Sciencemadness Discussion Board

Benzoic acid yield (from toluene)

vmelkon - 27-1-2014 at 04:43

My main question is "What was your yield?".

There are some nice videos on youtube but they don't calculate the yield or do a melting point test.

I did the experiment twice (toluene oxidized by KMnO4 to potassium benzoate then acidified to precipitate benzoic acid).
The first time I obtained 62%
and the second time was 93%.
That doesn't make any sense. It was the same process. I think I made a mistake when I was weighting the sample the first time.

What was your yield? I want to compare.

TheChemiKid - 27-1-2014 at 12:31

My reaction didn't work, refluxed for 4 hours, and there was still lots of permanganate.

DraconicAcid - 27-1-2014 at 12:33

I haven't done that particular reaction, but I find that my yields are always better the second time.

HeYBrO - 27-1-2014 at 15:12

Quote: Originally posted by TheChemiKid  
My reaction didn't work, refluxed for 4 hours, and there was still lots of permanganate.
what procedure did you follow ( amounts of reactants) ? Magnetic stirring would of also helped if you didn't do it because of toluene's low solubility. Your reagents also could of also not been pure. what temp did you run it at? with some more information and we can help you get a successful reaction. If you still have the reaction mix you could add some sodium bisulphite to reduce the remaining permanganate.

[Edited on 27-1-2014 by HeYBrO]