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Author: Subject: Making 3-nitrophthalic Acid Failure
VSEPR_VOID
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[*] posted on 21-10-2018 at 20:56
Making 3-nitrophthalic Acid Failure


I am making luminol from phthalic anhydride I purchased.

Using Nerd Rages Procedure, 19 grams of sodium nitrate, 13 grams of phthalic anhyride, and 50 mL of drain opener (93%) sulfuric acid was added to a flask.

The flask was heated over 20 minutes to 110 C. Using a dry bath the solution was heated for 2 hours.

The solution was then quenched with 150 mL of ice water. A white precipitate formed then quickly dissolved again when the solution heated.

No precipitate was seen, at all, even when it was cooled to 20 C.

Even scrapping the glass and adding a few mg of phthalic anhydride crystals did not help. The solution remains a very light yellow.

Does anyone have an idea why this did not work.

Tomorrow I am going to boil it back down to 75 mL and try again to quench it with water.

[Edited on 22-10-2018 by VSEPR_VOID]




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[*] posted on 21-10-2018 at 21:55


Because a nitration uses nitrate, not a nitrite? You did not mention a huge brown cloud of nitrogen oxides, did you use sodium nitrate?
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[*] posted on 22-10-2018 at 03:33


Typo: Nitrate not nitrite. Upon dissolving the sodium nitrate during heating, there was some NOx and other fumes evolving. There was a clear smell of nitric acid.



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[*] posted on 22-10-2018 at 07:29


I have made this with no problems. I would check your phthalic anhydride and make sure it is not instead phthalic acid. I bought the "anhydride" from 3 suppliers but it was all the acid. Make your own from the acid. I show how to do this on this forum.



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[*] posted on 22-10-2018 at 10:50


Is there a simple test for it? I purchased it from onyxmet



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[*] posted on 22-10-2018 at 13:27


You could dissolve the product in boiling water to convert the phthalic anhydride to phthalic acid (boiling should be sufficient to hydrolyse). The phthalic acid already present will obviously be unchanged. Then evaporate the water and weigh the phthalic acid left. It might form hydrates, I don't know so you'll have to check. In any case with some math you can figure out how much anhydride there was originally.

The method is also not wasteful since you can convert the acid back into the anhydride by strong heating.
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[*] posted on 22-10-2018 at 14:39


Quote: Originally posted by VSEPR_VOID  
Is there a simple test for it?


mp




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[*] posted on 22-10-2018 at 15:20


https://www.sciencemadness.org/whisper/viewthread.php?tid=25...



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[*] posted on 22-10-2018 at 18:24


So I left the solution out over night and got a cake when I came back. I was expecting a lot more yellow in the supernate. Its not very so. I am going to recrystallize my phthalic acid/phthalic anhydride and try again to see if that is the issue.



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[*] posted on 23-10-2018 at 14:36


I tried it again with phthalic anhydride I made and it worked as expected. Be weary of the phthalic anhydride you buy online.



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[*] posted on 24-10-2018 at 06:20


as i remember i reduced the solution a big by boiling it out and then i let it cooled down. You can also boil the water from remaining 4 nitro phthalic acid and try to make luminol from it too because i read somewhere that 4 amino phthalhydrazide has also glowing properties like luminol.
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