Sciencemadness Discussion Board - Salicylic acid

Salicylic acid

Picric-A - 26-7-2008 at 08:10

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

kclo4 - 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!

Picric-A - 26-7-2008 at 09:03

yea

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

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]

kclo4 - 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.

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]

pantone159 - 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.

kclo4 - 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?

Picric-A - 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?

Picric-A

kclo4 - 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

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.

joeflsts - 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!

Picric-A - 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.)

DJF90 - 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]

not_important - 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]

Picric-A - 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

kclo4 - 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.

The_Davster - 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.

Picric-A - 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

UnintentionalChaos - 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.

The_Davster - 28-7-2008 at 10:28

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

pantone159 - 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.

UnintentionalChaos - 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.

Picric-A - 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

:
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.

pantone159 - 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.

Picric-A - 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

UnintentionalChaos - 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.

kclo4 - 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

Picric-A - 28-7-2008 at 15:25

Yes that reminds me of making picric acid, and that must be the reason you can start with SA... becuase it changegs to phenol during the reaction...
as for the benzene synthesis- that seems a very simple process to make benzene- the holy grail of aromatic compounds! :p thanks!

Picric-A

kclo4 - 28-7-2008 at 15:32

Your welcome, and good luck to you!
Well hey, if your interested in making benzene check out this; http://www.sciencemadness.org/member_publications/benzene_pr...
Also there is a lot of information about it on this forum.

Ritter - 28-7-2008 at 15:56

$12/pound on eBay, item # 270259620322. U.S.P. grade.

kclo4 - 28-7-2008 at 16:20

Ritter is referring to Salicylic acid, not the many other chemicals that were mentioned.

http://cgi.ebay.com/Salicylic--Acid-U.S.P.-Grade-1-lb._W0QQi...
there is the link that goes with his description I believe.

+ $7.50 for shipping.

So, for a single pound of salicylic acid, its about $20.

Ritter - 28-7-2008 at 17:02

Quote:

Originally posted by kclo4
Ritter is referring to Salicylic acid, not the many other chemicals that were mentioned.

http://cgi.ebay.com/Salicylic--Acid-U.S.P.-Grade-1-lb._W0QQi...
there is the link that goes with his description I believe.

+ $7.50 for shipping.

So, for a single pound of salicylic acid, its about $20.

Given the cost of materials & your time, that is a cheap price to pay for buying something that's pretty basic rather than trying to make it.

kclo4 - 28-7-2008 at 18:08

Well, not if you only need an ounce or so I would just make it personally.
Besides we are likely to already have some of the chemicals and glassware needed to make it.
I'd bet most of us here could make it with out buying any additional chemicals.
But I agree, if you need a large quantity of it, just buy it.
I think for what he is doing with it however you wouldn't need very much.
Plus, making chemicals is what its all about, right?

Ritter - 28-7-2008 at 18:43

Quote:

Originally posted by kclo4
Plus, making chemicals is what its all about, right?

At a certain point common sense (and your pocket book) will decide the question.

I'd rather have that extra USP sal acid in stock as a source of inspiration for future projects then spend a week boiling aspirin.

[Edited on 28-7-2008 by Ritter]

pantone159 - 28-7-2008 at 19:45

I'm usually in the camp of buying reagents instead of making them, many more of my collection are purchased rather than synthesized, but there is something appealing in making something interesting from a substance as ubiquitous as aspirin.

It does depend on how much you need, I doubt I would try and synthesize a kilo, but for a few tens of grams, why not make it?

Picric-A - 29-7-2008 at 01:01

I am with Kclo4 on this one, i try to make all most of my chemicals, the only ones i dont make are very basic chemicals like sulphuhric acid, sodium sulphate anyhrous and solvents ect...
Yes i am sure you can buy salicylic acid fairly cheap, i can buy it 250g for £3.50 but this thread was about making it and some of its uses, properties ect....

S.C. Wack - 29-7-2008 at 02:56

Walgreens aspirin is $4/162.5 g. ASA, which is 125 g. SA. So for $16, you get 500 g. SA instead of 454 g. for $17.50, if no one bids it up. Though isolating all 500 g. in pure form will be a little more of a venture. The corresponding amounts of H2SO4 and NaOH for this are pretty cheap.
I must disagree about the
Horrible!
Chore!
of dissolving aspirin tablets, filtering, and boiling with NaOH for an hour or two in a teflon-coated saucepan on the stove. Maybe checking in once in a while to add water.
And then adding acid.

