Murexide
Hazard to Self
Posts: 51
Registered: 1-12-2018
Member Is Offline
|
|
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.
|
|
|
XeonTheMGPony
International Hazard
Posts: 1640
Registered: 5-1-2016
Member Is Offline
Mood: No Mood
|
|
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.
|
|
|
UC235
National Hazard
Posts: 565
Registered: 28-12-2014
Member Is Offline
Mood: No Mood
|
|
Boric acid is extremely weak and will not catalyze esterification meaningfully. Use sulfuric.
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
|
|
|
Tsjerk
International Hazard
Posts: 3032
Registered: 20-4-2005
Location: Netherlands
Member Is Offline
Mood: Mood
|
|
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.
|
|
|
SaccharinSlayer751
Harmless
Posts: 6
Registered: 28-3-2019
Member Is Offline
Mood: Newfound respect for TATP
|
|
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.
|
|
|
Abromination
Hazard to Others
Posts: 432
Registered: 10-7-2018
Location: Alaska
Member Is Offline
Mood: 1,4 tar
|
|
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
-------------- |
|
|
nezza
Hazard to Others
Posts: 324
Registered: 17-4-2011
Location: UK
Member Is Offline
Mood: phosphorescent
|
|
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.
|
|
|
mayko
International Hazard
Posts: 1218
Registered: 17-1-2013
Location: Carrboro, NC
Member Is Offline
Mood: anomalous (Euclid class)
|
|
This was a new one for me too. I wonder if boron trioxide would work while also sponging up the water produced?
al-khemie is not a terrorist organization
"Chemicals, chemicals... I need chemicals!" - George Hayduke
"Wubbalubba dub-dub!" - Rick Sanchez
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
|
|
|
Ubya
International Hazard
Posts: 1247
Registered: 23-11-2017
Location: Rome-Italy
Member Is Offline
Mood: I'm a maddo scientisto!!!
|
|
well, it's strange, it's a common didactic experiment, it's hard to get absolutely nothing
---------------------------------------------------------------------
feel free to correct my grammar, or any mistakes i make
---------------------------------------------------------------------
|
|
|
Bedlasky
International Hazard
Posts: 1241
Registered: 15-4-2019
Location: Period 5, group 6
Member Is Offline
Mood: Volatile
|
|
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]
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
|
|
|
Bedlasky
International Hazard
Posts: 1241
Registered: 15-4-2019
Location: Period 5, group 6
Member Is Offline
Mood: Volatile
|
|
I didn't add NaOH. Mixture after reflux even didn't smell like wintergreen, it smell like EtOH. Reaction simply didn't occure.
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
|
|
|
arkoma
Redneck Overlord
Posts: 1763
Registered: 3-2-2014
Location: On a Big Blue Marble hurtling through space
Member Is Offline
Mood: украї́нська
|
|
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)
"We believe the knowledge and cultural heritage of mankind should be accessible to all people around the world, regardless of their wealth, social
status, nationality, citizenship, etc" z-lib
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
