Polverone
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toluene oxidation fun
I have recently been attempting to prepare derivatives of toluene by oxidation. I have previously obtained benzoic acid by alkaline permanganate
oxidation of toluene. Now I want to try agents that are less expensive and harsh than permanganate, with hopes of perhaps obtaining benzyl alcohol or
benzaldehyde (or even benzoic acid again).
Last night I tried two oxidations. In the first, I mixed 25 mL of toluene and enough 27.5% H2O2 solution to (in theory) oxidize it all the way to
benzoic acid. I then added a small amount of KMnO4 solution to serve as a catalyst. Curiously, after a small initial reaction, the pink color of
permanganate changed to the brown of MnO2 (expected) and then disappeared entirely (unexpected). I heated the solution on a hotplate to around 50 C
and shook it repeatedly to mix it. There was no apparent change occurring after a couple of hours. Recalling that peroxides are unstable toward
alkaline conditions, I added some clear household ammonia solution. The aqueous layer changed appearance: it turned a light tan color. The H2O2 now
began decomposing as well. I continued to swirl and shake the liquid around. The H2O2 repeatedly began undergoing self-accelerated decomposition as it
rose in temperature, so I had to cool the container under cold water several times before the peroxide was exhausted.
I acidified the mixture with HCl, and when I shook up the contents the entire interior of the vessel was filled with a thin white slurry. I presume
that this was benzoic acid. After sitting overnight the slurry had disappeared; re-shaking brings it back, but it slowly disappears again. Is the
presumed-benzoic acid dissolving in the non-aqueous layer? I'm not sure.
In the second oxidation, I was much less careful with measurements. I used a "dash" of toluene, a "quarter jarful" of water, and maybe a further
"quarter jarful" of ammonium persulfate. I warmed the jar's contents and periodically shook/stirred them. The aqueous layer slowly turned a pale
orange, while the non-aqueous layer turned a progressively deeper red. There was a marked change as the aqueous layer reached the boiling point. I
decided that I really didn't want to boil the solution, but it actually boiled more vigorously after I removed it from the heat. I believe I had
achieved the runaway oxidation stage. Fortunately, I was able to fetch some cold water to dump into it before it got vigorous enough to boil out upon
the table. This effectively killed the reaction.
I smelled some very interesting scents coming from that mixture. There was an aromatic smell sweeter and lighter than toluene. The non-aqueous layer
mostly turned into floating chunks of red goo. The goo was soft and sticky like recently chewed gum, and needed a non-polar solvent to remove it from
the jar.
Today, when preparing for another persulfate oxidation of toluene, I noticed something interesting about the persulfate solution. Ammonium persulfate,
dissolved in warm water, gave off a faint sweetish odor that was familiar but that I didn't immediately place. Then I remembered that I had smelled it
near laser printers and photocopiers before. It was ozone!
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Organikum
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thats my turf.....
You can go the chlorination pathway, to many possibilities to name them, but the masterpiece is the chlorine free benzaldehyde of course.
I am working on a electrolytic cell like in the patent US0780404 just now for production of manganese persulfate from manganesesulfate. The
persulfate together with H2SO4 oxidizes toluene to benzaldehyde or if you want to benzoic acid.
Everything is to reuse, to recycle in the process thats the charming and manganese sulfate is easy.
I could write a book on this but not now.
ORG
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fluffy bunny
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benzaldehyde
Interesting experiments. Is benzaldehyde your ultimate goal from all of these experiments?
If it is i have a very breif description saying it can be made from hydrolysis of dichloromethyl benzene.
Dichloromethyl benzene shouldn't be too difficult to make, i assume you could make it by direct halogenation of toluene, as most aryl halides are
made, but im not sure, i don't have any synthesis information on it.
The hydrolysis step should also be easy, but i'll try to find some specific information on synthesis
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Polverone
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no particular target
I am interested in making benzaldehyde, benzyl alcohol, and benzoic acid. Benzoic acid is easy. Benzaldehyde is probably the greatest challenge,
especially since I can't just buy it. Forbidden == interesting!
