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leu
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JACS 86 2846-50 & 2851-7 (1964) discuss the transalkylation and disproportionation aromatic reactions in some detail
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Chemistry is our Covalent Bond
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solo
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Reference Information
Thermal decomposition of acetylsalicylic acid (aspirin)
Y. Asakura Ribeiro”, A.C.F. Cairesb, N. Boralleb, M. Ionashirob
Thermochimica Acta 279 (1996) 177-181
Abstract
The thermal decomposition of aspirin in air and dry air flux was investigated. Thermog- ravimetry-derivative thermogravimetry
(TG-DTG), differential scanning calorimetry (DSCI, nuclear magnetic resonance (NMR), infrared absorption spectra and thin layer
chromatography have been used to study the thermal decomposition of this compound. The results permit the identification of some
compounds revealed in the first step of the TG-DTA curves, and also suggest the thermal decomposition mechanism.
Keywords: Acetylsalicylic acid; Differential scanning calorimetry; Infrared absorption spectra: Nuclear magnetic resonance;
Thermal decomposition; Thermogravimetry
Attachment: Thermal decomposition of acetylsalicylic acid -aspirin .pdf (272kB)
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jimmyboy
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just check Vogel's ... probably still the best way to make phenol in a lab - its a long route though but i think the yield's are high all the way
through -- get benzene from toluene and start from there
toluene -> benzene -> nitrobenzene -> aniline -> phenol
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solo
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Reference Information
The Mechanism of the Copper-Induced Pschorr Cyclization. A New Phenol Synthesis Involving Hydroxylation of the Intermediate Radical by
Cupric Ion’
ANITA H. LEWIS AND THEODORE COHEN
Journal of Organic Chemistry yr:1967 vol:32 iss:12 pg:3844
Abstract
The copper-catalyzed decomposition of aryl diazonium salts at low temperatures has been shown to yield an aryl radical and has been utilized to
effect essentially unidirectional (a) Pschorr cyclizations, (b) hydroxylations, and (c) reductions. Excellent yields of the following products are
obtained when the cuprous oxide catalyzed decompositions of Zdiazobenzophenone tetrafluoroborate are carried out under the conditions specified:
(a) fluorenone, in dilute aqueous acid; (b) 2-hydroxybenzophenone, in dilute acid in the presence of a large excess of aquated (cupric ion; and (c)
benzophenone, in dioxane. Analogous results are obtained in decompositions of 2-(o-diazobenzoyl)naphthalene tetrafluoroborate; a-ring closure to
give benzo -fluorenone exceeds p-ring closure to give benzo-fluorenone in a 9: 1 ratio at low temperatures. These results are discussed in terms of
the mecha- nism of the copper-catalyzed reaction which, contrary to suggestions in the literature, does not involve a cationic component. The
oxidation by cupric ions of aryl radicals generated by diazonium ion decomposition constitutes a promising new method for the introduction of
hydroxyl groups into aromatic nuclei. This method leads to high yields of phenols and no “diazo resins” which accompany the thermal production
of phenols from diazonium salts. Phenols which could not be previously prepared from the corresponding amines are accessible by this new
procedure. Evidence is presented that this reaction does not involve a phenyl cation intermediate but instead proceeds by transfer of H20++ from
the hydration shell of the cupric ion to the aryl radical (ligand radical trans- fer).
[Edited on 27-9-2006 by solo]
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Chemguy
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The easiest way to make phenol from ASA, is to heat it in H2SO4 for a while.
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not_important
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| Quote: | Originally posted by jimmyboy
just check Vogel's ... probably still the best way to make phenol in a lab - its a long route though but i think the yield's are high all the way
through -- get benzene from toluene and start from there
toluene -> benzene -> nitrobenzene -> aniline -> phenol |
toluene -> benzene either the FC methyl exchange that uses AlCl3, not OTC so must be made, or via two step tol->benzoic acid->benzene, where
benzoic acid is harder to decarboxylate than salicylic acid. Difficult to do better than 4 toluene -> 3 benzene + 1 durene, or 75%; more typically
3 tol -> 2 benz + 1 mesitylene, yield is 2/3. Anhydrous conditions needed.
benzene -> nitrobenzene : nitrates and bisulfates needed as a minimum, some people have a difficult time finding nitrates. yields are good,
especially if undernitrated and unreacted benzene is recycled.
nitrobenzene -> aniline : OK, this one is easy, iron and acid will do, yields are good.
aniline -> phenol : nitrites are often hard to obtain, and must be made from nitrates. Clean sulfuric or phosphoric acid needed, I'm not sure if
you can get away using bisulfate. Yields are fair to good, using Norris' example 20 g aniline gives around 15 g phenol, roughly 75%.
