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Picric-A
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[*] posted on 26-7-2008 at 08:10
Salicylic acid


I plan on making some methyl salicylate,
i have the methanol for the esterification however i need the Salicylic acid.
Once way i have found of getting this is reacting Asprin, Acetylsalicylic Acid , with NaOH producing sodium acetate and Salicylic acid. how would i go about doing this?
another way would be adding an acid to catalyse hydrolosis into acetic and salicylic acid. how would i the go about seperating the two without them reacting again? are they on a equilibrium:
( i mean Acetic acid + Salicylic acid <--> Acetylsalicylic Acid) ?
any other methods for preparing salicylic acid would be cool,
thanks
Picric-A
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kclo4
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[*] posted on 26-7-2008 at 08:52


Cool! its a nice smelling chemical, correct?
No need using up your NaOH when you can just reflux some, or probably just boil the ASA in water, the acetic acid formed from hydrolisis will help it hydrolyze even faster and won't react with the salicylic acid.

In order to make ASA you need to use acetic anhydride and salicylic acid, not acetic acid.

I'm sure if you search around there will be a lot more detailed information on this board and other places too so check that out.

Let me know how your reaction goes! :D
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Picric-A
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[*] posted on 26-7-2008 at 09:03


yea:P very strong smelling chemical lol.
thats a good idea, as far as i remember, salicylic acid has low solubility in water, let alone acetic acid so it should precipitate out?
cool thanks for your help,
will do :P
does anyone have any other cool reactions one can do with Salicylic acid now i have opened a thread on it and all :)

[Edited on 26-7-2008 by Picric-A]
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kclo4
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[*] posted on 26-7-2008 at 09:14


Well, you can decarboxylate it to form phenol, or you could turn it into picric acid, as i am sure you are aware of.
Phenol can be easily halogenated and also can form Bakelite with Formaldehyde.
Sodium Salicylicate can also be used in place of Sodium Benzoate for whistle mixes, or so I have heard.

You could also try the esterification of it with other alcohols and see how they smell compared to each other.



Edit: "This chemical (acetaphenone) may be obtained by the dry distillation of a mixture of the calcium salts of acetic and benzoic acids." - http://en.wikipedia.org/wiki/Acetophenone

Since salicylic acid is 2-hydroxybenzoic acid, maybe Hydroxyacetaphenones could form by the destructive distillation of salicylic acid and Acetic acid calcium salts?
Just a last moment thought, no clue if it would work at all, or what they would even be good for.

:P

Also, you could make various nitration products (mono, di, tri, + isomers of such) by the nitration of the ASA, SA, or Phenol, and then reduce the NO2 to NH2 via HCl/Zn and then do a sandmeyer reaction to get various multiple hydroxy groups on the benzene ring, with which you could probably form more esters with alcohols and such, but that sounds like a total waist of time unless you have some use for one of the isomers that forms in good yield or something like that.

[Edited on 26-7-2008 by kclo4]

[Edited on 26-7-2008 by kclo4]
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pantone159
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[*] posted on 26-7-2008 at 10:12


Salicylic acid makes a nice purple color with Fe(III) ion.

IIRC when I made some, I used 2 eq of NaOH with ASA, one for the hydrolysis and one to remove the proton from SA to keep it in solution as the salt. I let it sit at RT for several days, you can surely make this go faster but I was in no hurry. You may not need that much NaOH, I am not sure. After the hydrolysis is complete, add conc HCl, the salicylic acid is insoluble in water and precipitates, thus separating it from the acetic acid.
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kclo4
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[*] posted on 26-7-2008 at 10:27


Wow the Iron complex is pretty cool looking!
http://en.wikipedia.org/wiki/Salicylic_acid#Analysis
Seems like that would be good for something but i can't imagine what.
Wonder if it forms interesting complexes with Zinc, Nickel, or Copper?
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Picric-A
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[*] posted on 26-7-2008 at 13:12


ok, quick update on how i am going.
I crushed up and dissolved 5 350mg (wheight of the whole pill) in about 50ml of boiling water. there was 300mg of asprin in the tablet ( the rest is maize starch)
To my amazement it is very soluble in water at around 50-90 degrees C!
i then started boiling and held it at around 100degrees C (just boiling). After about 5mins the occasional puff of white smoke that smelled of vinegar but much sweeter ( i admit i have never smelt pure acetic acid, only vinegar). the PH of the soloution was around 3.
I kept the heating up, letting it cool and topping up with water every so often. after about 30 mins i put it on reflux and left that for 3 hours.
After it had been going for 3 and a half hours i decided this is definitly not an economical way to make Salcylic acid!
i took the mix off reflux and boiled down all the water. what i was left with was a slightly blackened (probably due to burnt starch) white powder, visibly less than what i started with.
I mixed the powder with methanol and tried to begin an esterification. Failiure. i barely noticed the smell of methyl sacilate, even though it is a strong smelling ester :mad:

To conclude all of this, i think making a decent amount of Salicylic acid would take around 5 hours of refluxing at 100degrees C. (if you are working with about 5 grams of asprin!) dont think i am going to try that one again!

Does anybody know of any other way to make Salicylic acid?

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kclo4
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[*] posted on 26-7-2008 at 15:53


Add a little bit of Hydrochloric acid to it or probably Sulfuric acid would work too, but that wouldn't boil away, or do what pantone159 did I guess :P
How long did you reflux the Methyl alcohol, salicylic acid, and acid catalyst together?
Honestly I am rather surprized that you can't just mix aspirin, Methanol, and an acid catalyst and reflux to make what you want.
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[*] posted on 26-7-2008 at 17:06


Quote:
Originally posted by Picric-A
I plan on making some methyl salicylate,
i have the methanol for the esterification however i need the Salicylic acid.
Once way i have found of getting this is reacting Asprin, Acetylsalicylic Acid , with NaOH producing sodium acetate and Salicylic acid. how would i go about doing this?
another way would be adding an acid to catalyse hydrolosis into acetic and salicylic acid. how would i the go about seperating the two without them reacting again? are they on a equilibrium:
( i mean Acetic acid + Salicylic acid <--> Acetylsalicylic Acid) ?
any other methods for preparing salicylic acid would be cool,
thanks
Picric-A


I did this a few years ago:

2g of powdered aspirin tablets
50ml 1m NaOH Solution
50ml 34% HCl

Step 1: Saponification of acetylsalicylic acid
Extract acetylsalicylic acid from a ground up aspirin tablet using acetone. Prepare a strong solution of NaOH and disolve the acetylsalicylic acid in it. Heat to a boil for about 2 minutes, then cool to room temperature.
This will saponify the acetylsalicylic acid (an ester itself) to produce salicylate and acetate.

Add an ice-cold solution of dilute HCl to protonate the salicylate and precipitate it from solution. Collect the solid (salicylic acid) and dry well (let it sit in an open beaker and let the water evaporate off).

Step 2: Fischer esterification of salicylic acid and methanol
Disolve the salicylic acid from part 1 in methanol, then add a catalytic amount of conc. sulfuric acid. Heat to produce methyl salicylate. If you want to isolate the methyl salicylate, remove the excess salicylic
acid and catalyst by extracting with cold aqueous base (so the base does not promote hydrolysis of the ester), dry with a drying agent (important if you want to distill off the excess methanol), then distill off the methanol (bp =64.6C) from the
methyl salicylate (bp = 220 - 224C). What remains should be colorless, yellowish or reddish oily liquid.

Combined dried salicylate on watch glass ~ 24hrs.

Combined Salicylate with methanol & catalytic amound of concentrated H2SO4 in test tube.

Heated to boiling in water bath.

Slight smell of wintergreen is evident in the test tube.

Good experiment / poor yield.

Need to try another time but with more precise methods and 6m NaOH solution (Stock Solution)


I copied it from somewhere but it worked and still smells very nice!;)
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Picric-A
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[*] posted on 27-7-2008 at 02:17


cool, will try that when i get a few more asprin.
slightly off topic, when you nitrate salicylic acid you get picric acid right?
Well picric acid is 2,4,6-trinitrophenol so..:
My question is is there anyway of making 2-4-dinitrophenolhydrazine with it ?
(p.s.moderators, i wasnt sure if this question beloged in a new thread or not so if so move it, thanks.)
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[*] posted on 27-7-2008 at 04:23


We made oil of wintergreen at school during the A-level course last year. The results were a reasonable amount of strongly smelling liquid.

Preparation:

Add to a 50ml pear shaped flask 9g of 2-hydroxybenzoic acid (salicylic acid), 15ml of methanol and 2ml of conc. sulphuric acid.