Benzaldehyde and benzyl alcohol can be made from halogenated toluene derivatives, but in practice the halogenation is messy and the product obtained
contains impurities. This is why other methods interest me, although I am not entirely disinterested in halogenation.
I made another attempt at oxidizing toluene using ammonium persulfate and a procedure from US patent 4,146,582. Unfortunately, in my haste I botched
the procedure. Nevertheless, the leftover reaction mixture has the smell of almond flavoring to it: there's definitely some benzaldehyde in there.
Next time I will be a good chemist and follow the directions more exactly. But I need to order some more equipment first.
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Organikum
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The substrate to ammonium sulfate ratio?
Isn´t the ratio quite insane as 1 to 8 or something else?
Following the patent you named.
In the electrolytic Manganese persulfate reaction the ratio is also very high but the recycling is included so I don´t mind.
just a thought
ORG
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FloridaAlchemist
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Toluene 2 Benzaldehyde
To prepare benzaldehyde from Toluene use a mild oxidation..such as Manganese dioxide and 65% Sulfuric acid.
Potassium Permanganate is too strong a oxidizer for preparing aldehydes..They always seem to make the carboxylic acid in this case benzoic acid.
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Organikum
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Also with MnO2 and H2SO4 you will get an mixture of benzaldehyde, benzylalcohol and a small amount of benzoic acid. IMHO the byproducts are not so
bad as useful but the separation, the whole workup is what I hate so much.
I recommend to use an huge excess of toluene as this is actually the only working way to suppress byproductformation. And its cheap and easy. Ten
times overfold is not to much believe me. As product recovery is best made by steamdistillation the more toluene doesn´t hurt and it can be reused
without problems.
attached the brandnew patent for my recommendation 
Attachment: us613460_excess_toluene.djvu (29kB)
This file has been downloaded 1603 times
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FloridaAlchemist
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Thanx Organicum
Thanx
Thats a excellent Patent.
Toluene is getting harder to come by these days but still available if you look hard enough.
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Darkfire
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Where have you found it, and what was it sold as, to this day ive never seen any.
\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I
will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
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Organikum
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I bet my ass you have "seen" heaps of it. Gasoline unleaded high octane contains moe than 10percent toluene, (and up to 50percent
toluene/xylene at all) but is near impossible to distill.
But this should be hint enough and enable you to aquire this compound. Of course not as toluene.
CAS: 108-88-3
Trade name: Methacide
other names: methylbenzene, methylbenzol, phenylmethane and thousands more - search!
Belongs to the C7 aromatic hydrocarbons. Every semiprofessional paint store, airbrush supply, automotive store, agricultural technic supply, and and
and.....
I suggest to start an "synonyms/abbrevations" thread where the namings get listed, that whats on back of the can. NO brand names! A
small rest of challenge has to be left IMHO
[Edited on 21-6-2003 by Organikum]
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solo
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RE: toluene to Benzaldehyde
Note: this was taken fro the Hive , by straightedge in the serious chem forum it deals with the topic through biotransformation...solo
Benzylic biooxidation of various toluenes to aldeh
Substituted benzaldehydes are often used as feedstock in industrial chemistry. The selective oxidation of aromatic methyl groups to the respective
aldehyde is, however, difficult.[1] The chemical oxidation of the methyl group commonly proceeds directly to the carboxylic acid. We therefore chose
to investigate enzymatic methods, because enzymes can be chemoselective. We started with the laccase/2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic
acid) (ABTS) system of Potthast et al. [2] However, with toluene and laccase from different fungi, such as Bjerkandera adusta, Coriolus sp., Phellinus
sp., and Pleurotus ostreatus, we found no transformation at all, which is in accordance with the findings of Fritz-Langhals and Kunath.[3]
Subsequently, we tried several peroxidases with hydrogen peroxide as the oxidant. Using lignin peroxidase from Phanerochaete chrysosporium[4] or
Coprinus cinereus,[5] we found no transformation of toluene. Chloroperoxidase from Caldariomyces fumago gave a slight transformation to benzyl alcohol
and benzaldehyde, as reported earlier.[6 and 7] Finally, peroxidases isolated from a Coprinus species of our strain collection were able to catalyze
the transformation of toluene to benzaldehyde and, only to a minor extent, benzoic acid (Table 1).
