Sciencemadness Discussion Board

3-nitrophthalic acid fail (EVERY TIME)

shivam - 25-2-2016 at 01:23

Hello!
So I've been trying to make 3-nitrophthalic acid as a precursor to luminol and failing miserably every single time..

I have practically unlimited supply of Phthalic anhydride and I've nitrated it more than 5 times

After adding the nitrated mixture to cold water and leaving it to hydrolyze, I don't get any precipitate. Not even after chilling it completely in freezer. The solution stays lime-green to fluorescent-yellow colored and there's no sign of 3-nitrophthalic acid crystallizing. I have used really minimal to a good big amount of water to hydrolyze it in different runs. But nothing has worked so far..

Is there any problem or solution that you guys can point out??
Thanks in advance..

Schleimsäure - 25-2-2016 at 01:45

Here is an instruction, but in German:
illumina-chemie.de/3-nitrophthalsaeure-t956.pdf


The phthalic anhydride in H2SO4 is held in a water bath with 85 C until dissolved completely. HNO3 is dropped to it with 1-2 drops per second. This should give the first precipitate. Later after cooling add destilled water while cooling the beaker/flask.
Let the beaker/flask stand for a few days and the 3-nitrophthalic should crystallize out. 4-Nitrophthalic should stay in solution and can be filtered.
The pictures show that it worked this way.







[Edited on 25-2-2016 by Schleimsäure]

HeYBrO - 25-2-2016 at 01:45

Give some quantities and concentrations of your reactants and details of your procedure. Also have you confirmed your phthalic anhydride is indeed the anhydride and not the acid? (m.p?)

shivam - 25-2-2016 at 02:04

The way i did it, I first made a fresh batch of Phthalic anhydride by dehydrating Phthalic acid and subliming the Phthalic anhydride.
Then i prepared nitrating mixture by combining 3 volume parts 98% Sulfuric acid and 1 volume part 72% Nitric acid.

I used a bit excess of nitrating mixture (excess calculated on HNO3 present) to make sure all the Phthalic anhydride is nitrated
The temperature range was kept from 100C to 120C

DJF90 - 25-2-2016 at 03:37

Are you using a reflux condenser? Nitric acid boils at 83 *C

shivam - 25-2-2016 at 03:45

No. I didn't actually..
I used quite a bit of excess so i thought it wouldn't be a problem..
Plus the lime green fluorescent colored solution actually kinda confirmed the 3-nitrophthalic acid
I just can't get it to crystallize..

byko3y - 25-2-2016 at 06:24

Obviously, you've failed because you are moron. Still after three messages you did not describe in details actual nitration process. I mean order of addition, time of reaction, changes in reaction mixture dring the process, etc. Neither did you provider a literature where you 've got the procedure from The preparation of 3-Nitrophthalic acid , nor you used a search engine to find existing threads Synthesis of 3-Nitrophthalic Acid; Luminol Precursor

Amos - 25-2-2016 at 07:50

Quote: Originally posted by byko3y  
Obviously, you've failed because you are moron. Still after three messages you did not describe in details actual nitration process. I mean order of addition, time of reaction, changes in reaction mixture dring the process, etc. Neither did you provider a literature where you 've got the procedure from The preparation of 3-Nitrophthalic acid , nor you used a search engine to find existing threads Synthesis of 3-Nitrophthalic Acid; Luminol Precursor


The procedure is fairly well-known. And the OP posted it in beginnings. And nobody here should be calling anyone a moron, least of all you.

shivam - 25-2-2016 at 07:59

There's a reason why I posted in Beginners section
I did not exactly claim to be Antoine Lavoisier before posting the query..
Anyway, this moron will see himself out. Sorry for wasting your time, "sir".

p.s. you're a 30 year old (seemingly experienced) person in the field
I'm a 19 year old trying to learn new things in this area because it interests me..
How does that even remotely justify you calling me a moron?

[Edited on 25-2-2016 by shivam]

Magpie - 25-2-2016 at 08:50

shivam, I hope this one incident does not prevent you from further participation in this forum. Maybe he had a fight with his wife, or just hadn't had his morning coffee...

Here's a link to my post on making 3-NPA. So keep at it. I have high confidence you will eventually find your problem. ;)

http://www.sciencemadness.org/talk/viewthread.php?tid=12389#...

[Edited on 25-2-2016 by Magpie]

shivam - 25-2-2016 at 09:15

Thanks a lot Magpie
I'm not even mad really.. Maybe he had his reasons to react violently (lame chemistry pun intended lol)
Thanks for the moral support and for the link as well..
And don't worry, my passion for chemistry is not something that can just be ended by someone saying a few words like that..

Well, off I go, Gotta work on these problems now :)

[Edited on 25-2-2016 by shivam]

byko3y - 25-2-2016 at 10:29

Amos, I know the procedure is well known, but I don't know what shivam knows, neither I know what he actually obtained. "I can't get the final product" is a bad input to work with.
Quote: Originally posted by shivam  
There's a reason why I posted in Beginners section...
you're a 30 year old (seemingly experienced) person in the field
I'm a 19 year old trying to learn new things in this area because it interests me..
How does that even remotely justify you calling me a moron?
I'm a young amateur chemist, just like you. The difference between me and you is that I'm trying to figure things out, while you don't.
Do you really think I'm wrong? Than explain me why did you perform 5 experiments with the same reagents and conditions, over and over and over and over again, despite the fact it does not work.
You posted in the begginning section, that's why I kindly explained you why you are a moron, and I gave the links to further describe my point. I don't see anything wrong in my actions.
Magpie, that's the link I provided.

chemrox - 25-2-2016 at 13:03

I don't care for name calling! This was posted in the beginner's thread. You might have simply suggested a few things to the guy instead of blasting him. Please gentlemen a little harmony for christsfockingsake.