Though some brands have some pretty goopy binder.

Apparently Ritter's time is better spent posting, instead of making salicylic acid.

Ritter - 29-7-2008 at 05:06

Quote:

Originally posted by S.C. Wack
Walgreens aspirin is $4/162.5 g. ASA, which is 125 g. SA. So for $16, you get 500 g. SA instead of 454 g. for $17.50, if no one bids it up. Though isolating all 500 g. in pure form will be a little more of a venture. The corresponding amounts of H2SO4 and NaOH for this are pretty cheap.
I must disagree about the
Horrible!
Chore!
of dissolving aspirin tablets, filtering, and boiling with NaOH for an hour or two in a teflon-coated saucepan on the stove. Maybe checking in once in a while to add water.
And then adding acid.

Though some brands have some pretty goopy binder.

Apparently Ritter's time is better spent posting, instead of making salicylic acid.

I would never waste time making what I could buy at a reasonable price. Since few amateur experimentalists have the necessary analytical equipment to determine the purity of their produced materials, they may wind up defeating themselves by screwing up the downstream chemistry.

And Wack, please feel free to share your personal concerns via U2Us. You're starting to get needlessly repetitive.

[Edited on 29-7-2008 by Ritter]

Picric-A - 29-7-2008 at 05:14

I buy my asprin for 39p for a pack of 16. Personally this is an extremly cheap source of SA if i can master the hdyrolosis aspect of it.
I know this is silghtly paranoid but dont you think making things is etter than buying them because the more chems you buy the more the DEA take notice of you?
i mean SA is probably not used to make drugs (not that i know of anyway) but just generally.

ScienceSquirrel - 29-7-2008 at 05:31

The hydrolysis should be quite straight forward, this is for the methyl ester;

http://www2.truman.edu/~jobrien/Org%20I%20Labs/SalicylicAcid...

I would extract the tablets with sodium hydroxide, boil the solution and then acidify and recrystallise the acid.
If you get a good melting point then I would take it as being fairly pure.

Picric-A - 29-7-2008 at 05:45

yea that is the way i do it, how long should i boil it for?

Ritter - 29-7-2008 at 06:12

In real organic chemistry the U.S.P. grade is specified: http://www.orgsyn.org/orgsyn/pdfs/CV2P0341.pdf

Aspirin tablets contain binders & excipients that a crystallization will not guarantee to remove. For instance, what final wash solvent will you use? Do you know the nature of these binders & excipients & therefore be able to successfully wash them out?

ScienceSquirrel - 29-7-2008 at 06:26

Most of the filler material in the tablet is insoluble in water so grinding up the tablets, extracting with warm sodium hydroxide solution and filtering will remove all that.
After heating you will be left with a solution of di sodium salicylate and any water soluble glue.
Adding the sulphuric acid will precipitate the acid and leave the glue in solution.
Salicylic acid recrystallises easily from water, it is one of the great classics for undergraduate labs.

Picric-A - 29-7-2008 at 06:54

Yes i quite agree with you... some makes of asprin do contain lots of nast contaminents that you will want to remove but what i am saying is my tablets are 400mg ASA and 50mg starch. plain and simple (not to mention cheap!)
my point is if i can buy tablets like these then other people must be able to buy them

DJF90 - 29-7-2008 at 13:57

In the uk these usually come in small plastic tubs, about 15p for 20 tablets (used to buy paracetamol like this

) and are available from most supermarkets

Picric-A - 30-7-2008 at 00:19

yep thats how i buy myn

DJF90 - 31-7-2008 at 09:01

Ok... went into the shop today

saw these little tubs, £0.13 (about $0.07?) for 20 300mg aspirin tablets in a plastic tub, only other ingredient is lactose (I assume it's used to bind the ASA crystals).

Picric-A - 2-8-2008 at 06:13

i saw the ones with lactose in. i think it was in wilkinsons.
i just thoght, even though they are cheaper they are probably more difficult to purify becuase i have no knolage on lactose's solubility ect...
I cant remember who said this but someone made as claim that paracetemol was cheaper than Asprin, i i have to disagree with that.
could someone tell me the properties of phenol? i reacted salicylic acid with conc sulphuric acid and got yellowish crystals, and i saw the msds of phenol and it states collourless, hmmm....
Picric-A

kclo4 - 2-8-2008 at 11:13

When you reacted the salicylic acid with sulfuric acid did you see carbon dioxide evolution?
The phenol would be in some sort of sulfuric acid salt. Also the color might be explained by some possible impurities in the sulfuric acid?
I think it needs to be neutralized to get the phenol alone.
You could then probably fractionally crystallize it from an aquas solution since its solubility seems to be pretty low at 8.3 g/100 ml at 20*C according to Wikipedia.
Phenol forms a highly soluble salt with sodium hydroxide so perhaps use a carbonate.
Phenol doesn't react with carbonates, does it?