The transformation of 21 different substituted methyl aromatics by hydrogen peroxide and Coprinus peroxidase was tested. Only three of the compounds
tested, p-cymene (4-isopropyl-toluene), m-cresol, and p-cresol, were not at all transformed into the corresponding benzaldehydes. All other 18
compounds were transformed into the respective benzaldehydes whereby the efficiency of the reaction varied (Table 1). Suitable substituents comprised
methyl, halogen, methoxy, and nitro groups. It seems that the position of the substituent was more important than its composition. Ortho or para
positions of the substituent to the methyl group were preferred against meta, except for the nitrotoluenes. o-Nitrobenzaldehyde was obtained in a low
yield, whereas m-nitrobenzaldehyde was formed with yields comparable to the p-isomer. In the case of o-nitrotoluene, an interaction of the
intermediate methyl cation radical with the nitro group perhaps prevented the formation of the aldehyde. o-Nitrotoluene was the only substrate that
produced the alcohol derivative. The cresols were found not suitable for catalytic conversion by Coprinus peroxidase and hydrogen peroxide, probably
due to polymerization reactions as described for lignin peroxidase.[4] The preparation with o-cresol immediately turned yellow after addition of the
enzyme. A weaker discoloration to yellow was observed for m- and p-cresol, as well as toluene, 3-chloro-, 4-methoxy-, and 4-fluorotoluene. p-Cymene
was transformed into two compounds that were not identified. A molecular mass of 132 and 136 inferred that none of the compounds was either an
aldehyde- or carboxyl-derivative of p-cymene.
In summary, the method presented here used Coprinus peroxidase and hydrogen peroxide to oxidize a variety of toluene derivatives to their
corresponding aldehydes. Further studies are underway to characterize the enzyme responsible, as well as improving the reaction conditions to provide
better yields.
References
1. W.J. Mijs and C.R.H.I. de Jonge. Organic syntheses by oxidation with metal compounds, Plenum, London (1986).
2. A. Potthast, T. Rosenau, C.-L. Chen and J.S. Gratzl. J. Org. Chem. 60 (1995), pp. 4320–4621.
3. E. Fritz-Langhals and B. Kunath. Tetrahedron Lett. 39 (1998), pp. 5955–5956. Abstract | PDF (107 K)
4. M. Tien and T.K. Kirk. Proc. Natl. Acad. Sci. USA 81 (1984), pp. 2280–2284.
5. F. van Rantwijk and R.A. Sheldon. Curr. Opin. Biotechnol. 11 (2000), pp. 554–564. SummaryPlus | Full Text + Links | PDF (234 K)
6. V.P. Miller, A. Tschirret-Guth and P.R. Ortiz de Montellano. Arch. Biochem. Biophys. 319 (1995), pp. 333–340. Abstract | PDF (735 K)
7. J. Geigert, D.J. Dalietos, S.L. Neidlman, T.D. Lee and J. Wadsworth. Biochem. Biophys. Res. Comm. 114 (1983), pp. 1104–1108. Abstract-MEDLINE
There is a graphical abstract and a table that I can put up if anyone is interested.
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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frogfot
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A question. I've found a source of toluene (probably paint thinner) which said "contains 30-100% toluene" what exactly do this mean?
What could be impurities and is there any way to remove them?
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Smoer
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Maybe a little late to react,but I have a question.
Can toluene also be oxidized with H2SO4/H2O2?Or with H2O2 and CuSO4 as a katalyst?
cheerz
[Edited on 20-2-2005 by Smoer]
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Organikum
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| Quote: |
Can toluene also be oxidized with H2SO4/H2O2?Or with H2O2 and CuSO4 as a katalyst?
