zule21
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Isatoic anhydride hydrolysis to anthranilic acid
Hi everyone,
I'm trying to hydrolyze isatoic anhydride to anthranilic acid. I found a paper stating when done using NaOH a major side product occurs during
heating that causes the formed intermediate to react with itself before CO2 is lost. I know HCl should do the trick and am wondering if 10-15%
refluxed for 30-40min will do it? I know in this instance most are trying to go the opposite way here but I have excess isatoic anhydride and this
seems easier than running a hofmann rearrangement. Any help anyone can provide here would be greatly appreciated.
[Edited on 17-8-2015 by zule21]
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Nicodem
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Thread Moved
17-8-2015 at 11:39 |
Waffles SS
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For making Anthranilic acid i usually dissolve Isatoic anhydride in alkaline solution an add Acetic acid
Carbon dioxide release and Anthranilic acid precipitate as brown Crystal Needles after some times
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zule21
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Hey, thanks for the response. Think I just wasn't thinking things through. The paper I have (Isatoic Anhydride. IV. Reactions with Various
Nucleophiles) states equimolar amounts of NaOH, anthranilic acid and IA form anthraniloylanthranilic acid. With excess sodium hydroxide present the
formed amide would undergo hydrolysis if it formed. I gave it a try and the melting point is spot on =) Thanks again
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MountainMan
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I'm trying to make a small amount of anthranilic acid from isatoic anhydride. (The anthranilic acid will be used to prepare methyl anthranilate.) I
only have a limited amount of the isatoic anhydride and was seeking some help on the hydrolysis conditions to use, e.g., acid or base hydrolysis,
actual amounts/concentrations of the reactants, temperature, etc..
Note: I did perform a search but didn't really come up with any references other than the posts above.
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Pumukli
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I hope you didn't wasted your anhydride in a hydrolysis attempt - because I have good news for you! 
A few days ago I prepared your wanted ester from your anhydride without hydrolysis, via the direct route. It worked nicely.
The method: mix methanol:anhydride:solid, dry NaOH pellets in roughly 60:20:1 molar ratio and slowly warm the mixture. I don't have my lab notes at
hand but from the top of my head CO2 started to evolve around 25 C, albeit slowly. With careful heating you can heat up the mixture slowly to the
reflux temp of methanol, though I stopped at about 50 C because I had no reflux cooler attached. (I worked in a bigger test tube with 6-8 mmol
anhydride.) I got an ugly black oil what I purified by steam distillation and got some (maybe a ml) faintly orangish oil. The smell is not bad but I
expected something much more fruity. Vacuum distillation is the preferred purification method though.
Use dry methanol and dry NaOH, because water causes some anthranyloanthranylic acid to form. With proper reagents the achievable yield is almost
quantitative! (Compare this with the yield of the combined hydrolysis - esterification route's.)
The method was unfortunately not popped out of my head but the reference is in the lab notes... The authors wrote that if you use regular, 96% ethanol
instead of absolute ethanol then the yield would suffer from the mentioned side reaction and yield "only" 80% ester. (Which is still pretty good.)
Btw I used roughly a 240:20:1 mixture and all went well.
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