Picric-A
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4-AminoBenzoic Acid from PET
Depolymerization of PET using the ethylene glycol/NaOH mixture documented in preppublication, produces Terephthalic acid.
one mole of terephthlaic acid was reacted with one mole of ammonia (generated by reacting one mole of ammonium chloride with one mole of NaOH). This
produced ammonium hydrogen phthalate.
This compound was heated to decomposition to produce 4-carbamoylbenzoic acid. Hoffman rearrangement of this yielded (almost- 8g off) one mole of PABA.
Ideas? comments? Improvements?
(Edit- changed file to a different format)
[Edited on 25-7-2009 by Picric-A]
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smuv
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This sounds like very good work. Unfortunately it helps no one if you withhold the experimental procedures.
I look forward to reading a more complete writeup.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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not_important
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I agree with smuv, more info is needed - yields at each step. How did you verify the final product?
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Picric-A
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I will make a PDF when im next free.
Verification, purity analysis ect, was dont with m.p. test
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UnintentionalChaos
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Quote: Originally posted by Picric-A  | This produced ammonium hydrogen phthalate.
This compound was heated to decomposition to produce 4-carbamoylbenzoic acid. Hoffman rearrangement of this yielded (almost- 8g off) one mole of PABA.
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Ammonium Hydrogen Biterephthalate
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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Picric-A
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[/rquote]
Ammonium Hydrogen Biterephthalate[/rquote]
No, the correct naming is ammonium hydrogen terephthalate.
Saying ammonium hydrogen biterephthlate would be the same as saying Sodium hydrogen bisulphate, which is wrong.
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UnintentionalChaos
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Wow, I failed hard there >.<
Sorry, I was rather tired at the time, typed out ammonium Biterephthalate and then said, "oh wait, I'm missing the 'hydrogen'" without thinking.
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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Picric-A
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Ok after taking lots of pics of the synthesis thus far i keep hitting a brick wall... that being the hofmann rearangement.
Instead of using the Br/NaOH route am i using straight NaClO... this works i know but the 4-carbamoylbenzoic acid doesnt dissolve in the hypochorite
vry well so yields are poor... can somebody suggest a solvent the 4-carbamoylbenzoic acid can be dissolved in that would be affected by the 'haloform
reaction' like conditions.? eg, ethanol, propanone ect. are out..
Another possible route is the reaction of one mole of TPA with one mole of Sodium azide yielding the desired PABA...
This is completly random however, i have never attempted this myself as i have never had the guts to use azides... any comments on this reaction?
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not_important
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You're still not giving sufficient details - is the 4-carbamoylbenzoic acid already in the salt form when you add it to the hypochlorite? If not try
first converting it using NaHCO3 or Na2CO3, the salt should be more soluble in water.
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Random
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maybe chloroform or DCM could work as solvent
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