Sciencemadness Discussion Board - run away nitrocellulose nitration

run away nitrocellulose nitration

aquaregia - 8-5-2011 at 07:12

hi gent,
I finished distilling half a liter of fuming HNO3, and since I had some left, (a few CC) I mixed it 1/3 to 2/3 98% H2SO4 and dropped some cotton in it. nothing much happened, so after 20 minutes, I started addind some H2O to the flask to start rincing the cellulose. What surprised me is that the reaction started to kick off as soon as I diluted the acid, with NO2 emissions! Well, I drowned the reaction in water and dried the cotton.
While the cotton was drying, I repeated the experiment with 61% diluted HNO3 and 98% H2SO4. I dumped some cotton in it and the cotton seemed to desolve in the nitration bath. then I left it. when I came back 15 minutes later the reaction had run away with massive amount of NO2 being generated. There was no cotton in the flask, just a bubbling red liquid. what went wrong?
Why does the reaction seem more energetic with dilute acids?
this was done outside, but you do not need to tell me I am stupid to have left it unatended, I know!

Can someone tell me how to nitrate Cellulose with fuming nitric acid? or is it better to use commercial 61% concentration?

Bot0nist - 8-5-2011 at 07:44

Did you pre-cool the acids or use a heat sink? The dilution of a nitrating mix with water is exothermic, so I imagine that by adding water, the heat rose enough to run away. What proportions of acids are you using? Hopefully no one down wind casually strolled through your cloud of NOx

hissingnoise - 8-5-2011 at 08:12

Quote: Originally posted by aquaregia

. . . nothing much happened.

Nothing visible happens but the cellulose is transformed to its poly-nitrate while sitting in the acid mixture!
NC should be removed from the acid after immersion, the surplus acid allowed to drip off before plunging it into wash-water!
Because of dilution, 68% HNO3 is more oxidising than fuming HNO3.
And if you're diluting H2SO4 always add the acid to water . . .

aquaregia - 8-5-2011 at 08:22

As for cooling, as a matter of fact, everything was done under ambiant T (no cooling).
Still, I am amazed that fuming HNO3 seems to work "less" or more slowly than diluted acid.
as for the diluted 1/3 61% HNO3 2/3 98% H2SO4 mix which ran away, it was about 50 deg C (from mixing the nitric with the sulfuric ) when the coton was dropped.

The WiZard is In - 8-5-2011 at 08:57

Quote: Originally posted by aquaregia

hi gent,
I finished distilling half a liter of fuming HNO3, and since I had some left, (a few CC) I mixed it 1/3 to 2/3 98% H2SO4 and dropped some cotton in it. nothing much happened, so after 20 minutes, I started addind some H2O to the flask to start rincing the cellulose. What surprised me is that the reaction started to kick off as soon as I diluted the acid, with NO2 emissions! Well, I drowned the reaction in water and dried the cotton.

Have you? Been watching the Myth Buster's?

Their (Busty) Nitrocellulose expert in the episode on
exploding pants, had copious amounts of nitrogen oxides
pouring from the cylinder she was using. Luck was she - yes!
That it didn't inflame.

This is from a page in my file removed form a chemistry book
a 'hole bunch of years ago. This method has always worked
for me over the years. You can use the left over acid to again
nitrate some cotton though the results are poor.

Cellulose nitrate

In a beaker mix carefully, exactly 10 cc. of water, 68 cc. of concd. sulphuric acid,
and 30 cc. of concd. nitric acid. Cool the solution too 30o and introduce 1 g. of
absorbent cotton, in a single pierce. Stir the mixture from time to time and
maintain a temperature of 30o for twenty minutes. At the end of this time remove
the nitrated cotton by means of a glass rod and transfer immediately into a large
volume of cold water. Wash thoroughly with cold water, and finally with warm
water, until the washings do not show an acid reaction to litmus paper. Squeeze
as dry as possible and spread out to dry in the air, at room temperature. The
product obtained this way contains about 11.0 per cent nitrogen. It is a mixture of
the lower nitrates, with only a small quantity of the trinitrate (mono-nitrate = 6.77
per cent nitrogen, di-nitrate = 11.13 per cent nitrogen, tri-nitrate 14.17 per cent
nitrogen.)

I remember dissolving my cellulose nitrate in ethyl ether
made by the standard lab method, to make cellophane.

djh
----
My favorite MB episode was the one on airplane toilet seats
where they had the wouldn't have any trouble riding a
motorcycle Myth Buster bent over in body suit....!