Fit the flask with a reflux condenser and boil the mixture for about an hour.

Cool the mixture to room temperature and pour it into a separating funnel that contains 30ml of water. Rinse the flask with 15ml of ethyl ethanoate and add this to the separating funnel.

Mix the contents of the separating funnel and allow them to settle. If an emulsion forms add a little more solvent (EtOAc). Run the lower aqueous layer into a conical flask.

Wash the organic solvent extract with 30ml of 0.5M aqeous sodium carbonate, carefully releasing the pressure in the separating funnel frequently as there is likely to be considerable evolution of carbon dioxide. Serparate the aqueous and organic layers by running into seperate small conical flasks. The aqueous layer can be discarded.

Dry the organic extract with solid anhydrous sodium sulphate.Leave to dry for about 10 minutes while you set up the apparatus for distillation. Then remove the drying agent by filtering (book says use a cotton plug in a funnel).

Remove the organic solvent by distillation (ethyl ethanoate boils at 77C). Complete the distillation, collecting the distillate boiling above 220C as oil of wintergreen; methyl 2-hydroxybenzoate.



[Edited on 27-7-2008 by DJF90]
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[*] posted on 27-7-2008 at 04:24


Alternatively, dissolve powdered aspirin in a large excess of warm methyl alcohol, filter to remove the tableting additives. Add a trace of H2SO4 to the filtrate and reflux for some time.

Both methyl salicylate and methyl acetate are formed. Stop heating, add NaHCO3 until the H2SO4 is neutralized, the filter off the Na2SO4 and and any excess NaHCO3; the bicarbonate is not a strong enough base to rapidly hydrolyse the esters.

As the acetate boils at a slightly lower temperature than methanol, it and the excess methanol can be distilled away from the methyl salicylate (but you'd best neutralised the H2SO4 as above).

[Edited on 27-7-2008 by not_important]
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Picric-A
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[*] posted on 27-7-2008 at 05:34


ok, i have solved my question on 2-4dinitrophenylhydrazine. Here is the synthesis:
'2,4-Dinitrophenylhydrazine is commercially available usually as a wet powder. It can be prepared by the reaction of hydrazine with 2,4-dinitrochlorobenzene'
the source was wikipedia :P
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[*] posted on 28-7-2008 at 02:03


Interesting, I like not_important's way of doing it the most so far! Sounds a lot easier in some ways and probably better yielding since you don't have the risk of decomposing it, and you could do it as a one-pot synthesis, assuming you can filter at the end of a one pot synthesis and still call it such. I wouldn't see much of a reason to filter out the additives because you have to filter out the Sodium Sulfate and excess Bicarbonate later anyways. Of course, the additives may be some sort of carbohydrate and start to dehydrate with the addition of the sulfuric acid. But even then, still likely they could filter out, unless something soluble formed.
:D
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[*] posted on 28-7-2008 at 08:27


While it is possible to hydrolyse esters to acid and alcohol via heating in acid, as you found it is not very practical. I have made salicylic from aspirin by adding the crushed aspirins to boiling NaOH, boiling for a short while (20min?) and then acidifying and then filtering the instantly produced salicylic acid.
joeflsts procedure is nice.




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Picric-A
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[*] posted on 28-7-2008 at 09:48


Yes i have just done this method. (on a small scale)
i crushed up 4 asprin and put it in about 10ml of water. I then added about 5 grams of NaOH (in exess).
i held this soloution boiling for about three minutes. after about 1 minute everything had dissolved.
After three minutes i left it to cool and nothing precipitated, indicating that the asprin had turned to sodium salicylate and sodium acetate. Lastly i added a slight exess of sulphuric acid and immedietly a thick, fluffy white precipitate fromed ( surprisingly a lot of salicilic acid was formed from just 4 tablets :) )
i then filtered the precipitate and dried it.
my verdict: a LOT more productive than refluxing with water for ages :)
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[*] posted on 28-7-2008 at 10:13


Well, there is not as much salicylic acid present as you think. It just happens to exist as "fluffy, fine needles. You should wash the ppt with ice water before drying. Recrystallization from boiling water is optional, but for most simple uses, probably unnecessary.



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[*] posted on 28-7-2008 at 10:28


Nice long crystals form on recryst from hexane( camp fuel). And they dry real quick after too!