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After my best of knowledge from theory and experiments this does not work.
I remember an article though where a vanadium based catalyst was activated and regenerated in situ with H2O2. I hope this will work with manganese
based catalysts too - I am working on this by now. (Mn(II)sulfate to Mn(III) or Mn(IV)sulfate)
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Nicodem
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I doubt you can make benzaldehyde using persulphates, H2O2 with catalysts or other such oxidants in a two phase system. You should have a homogenous
system by using acetic acid as a solvent in order that the oxidant is in the same phase as toluene. Especialy because these oxidants easily oxidaze
benzaldehyde further to benzoic acid if water is present.
You might try SET oxidazing metals like cobalt, manganese or cerium salts in any of their oxidation state and in combination with 30% H2O2, but with
at least as much acetic acid cosolvent as there is toluene. Unfortuately with the water from H2O2 present you would most likely get only benzoic acid
as a product. However there are patents and papers where air is used as the oxidant in the presence of Co(OAc)2 in acetic acid that give good yields
of benzaldehyde. But this should be already known here I think.
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trilobite
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I believe it is possible, but not sure about the yields. With peroxodisulfate/Fe++/Cu++ the first step is the reduction of the peroxodisulfate to a
sulfate and a sulfate anion radical, then the radical oxidises the toluene to toluene radical cation. This species that is somewhat stabilized by the
aromatic ring. It is then oxidised to benzyl alcohol through a complex of the benzyl radical, cupric cation and water. The reason for using both
cupric and ferrous salts is that this oxidation step is much slower with iron, whereas iron reduces hydrogen peroxodisulfate more easily. The benzyl
alcohol is further oxidised to benzaldehyde, the mechanism might've been different but I can't remember how it was. There was one paper
studying benzyl alcohols too.
Fe(2+) + S2O8(2-) --> Fe(3+) + SO4(2-) + SO4(-)
SO4(-) + CH3-C6H5 --> SO4(2-) + CH3-C6H5(+)
CH3-C6H5(+) --> CH2-C6H5 + H(+)
CH2-C6H5 + Cu(2+) + H2O --> HO-CH2-C6H5 + Cu(+) + H(+)
Fe(3+) + Cu(+) --> Fe(2+) + Cu(2+)
With hydrogen peroxide the oxidising species is a hydroxyl radical which is more nucleophilic than the sulfate radical anion, so instead of oxidising
toluene it adds to the ring. This can be rationalized by the fact that sulfate is a better leaving group than hydroxyl, even if it has been concluded
that sulfate doesn't actually add to the ring and then eliminate. The product, a methylated hydroxycyclohexadienyl radical can be reduced to a
phenol by Cu(2+) or the hydroxyl group can be protonated making it a better leaving group, and eliminated to give a toluene radical cation, the
reaction intermediate of our interest. So the path taken depends on the pH of
the reaction medium.
Fe(2+) + H2O2 --> Fe(3+) + OH(-) + OH
OH + CH3-C6H5 --> CH3-C6H5-OH
CH3-C6H5-OH + H(+) <===> CH3-C6H5(+) + H2O
In the peroxodisulfate version of the reaction it is possible for water to add to the aromatic radical cation and then deprotonate to the
hydroxycyclohexadienyl radical, which could be reduced to a phenol. Apparently this reaction isn't fast enough compared to the formation of
benzyl alcohol that it doesn't matter if the pH isn't that low. I believe that small amounts of phenols are produced anyway, but obviously
very little. There are several articles on the subject, here are two. More available on request. Coming across US3531519 in the toluene -->
benzaldehyde thread was very interesting, why I hadn't seen it before is a mystery. I think it could be improved with cupric salts. This is from
the researchers behind the patent US4146582 and discusses the process using peroxodisulfate.
Electron-transfer processes. Selective syntheses of aromatic aldehydes of industrial interest by catalyzed peroxydisulfate oxidation.
Maggioni, Paolo; Minisci, Francesco.
