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Author: Subject: Isopropyl salicylate sensitivity
night429
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[*] posted on 5-4-2024 at 22:33
Isopropyl salicylate sensitivity


I recently made isopropyl salicylate following a paper that detailed its synthesis. I did it a little bit fast and loose, using pressed-dry salicylic acid and non-distilled isopropyl alcohol I dried from 91% using sodium hydroxide, followed by decanting the upper layer and neutralizing with 93% sulfuric acid (which I also used as the catalyst in the esterification).

In using heptane to extract instead of chloroform, since the paper mentioned it was "extremely soluble in hydrocarbons", I only got about 1mL of the expected 12mL. The only reason I can think of as to why this was so low is because of the small amount of water present.

I did manage to recover 8.6g of salicylic acid after acidification and a recrystallization. Was this low yield due to my fast and loose method of synthesizing it?




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Dr.Bob
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[*] posted on 6-4-2024 at 17:31


isopropyl alcohol is pretty sterically hindered, so I would expect it may just be really slow, plus the water will slow it down some. But I suspect if you could reflux it longer, it would go much closer to completion. isopropanol should not be too hard to find dry, so it might be worth trying.
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night429
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[*] posted on 7-4-2024 at 16:07


Quote: Originally posted by Dr.Bob  
isopropyl alcohol is pretty sterically hindered, so I would expect it may just be really slow, plus the water will slow it down some. But I suspect if you could reflux it longer, it would go much closer to completion. isopropanol should not be too hard to find dry, so it might be worth trying.


Thanks for the recommendation. I'll have to repeat the synthesis and reflux it for at least double the time to see how much it increases yield.

Honestly, I'm just shocked that the paper reports having a good yield in only 8 hours.
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DraconicAcid
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[*] posted on 7-4-2024 at 17:51


Quote: Originally posted by night429  

Honestly, I'm just shocked that the paper reports having a good yield in only 8 hours.


Well, it is a Russian paper.....

Anyway, what did it smell like? We all know that methyl salicylate is wintergreen, butyl salicylate is supposed to smell like blackberry, and I find that propyl salicylate smells exactly like celery.

[Edited on 8-4-2024 by DraconicAcid]




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night429
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[*] posted on 7-4-2024 at 19:27


Quote: Originally posted by DraconicAcid  
Anyway, what did it smell like? We all know that methyl salicylate is wintergreen, butyl salicylate is supposed to smell like blackberry, and I find that propyl salicylate smells exactly like celery.


I've found it smells similar to a glossy magazine while dilute, turning slightly wintergreen-like when concentrated.

It's always fascinating how a small change in alcohol length makes a large difference in smell with these.
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