Murexide
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Preperation of ethyl salicylate
Ethyl salicylate is an oil that is somewhat similar to wintergreen. Its preperation is from aspirin (extraction, hydrolysis, esterification).
For the esterification step 0.5g of boric acid (catalyst), 20mL of ethanol (95% methylated spirits) and ~4g of salicylic acid was used. Reflux was
done for 1.5 hrs.
According to numerous papers and online sources, this should yield a milky suspension which seperates into two layers upon addition of 2M NaOH. I have
done this experiment twice now, and the in neither attempt did two layers (or milky suspension) form. Salting with NaCl did not help any layers
seperate.
However, there is a strong smell resembling wintergreen (especially after pouring it down the sink - where a cloudy suspension somehow suddenly
forms!?). This indicates that there must be product, however I am unsure how to seperate it.
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XeonTheMGPony
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Well start form pure ethanol.
Distill and dry, Same for the Boric acid dry it out first. See where that gets you.
then on termination add your hydroxide solution.
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UC235
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Boric acid is extremely weak and will not catalyze esterification meaningfully. Use sulfuric.
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DraconicAcid
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Actually, it will.
https://www.scientific.net/AMR.466-467.319
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Tsjerk
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I would run the reaction for a significantly longer time. For example 6 hours or so. Or maybe let it go for a day, I don't know of side products
building up when run after equilibrium is reached.
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SaccharinSlayer751
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I wouldn't worry much about getting the methylated spirits too pure. They're already >80% ethanol with the rest being methanol and negligible
amounts and ketones in some formulations. Your main problem seems to be that you are using a very weak acid. I've run the methyl esterification with
sulfuric numerous and it's worked flawlessly so I would recommend trying the same here.
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Abromination
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I'm interested in the idea of the boric acid catalyst. I will try it with methyl salicylate and see how it goes.
List of materials made by ScienceMadness.org users:
https://docs.google.com/spreadsheets/d/1nmJ8uq-h4IkXPxD5svnT...
--------------------------------
Elements Collected: H, Li, B, C, N, O, Mg, Al, Si, P, S, Fe, Ni, Cu, Zn, Ag, I, Au, Pb, Bi, Am
Last Acquired: B
Next: Na
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nezza
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Water is the enemy. While boric acid will catalyse the reaction it will not increase the % product at equilibrium. Sulphuric acid both catalyses the
reaction and removes water driving the equilibrium to the right (more product).
If you're not part of the solution, you're part of the precipitate.
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mayko
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This was a new one for me too. I wonder if boron trioxide would work while also sponging up the water produced?
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DraconicAcid
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I tried again to make butyl salicylate, once using boric acid as a catlyst, and once using sulphuric. Neither gave me a damned thing.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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DraconicAcid
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I've given up on trying to make esters of salicylic acid. I've switched to cinnamates. They work better.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Ubya
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well, it's strange, it's a common didactic experiment, it's hard to get absolutely nothing
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feel free to correct my grammar, or any mistakes i make
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Bedlasky
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I agree with Draconic acid. Salicylic acid, 4x excess of EtOH, sulfuric acid, 2 hours reflux - nothing, all salicylic acid crystallize. More sulfuric
acid, 3,5 hours reflux, after that everything mixed with water to see if ester layer separate - nothing, just few oil droplets on water surface.
Organic chemistry in practice... Organic chemistry works well on the paper, but reality always sucks. I go back to inorganics, I really don't have
patience for these stupid equilibriums, poor yields and long reaction times.
[Edited on 28-11-2022 by Bedlasky]
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DraconicAcid
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Wait- the OP said they added sodium hydroxide? You don't want to try neutralizing the acid mixture with hydroxide- if it doesn't hydrolyze the ester
you just made, you'll deprotonate the salicylate. Neutralize with carbonate.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Bedlasky
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I didn't add NaOH. Mixture after reflux even didn't smell like wintergreen, it smell like EtOH. Reaction simply didn't occure.
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DraconicAcid
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I was referring to Murexide, who got the smell, but not the product.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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arkoma
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hmmm. i love esters, and have done salicylates. Mebbe i'll get up off of my crippled but and run some.(arky gets up to find his lab notebook and check
when he did those reactions)
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DraconicAcid
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I did manage to make the propyl salicylate once, and it smelled like celery. Never managed butyl, which is supposed to smell very strongly of
blackberries.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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