DJF90 - 2-8-2008 at 12:46

No its too weak of an acid. Mixing with Na2CO3 should be fine

kclo4 - 2-8-2008 at 13:15

Sweet!
I wish I had a use for phenol, this thread is making me want to make it.
I wonder if chlorobenzene could be produced from phenol? That would make me very happy

--I wouldn't be to surprized if chlorobenzene was produced by refluxing anhydrous phenol while bubbling anhydrous Hydrogen chloride Into it? Along with a lewis acid probably, such as Zinc chloride, which I would produce in situ from zinc metal.

Does anyone have an idea how to make chlorobenzene?

[Edited on 2-8-2008 by kclo4]

ScienceSquirrel - 3-8-2008 at 13:10

Quote:

Originally posted by kclo4
Sweet!
I wish I had a use for phenol, this thread is making me want to make it.
I wonder if chlorobenzene could be produced from phenol? That would make me very happy

Chlorobenzene cannot be made from phenol.

Chlorobenzene can be made by reacting benzene with chlorine in the presence of aluminium chloride.

kclo4 - 3-8-2008 at 14:14

That is sad

Klute - 3-8-2008 at 14:46

I would rather use bicarbonate as a base, phenol does react with carbonates to some extent....

Phenol very quickly takes a amber/orange colour from oxidized byproducts upon standing, and only pretty pur phenol is colorless. Be very carefull, phenol is a very toxic compound, spilling an aqueous solution on your hands can kill you in a few hours.... It also readily sublimes.

Phenol can be usefull for lots of stuff, it can be formylated to salicylaldehyde for example, which is a very important precursor for coordiantion chemistry ligands, forming complexes with Fe, Ni, Cu, etc
Being highly actiavted, it can also be pretty easily ring-alkylated, nitrated, etc

ScienceSquirrel - 9-8-2008 at 10:22

<u>Preparation of acetylsalicylic acid from Aspirin tablets BP and hydrolysis to salicylic acid</u>

Rationale

Careful reading of the insert in the box revealed that they contained aspirin 300mg and lactose, starch and talc as excipients, each tablet weighed 0.36g.
Hence it was decided to dissolve the aspirin in cold sodium carbonate solution, filter to remove the talc and starch and then precipitate the acetysalicylic acid with hydrochloric acid.
Hydrolysis with sodium hydroxide and precipitation with hydrochloric acid would produce salicylic acid.

Experimental

Acetylsalicylic acid

Sodium carbonate (2g) was dissolved in deionised water (25mL) and five aspirin tablets were added. After gently stirring for 10 minutes they dissolved to yield a faintly cloudy solution. The solution was filtered and the filter washed with deionised water (25mL). 8M hydrochloric acid (5mL) was added dropwise to the filtrate with gentle stirring. The suspension was cooled in ice and filtered and the crude solid was washed with 25ml of iced water. The solid was suspended in deionised water 15ml and heated to boiling, it was allowed to cool to RT and then cooled in ice Yield 1.2g, 80% mp 134 C lit 135 C

Salicylic acid
The crude solid prepared in the method above was suspended in deionised water (14ml) and a solution of sodium hydroxide (2g) in deionised water (7mL) was added. The solution was boiled for 15 minutes and then allowed to cool for 5 minutes. Hydrochloric acid (8mL) was added dropwise and the suspension was cooled in ice. The crude salicylic acid was filtered off and washed with ice water (25mL). The crude solid was suspended in deionised water (15mL) and heated to boiling, slow cooling to room temperature and cooling in ice yielded silky needles (0.9g 75%) mp 159-160 C lit 159 C.

Conclusion

This is not an economic way to prepare salicylic acid but it produces nice crystals in a good yield and would be a cheap way to practice some chemical techniques. The tablets are 15p for a packet of 16 out my way and the cost of the other consumables is small.

[Edited on 9-8-2008 by ScienceSquirrel]