Overall, maybe 50% yield top for start-to-end, using equal mole amounts of nitrate, nitrite, more than 2 moles of acid.
Direct decarboxylation needs 2+ moles of hydroxide, which can be done using sodium carbonate or bicarbonate, and slaked lime. Say 2 moles each Na2CO3
and Ca(OH)2. If you grind the residue with lime - either Ca(OH)2 or CaCO3, ignite in air, cool, and boil with water you recover low grade NaOH which
can be used for the next batch.
OTC Asiprin and from-the-garden chalk/lime in, phenol out; some OTC NaHCO3 or Na2CO3 needed for makeup. Yields are not great, but you can run the
reaction in a piece of pipe.
Copper often catalysis such decarboxylations.
Another route would be toluene -> benzoic acid -> benzamide -> aniline -> phenol. Polystyrene scrap can replace toluene, there are some
catalysed air oxidation routes the might be usable. Reduces the amount of nitrate needed.
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matei
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I think the easyest method for obtaining phenol from benzene is by heating the sodium salt of benzenesulphonic acid (which can be made from benzene
and H2SO4) with NaOH. (Vogel's 5th Ed., p. 971 - the method described is actually for 2-naphtol, but can be used for phenol too).
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hell-fire
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Phenol/ phenol sulfate can be synthed from asprin. First extract the acetyl salicylic acid from the asprin using acetone then let it dry. Messure out
100ml of H2SO4 and heat it to about 70°C. Keeping the H2SO4 at 70°C slowly add 20g of acetyl salicylic acid bit by bit. Once all the acetyl
salicylic acid is added the mixture should be a nasty dark colour, the reaction goes from phenol to phenol sulfate.
There's also the possibility of going from benzaldehyde to phenol but that just seems like a waste fo benzaldehyde.
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not_important
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| Quote: | Originally posted by matei
I think the easyest method for obtaining phenol from benzene is by heating the sodium salt of benzenesulphonic acid (which can be made from benzene
and H2SO4) with NaOH. (Vogel's 5th Ed., p. 971 - the method described is actually for 2-naphtol, but can be used for phenol too).
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It's fairly easy, but good yields are a little tricky. First, getting good conversion of benzene may take very strong to fuming H2SO4, or using the
prefered method of passing benzene vapour through the 98% acid at 130 to 150 C but stopping before the point of forming too much sulphone.
The alkali fusion stage is simple in concept, but not always easy to get satisfactory results from. The fusion mix is susceptable to air oxidation,
yet must be well stirred. Using KOH or mixed sodium/potassium hydroxides is preferred.
And you need to get benzene to start with, as I said earlier going from toluene means no better than 75% conversion and likely 2/3 or less.
On a small scale the decarboxylation of phenol seems to give yields around that of the sulphonic acid fusion, with less overall reagent cost and
without having to deal with benzene. Including starting with toluene may put the decarb route on top.
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crazywantabies
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I have search the U.S. over. Finding Phenol Crystals is hard for me, yet if one can help.?
(I speak in lieu of part time job, pt. managers, slow stickers on vehicles bumpers, and the box, for many (8) years
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crazywantabies
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Aspirin today has a couple other things. Easy, as the one said, to FRACTIONAL crystalize the aspirin [after boiling with a tad of sodium hydroxide],
and with only about 20 millileters of boiled down asprin, put it on a metal plate and heat it outside until you get what looks like three different
crystals. Test each crystal you got from light heating on stell pan with iron iii
chloride (easy stuff to make too), and the PURPLE-BLUE is PHHHHHHEEEOL!!!! PRAISE THE LORD ALMIGHTY AND that one with this FRACTIONAL crystalizing
method.I speak in liue of part time jobs only, slow bumper stickers, THE BOX, and Future consiousness sin detection unit for 8 years.
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crazywantabies
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WHOOPS, forgot to say, "After boiling it down slowly on a steel plate outside, add a little HCl, about one capfull for every four or so capfulls of
crystals that you gotta seperate on your steel pan (don't worry, these crystals with slowly heating will seperate themselves on that pan) and let it
stand a long time. THEN test with Iron III CHLORIDE. pTL, part time and saying it to all for 8 years.
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crazywantabies
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ok, last time, gotta add some CaO with your Sodium Hydroxide when you first decarboxylate salicylic acid like Marvin said. Otherwise, the salicylic
acid from the aspirin will evaporate with the acetic acid as you heat it. THEN, you can fractionalize it on a pan, (waxy stuff, medium waxy stuff,
and aspirin looking sticky stuff). Last, slap a little HCl in there to deacidize it. ok, sorry for the bum steer.  That should do it.
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AndersHoveland
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I know this is somewhat of a different topic, but I found the following reaction to be very interesting:
http://www.chemicalforums.com/index.php?topic=46423.0
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