Chimica e l'Industria (Milan, Italy), 61(2), 101-5 (1979).
Abstract
The oxidation of methyl- and hydroxymethyl-substituted benzenes by S2O82- catalyzed by FeSO4 and Cu(OAc)2, took place via an electron-transfer
process. Thus, p-MeC6H4OMe oxidation gave p-MeC6H4CHO. Other carbonyl compounds prepared were p-MeOC6H4COMe and protocatechualdehyde.
http://www.geocities.com/tatssnart/Electron_Transfer_Process...
pH-dependence in the copper(I) mediated oxidation of toluene with oxygen or hydrogen peroxide.
Okunowski, J. K.; Van Dam, H. E.; Van Bekkum, H.
Recueil des Travaux Chimiques des Pays-Bas, 109(2), 103-6 (1990).
Abstract
PH exerts a profound effect on the selectivity of the Cu(I)-mediated oxidation of PhMe with O2 or H2O2. At low pH, Me group oxidation predominates,
whereas at pH >3, ring hydroxylation prevails. A common mechanism for O2 and H2O2 oxidation is suggested.
http://www.geocities.com/tatssnart/pH_dep.pdf
[Edited on 21-2-2005 by trilobite]
[Edited on 21-2-2005 by trilobite]
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trilobite
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It seems I also managed to find a bug in the board software as the new message is there but the post by Nicodem was still marked as the newest in
Organic Chemistry index. I think this is related to the attachment I tried to upload first being too large. The message still got posted though.
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Organikum
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Nicodem, the oxidation of toluene by persulfates in sulfuric acid is one of the best known methods of making benzaldehyde, it was a long time the main
method used in industry. A sufficient amount of H2SO4 must be used (about 60% strength) and strong stirring is a must.
It is unclear though if the reactivation of the catalyst by H2O2 can be done continously or if it has to be done in a separated step to prevent
overoxidation to benzoic acid. I guess it must be done separated but thats up to experiment.
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trilobite
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In the first article I posted they say that the peroxodisulfate reaction is very selective towards the benzaldehyde, oxidation to carboxylic acid is
no problem at all. I haven't found any practical information of an acidic H2O2/Fe(II)/Cu(II) system yet, so I don't know who well could it
work. The two articles explain the reasons for why it should work, in one step.
Note that when chloride ion is present this reaction gives also benzyl chloride. Similarly when the reaction is performed in acetic acid benzyl
acetate is also produced, so I think FeSO4 and CuSO4 could be the salts of choice here and H2SO4 the acid.
[Edited on 21-2-2005 by trilobite]
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Organikum
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The article are indeed very interesting, I feel tempted to repeat some experiments with copper catalysts which failed in the past anew with addition
of acids.
Also the mentioning of benzene to phenol by Cu(I) catalysts at ambient temperatures is interesting. Benzene is quite tough usually....
I am still convinced that there is a way to react benzene with acetone to P2P in the gasphase, preferable in a reactive distillation setup. But maybe
I am just dreaming....
I hope I will be able to get me some hardware soon to work on this.
/ORG
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BromicAcid
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| Quote: | Originally posted by Organikum
Also the mentioning of benzene to phenol by Cu(I) catalysts at ambient temperatures is interesting. Benzene is quite tough usually....
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I remember reading about phenol being produced via decomposition of benzoic acid in the presence of copper catalysts but this was a high temperature
method. Of course there is always fentons reagent, but isolating phenol from that would be a pain in the butt right?
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Organikum
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Good practical information on Fentons reagent is found here
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trilobite
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In case anyone is thinking whether I'm talking out of my ass or not, I did make a few mistakes.
| Quote: | | hydroxyl radical which is more nucleophilic than the sulfate radical anion |
Should read electrophilic, not nucleophilic.
| Quote: | The product, a methylated hydroxycyclohexadienyl radical can be reduced to a phenol by Cu(2+)
....
which could be reduced to a phenol
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It is obviously an oxidation of the hydroxycyclohexadienyl radical to a phenol, not a reduction. Damn those electrons...
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