The technical/anthropological term is Steatopygia — a
learned borrowing from the Greek whoes meaning
is obvious.

The WiZard is In - 8-5-2011 at 09:06

Quote: Originally posted by The WiZard is In

This is from a page in my file removed form a chemistry book
a 'hole bunch of years ago. This method has always worked
for me over the years. You can use the left over acid to again
nitrate some cotton though the results are poor.

Ran the ref down —

Elementary laboratory experiments in organic chemistry
Roger Adams, John Raven Johnson - 1936 - 363 pages

Elementary laboratory experiments in organic chemistry
Roger Adams, John Raven Johnson, Charles F. Wilcox - 1963 - 560 pages.

hissingnoise - 8-5-2011 at 09:42

Quote: Originally posted by aquaregia

Still, I am amazed that fuming HNO3 seems to work "less" or more slowly than diluted acid.

You still don't get it . . . ?
Read COPAE!
It's in the site library!

aquaregia - 8-5-2011 at 10:23

thanks to the wizard for his enlightments. Unfortunately, I am unable to get mythbuster and busty Kari, where I live, even though we do understand English and have access to red fuming nitric acid.
As for the library reading as to why diluted acid works better than fuming, I sure will check it out when I get the chance or if I knew WTF you are on about. It be quicker if YOU enlighten me/us but never mind.

so long.

hissingnoise - 8-5-2011 at 10:31

Look, it's simple enough - strong nitric acid nitrates - dilute, it's an oxidiser!
A runaway is caused by excessive oxidation . . .

decryption

aquaregia - 8-5-2011 at 10:33

for those who read this who are like me:
COPAE= Chemistry of powder and Explosives. It is indeed in the site Library and full of useful info.

aquaregia - 8-5-2011 at 10:40

hissingnoise, thanks! that was not too hard, was it?
Now, please forgive my ignorance, but, we are nitrating the cellulose, not oxydizing it? or at least that is what we want to do..
So you mean to tell me that when the reaction runs away, it is that the nitrocellulose is being oxydised, after being nitrated? Why is fumic nitric acid not as oxydizing as diluted? it does not make sense...

woelen - 8-5-2011 at 12:29

I do not agree with hissingnoise. Both fuming nitric acid and dilute nitric acid are oxidizers. The fuming acid is more reactive than the dilute acid. In fact, nitrate ion is quite stable and only when there is a large amount of non-ionized HNO3 present, the acid really acts as an oxidizer. For this reason dilute HNO3 (e.g. 10%) only acts as an acid and hardly as an oxidizer, e.g. metals dissolve in this giving hydrogen gas. Only the concentrated acid (starting from around 30% and becoming more reactive with increasing concentration) contains non-ionized and hence non-resonance stabilized molecules of HNO3 which are the more reactive species and act as an oxidizer in a different way than simple H(+) ions.

There are two reasons which I can imagine for the lower activity of the mix based on red fuming nitric acid.
1) Mixing red fuming nitric acid with concentrated H2SO4 does not lead to an increase in temperature. So, the mix might have been cooler in that case and hence the reaction was slow. Adding the water caused heating up, both due to hydration of the H2SO4 and because of reaction of water with fuming nitric acid, which is highly exothermic as well.
2) Red fuming nitric acid contains a lot of NO2, dissolved in the liquid. This compound does not contribute to nitration. It is a strong oxidizer, but it is not a nitrating agent.

So, in your case, take white nitric acid (or acid of 65% concentration or something close to that) and mix with conc. sulphuric acid. ALLOW THE MIX OF ACIDS TO COOL DOWN. Then add the cotton and wait for 20 minutes or so, occasionally stirring the cotton such that fresh nitrating acid mix also is capable of moving inside the cotton wadding.

http://woelen.homescience.net/science/chem/exps/nitrocotton/...

hissingnoise - 8-5-2011 at 13:10

Woelen, I wasn't saying strong nitric acid isn't an oxidiser!
It has after all been used as an oxidiser in RF.
But at certain dilutions its oxidising properties become more prominent than those in say, anhydrous acid. . .

The WiZard is In - 8-5-2011 at 13:58

Quote: Originally posted by aquaregia

thanks to the wizard for his enlightments. Unfortunately, I am unable to get mythbuster and busty Kari, where I live, even though we do understand English and have access to red fuming nitric acid.
As for the library reading as to why diluted acid works better than fuming, I sure will check it out when I get the chance or if I knew WTF you are on about. It be quicker if YOU enlighten me/us but never mind.

so long.

