ADP - 4-4-2005 at 19:54
Is there any certain method or calculation one can perform to determine the amount of H2SO4 to use as a catalyst/dehydrant in a given nitration? This
is after stoichiometry of the main reaction and assuming 98% H2SO4.
It appears to me that one uses three times as much H2SO4 as one does HNO3, but this isn't very precise considering conc. differences.
cyclonite4 - 4-4-2005 at 21:47
The 3:1 H2SO4/HNO3 ratio is rule of thumb.
There is no correct, stoichiometric amount of H2SO4. As a catalyst, no definite amount is required. As a dehydrant, the more the better right? 
Don't be too worried about precision, the amounts of the acids used aren't calculated by concentrations, and don't need to be. Rule of
thumb.
JohnWW - 5-4-2005 at 00:07
You should be mindful of the possibility that excessive H2SO4 may result in sulfonation occuring to produce a sulfonic acid, instead of a
nitro-copound, under circumstances which favor it.
vulture - 5-4-2005 at 01:06
An aromatic sulfonate group is rapidly exchanged against a nitro group and might even aid in nitration (TNP synthesis for example).
ADP - 5-4-2005 at 05:12
Thanks guys, I'll just find the amount that best fits the synth. Practice makes the perfect ratios...