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[*] posted on 28-7-2008 at 11:15


Quote:
Originally posted by Picric-A
After three minutes i left it to cool and nothing precipitated, indicating that the asprin had turned to sodium salicylate and sodium acetate.


How do you conclude that? Acetylsalicylic acid will dissolve in NaOH just fine, the fact that it is dissolved does not necessarily indicate that the ester has been hydrolyzed.

P.S. Recrystallization from mixed alcohol-water works also.
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[*] posted on 28-7-2008 at 11:24


Pantone159 is right. Sodium acetylsalicylate is quite soluble...When I did this, I heated the mixture (a little more than 2 molar equivalents of NaOH...one for sodium salicylate and one for sodium acetate plus a little more) for half an hour, left it to stand overnight, then acidified. I recrystallized from boiling water with no problems (except drying it took bloody forever...at least a week over anhydrous CaCl2 due to the "fluffiness" of the acicular crystals that tends to trap lots of water. The hexane is probably a much better idea in retrospect.



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Picric-A
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[*] posted on 28-7-2008 at 12:44


i did not realise Sodium acetylsalicylate existed... how do you make it?
pantone159- i thoguht that as acetylsalicylic acid is ( practcally) insolouble it would be (practically) insoluble in sodium hydroxide. the only reason it dissolves much quicker is becuase it is undergoing hydrolosis.
i guess my source is not the most reliable thing to go by :P :
http://wiki.answers.com/Q/Why_aspirin_is_soluble_in_sodium_h...

pantone159- do you think because i jumped to the conclusion that as soon as it dissolves it undergoes hydrolosis that the fluffy crystals i made by acidification of the left over soloution is not salicylic acid but asprin? hope not :( I will reflux it with water tommorow to see if i can smell acetic acid by hydrolosis.
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[*] posted on 28-7-2008 at 12:51


There is nothing wrong with that Wiki entry... It doesn't mention hydrolysis, just the conversion of the acid to the salt (by losing its proton). You make NaASA by dissolving ASA in NaOH solution.

It is common/normal for organic acids to be insoluble in water but soluble in base, as under those conditions they lose a proton and become charged, and much more suitable for solution in water. Small acids like acetic are soluble even as the acid form, but that is kind of non-typical.

You may have recovered aspirin, or more likely mix of ASA/salicylic acid as some hydrolysis, at least, should have occurred.
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[*] posted on 28-7-2008 at 13:38


ah kk, thanks.
how do i go about turning Salicylic acid to phenol?
i understand you must decarboxylate it but i admit i have never done this type of reaction (i am only just getting into the wonderful world of organic chemistry :) )
thanks for help,
Picric-A
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[*] posted on 28-7-2008 at 13:42


You can make sodium acetylsalicylate by dissolving ASA in room temperature NaHCO3 solution. Since it is a much weaker base, the bicarbonate does not risk ester hydrolysis like NaOH. AFAIK, even heating ASA in plain water will give some hydrolysis, with extended heating leading to complete hydrolysis. Keep the solution cool to minimize this. If you were to add a copper salt to the NaASA solution, you'd get a precipitate of copper acetylsalicylate, which is quite a bit different in color (and solubility) than copper salicylate. There's a thead on that elsewhere though.



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[*] posted on 28-7-2008 at 14:38


I've never made phenol in a significant quantity so i couldn't tell you much about how to make it.

However mixing Sodium Salicylicate with Sodium Hydroxide and heating would decarboxylate it. Some people make Benzene by adding Sodium Hydroxide with Sodium Benzoate and heating and Salicylic acid is less stable then benzoate. Copper salts often help decarboxylation proceed, I believe they work as some sort of catalyst. It may be difficult to collect the phenol after it has formed, since it may need higher temperatures and could vaporize. I wouldn't be surprised if the decarboxylation happened in solution assuming you had the NaOH and Sodium Salicylicate concentrated, and then refluxed for a while. refluxing a solution of Sodium hydroxide in glass may destroy your flask. I have also read that phenol can be produced by quickly and strongly heating salicylic acid.
Also when making Picric acid, I believe ASA, or SA is decarboxylated to some phenol sulfuric acid salt. CO2 is liberated when mixing(and heating?) the Salicylic acid with Sulfuric acid when producing Picric acid, correct?

But remember, I've never made it in any significant amount, and it was quite some time ago just telling you what I know about it :P
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