You don't need - want to use RFNA. RFNA is an oxidizing agent...
think rockets.

http://en.wikipedia.org/wiki/Red_fuming_nitric_acid

---
If you can't dazzle them with your brilliance ... boodle them
with your references.

This from :—

Hanson, Pratt & Sohrabi
Some Aspects of Aromatic Nitration in Aqueous Systems
In:— Industrial and Laboratory Nitrations
American Chemical Society
ACS Symposium Series 22
1976

I would be less then honest if'n I didn't note - that I assume
they used RFNA and not WFNA.

There is a large amount of literature on theory(ies) of nitration.
I am not planning of going through it here.

Synthesis

aquaregia - 8-5-2011 at 22:42

Gents,
I would like to thank those of you who tried to shed some light on this interresting questions, especially Hissingnoise and woelen.
Woelen is right in saying that the mix of "diluted" 61% HNO3 was alot warmer than the mix of fuming HNO3 because of the heat generated by the H2O dilution in H2SO4. Now I am not sure that heat is the only factor in why the reaction went amok, and here is why: Part of the problem of cotton nitration is that you just have no way to know it has been nitrated (no change in cotton aspect...). So what I did with the concentrated mix (i.e fuming nitric+H2SO4) was to heat it up after 20 min, just to make sure the cotton was well nitrated. Heating it up did not kick off any energetic reaction like that witnessed with the warm diluted mix!
I tested the cotton I nitrated using the concentrated acid, and "oh boy" it is nitrated allright. I deflagrates without leaving any residues...
As things stands, the concentrated mix seems really appropriate for this nitration as "runaway" is inexistant, but then again, it is a bit of a waste of concentrated fuming nitric acid. I will try this nitration again with a cold diluted mix and try to compare results.
But, as I said, even with a boiling highly concentrated nitration bath, runaway does not take place. There is more to it than meet the eye when using lower concentration nitration bath... for some reason, the nitrocellulose is allowed to decompose in the weaker mixture generating heat, while that is inhibited is the stronger one.

quicksilver - 9-5-2011 at 05:49

As a generality this is a mixed acid esterifiaction. Utilizing cooled acids, of a ratio of 5 grams cellulose to 150cc of 1.42 HNO3 & 1.84 H2SO4 of mixed acids. (see pp259 Davis for extended explanation) 30 minutes of exposure of this ratio is followed by a wash with pressing and continued washing & boiled w/ distilled water. The mixed acid is cooled prior to exposure of the cellulose as are many nitrated esters. The activity is subtle & in many ester processes, maintained as a gentle exposure & elimination of excess acids from finished material. Elimination of the slightest acidity is standard & exposure time frame & temperature limited as well. Pyrocellulose/nitrocellulose has become quite standardized & studied in depth.

woelen - 9-5-2011 at 12:28

Aquaregia, your observation is quite interesting. I recently found similar effects of higher concentration being less reactive (reaction between periodic acid and hydrazine is more violent at 30% hydrazine concentration than with 64% hydrazine concentration). In the case of the cellulose nitrating reaction I do not see a direct reason for the lower reaction rate with fuming nitric acid. Maybe the presence of NO2 has some inhibiting effect on the reaction.

I noticed that white fuming nitric acid tends to build up pressure in its container when stored, while red fuming nitric acid has less so. The large amount of NO2 already present in the red fuming acid may inhibit decomposition reactions of HNO3 to O2, NO2 and H2O. In a similar way it might be that a high concentration of NO2 might suppress the tendency to form more NO2 in a runaway reaction.

The WiZard is In - 9-5-2011 at 16:37

Quote: Originally posted by aquaregia

thanks to the wizard for his enlightments. Unfortunately, I am unable to get mythbuster and busty Kari, where I live, even though we do understand English

http://dsc.discovery.com/videos/mythbusters-clips-exploding-...

38-42 seconds in. Notice the copious nitrogen oxide fumes
Busty MB was nitrating a pair blue jeans.

This is what started the myth.

Histories: Farmer Buckley's exploding trousers
* 11 December 2004
* NewScientist.com news service
* Stephanie Pain

In 1931, the peace and quiet of the New Zealand countryside was shattered by a terrifying new phenomenon: suddenly and apparently at random, men's trousers began to explode. Some pairs detonated on the washing line, others as they dried in front of the fire. More seriously, some were occupied when they started to smoulder. At first there were just a few isolated reports, but soon the nation was in the grip of an epidemic of exploding trousers.

