Cou
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(success) Preparation of isopropyl salicylate fragrant ester
Reference: doug's lab methyl salicylate video https://www.youtube.com/watch?v=vvrfHS4DRoM
To a round bottom flask in an ice water bath (to prevent dehydration of isopropyl alcohol to propene), I added these 2 chemicals:
* 13.80 grams / 0.1 moles salicylic acid (mole ratio 1)
* 28.40 mL / 0.371 moles isopropyl alcohol (mole ratio 3.7)
Then added 1 mL per minute while stirring:
* 5 mL / 0.0933 moles sulfuric acid (mole ratio 0.933)
I refluxed for 1.5 hours. Only 20 minutes in, I noticed the distinct smell of isopropyl salicylate coming out of the drying tube.
Once the mixture cooled down, a lot of unreacted salicylic acid precipitated out.
I filtered out the unreacted salicylic acid.
after adding an arbitrary amount of saturated sodium bicarbonate solution, I was ecstatic to see an oily layer form on top of the aqueous layer. I
collected the top layer, and did one more sodium bicarbonate wash.
I collected the crude isopropyl salicylate in a vial, to add to my collection of fragrant esters.
My current collection of esters (left is methyl salicylate, right is isopropyl salicylate)
Odor
It smells very different from methyl salicylate.
Methyl salicylate odor: sweet, wintergreen, root beer, mint lifesavers, mint mouthwash
isopropyl salicylate is not sweet at all, not as pleasant, but still smells nice. It's vegetal, green, spinach, limey, floral, herbal. Confirms
observations at https://www.sciencemadness.org/whisper/viewthread.php?tid=98... I would definitely make a green candle out of this, to give a room a herbal floral
vibe.
Since isopropyl alcohol forms an azeotrope with water, if you are doing this on larger scale (e.g. for making candles), you can improve yield with
soxhlet extractor and molecular sieves. reference: https://www.youtube.com/watch?v=Ah5ds_3s5BI
[Edited on 16-12-2019 by Cou]
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Cou
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it's cloudy and slightly yellow, but not gonna distill it because it's such a small volume that i risk losing it in my 24/40 distillation apparatus.
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Cou
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It seems that isopropyl alcohol is unusually soluble in isopropyl salicylate, because even with 2 water washings it still smells like rubbing
alcohol. I am redoing this, but skipping the water washes and going from 2 bicarb washes to simple distillation.
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Tsjerk
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Is there a reason you don't let the reaction run longer? Or with less salicylic acid, or with more alcohol? Obviously there is too much salicylic acid
in you reaction for the conditions you're using now.
I would also skip the water washing, a little bit of bicarb shouldn't matter
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Amos
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Quote: Originally posted by Tsjerk  | Is there a reason you don't let the reaction run longer? Or with less salicylic acid, or with more alcohol? Obviously there is too much salicylic acid
in you reaction for the conditions you're using now.
I would also skip the water washing, a little bit of bicarb shouldn't matter |
Yes, I've run most of my successful esterifications for at least 4 hours. Best way to get rid of excess isopropanol is to simply distill it off. Make
sure to water wash AFTER the bicarbonate washes until you can't detect high pH or you'll end up destroying the ester on heating.
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Cou
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I successfully purified the ester by simple distillation. It smells green, vegetable-like, herbal
in the doug's lab methyl salicylate video I referenced, and also nile red's methyl salicylate video, they both reflux for only 1.5 hours. Probably why
they use such a large amount of sulfuric acid, to speed it up? Anyway I did have success with only 1.5 hours. I distilled over about 10 mL of
isopropyl salicylate (following about 10 mL of isopropyl alclhol that distilled over before that), and it no longer smells like alcohol
Isopropyl alcohol seems to be unusually soluble in isopropyl salicylate, even 2 water washes doesn't remove the alcohol smell. About half of the crude
ester was isopropyl alcohol by volume, before distillation. Simple distillation is necessary to remove it
[Edited on 18-12-2019 by Cou]
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SWIM
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Congratulations!
Now sneak that isopropyl salicylate into the gym and pour some it on the Jock-strap of somebody you dislike.
No, put it in an ampoule and keep it.
Like the way a new store keeps the first dollar they take in as a memento.
Edit: that should've been the methyl salicylate.
You made that first, right?
[Edited on 18-12-2019 by SWIM]
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Cou
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I already keep a collection of fragrant compounds, and this is my 3rd one
I have:
Methyl salicylate (root beer, sweet, mint lifesavers, mint mouthwash)
Isopropyl salicylate (vegetables limey herbal)
1-pentanol (sweet bready yeasty fusel)
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RedDwarf
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What do you use to print/prepare your labels Cou? I like the structural formulae.
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Cou
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Chemdraw, then screenshotting the structure, pasting into Microsoft word
[Edited on 19-12-2019 by Cou]
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Cou
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I let some coworkers smell it, and one of them commented that it smells somewhat like latex in bouncehouses; i agree
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Jinc8
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I'm kinda 3 years late, but im suspecting that I accidentally produced some isopropyl salicylate while distilling the isopropanol I used in an aspirin
extraction. The liquid that remained in the flask smelled like neither IpOH or acetic acid, I'd also say it smells kinda latex/glue-like.
Anyway I'll definitely try this synthesis in the future, this is the first ester I've made and even though it was a byproduct it was really cool
nonetheless.
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