AWLB
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Phenol (hydroxybenzene) preperation from aspirin tablets
Phenol is a very useful reagent in organic chemistry. It is used to produce various other compounds such as dyes. Phenol is a clear crystalline
substance that has a melting point of around 40 degrees celsius. It has a pleasant sweet tarry smell. It can be produced by the decarboxylation of
salicylic acid (which will be obtained from aspirin tablets-which contain acetylsalicylic acid). If you have salicylic acid this can also be used, but
omit the hydrolysis with NaOH stages(step 1-6).
Salicylic acid---heat--->phenol+carbon dioxide
C7H6O3---heat---->C6H5OH+CO2
Equipment
10 g aspirin tablets.
Sodium/potassium hydroxide
500ml Round bottom flask, with 20-30cm glass pipe.
Source of heat (that can reach over 200 degrees celsius)
Isopropanol
Filtering equipment(funnel,paper)
100ml 10%(approx.) Hydrochloric acid
Clamp stand
Method
1. Place aspirin tablets (acetylsalicylic acid) in the round bottom flask.
2. Add an excess of sodium hydroxide.
3. Add 300ml water.
4. Stir at around 70 degrees celsius for 1 hour, then allow to cool.
5. Add the HCl, salicylic acid is precipitated (you should get around 6g)
6. Filter and wash with distilled water (you can recrystallize with 100 degree celsius water).
7. Dry your salicylic acid well.
8. Clean and dry the flask (or use another one)and add the salicylic acid.
9. Attach glass pipe to the top of the flask and attach with aluminum foil (use ice to cool the glass pipe)
10. Hold this apparatus with a clamp stand (the final set-up should resemble a reflux set-up).
11. Heat the flask to around 200 degrees celsius. More volatile phenol will begin to rise.
12. The reaction should be heated for 5 minutes.
13. Phenol will condense in the glass pipe.
14. Remove pipe and pour in isopropanol to dissolve phenol.
15. Recrystallize phenol by evaporating isopropanol at room temperature
16. Safely store phenol
17. You can test the phenol by mixing with an iron salt solution such as iron chloride (it should turn purple)
Safety
Phenol is toxic and corrosive.
Acetylsalicylic acid and salicylic acid are harmful and irritant
Sodium hydroxide and hydrochloric acid (10%) are corrosive
Thank you very much for reading.
[Edited on 27-7-2015 by AWLB]
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aga
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Have you actually done this procedure ?
Any photos perhaps ?
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AWLB
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I have done this procedure, but using salicylic acid. The hydrolysis of acetylsalicylic acid was added to to make the experiment feasible to those
without a direct source of salicylic acid.
I sadly do not have any photos because I performed this experiment quite a while ago.
I will redo the experiment including the hydrolysis part and take photos and add them to this post.
Thank you again for helping me with my posts.
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aga
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That'd be great !
We like photos.
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AWLB
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I would like to attempt to synthesize bisphenol A from phenol. I believe the reaction (between phenol and acetone) requires a catalyst, do you happen
to know which catalyst is required and how long and at what temperature the reaction should be refluxed for ?
Thanks in advance.
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aga
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A few seconds ago i had no idea at all.
Then a quick Google with "bisphenol from phenol acetone" came up with reams of information.
All that writing, indexing, making data available, and so little U of the FSE.
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AWLB
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Sorry, I just found finding a full method (with temperatures and times of reactions) quite difficult.
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aga
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Doing it over and over to work out the best temperature, time, relative concentration of the reactants etc is what they call 'Experimentation'.
Sometimes works faster than web searches. Not often, but sometimes.
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AWLB
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In a few days I might attempt to sythesise BPA and I may post a method and pictures.
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Nicodem
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This post is not fully on topic, but it deals with interesting reactions of salicylic acid. I was checking out the Houben-Weyl entry on quinones when
I saw a seemingly simple reaction of salicylic acid with hydrogen peroxide and NaOH to give an interesting compound, 2,5-dihydroxy-1,4-benzoquinone
(see below).
It appears an interesting preparative synthesis for the average amateur. Unfortunately I cannot access the cited article (J. Am. Pharm. Assoc.
Sci. Edit., 1940, 29, 178) - it appears to me it would require an old-fashioned visit to a library. Nevertheless, the Chem. Abstr.
review of the article gives sufficient details (see quote). The same product is accessible also by oxidizing hydroquinone with hydrogen peroxide in
aqueous NaOH at 50 °C (DOI: 10.1002/ejoc.201001627), but that is not as rewarding as starting from salicylic acid.
| Quote: | CA34:26495
The oxidation of salicylates in alkaline solutions
By: Brecht, E. A.; Rogers, C. H.
The brown oxidn. product (termed temporarily "sodium salicylate-brown" or, in the acid form, "acid salicylate-brown" (I)) formed in the
discoloration of salicylate solns. is an intermediate product because it is further oxidized to colorless compds. (oxalates and carbonates); 3
methods are described for its prepn. in slightly acid, slightly alk. and strongly alk. media, resp., by oxidizing with air and with H2O2. I has the
formula C12H8O6 and contains 3 OH groups which are easily methylated and form metallic salts with alkalies. 2,5-Dihydroxyquinone yields a
dehydro compd. (C12H6O6) having the same chem. and phys. properties as I. To prep. Na2O2.8H2O add 13.5 cc. of 30% H2O2 (d. 1.11) to a cooled soln.
of 62.5 g. NaOH in 175 cc. H2O, collect the crystals formed on a filter, mix twice with portions of alc. and drain well on a filter after each
washing, and dry in a vacuum desiccator over H2SO4 for 3 h. To prep. a dihydrated form of the di-Na deriv. of 2,5-dihydroxyquinone, to a
reaction mixt. composed of 125 g. Na salicylate, 625 g. NaOH and 1875 cc. H2O add not over 15 cc. (to avoid formation of Na2C2O4) of 30% H2O2,
after redn. of the H2O2 is complete (about 3 days) add another similar portion, and continue until up to 18 portions of H2O2 have been added, collect
the orange needle crystals on a suction filter, wash twice with 25% NaOH and then 5-6 times with alc. The formula of the crystals was proved by
assay for Na content and by conversion to 2,5-dihydroxyquinone, m. 222° (cor., decompn.), obtained by acidifying the red aq. soln. of the
di-Na deriv. |
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unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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