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mr_bovinejony
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Large scale anthranilic acid prep
All credit goes to a user formerly known as loft on another forum.
45 grams of methyl anthranilate is added to 200 ml of a 2M solution of NaOH. This is refluxed for 4 hours with stirring. After the 4 hours this is
cooled down and the top water layer is decanted from the small bit of oil at the bottom. 20% hardware store hcl is added until the stir bar doesn't
work, and this is filtered. Presumably the anthranilic acid but still waiting for it to dry so I can get a melting point.
Probably the most easiest synthesis for this stuff that I've found. The product filtered off is pure white. I have reason to believe this is the
product because the mother liquor which was filtered off was acidifed again to crash out more, but more acid than necessary was added and it all
dissolved again. Zwitterionic I think is the word used for anthranilic acid, which dissolves when ph is too high or too low. But I made no effort to
recover it.
I think I probably have around 30 to 35 grams of the powder but I'll update after it's dried. Reflux should be held longer until no oil remains after
cooling for a higher yield. Loft gets a 99% yield in his prep which I think is definitely achievable. Don't know why people struggle with this one, it
seems very simple
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Bubbles
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Methyl anthranilate 50ml or 58g was added to 150ml 3M NaOH solution and heated to 80C in a 600ml beaker. Quickly, all dissolved (about 30 min),
indicating conversion to anthranilic acid. After 45 min there was added 40ml GAA in 160ml water. Beaker, now full of precipitate, was cooled with a
cold water bath and then placed in freezer for a bit until ~8C. The off-white precipitate was filtered and washed with water. Yield=49g or 94%
[Edited on 22-2-2021 by Bubbles]
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karlos³
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Oh bubbles you're here too!
Of course you are
I miss the very nice grape flavour of that stuff, guess next time I'm going to get me some too, making IBX and DMP.
He's called attic on here
[Edited on 22-2-2021 by karlos³]
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Benignium
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Quote: Originally posted by karlos³ |
I miss the very nice grape flavour of that stuff, guess next time I'm going to get me some too, making IBX and DMP.
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Have you made IBX and/or DMP before? I wasn't aware of these compounds, they seem very useful and I'd appreciate any writeups you may have.
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Texium
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It’s something that I was really wanting to do, back before I became a grad student and thus forfeited all my time to do my own chemistry. I got as
far as making some 2-iodobenzoic acid.
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mr_bovinejony
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I got as far as ibx but the dmp failed for some reason
https://www.thevespiary.org/talk/index.php?topic=18228.0
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SuperOxide
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Very interesting... I have 500g of phthalimide that I will probably never use, which I could make the anthranilic acid from. But I was wondering if
this was a viable reaction route (which I was sure it was).
Good job guys, glad I found this.
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mr_bovinejony
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I recently did a run of 150 grams of the grape stuff, ill have more product than I'll ever need now. Recrystalization is fun too, although the size of
the run made it difficult. I have one half of pure white and the other half is the tan color
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SuperOxide
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Quote: Originally posted by mr_bovinejony | I recently did a run of 150 grams of the grape stuff, ill have more product than I'll ever need now. Recrystalization is fun too, although the size of
the run made it difficult. I have one half of pure white and the other half is the tan color | Pictures, or it
didn't happen
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Fery
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Btw the methyl anthranilate is available at https://shop.es-drei.de/ester/11927/anthranilsaeuremethylest...
I've bought it from there
1 L for 73 EUR
100 ml 14 EUR
check also the price of delivery and countries where they send by currier (DHL, DPD).
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mr_bovinejony
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https://imgur.com/ujQ4mhy
https://imgur.com/tnqXB1u
https://imgur.com/p92ZDLC
Here are some pictures from a 200 ml prep. The one I am holding came from the glass pie dish, it shows nicely the crystalline structure and difference
of color when left in open air. These were both from the same batch, and recrystallized from boiling dilute hcl. Evaporated over 3 weeks
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karlos³
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Yeah I order that from the thais, perfumersworld.
Its not exceptionally cheaper, not at all, but it slips right through the EU customs, so its much better to order from there than from the inside.
By the way(hint, hint!), check their products, they have LOTS of other cool things for the home chemist
I just made an order of almost 200$, and it landed here(DE) in just four days!
Only once in seven orders I had to pick it up from customs(despite having phenylacetic esters, helional and whatnot included), but only had to pay
importation tax.
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SuperOxide
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Heyy, very nice. I was expecting some nice white crystals though from your original post ;-)
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RustyShackleford
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Wow. Your anthranilic acid looks awful considering you started from the ester. Recrystallize it from water bare minimum, or better soxhlet it with
heptane to get pure white crystals.
