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SuperOxide
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Quote: Originally posted by mr_bovinejony  | | @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 |
The bleach titration is a
little tedious, but nothin too bad. As for the temperature, just lots of salt and ice does the trick for me.
I've decided I'm going to do it one more time (even though I have a lot of anthranilic acid), I want to test a recryst of the crude product (which is
almost white) with solvents other than water (MeOH, ether, chloroform/heptane, etc). I have a feeling that may yield some nicer crystals.
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karlos³
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| Quote: Originally posted by mr_bovinejony |
@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 |
Oh look who's talking, its mister large scale bragging again
Hehehe 
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SuperOxide
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njl
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Details?
Reflux condenser?? I barely know her!
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karlos³
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No need for this, we are actually quite good friends and I'm just teasing my pal
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mr_bovinejony
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My inability to do reactions under a 3 gram scale has been my downfall. But when it works its the greatest feeling ever
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SuperOxide
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Oh I know. I got the feeling you two were just messing about. 
I know how you feel! When I do a reaction on a small scale, even when it works it's not too exciting. I try to keep smaller scale reactions to test
runs or POC's.
[Edited on 20-4-2021 by SuperOxide]
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SuperOxide
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Well, embarrassingly enough, I can't get this to work 
Your procedure that you outlined in the first post was basically as follows:
Add 45g of methyl anthranilate to a flask.
To the same flask, add 200mL of 2M NaOH solution
Reflux for 4 hours with stirring, then let cool.
Upon cooling the reaction mixture should separate into a biphasic mixture.
Separate the bottom layer and add 20% HCl until enough AA precipitates that the stir bar will no longer work.
Filter and purify.
Which seems dead simple... I tried this first with the same scale that you did (45g MA + 200mL of 2M NaOH), and after the refluxing I let it come to
room temperature, but it remained one phase. I tried salting out the oil phase with varying amounts of salt with no success.
I assumed it was the (likely) low purity methyl anthranilate I got off ebay, so I decided to get some decently pure methyl anthranilate from HiMedia
off of Amazon. I was so sure that it would work this time that I bumped the scale up 2x (90g MA + 400mL 2M NaOH), but after refluxing for 4 hours and
letting it cool, I was disappointed to find out that there was no second phase.
More pictures here.
The NaOH solution was freshly made by adding 40.0g of NaOH to some distilled water, once dissolved and cooled to 25 °C, it was added to a 500mL
volumetric flask and enough distilled water was added to get it to the 500mL volume line. Then 400mL of that was added to the 1L RBF for the reflux.
What could I be doing wrong here? I'll let it sit over night, maybe something will separate over night (doubtful).
Unless someone here has any suggestions, I may try distilling off some of the volume to see if that helps the denser phase containing the MA to
separate.
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Tsjerk
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mr_bovinejony just describes he had an oily contamination (unreacted methyl anthranilate?) which he got rid of by decanting the reaction mixture. If
your starting material is pure and the reaction goes to completion, I don't expect any separation.
All that is in there is sodium anthranilate, NaOH, methanol and water. Sodium anthranilate dissolves in water.
Just add a calculated amount of HCl (exactly enough to neutralize the NaOH you used) and filter the precipitated anthranilic acid.
[Edited on 19-9-2022 by Tsjerk]
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SuperOxide
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| Quote: Originally posted by Tsjerk | mr_bovinejony just describes he had an oily contamination (unreacted methyl anthranilate?) which he got rid of by decanting the reaction mixture. If
your starting material is pure and the reaction goes to completion, I don't expect any separation.
All that is in there is sodium anthranilate, NaOH, methanol and water. Sodium anthranilate dissolves in water.
Just add a calculated amount of HCl (exactly enough to neutralize the NaOH you used) and filter the precipitated anthranilic acid.
[Edited on 19-9-2022 by Tsjerk] |
Oh wow, holy crap.. I thought he discarded the top later and did the workup on the oily bottom layer.. this makes so much more sense.
Thanks!
Edit: Here are pics of the crude results (not yet weighted out)
It's in the vacuum desiccator now. Once it's dry, I think I'll experiment with different methods of purification. I really want to try the sublimation
as pointed out by Fery.
[Edited on 19-9-2022 by SuperOxide]
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Tsjerk
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That looks nice doesn't it? Let us know how the sublimation works out.
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SuperOxide
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It does! I have a theory that water may be part of what causes the discoloration upon recryst. When I did the purification using heptane in the
soxhlet extractor it came out nearly colorless when I did the recryst using MeOH. But then I (stupidly) added some water and that's when it started ti
discolor. So I want to get it 100% dry, then I will try the sublimation and also a recryst using MeOH (or EtOH).
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DocX
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This is great stuff! Wonderful to see this route successful. Now all I need is some methyl anthranilate ....
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SuperOxide
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| Quote: Originally posted by DocX | | This is great stuff! Wonderful to see this route successful. Now all I need is some methyl anthranilate .... |
I would recommend getting it from HiMedia off Amazon... It's 102% pure. Can't beat that, lol.
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DocX
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Not the same economic area mate . Doesn't show up when I search Amazon.
