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Author: Subject: Denatonium Benzoate synth and purification?
foxofax474
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Registered: 17-4-2023
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Mood: Still processing

[*] posted on 7-1-2025 at 01:01


So recently after I finished purifying my benzyl chloride I decided to go try to synthesize denatonium benzoate following Nilered’s procedure scaled up 7x (molarity wise), and also partly referring to https://pubs.acs.org/doi/10.1021/acs.jchemed.1c00995

To a rbf I added water, freebased lidocaine (from lidocaine HCl bought from Carolina chemical), and my triple distilled (2 fractional, 1 regular) benzyl chloride, and refluxed overnight. The reagents I used should be pure, however, unlike nilered who got a clear product, I got a blue opaque solution



I thought this was odd, but it could be possible that I decomposed the lidocaine on accident by doing a reflux instead of just heating between 70-90C :upside_down:but regardless I proceeded with the toluene cleanup step by washing the crude solution with toluene



which seemed to take out a lot of the blue color.

Then, after removing toluene, adding sodium hydroxide turned the blue color yellow and precipitated what I presume is denatonium hydroxide



after which boiling down the solution gave a beaker with a layer of goey, viscous yellow oily substance (I think very impure denatonium hydroxide) and some wierd crystals of something in the water



I tried purifying it by washing it with acetone, since from nilered's video denatonium hydroxide doesn't seem to be soluble in cold acetone, but it just seemed to dissolve the goop instead. So whatever, I proceeded by adding excess benzoic acid in acetone and boiled the solution down like nilered did, and arrived at a solid opaque chunk of green goop



Trying to mix it with acetone to wash it does not work and I just have this blob of what seems to be a bunch of polymerized junk and little to no denatonium benzoate. There goes 20 out of the 100 grams of lidocaine HCl :cry:

=================================

So overall I kinda fucked up hard on this supposedly easy synth :sweat_smile:

Does anyone have any advice on this synth?

I'm assuming that the denatonium ion is quite heat sensitive, so I would have to actually be careful and control the temps during the first reaction, and instead of boiling down the solution I would pull a vacuum and heat it gently to drive off everything. But is there anything else I should note or be careful about?

Furthermore, I have 0 clue how to purify the denatonium salts. There is little to no information online that I could find (the paper was all I could find but they don't purify anything bruh) on the solubilities of denatonium salts in various solvents, and my limited testing using ethyl acetate, isopropyl alcohol, toluene, and acetone yielded no results (it seems like denatonium hydroxide/benzoate along with its impurities are jointly insoluble in toluene and soluble in everything else).

If anyone has any idea how to purify denatonium salts along any step of the procedure (purifying say denatonium chloride, hydroxide, or benzoate, or even saccharin) please let me know.




(∩^o^)⊃━☆ the proof is by magic


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