The explanation wasn't hard to find. The dangerously self-destructive garments all belonged to farmers who had been trying to destroy the ragwort that was ruining their pastures. This pernicious weed had reached New Zealand decades earlier and was now running riot across the country. The farmer's latest weapon in the war on the weed was sodium chlorate. But when combined with organic material, such as cotton and woollen fibres, the mixture becomes violently explosive.

RICHARD BUCKLEY was lucky. When his trousers blew up he wasn't wearing them. He was badly shocked, but as the Hawera Star reported on 12 August 1931, his quick thinking saved him from serious injury. "While Mr Richard Buckley's trousers were drying before the fire recently, they exploded with a loud report. Although partially stunned by the force of the explosion, he had sufficient presence of mind to seize the garments and hurl them from the house, where they smouldered on the lawn with a series of minor detonations."

According to the Star, there was only one suspect in the case: sodium chlorate. Until recently the chemical had been more familiar to quarrymen than farmers, but when government scientists declared it the best ragwort killer they had seen, farmers began clamouring for it. Buckley, who farmed in Taranaki, on the western side of the North Island, was just one of a growing number of people falling foul of the new, miracle weedkiller. And not everyone got off so lightly. Some were injured and a few died. In one tragic case, a farm worker who wanted to check on his sleeping baby struck a match to see by. His clothes went up in flames and he died a few days later.

According to New Zealand historian James Watson of Massey University in Palmerston North, there was more to the rash of explosions than dodgy weedkiller and bad advice from the authorities. Ragwort, Senecio jacobaea, was accidentally introduced to New Zealand in the late 19th century and, like so many foreign invaders, quickly became a pest. By the 1920s, the weed was rampant. What made matters worse was that its proliferation coincided with sweeping changes in agriculture. "There was a massive shift from sheep farming to dairying," says Watson, "and that meant ragwort was an even bigger problem."

Ragwort contains a battery of noxious alkaloids: it is so toxic that even honey made from its flowers is poisonous. Livestock usually avoid the plant, but once it displaces grass and clover the animals have little else to eat. Sheep can eat it for months before showing signs of illness, but cattle and horses sicken quickly and can die of liver failure.

The boom in dairy farming followed the arrival of new technology, first refrigerated ships, then motor vehicles and machines to separate cream from milk. The first refrigerated ships began to carry produce to the UK in 1882. At first they took mainly meat. Shipments of dairy produce only took off once motor vehicles began to replace horses, allowing farmers to get fresh milk to the local dairy factory. When farmers began to separate the cream themselves, the butter factories introduced collection rounds, picking up the cream from the farm gate. As demand and factories grew, dairy farms proliferated and spread into remote areas once thought too marginal to bother with. Between 1899 and 1919 the number of dairy cows doubled. Over the next two decades it doubled again.

“Although partially stunned by the force of the explosion, he had sufficient presence of mind to seize the garments and hurl them from the house” In the past, farmers had grubbed up ragwort by hand, a labour-intensive job that brought only temporary relief: any roots left in the soil simply re-sprouted. But hands were becoming hard to find. Even the unemployed baulked at the hard work and poor pay. By the late 1920s, farmers couldn't even turn to their families. Farmers who put their wives to work in the fields were frowned on. It wasn't respectable. Nor could they rely on their children. School had become compulsory and there were buses to collect children from the farms and inspectors with cars to check on any who didn't turn up.In any case, the one-man operation was part of the New Zealand farmer's ethos. They adopted the latest labour-saving devices and kept abreast of agricultural research. And they would try anything to get rid of ragwort. "When sodium chlorate came along they saw it as a means of rescue. They would try anything that would save them from hiring labour," says Watson.

The first they heard of the weedkiller was in 1930, when a scientist at the department of agriculture wrote an article extolling its virtues. When a government expert said the weedkiller was far superior at killing ragwort than any other and would, "where properly applied...completely destroy all the plants", then farmers listened. Within a year, imports soared from almost nothing to hundreds of tonnes.

The accidents started immediately. Mixed with organic material such as the fibres of a farmer's working clothes, sodium chlorate is extremely dangerous, forming compounds that will detonate at the first sign of a spark or a glowing cigarette. Sometimes just a shock or a knock is enough. Washing contaminated clothes made little difference.

Why had the government recommended such a dangerous substance? "The scientists were more concerned with how effective it was against ragwort than how dangerous it was," says Watson. This was a time when arsenic was recommended for getting rid of another serious weed, the blackberry.

