I was working on this a few months ago, but I came under some heavy scrutiny all of a sudden. Had my house surrounded in fact. So I never got to finish anything, but I have a book on green chemistry which I paid over $200us that has a moderately good writeup.
I will try to scan the reference, as well as one other on using Zeolites to catalize Tol->Benz oxidation.
I do remember that they were using flame deposition of a Ti salt on a polymer substrate as the physical catalyst. They were bubbling O2, sorry I don't remember if any additional solvent was used. I also remember that plenty of UV made a real difference to the reaction.
I intended to try suspending TiO2 in the tol, bubble O2, slam it way some MAD FUNKY UV radiation and see what happened.
I had one other odd idea, which seemed like it might be interesting...
If tol were evapped on a steam bath and then condensed above a reaction chamber
| |
Water /| |\
out = | ||
|| ||
|| || -- Toluene condenses to
|| || drop onto catalyst
Water = | ||
in \| |/
| |
| | Toluene vapor passes from
| \ / boiling flask around column
| |\\ /
| | \\
/|%|\ \\
||%|| ||
UV / ||%|| || % Column packed with TiO2
Light - ||%|| || % on polymer, carbon or something
\ ||%|| ||
||%|| ||
\|%|/ ||
| | //
| |//
Oxygen | /
inlet->= |
| | boiling flask
/ \ /
/ \ /
/ \
---| |---
| \_____/ |
| |
+-------------+
Steam Bath
Toluene boils in the flask, passes mostly around the packed column, condenses and drips into a column packwith with a supported TiO2 catalyst. O2 is passed in through a side adapter to bubble through the Tol and catalyst while being iluminated with intense UV from a mercury lamp.
When the tol exits the column, hopefully a portion has tol has oxidised to benz. If so, then the benz would remain in the flask as the tol continued through the evap/condense/seep through catalyst cycle. This would seem to be the likely outcome because benz, unlike tol, has a higher boiling point than H2O.
So the benz would collect in the flask, and the flask would remain at the boiling point of tol until all the tol had been converted to benz(or something else), at which point the temp should rise even with the steam bath. Since the benz would not continue cycling it should have a low likelyhood of being over oxidised to benzoic acid. And a jump in the flask contents internal temp would be a good indicator of a nearly complete reaction.
I read of another reaction being done like this, acetone -> cloroaceton, I think. But I have no references on whether it might work for tol->benz, but it seems reasonable from my feeble understanding of chemistry.
Let me know what you think,
TrickE
And on the eight day, God created Meth...
... and hasn't done much of anything usefull since!
The azeotrope of water and benzene boils at 69.40°C. The link on Rhodium archive is dead but this is where is should lead to: http://www.chemeng.ed.ac.uk/people/jack/azeotrope/hetero.html (http://www.chemeng.ed.ac.uk/people/jack/azeotrope/hetero.html)
.
While on the subject of toluene->benzaldehyde routes, here's an interesting one I didn't find with TFSE using O2 and toluene on zeolite, http://pubs.acs.org/hotartcl/chemtech/96/jun/zeo.html (http://pubs.acs.org/hotartcl/chemtech/96/jun/zeo.html)
the molecular structure of which is cage-like,
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000363270-file_ufxq.gif)
allowing small molecules to become trapped meaning a "high steady-state concentration of collisional pairs can be achieved".
http://pubs.acs.org/hotartcl/chemtech/96/jun/jun.html (http://pubs.acs.org/hotartcl/chemtech/96/jun/jun.html)
Toluene to benzaldehyde
"..When we loaded a dehydrated BaY matrix with toluene (5 Torr) and O2 (1 atm) from the gas phase and exposed it to visible light at room temperature, we found that benzaldehyde is produced without side reaction "
An addendum to Praes' post:
http://deathstar.chem.uiowa.edu/catalysis.html (http://deathstar.chem.uiowa.edu/catalysis.html)
Has these references:
1. Photooxidation of Hydrocarbons in Cation-Exchanged Zeolites, Vicki H. Grassian and Sarah C. Larsen, invited review article in Handbook of Photochemistry and Photobiology, in press.
2. A Kinetic Study of the Thermal and Photochemical Partial Oxidation of Cyclohexanewith Molecular Oxygen in Zeolite Y, R.G. Larsen, A. C. Saladino, T. A. Hunt, J. E. Mann, M. Xu, V.H. Grassian, and S.C. Larsen, Journal of Catalysis, 204, 440-449 (2001).
3. Photooxidation of Toluene and Para-Xylene in Cation-Exchanged Zeolites X, Y, ZSM-5 and Beta: The Role of Zeolite Physicochemical Properties in Product Yield and Selectivity, A. G. Panov, R. G. Larsen, N. I. Totah, S. C. Larsen and V. H. Grassian, Journal of Physical Chemistry B, 104, 5706-5714, (2000).
4. Photooxidation of Toluene in Cation-Exchanged Zeolites, Y. Xiang, V. H. Grassian, S. C. Larsen, invited chapter in Green Chemical Syntheses and Processes, ACS Symposium Series767 (ed. P. T. Anastas, L. G. Heine, and T. C. Williamson), 2000, pp. 206-216, American Chemical Society.
5. CO Adsorption as a Probe of Acid Sites and the Electric Field in Alkaline Earth-Exchanged Zeolite Beta Using FTIR and ab initio Quantum Calculations, Ping Li, Yan Xiang, Vicki H. Grassian, Sarah C. Larsen, Journal of Physical Chemistry B, 103, 5058-5062, (1999).
I'd never heard of the shit before I independently came across the same site Praesedonym posted, usedTFSE and low and behold - this thread... Nifty stuff