS shows, the only ingredient is DEG, without any dyes or water. I found that each can yields about 235mL, but needs filtration through real
filter paper to remove stray fibers from the wick material. Coffee filter allows short pieces of the material through and it's too viscous to pass
through cotton. Of course, if you filter the mixture after the heating, this isn't necessary, but I mean this more for other reactions.
Purchased locally, each can costs me $1. It'd be a waste of my time to boil the waste down unless I was doing this on a massive scale, since less than
half a can (100mL) is enough solvent to handle 0.25mol of shredded PET.
Update: Okay, someone else who's done this, take a small sample and heat it intensely, like on the surface of a hotplate. Does it char or leave black
residue?
The reason beaing that I was drying some of my product with heat last night (very high sublimation point, so why not crank it up?) and noticed a good
deal of charring on the bottom of the evaporating dish.
So, I ramped up the heat until I got white fumes and no more water was condensing on a watch glass, moved the sample to a crystallizing dish, and
sublimated it under atmosphere.
I got pale yellow, fluffy crystals. A small spatula, placed directly on the ceramic of my hotplate sublimated without residue when heated strongly.
I'm not exactly happy about whatever the yellow is, but I've eliminated whatever was charring.
[Edited on 7-2-09 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Paddywhacker
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The product is fiendishly insoluble in water, methanol, hexane & dichloromethane. Any ideas how to recrystallize it?
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User
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Terephthalic acid (benzene-1,4-dicarboxylic acid) [100-21-0] M 166.1, m sublimes > 3 0 0o
without melting, pK1
20 3.4, pK 2
20 4.34. Purify the acid via the sodium salt which, after crystallisation
from water, is re-converted to the acid by acidification with mineral acid. Filter off the solid, wash it with H2O
and dry it in a vacuum. The S-benzylisothiuronium salt has m 204o (from aqueous EtOH). [Beilstein 9 IV
3301.]
This is from the book : purification of laboratory chemicals 6e (2009).
It actually is the only way i found so far to clean this chemical
It is the same way that chromium used to crystallize it.
So maybe doing it a second time gives a quite pure product.
Especially because all the chems used are all very soluble in H2O.
I produced this same substance a few days ago and iam thinking of using this method somewhere these days.
Sadly enough i have no equipment available to test purity except for crude melting point determination.
What a fine day for chemistry this is.
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turbosnigel
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Copper salt
I prepared 16 Moles of Terephthalic acid by saponification with KOH in PG and then percipitate the TA with dilute H2SO4.
The TA was then washed with H2O and filtered a few times.
The Ta was then made in to its water soluble diamonium salt by a slight exes of ammonia.
The di amonium salt solution was left in a shed for some months to let the exes ammonia evaporate and the contaminant to aglomerate to some extent.
I suspect Bismuth used at about 2% as a catalyst in the polymerisation of TA to PET to constitute the colored contaminant. A 20 liter bucket of the
crude di ammonium solution locks similar to tea in the color.
I then purified activated coal (Norit) by boiling in water so remove salts and other impurities as well as increasing its activity a few 100%
Repeated filtration with the purified activated coal made the solution clear.
I then purified an slight molar exes amount of copper sulfate solution by filtration with some purified activated charcol to eliminate insoluble
(copperoxycloride and possibly som copperoxide?) and other cotaminating components.
The resulting clear blue solution was combined with the di ammonium terephthalic acid to percipitate a skye blue coppersalt of terephthalic acid.
Repeated washings and filtration trough a peace of cotton eliminated the soluble ammonium sulphate generated by the reaction. washings was repeated
until the exes blue copper sulfate was no longer visible in the removed water.
(The particles are extremely small so filtration is rely a bitch!)
A half year after i started this i have quite a bit of a very pure non hygroscopic i insoluble copper salt with all its possible uses
Thanks for posting the info that made me realize i needed to do this 
"TurboSnail"
>>>_@/"
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Chemistry Alchemist
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What would the procedure be when doing it with Permanganate? really wanna preform the experiment but i dont know how to do so
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DJF90
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Something akin to this procedure: http://cssp.chemspider.com/Article.aspx?id=270
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theflickkk
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I tried oxidising napthalene moth balls with KMnO4. I can't remember the exact details of the experiment as it was just an experiment to determine if
a reaction even occurs.
A hot conc. KMnO4 solution was made and acidified with dilute sulfuric acid.
A moth ball was slowly lowered into the solution and some bubbling followed. The solution was left to cool for a day and I found that there was a
white crust that formed on the surface of the solution. There was some brown residue present although much of the solution remained dark purple. It
doesn't look as if there was much of a reaction but is there any way to test whether phthalic acid was formed? Initially I thought that an excess of
napthalene was used but this is unlikely as the solution was still purple-ish. The napthalene moth ball remained largely intact also.
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Chemistry Alchemist
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i think you need to reflux it, just like how myst32YT Refluxed KMnO4 with Toluene to form Potassium benzoate and Manganese Dioxide, i think it will
work the same way as that with this, Heating a acidified solution of permanganate with Naphthalene to react and make Manganese Dioxide and Potassium
Phthalate when then is reacted with an acid to form Phthalic Acid and then dehydrated to form Phthalic Anhydride
Just a guess...
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Waffles SS
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What will be made if we use PP(Poly Propylene) instead of PET(Poly Ethylene)?
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PHILOU Zrealone
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Nothing! Wrong reading !
*PET is Polyethyleneterephtalate thus a polyester ((-CH2-CH2-)n-O2C-C6H4-CO2-)
*PE is Polyethylene thus an alkane (-CH2-CH2-)n
*PP is Polypropylene thus an alkane (-CH(CH3)-CH2)n
Alkanes are relatively inert towards hydrolysis reagents what is not the case of polyesters!
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Waffles SS
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Sorry
I thought That is Poly ethylene but it seems i did mistake
Thank you
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