New Zealand's farmers were prepared to take the risks, and they didn't blame the authorities. "Quite the opposite. They'd have been annoyed if the government had got in the way of them using it," says Watson. "If they hadn't had it, many would have been forced off the land. The accidents were the price they paid to keep their farms in production."

Besides, by the time Buckley's trousers hit the headlines in Hawera, farmers must have known of the dangers of sodium chlorate. "Most men smoked then and that would undoubtedly have brought it to their attention," says Watson. "You can't deal with it for long without discovering that it's dangerous."Farmers continued to use the weedkiller until the late 1930s, when word got around that those same government scientists were arguing about just how effective sodium chlorate really was. "Once farmers heard that it wasn't all that good, they started looking for alternatives." They are still looking.

Ragwort remains a serious pest in New Zealand. Today's weapons of choice are not herbicides but insects, the plant's natural enemies in its native Europe. The ragwort flea beetle was introduced in the early 1980s and has been very successful, destroying every single plant in some parts of the country. But the beetles haven't taken to the wetter climate of western New Zealand, where the ragwort problem is as bad as ever.

Earlier this year, Hugh Gourlay of Landcare Research, an independent research institute, began trials with two European species of moth that might be better suited to a wetter climate. The caterpillars of plume moths attack ragwort's roots. Plants attacked by the crown boring moth produce fewer seeds and their growth is restricted. "Studies in Australia suggest that both moths, but especially the plume moth, can reduce ragwort populations by up to 80 per cent in a wide range of climates," says Gourlay.

For now the moths remain confined to quarters until they've proved they won't attack any native plants. This time, scientists are keeping their miracle cure safely under lock and key until they are certain ragwort will be the only victim.

aquaregia - 10-5-2011 at 01:01

Thanks Mr Wizard,
I googled it when I saw your post... Well, all I can say watching the clip is that my "runaway" reaction was the same as that of Kari's...
It really was an NO2 generator...

Thank god I live in the boonies!

The WiZard is In - 10-5-2011 at 13:12

Quote: Originally posted by aquaregia

Thanks Mr Wizard,
I googled it when I saw your post... Well, all I can say watching the clip is that my "runaway" reaction was the same as that of Kari's...
It really was an NO2 generator...

Thank god I live in the boonies!

NB - It's WiZard.

What is missing is the scale, she had a large glass cylinder
and probable a couple of gallon of mixed acid. In my experience
this is what happens if the acids are toooooo hot. I would not
be amazed if her (their "gun cotton expert") mixture didn't inflame.

This is what an expert could do.

Hudson Maxim - Dynamite Stories 1916

WHEN THE WASH VANISHED

I WAS once invited to speak at a County Fair at Pittsfield, Massachusetts,
where I used to live when in the publishing business. My subject was
Explosive Materials and Their Use in Warfare.

The management was especially desirous that I should give my auditors
some sort of spectacular demonstration, to show what explosives would
do. A platform was erected in an open field, and I had an arena roped off
at the rear of the platform about fifty feet wide, and running back several
hundred feet. In the rear portion of this arena I buried several sticks of
dynamite, and connected them with an exploder and a battery on the
platform.

Also, I brought several cotton bosom-shirts, several cotton undershirts,
half-a-dozen handkerchiefs, a couple of towels, half-a-dozen pairs of
cotton socks, and as many cheap cotton collars and cuffs. These I had
immersed in a concentrated mixture of nitric and sulphuric acids,
converting them all into guncotton. Then I washed and soaked the acid out
of them, and dried them.

I stretched a clothes-line from the speaker's platform to a distance of
about thirty feet to my right, and on this I hung my guncotton clothes, only
a few feet away from the front of the audience.

There were, perhaps, a thousand people massed in front of me, crowding
up close, that nothing should miss them. I made a brief talk on the nature
and use of explosives, and burned some smokeless powder under water,
and then I touched off the dynamite in the rear of the field, which made a
very pretty showing.

The audience was very curious about that wash. That I should have hung
my linen out to dry on that occasion they thought was very peculiar taste,
to say the least; and some of them did not hesitate to say that they
considered it very bad taste.

I then said to the audience that I must beg their pardon for displaying my
underwear as I had done; that I appreciated the fact that it was an
unsightly display, and, to accommodate them, I would immediately
proceed to get it out of sight. I then touched it off with an electrical igniter,
and that laundry disappeared in one great bright flash of flame.

