Reductant (1 mmol)???

[Chewbacca]

https://www.thevespiary.org/rhodium/Rhodium/chemistry/benzaldehydes.kmno4.html

it states here that to oxidise styrene to benzaldehyde, 4.65g of KMnO4/alumina reagent is required to oxidise 1mmol! that seems entirely rediculous! if one wanted to oxidise 100mmol, which is only about 5 grams, one would require over a pound of KMnO4/alumina reagent plus enough DCM to dissolve everything! why is so much reagent required to reduce so little? this seems entirely impractical if one wanted straight benzaldehyde...

[hypo]

if my calculations are right, then that's 5mmol KMnO4 per
1mmol styrene. do you know the theoretical amount? even
if it's equimolar (which i doubt), that's still 90g of
catalyst for 100mmol. sounds impractical.  
maybe using less alumina works too?
(afaik KMnO4 oxidations suck anyway)

> if one wanted to oxidise 100mmol, which is only about 5 gram

no, that's about 10g (styrene or benzaldehyde)

> plus enough DCM to dissolve everything!

no, i don't think the alumina/KMnO4 will dissolve in DCM  

[Chewbacca]

yeah it is about 10g, my bad. when i say "enough DCM to dissolve everything" i mean enough DCM to hold everything together in a slurry for stirring. i sorta figured that the reagent wouldn't dissolve in a NP, me stoopid again.  

i noticed in another writeup for oxidising styrene to benzaldehyde styrene was used basically as a toluene substitute, it too being reacted with mnO2 + H2SO4 to form the aldehyde. i was wondering, since toluene can bee chlorinated to benzal chloride then reacted with either ZnCl or CaCO3 + H2O to form benzaldehyde, could styrene also bee chlorinated in the same fashion then reacted similarly to form benzaldehyde, just like a toluene substitute? (since they form the same compound when reacted with mnO2 + H2SO4)

any ideas?

[hypo]

the alternative low yielding aqueous permanganate oxidation doesn't
look tasty either:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/tma2np.html

seems like permanganate oxidations simply do suck.

> i was wondering, since toluene can bee chlorinated to benzal chloride
> then reacted with either ZnCl or CaCO3 + H2O to form benzaldehyde, could
> styrene also bee chlorinated in the same fashion then reacted similarly to
> form benzaldehyde, just like a toluene substitute? (since they form the same
> compound when reacted with mnO2 + H2SO4)

no. chlorine would add accross the double bond giving an unwanted compound.
(something like 1,2-dichloro-1-phenyl-ethane)

but tell: you can get styrene and not toluene!?