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mr_bovinejony
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Eh that's what happens when its left out in the open for 3 weeks!
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SuperOxide
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Quote: Originally posted by RustyShackleford | Wow. Your anthranilic acid looks awful considering you started from the ester. Recrystallize it from water bare minimum, or better soxhlet it
with heptane to get pure white crystals. |
Are you spying on me?! jk. That's what I'm doing - literally right now
I have 20g of anthranilic acid (which was already through a water recryst), with some distilled/dried heptanes. Been in the soxhlet for a few hours
now. I may just let it run overnight (though I'm slightly uncomfortable knowing there's boiling heptane in the kitchen), and see how well it works. I
did a small scale earlier and it went for like 5 hours and it was less than a ~28% yield (only got 2.8g out of 10g), so it needs to run for a lonnnng
fricken time.
I'm sure you got this from the anthranilic acid purification thread by B.D.E, which is where I will post the results (yield and photos) after I'm
done. Likely tomorrow.
[Edited on 18-4-2021 by SuperOxide]
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SuperOxide
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This got me thinking - Have you ever had a white (or even slightly off white) purified product? Or does it always end up taking on
that brownish color? I ask because when I synth anthranilic acid from phthalimide (ACS grade, even), the crude product looks almost white, as seen
here:
But when I recrystallize the crude product in boiling water, the product comes out looking light brownish in color:
I've tried tweaking various things such as the temperature during the reaction or how quickly/slowly I add the reagents, how concentrated they are, or
what solvent I use in the recryst, it always comes out the same:
(The middle one is a different color because I took it out of the ice bath a little too early when adding the
phthalimide. All other runs were the same color as on the two sides).
So when you say:
Quote: | The product filtered off is pure white. |
are you talking about the crude product?... because if that's the case, then I'm a little less impressed, lol. (don't take that as an insult, this is
still a much better synthesis route than using phthalimide).
[Edited on 18-4-2021 by SuperOxide]
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mr_bovinejony
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From what I've seen, the hoffman route usually gives a brown product. When I was filtering this product from the boiling dilute hcl, it turned to pure
white crystals when it hit the cold crystallizing dish which is where that statement came from. It was very nice to look at, I should have covered it
before it was left alone
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SuperOxide
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Quote: Originally posted by mr_bovinejony | From what I've seen, the hoffman route usually gives a brown product. When I was filtering this product from the boiling dilute hcl, it turned to pure
white crystals when it hit the cold crystallizing dish which is where that statement came from. It was very nice to look at, I should have
covered it before it was left alone | For sure. I would love to see if it can yield a more pure
product than the Hoffman route.
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mr_bovinejony
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I definitely think so, even with the brown discoloration it had a very sharp melting point.
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SuperOxide
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As did the recryst product from the Hoffman route.
Regardless, this route is still wayyyy better, and much higher yielding. You just teased me with the "yields a white product" part - especially
considering I just spent over 12 hours running a soxhlet extractor with heptane to purify some anthranilic acid, and while it's almost white (just
barely off white), it's so low yielding that I'll never try it again, lol.
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mr_bovinejony
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The hoffman reaction is bullshit for any chemical lol. I weighed all this yesterday and it was 210 grams. Way more than I'll ever need.
Just remembered I added my old batch to the new stuff. So 180 grams from 200 mls of the grape stuff
[Edited on 18-4-2021 by mr_bovinejony]
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SuperOxide
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Quote: Originally posted by mr_bovinejony | The hoffman reaction is bullshit for any chemical lol. I weighed all this yesterday and it was 210 grams. Way more than I'll ever need.
| Pardon my noobness - but why do you say that? Chemistry is a relatively new hobby to me, and the anthranilic
acid synthesis from phthalimide was my first hofmann rearrangement reaction (I think... in the beginning I was just copying procedures online without
looking into the chemistry behind it, so perhaps I did it and didn't even realize it). But I'm curious why you say it's bullshit for any reaction and
what you mean by that.
I too
have more than I will likely ever use (I think 100g of the anthranilic acid), so I doubt I'll ever need to make more, but if I do then I definitely
will use this route!
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karlos³
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Said the guy who uses the hofmann for his favorite substance
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mr_bovinejony
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@oxide I just don't like the reaction, titration of store bought bleach is a pain and temperature control during the reaction is hard. It may be
different now that I upgraded my hotplate, but I'm in no rush to do it again
@carl I've done the hoffman twice and it's provided me with enough compound to last at least two more years sometimes you gotta go through pain to get to the good stuff
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