I have fairly limited experience with nitrations however while attempting a nitration of cellulose the nitration bath turned a brownish, pinkish
color. Is this normal? It was a white/grey color when I first mixed it up.
Impurities in the sulfuric acid, maybe? I used rooto brand acid and did not decolor it because I read that there was no benefit in doing so.
This was done with ammonium nitrate as my salt. In the future I'll use potassium nitrate. It's not as cheap for me, but easier to get.
Shit, I was going to upload a photo but it won't load, it's too big.
Motherload - 8-3-2013 at 10:56
You probably ran the nitration too hot.
The red brown color maybe due to partial decomposition of cellulose nitrate and/or nitric acid due to the formation of NO2.
What was the source of your cellulose ?Bot0nist - 8-3-2013 at 19:14
Trotsky, I dont think the ammonium nitrate was the problem, unless it was from a dirty source. NH4NO3 works great for most mixed acid nitrations
because of its better solubility. Though, some nitrations seem to work better with alkali salts, like KNO3 or NaNO3. The TNP nitration is one of the
top of my head, IIRC. Dirty looking drain cleaner acid is often cleared up quite well just by adding the nitrate salt. I assume by oxidation or
breakdown of carbon and other dark impurities.
Heat, partial runaway, or decomposition could be it, but I also have ran cellulose nitrations pretty warm with no trouble. Once, even at a very slight
reflux (test tube scale!), with minimal decomposition, and a good, complete nitration.
Despite the color change, did the nitration proceed as expected?
edit:
We need many more details to help much more. If you dont have them, then you should recreate the experiment and note all reaction conditions, incuding
temps, additions, durations, etc. Anything you can think of could be helpful
[Edited on 9-3-2013 by Bot0nist]Trotsky - 8-3-2013 at 19:23
I was using cotton balls. I'm not sure what brand.
Upon addition of the AN the solution turns an opaque, whitish-grey color. The H2SO4 is a light amber color.
The solution was fuming pretty well, annoyingly well.
However, the temp was maintained at -2C for the first hour, and allowed to rise to a little under 20C (ambient temp). Every time I checked it, the
time was quite low.
Because of my concern I allowed the cotton balls to nitrate for 14 hours, and the nitration was complete. They're still drying, but the bit I dried
with a blow dryer burned quite well, and left very little residue. Not no reside, but very little (a little more than you'd get from a ping pong
ball).Motherload - 8-3-2013 at 23:24
Maybe your NH4NO3 had an anti-caking agent in it
Try with recrystalied nitrate.
I have nitrated toilet paper and it worked well with HNO3 and H2SO4AndersHoveland - 9-3-2013 at 00:04
Sometimes urea or calcium chloride is added to cold packs.
If it is calcium chloride, there will be problems, since the chloride gets oxidized under these conditions. If nitrosyl chloride is being produced in
your acid bath, some nitrite esters will likely be forming along with the nitrate. This is not a good thing, because your nitrated cellulose will have
poor thermal stability, and will not be as stable in storage (will tend to degrade over time).Trotsky - 9-3-2013 at 19:15
I made a new bath, and let it sit for an hour before I did anything with it- sure enough, it turned a pink-red color.
Handling the prills does't produce any powder on my fingers, so that suggests it's not an anti-caking agent.
I really doubt they'd mix urea and AN together- the risk from UN formation would be minimal, but I don't think they'd risk that happening. Don't
think, anyway...
What does nitrosyl chloride smell like? What do the nitrite esters smell like?
I did make more nitrocellulose with this batch, quite a bit more actually (20 balls instead of 3), and when I was washing it, when smelled closely,
they smelled terrible, hard to describe, but somewhat bleach-like (but worse).
However, I neutralized the acid with Sodium Carbonate Anhydrous instead of the usual sodium bicarbonate. I'm not sure whether this could result in
the odor.
It doesn't seem to be negatively effecting the finished material. Formed into a torpedo shape, wrapped tightly with tinfoil, leaving a small bit
hanging outside the nozzle makes for some excellent rockets. I've seen people do this with ANCP, but I never got it to work before. For thirty
seconds worth of work, they're pretty neat (if in need of stabilization!- using a cardboard tube to get them going forward instead of rapidly spinning
works fairly well, but once they're past that, all bets are off!)Trotsky - 10-3-2013 at 00:33
If my ratio of NH4NO3 to H2SO4 was too high, would that lead to a build up of nitrogen oxides? This color left my cotton stained pink, despite
washing it about a dozen times in water up to about 43C (I didn't check the temp, but it was just this side of scalding).
In the end the color was removed by drying. I painstakingly pulled each bit apart as thin as I could get it, fluffing them up, in a way, but as very,
very thin sheets. I piled them up and left them in front of a heating register for two more hours, and lo and behold, the pink color was completely
gone, and they now have a very attractive ivory color. Between the shaping, fluffing and color change, it now looks like insulation, or perhaps part
of a wig
I can only assume that it is indeed nitrogen oxides, but it was definitely not too hot, ever (the hottest it ever got was while I rinsed it).
I have read that the lower nitrated cellulose is soluble in acetone, but fully nitrated cellulose is not, is that accurate?
Is there a scale or chart or even just a written explanation somewhere detailing the effect on nitration level vs. solubility in various solvents (if
cellulose hexanitrate isn't soluble in acetone, is the pentanitrate? in anhydrous isopropyl alcohol (dried with anhydrous MgSO4) how high a nitration
will be soluble? Is it soluble at any level? I had very, very little dissolve in a test I did, but I'm not sure how anhydrous it really becomes,
I've used anhydrous MgSO4 to dry isopropanol in the past, but I've never really tested to see how complete it is.Bot0nist - 10-3-2013 at 09:56
No. Fully nitrated cotton is very soluble in acetone. And the lower nutation products to an extent as well. The best way to tell if you have fully
nitrated cotton is to do steel on steel impact testing. A good product will pop when wrapped tightly in foil and struck with a steel hammer on steel
anvil. Your shooting for a nitrogen content of ~13% IIRC.
[Edited on 10-3-2013 by Bot0nist]Trotsky - 14-3-2013 at 23:03
It doesn't say how much of an increase in power is achieved by the relatively small increases in nitration %.
If one were trying to detonate the NC, how much easier is this with High Nitrogen NC vs. Say, 10 or 11% material?
I've mostly used it as a propellant- would 14% material (if I could obtain it by nitrating and re-nitrating my NC) have the potential for deflagration
to detonation events? I'd hate to raise the N content just to find out that now my motors blow up on the stand ( a couple times I've already had the
nose blow off, solved by better engineering, but motors work badly with two nozzles )Trotsky - 19-3-2013 at 01:56
In an attempt to see if contaminated H2SO4 was the culprit, I very slowly added 35% H2O2 to 10.5oz until it began to warm considerably.
I'm letting it sit now, waiting for it to clear.
However, in all of the discussions of cleaning drain cleaner H2SO4 w/ H2O2 they say that it'll bubble a lot as it breaks down organic compounds to
CO2. However, I saw no bubbles form.
I'm not sure what it is, as i hadn't seen it described, but immediately upon addition of a drop of H2O2 a mist or perhaps whitish gas was immediately
released for 5-15 seconds. It wasn't a strong smell, but I didn't know what it was, so I immediately placed it in a fume hood where it will sit until
I'm ready to use it.
How long should it take to clear it? I only added 9ml H2O2, and that was quite a bit of H2SO4. However, I don't want Piranha solution, I just want
it a little cleaner.
Most importantly- is there any need to do anything else with it before using it in a nitration bath? I assume what little water was present wont
present any problems, will it?
)