evil_lurker - 4-4-2005 at 20:29
I can only find very little useful tidbits of information on the net about this process.
Basically toluene is heated to vapor and passed over a catalyst composed of 55% of 4:3 vanadium pentoxide/potassium sulfate maintained at over 400 C.
The activity was apparently related to the formation of needle-structure V/sub 2/O/sub 5/, as previously found for the activity for methanol
oxidation.
Yeilds are supposedly around 60%.
If anyone can dig up any info on this, such as patents, papers, and other publications, it would be greatly appreciated.
chemoleo - 5-4-2005 at 11:17
Do you mean the oxidation to benzaldehyde?
if so, there are numerous threads on toluene oxididation, you might have a look there for alternative oxidation routes.
enima - 8-4-2005 at 13:10
Vanadium pentoxide is a great oxidation catalyst, you can oxidize alcohols to aldehydes or ketones using atmospheric oxygen or oxidize benzyl halides
to benzaldehydes using hydrogen peroxide.
Why not go the benzyl alcohol route as it is not very difficult to obtain, most photochemical stores sell it and the proceedure is faily simple.
Proceedure:
A mixture of benzyl alcohol (0.5g) H2O (10ml) V2O5 (0.05eq), H2O2 (30%) and phase tranfer catalyst BTEAB adjusted to pH 4 using H2SO4 refluxed for 6
hours. After cooling reaction is basified with a 20% NaOH soluation and extracted with ether/non-polar solvent.
For benzaldehyde there is a 84% yield.
There are other ways to get the aldehyde but the vanadium pentoxide catalyst makes everything cheaper in the long run.
Keep in mind that vanadium pentoxide is a toxic substance that can be absorbed through your skin, if you choose to work with this method be sure to
wear gloves when handling the it in an aqueous liquid and a solid compound.