madscientist - 21-8-2002 at 09:49
I'm looking for cheap routes of preparing NO2 gas. Cu + HNO3 is expensive, as is nitrite + acid. So far the best idea I have is NH4NO3 + Cu. NH4NO3
can be quite inexpensive if it's bought as a fertilizer. Ideas, anyone?
vulture - 21-8-2002 at 10:34
Heavy metals + HNO3 or heating heavy metal nitrates.
Boiling HNO3...
HCl + NH4NO3
Polverone - 21-8-2002 at 13:58
Use a mixture of HCl and NH4NO3; inexpensive and distillation is not required. I've also tried HCl and KNO3 but it didn't seem quite as vigorous. You
may have to warm the mixture to get a good reaction rate. Zn + this mixture gives lots of NO2 in a hurry, presumably H2 as well.
rikkitikkitavi - 22-8-2002 at 12:28
heat Ca(NO3)2 to about 600 C
Ca(NO3)2 => CaO + 2NO2 + 1/2 O2
NO2=> NO + 1/2 O2 at the temperatures involved, however the reforming of
NO2 is fairly quick when the temperature goes down.
Not as simple , but definiately cheap if large amounts of NO2 is needed.
/rickard
thats the cheapest method i can think of:
Hoffmann-LaRoche - 10-9-2002 at 12:13
this process is unbeatable cheap as not even sulfuric acid is needed:
Ive successfully tested this method which only uses ammonium sulfate fertilizer, lead or zinc metal and potassium nitrate:
(NH4)2SO4 >(heating) NH3 + NH4HSO4
NH4HSO4 acts like a strong acid in aqueous solution and is able to help nitrate ions in attacking heavy metals such as lead, zinc and copper yielding
their nitrates and nitrous oxides, which oxidize to red brown nitrogen dioxide at the open air.
further heating of the reaction batch causes decomposition of the heavy metal nitrate and just more nitrogen dioxide.
hope i could help
Another interesting tidbit...
Polverone - 10-9-2002 at 12:22
According to a PDF I found on Rhodium's site (link available on request), phenols can easily be nitrated with excellent yields using an acid sulfate
(such as NaHSO4) in combination with a metal nitrate (such as NaNO3) in dichloromethane solvent. The example given was phenol to mononitrophenol; I
don't know if this can be used to produce more nitrated products or not.
madscientist - 10-9-2002 at 12:31
Link me. 
The link
Polverone - 10-9-2002 at 12:41
http://www.rhodium.ws/pdf/phenol.nitration.pdf
You may find other documents of interest if you just browse that pdf directory.