BenZeen - 22-6-2011 at 05:35
Hi everyone,
I have been playing around with the MAA cell (cycloknights variation) and have managed to get as far as generating the brown oxidative substance,
after adding 100 - 150 mls of toluene i can smell a very faint amount of benzaldehyde, attempts to isolate anything meaningful has proved completely
futile. (cell is 2 ltrs)
I have tried strong stirring, increase temp etc but to no avail, which has led me to believe there may be something in the toluene preventing it from
becoming benz. I remember something about thiotoluenes inhibiting benzaldehyde formation, so simply i just would like to hear any ideas or comments
regarding commercial toluene that may affect this reaction.
Thankyou very much
Panache - 25-6-2011 at 17:10
Do you have the msds of the product, this will let you know if anything is in the toluene, after that you can begin speculating, rather than
speculating upon a speculation.
smuv - 25-6-2011 at 18:54
Is thiophene(s) even an impurity any more? Back in the day, sure, aromatics came from coal pyrolysis. Now, aromatics are petrochemicals, I have a
hard time fathoming thiophene would make its way into even tech grade chemicals these days.
not_important - 25-6-2011 at 19:10
Not really, SFAIK most toluene is derived from petroleum (as you said). I believe the main impurity in commercial toluene is the corresponding
methyl-cyclohexane and cyclohexenes, as their boiling points are close to that of toluene. Dilute KMnO4 or bromine water will test for non-aromatic
unsaturates easy enough. Thioaromatics can be oxidised to sulfonones by H2O2 or other oxidisers, distillation would remove those.
BenZeen - 30-6-2011 at 10:57
Thanks guys, Always good to hear from more knowlegable chemists than I.
Perusing the interweb, I came across this pdf from the iupac detailing methods for purification of benzene and toluene.
www.iupac.org/publications/pac/1989/pdf/6110x1823.pdf
I thought it might be worth posting incase this thread pops up at some future date in the FSE.
Cheers, Benzeen.
Sedit - 30-6-2011 at 11:19
Iv said it before, try dripping the oxidizer into warm toluene with good stirring. Else your just wasting your time.