There happened to be in my audience an ingenious fellow with some
knowledge of chemistry, who was a noted wag and practical joker. Taking
the hint from my nitrated laundry, he nitrated a cotton handkerchief and
sent it to the Chinese laundry with the rest of his wash.

When he called for his clothes, he found John Chinaman with his right arm
in a sling. However, John was all smiles, and apologized for the absence
of the one handkerchief, but said nothing more about it.

A short time after the fellow had put on his clean underwear, he developed
a very severe case of prickly heat, followed, a little later, by a sensation
like that of needles being stuck into his body over the entire surface.
Anyone who had taken a bite of a wild Indian turnip knows what that
sensation is. The Chinaman had charged his customer's garments with a
preparation extracted from a Chinese variant of the Indian turnip. It took a
couple of weeks, with the aid of a physician, for the wag to recover from
the little unpleasantness which the Chinaman had inflicted upon him.

djh
----
There are a lot of books 'bout
explosives, however, there is only
on funny one. Maxim's Dynamite
Stories. I (The Analogue Guy)
own an original copy. You can buy
a reprise from — American Fireworks News

www.fireworksnews.com

---
Trivia fans — Why could have HM
produced an even more spectacular
demo if he had nitrated his wool underwear?

azo - 10-5-2011 at 20:49

Just a quick question can you use carboxy methyl cellulose in replacment for cellulose.

regards azo

hissingnoise - 11-5-2011 at 04:32

Why would you want a replacement for something as ubiquitous as cotton?

quicksilver - 11-5-2011 at 05:40

Quote: Originally posted by azo

Just a quick question can you use carboxy methyl cellulose in replacment for cellulose.

I don't think it would be possible as a "substitute". Although the two maintain the name 'cellulose' they are dissimilar in too many ways. This is to say that the end result of attempting to ester the CMC might result in a potential explosive molecule but it would not emulate NC in a familiar manner.

-=*=-
I was going to add some of what I had found but it was too off track for any value IMO. CMC is often used as a pharmaceutical binder and typically found use in the tablet-making process.
For example CMC has been used in the production of aspirin tablets. If not REMOVED from same and the material is sulfonated and nitrated to attempt to synthesis picric acid, the results are extremely poor. It might be that CMC is a difficult to nitrate/esterfy material as sulfonation can prep even easily oxidized materials.

[Edited on 13-5-2011 by quicksilver]

azo - 13-5-2011 at 05:39

Thanks for taking the time to explain it

many thanks

alhasan - 25-12-2014 at 16:26

I had something like that while trying to make NC; I hope I can get an explanation for this ..

I tried to make NC with the least possible amounts of acids; So, I used 30mL of Sulfuric acid (98%), added it to another 30mL of Nitric acid (68%), keeping temperature between 25 to 35C.

I put my mixture in an ice bath, then I added a whole 10 grams of cotton to it!

directly after the addition of cotton, it kneaded from the side got in contact with the acid, and no there was no remaining acid to be absorbed by other parts of the added cotton.

However, I went on

..

I mixed the cotton on, just like kneading. Minutes after, it gelatinized.
After some hours, I got an unknown orange liquid with alot of bubbles in it.

Does any one know what is the reaction happened here?!

Thanatops1s - 27-12-2014 at 17:02

Quote: Originally posted by The WiZard is In

Their (Busty) Nitrocellulose expert in the episode on
exploding pants, had copious amounts of nitrogen oxides
pouring from the cylinder she was using. Luck was she - yes!
That it didn't inflame.

That episode was just on yesterday. I had never seen it before but as soon as she was about to put the pants into a gallon or so of non-cooled mixed acids, I'm thinking to myself, oh god, you're just asking for a runaway nitration. Sure enough, it happened fast and NOx fumes started pouring out. I couldn't believe they didn't learn about what they were doing more before doing that. In an earlier episode she made a little and basically just dipped it in the acids for a second. And of course was garbage NC. She lit some and it took multiple seconds and left a big pile of carbon behind.

caterpillar - 29-12-2014 at 00:07

I had such runaway once. When I washed NC. I took pieces of NC from mixed acid and put them into water. I tried to crumple them quickly, but once not quickly enough. Temperature within one piece increased and I got runaway- bubbles of NOxes and residual carbon instead of white NC. But as for me, concentrated HNO3 is too valuable thing to waste it, preparing NC. It can be obtained without distillation- mixed acid can be prepared with the aid of reaction between H2SO4 and dry Ca(NO3)2. No distillation at all. Having conc HNO3, I'd better use it for preparation of nitramines.