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Author: Subject: Benzaldehyde By Reduction Of Benzoic Acid
Keras
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[*] posted on 13-3-2022 at 12:26


Quote: Originally posted by hodges  

From the videos I've watched, this reaction appears to work the best with acetone, with ethanol being a poor second. If you used isopropanol, I'm guessing you got acetone first of all, then that was probably oxidized second as well, which would explain why it worked better.

Not sure what reaction might occur with benzyl alcohol, but one thing to note (as you probably have already) is that benzyl alcohol boils at over 200C. So you will definitely need to heat it to get an appreciable amount of vapor for the reaction.


I’m not sure what acetone would be oxidised into. To me, isopropanol gives acetone, but acetone should be pretty unreactive. The reaction works pretty well with isopropanol, even better than with alcohol (but that can be just due to random circumstances).

As for benzyl alcohol, I tried once, but it didn't work. I suspect I didn't heated the beaker enough, so I’ll have to try again at a higher temperature.

It is surprising though that, in every case, when the red-hot copper coil is plunged into the vapour, it doesn’t burst aflame. That baffles me.
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[*] posted on 13-3-2022 at 12:54


According to this site: How to Make Copper Glow Red Hot With Acetone

Copper catalyzes the oxidation of Acetone to acetaldehyde, carbon dioxide, and water.
CH3COCH3 (g) + 3/2O2(g) --> CH3CHO(g) + CO2(g) + H2O(g)


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[*] posted on 13-3-2022 at 12:58


Quote: Originally posted by Keras  
It is surprising though that, in every case, when the red-hot copper coil is plunged into the vapour, it doesn’t burst aflame. That baffles me.


Oddly enough, that's happened to me every time I've tried that reaction.




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[*] posted on 13-3-2022 at 13:09


Quote: Originally posted by DraconicAcid  
Quote: Originally posted by Keras  
It is surprising though that, in every case, when the red-hot copper coil is plunged into the vapour, it doesn’t burst aflame. That baffles me.


Oddly enough, that's happened to me every time I've tried that reaction.


It did ignite two or three times, but that’s a very minor occurence (I must have tried it twenty or more times). Probably the reaction works best when there is not enough oxygen to sustain a full combustion?
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[*] posted on 13-3-2022 at 13:12


Quote: Originally posted by hodges  
According to this site: How to Make Copper Glow Red Hot With Acetone

Copper catalyzes the oxidation of Acetone to acetaldehyde, carbon dioxide, and water.
CH3COCH3 (g) + 3/2O2(g) --> CH3CHO(g) + CO2(g) + H2O(g)




Interesting. I also note that the web site quotes the formation of ketene, which would probably arise from acetone pyrosis on the red-hot copper (as well as methane). I suppose, however, that this is an endothermic, non self-sustaining reaction.
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[*] posted on 21-3-2022 at 21:45


The reduction of Benzoic Acid to Benzaldehyde is not especially difficult. But, it isn't exactly easy, in this era of chemical restrictions and overall high prices.

As I recall, the Rosemund reduction works pretty well. I'll find an example.

http://orgsyn.org/demo.aspx?prep=cv6p1007

[Edited on 22-3-2022 by zed]
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[*] posted on 23-3-2022 at 07:48


i tried benzoic acid with galinstan and aluminium- didnt work
it did reduce KNO3 into KNO2 in solution though, only very small scale experiment. its somewhat possible with ascorbic acid

seems you might have to turn benzoic acid into benzene and then go from there, sadly. not that big problem since theres toluene in gasoline.




~25 drops = 1mL @dH2O viscocity - STP
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https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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[*] posted on 23-3-2022 at 08:13


You mentioned earlier that you had some success with ascorbic acid, which I find hard to believe. How did you verify that?



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[*] posted on 26-3-2022 at 05:54


Quote: Originally posted by njl  
You mentioned earlier that you had some success with ascorbic acid, which I find hard to believe. How did you verify that?


simply by odor, i dont think i had generated enough to precipitate it out with NaHSO3. youre welcome to try it out for yourself

using galinstan i only used water, no base or acid was added- benzoic acid would react with base to form sodium benzoate which should be more resistant to reduction and im a bit worried the gallium would react with acid, though that would increase the reaction speed and hydrogen formation speed




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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[*] posted on 17-4-2022 at 10:37


i just came across one of chemplayers videos, it was about the video where he mixed up calcium salts and thermally decomposed them to form other compounds- benzaldehyde was attempted but he didnt use vacuum or inert atmosphere so it didnt work, but there was a hint of benzaldehyde so with vacuum it should be well doable

https://www.bitchute.com/video/DgHHnEGQVaCp/

calcium benzoate + calcium formate was the mix used, i believe someone hinted at it in this thread, maybe one could add some ethanol to push out oxygen from the apparatus, maybe simply add in some butane instead and then clamp the whole rig up so that it can just barely expel excess gas?




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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