Picric-A - 12-9-2008 at 05:15
I have read in a book 'Organic Chemistry- a concise approach' that if cyclohexane is heated in the presence of platinum, dehydrogenation occurs and
produces benzene and hydrogen.
Is this in vapour phase, eg passing cyclohexane vapor over heated platinum catalyst or can you reflux some cycloexane along with some platinum wire as
a catalyst and when things start boiling at 81 degrees C you know all the cyclohexane has been dehydrogenated..
comments/abuse welcome 
ScienceSquirrel - 12-9-2008 at 05:21
Cyclohexene is easily dehydrogenated with Raney nickel etc in the presence of a hydrogen acceptor.
Unfortunately you are going to have to hit cyclohexane a lot harder to convert it to benzene!
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi...
Getting that first double bond in is hard, after that the subsequent double bods are a lot easier and more energetically favoured.
Klute - 12-9-2008 at 05:29
And that would be a very expensive way to benzene 
Start from benzoic acid!
panziandi - 12-9-2008 at 06:28
Cyclohexanone is a cheap industrial solvent - could easily be reduced to cyclohexanol by aluminium isopropoxide then the cyclohexanol could be
dehydrated to cyclohexene. Cyclohexene could then be dehydrogenated as suggested up the page. Cyclohexene is much more expensive than
cyclohexane/cyclohexanol/cyclohexanone.
BTW Picric-A... a little abuse: cyclohexane boils at 80.74 °C and benzene at 80.1 °C so your comment about monitoring boiling point is... urm... not
gonna be helpful hehe
[Edited on 12-9-2008 by panziandi]
Picric-A - 12-9-2008 at 10:50
lol thanks for that panziandi... should of looked up cyclohexanes boiling point...
well it certainly sounds a lot harder than the book suggests
I may try the cyclohexene method on a small scale to see how difficult it is...
kclo4 - 12-9-2008 at 19:12
Hmmm.. Interesting idea Picric-A, but I still think if you needed benzene Benzoate decarboxylation would be the way to go, many people seem to have
had good luck with that. Personally I've never needed benzene, but this is how I would go about it.
You could also just buy it also. If you look hard enough, I bet you can get it for an "ok" price.
Personally I really like the idea of turning Toluene into benzene isomers via Transmethylation with AlCl3 as the catalyst. Someday, likely far from
now, I may just try this.
Also, how are you going to test for benzene when you try this?
[Edited on 12-9-2008 by kclo4]