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Lionel Spanner
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This site sells it at $11 per 100 g.
https://www.perfumersworld.com/view.php?pro_id=4NC00295
As far as I know it ships from Thailand, so depending on where you are it may take some time to get to you.
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Fery
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https://shop.es-drei.de/ester/11927/anthranilsaeuremethylest...
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Lionel Spanner
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They have a fantastic selection of reasonably-priced chemicals; the only drawback is that they don't deliver to anywhere outside the EU.
On a totally unrelated note, has anyone had chemicals shipped to a dedicated drop point in Germany and then had them successfully forwarded on thanks
to a dedicated forwarding service e.g. https://www.forward2me.com/ ?
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Mateo_swe
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es-drei.de dont deliver to all EU countries anymore.
I ordered lots of stuff from them a few years ago but now they say the paperwork to ship to Sweden is so much work so they stopped selling to Sweden.
Very sad as they have much stuff of intrest for hobby chemists.
I can understand them somewhat as my orders got stopped by DHL Sweden and they required the seller (es-drei) to deliver very much documentation on all
items if they were to deliver the shippment.
DHL also didnt accept electronic documents, they required the papers to be sent by paper form.
DHL is such a hassle to use, never do the shipping with them if you order chemicals.
And es-drei has some deal with DHL to use them for all shipping (at least a few years ago), i hope they change that so i can order from them again.
Otherwise es-drei is a very good supplier that has much stuff not found anywhere else for hobby chemists.
So if you are in some other EU country check them out, very recomended.
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SuperOxide
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Sublimation failure; Recrystallization success
Hey chaps. I had some time today to give this sublimation a shot. Initially I thought that maybe I should try to recrystallize it first, then
move on to sublimation. I decided against that because of how nice looking the crude anthranilic acid looked to begin with... But I will soon regret
this
Link to imgur album with all photos (not all shown below). To enlarge the below images, just right click -> Open Image In New Tab.
Here's the crude AA after it was thoroughly dried over P2O5 under vacuum. See how nice it looks? Kinda why I figured why it's probably pure enough to
move right onto sublimation.
Sublimation setup, in my state-of-the-art laboratory.
Note: I did flame dry the glassware used, which is totally overkill.
And right off the bat it liquified pretty quickly (as expected - it has a mp of 146 to 148 °C).
At this point, it's all entirely liquified. I continued to heat it to past 200 °C (sublimation point), but it started to boil, not sublime.
After I let it cool down, some interesting crystals started to form on the sides, but this was just from the liquids vaporizing then condensing and
solidifying on the sides.
I did try a few things like heating it up slower, heating it up faster, but the result seemed to be the same.
So now I get to go back to my first instincts - recryst then sublimation. I know I've mentioned in a few AA threads that I have a suspicion
that any anthranilic acid recryst using water seems to always result in dirty looking brown crystals. So I decided to go with my MeOH (which was
fractionally distilled from HEET and dried with sodium).
And this yielded the best looking anthranilic acid crystals I've ever made to date:
I'll recryst the rest of the AA in the same fashion.
I still do plan on trying the sublimation with the newly purified AA, but I don't have time to do it today. But I wanted to share the above results
thus far.
The takeaways:
Even though this AA prep from methyl anthranilate yields a much cleaner looking crude product, there's clearly still some impurities present
that caused the entire thing to liquify very quickly under a flame.
Stay away from using water in any recrystallization for anthranilic acid. A recryst from MeOH will probably yield a pure enough result for any
amateur needs.
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Fery
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Very nice experiment and a lot of effort! How strong vacuum produces your pump? Your recrystallized product looks very pure, it is very likely
unnecessary to sublime it. In org chem we usually do not need extra superior purity as almost every reaction has some side reactions.
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SuperOxide
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Thanks! And it's a KNF
UN726FTO. I think the valve reflects that it gets down to around -25 inHg.
| Quote: Originally posted by Fery | | Your recrystallized product looks very pure, it is very likely unnecessary to sublime it. In org chem we usually do not need extra superior purity as
almost every reaction has some side reactions. |
I couldn't agree more, especially when you consider that they
typically would look more like this:
http://www.sciencemadness.org/talk/files.php?pid=658533&...
http://www.sciencemadness.org/talk/files.php?pid=658511&...
If I had an actual synthesis planned for the anthranilic acid, then I would move on. But this thread has me curious about the sublimation method for
purification, so I think I'll give it one more shot. Benignium suggested that I don't use a flame next time and use a more conventional heat source,
so I'll probably get a smaller fabric heating mantle.
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Fery
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SuperOxide - also the. stronger vacuum the lover temperature at which anthranilic acid sublimes
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SuperOxide
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Just a quick recryst update - Whenever I do a recryst, after I pull the first and second crop out I usually let the mother liquor evaporate slowly,
just to see what else comes out. And I found an odd surprise this time. imgur album
Some nice, large single crystals of anthranilic acid started to show up, but a more obvious development was several crops of a much darker substance:
Pretty peculiar.. But I guess that's to be expected when you've already pulled a couple crops out of the main component. The residual impurities tend
to fall out.
But I did get some nice larger crystals of anthranilic acid:
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Pumukli
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Wow! This is separation and efficiency! Hats off, SuperOxide!
I want to do this to my "craps" too!
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