bajamar - 24-1-2006 at 09:44
I would be interested to know some specific procedures of nitration without the use of sulfuric acid. If nitric acid exceeds 90% it alone becomes
suitable enough for very efficient nitration. Unfortunately, the oxidation strength becomes exceptionally strong for HNO3 at around 99% and I wonder
whether it can have an effect on the stability of products. That is, if I do a nitration using practically 100% HNO3, am I trapped in a hazardous
situation where the products are at risk of exploding while they are being synthesized? I have produced 98% HNO3 with some success of synthetising
hexagene but working with the acid of such concentration is a challenge itself.
Marvin - 24-1-2006 at 10:02
Usually the topic of nitration without sulphuric acid covers alternative dehydrating and diluting agents. Are none of these methods useful for your
problems?
I would not be inclined to use such highly concentrated acid and the material to be nitrated alone. I would think you would be risking the very rapid
production of highly toxic and corrosive gasses, as well as fire and possible explosion.
Usually ensuring all oxides of nitrogen are absent from the liquid and the addition of urea reduces the tendency of of strong nitric acid to oxidise
destructivly, but I have no experience with what you seem to be trying.
Taaie-Neuskoek - 24-1-2006 at 10:09
For most nitro-esters 100% can be used as well as mixed acids. The sulphuric is often used as dehydration agant as it is relatively cheap and OTC.
I don't know about nucleophillic substitution of aromatic compounds, but I guess that if you toss benzene in 100% HNO3 a violent reaction would occur,
so these things need to be performed with small quantity's and very good cooling.
Besides, for most reactions 65%HNO3 with a dehydration agent will do, so why bother with 100%? It is a pain to make, store and handle.
So it all depends on you reaction, what were you trying to make?
Boomer - 25-1-2006 at 00:42
White (!!!) fuming nitric is used for many nitrations, like PETN, MHN, nitrosugars, and of course for RDX.
As mentioned, some urea (or its nitrate, or even AN) will make it safer, as will low temps. I regularly work below 0C without a problem.
Some synths will not even work if sulfuric is present (RDX,...). But generally it improves yield and reduces the excess of nitric needed. E.g. for NG
with nitric only, you need twice as much and get a quarter less product.
Madandcrazy - 25-1-2006 at 08:57
I think the nitration without H2SO4 is more a method to nitating sensible starting materials which the substitution with the hydrogen atom is violent
or by additional nitration. Contingently high concentrated nitric acid (95-99%) with 20 - 30 % content of acetic acid anhydride 
is possibly useful nitrating (substituting) more than one hydrogen atom in a second
step for sensible energetic materials.
[Edited on 25-1-2006 by Madandcrazy]
Nick F - 25-1-2006 at 09:15
There are also ways to introduce nitro groups without nitric acid for some compounds. Nitroalkanes can often be made from the corresponding carbonyl
by forming the oxime with hydroxylamine followed by treatment with trifluoroperacetic acid (I wonder if mCPBA or even OTC persulphates could be used
with success?), and aromatic nitro compounds can be formed from the amine by diazotisation with excess sodium nitrite and Cu(II) catalyst (Sandmeyer
reaction). If the aromatic compound is activated then you might be able to form the nitroso compound with sodium nitrite and conc. HCl and then
oxidise it to the nitro compound.
crankyperson - 25-1-2006 at 13:29
with 100 % nitric acid (doesn't need to be white,red one does it too) you can nitrate nearly everything.
the soluted NOx gasses in the red one don't care if you nitrate something!
Nick F - 25-1-2006 at 15:52
But they can lead to (potentially dangerous) side reactions.
Boomer - 26-1-2006 at 02:34
"the soluted NOx gasses in the red one don't care..."
... said the kewl noob. We dont care if you blow up either. 
If you dont believe me try ethyl nitrate. A *trace* of NOs *will* lead to violent runaway, even at temps far below zero C.
crankyperson - 26-1-2006 at 07:36
I talked about the nitrating process, and not about the NOx gasses are coming up...AND...i don`t nitrate anymore,since i've had a house search (
garage chemist told about that, i'm living in germany).
Boomer - 27-1-2006 at 00:06
Sorry for that legal trouble. You got my sympathy there, we are neighbours. They dont get it we are no terrorists, we would not hurt anyone or
anything but a test plate. Do you already know what punishment will follow?
And I *meant* NOx being in the acid from the beginning, i.e. only slightly red acid *will* lead to runaway with some synths. If red gas comes up
*during* nitration, it is too late anyway... 
Madandcrazy - 27-1-2006 at 08:14
Excuse me for the info Boomer,
every HNO3 contains NOx fumes always and every easy nitration causing NOx fumes and this have noting to do with legal trouble or terrorism.
I meant in my last post, easy nitrating of a sensible material with have two hydrogen atoms (-CH3-) is anyway difficultly (decomposition is possible)
and HNO3 which containing NO2 is for this useable always.
[Edited on 27-1-2006 by Madandcrazy]