Are there any substances with an NFPA rating of 444?

[CRSP]

As in the fire diamond. Such a substance would have to be extremely poisonous, with a low flashpoint and likely to explode. Is it possible for such a substance to exist, or are these properties mutually exclusive? If so, what are some examples of these substances?

[Erguotou]

From here (Yahoo Answers):

"I have looked for several years and not found a chemical with a 444 rating. This is because NFPA ratings are used for chemicals in commerce and nothing that might have that rating would be found outside of research labs or government labs. There are chemicals that have 2-4's such as 442 or 344. Pentaborane is one example."

[danceswithcats]

Yes, there is such a chemical. tert-Butyl hydroperoxide. That stuff is 4-4-4 with an OX, as it is an oxidizer.

[CRSP]

Hmm, that answers it, but it begs the question: what is an example of such a substance that would be given a 444 rating, if it was sold on the open market, and not the sole purview of government research labs?

[CRSP]

Yes, there such a chemical. tert-Butyl hydroperoxide. That stuff is 4-4-4 with an OX, as it is an oxidizer.

Excellent!

[danceswithcats]

That's the sort of stuff we yak about during HazMat training.

[CRSP]

So how would a large spill of that chemical be cleaned up?

[danceswithcats]

So how would a large spill of that chemical be cleaned up?

Right after calling CHEMTREC, I'd dike and dam with something nonreactive, such as clean sand or diatomaceous earth, and then test a small quantity of the material for reactivity with crushed clay (kitty litter), or absorbent pads. Once the material is absorbed, then all of the sorbent would be shoveled into plastic drums for disposal by an approved handler.

The purpose of damming and diking is to prevent contamination of underground aquifer, sewer systems, and also to preclude the material from coming into contact with a reagent.

[Derleth]

So how would a large spill of that chemical be cleaned up?

Right after calling CHEMTREC, I'd dike and dam with something nonreactive, such as clean sand

How would you clean up something that was hypergolic with sand, like chlorine trifluoride? In case you missed my thread a while back, here's more information:

There’s a report from the early 1950s (in this PDF) of a one-ton spill of the stuff. It burned its way through a foot of concrete floor and chewed up another meter of sand and gravel beneath, completing a day that I'm sure no one involved ever forgot.

Oh, yeah. Almost forgot about the by-product:

That process, I should add, would necessarily have been accompanied by copious amounts of horribly toxic and corrosive by-products: it’s bad enough when your reagent ignites wet sand, but the clouds of hot hydrofluoric acid are your special door prize if you’re foolhardy enough to hang around and watch the fireworks.

I won't go on much farther; you can read the blog post and my thread if you're hungry to know more.

[danceswithcats]

Without question, fluorine compounds are nasty. Thankfully, I've never had to deal with a spill/release of a fluorine derivative. We did have one oleum release from a tanker, but close proximity to the Rohm & Haas plant brought out their response team and the impact of the incident was minimal.

[Exy]

Clouds of hot hydrofluoric acid represent essentially everything I fear.

[Jurph]

...Once the material is absorbed, then all of the sorbent would be shoveled into plastic drums for disposal by an approved handler.

Won't an oxidizer that aggressive be hypergolic with any organic plastic? Are there plastics designed to be strongly inert, or plastics that you can coat with glass or some ridiculously neutral oil?

[OtakuLoki]

Derleth, that's one of the few compounds I've heard of that makes me think I'd rather deal with uranium hexaflouride.

[danceswithcats]

...Once the material is absorbed, then all of the sorbent would be shoveled into plastic drums for disposal by an approved handler.

Won't an oxidizer that aggressive be hypergolic with any organic plastic? Are there plastics designed to be strongly inert, or plastics that you can coat with glass or some ridiculously neutral oil?

You raise a very good question. Part of a HazMat team's research in the beginning stages of an incident is to determine if the suits on hand are subject to degradation upon exposure to the spilled material. If we don't have proper protection for the entry team, we aren't going to do anything until appropriately equipped. Further, how will we decon the entry team? Unless we're feeding them using air lines from a remote source, and those lines are suitable for exposure to the product, the person in the suit runs out of breathing air in 30-45 minutes, which is a bad thing.

Safe entry and decon are our priorities. Presuming we've stabilized the incident, final cleanup and disposal are the responsibility of the manufacturer/hauler, or their designated cleanup contractor. When speaking of shoveling the absorbed material into a plastic drum, that was predicated on first having ensured no incompatibility issues. If the HazMat team can't safely package the spilled product, the responsibility goes back to the manufacturer/hauler.

I hope that makes more sense.

[Jurph]

That makes more sense to me. Do you typically have one (or two, or three) "standard" drums and sorbents around that are generally inert with most stuff? I would imagine you'd want cheap stuff like sawdust, kitty litter, or sand if possible before going to more exotic stuff like granules of that material that's in diapers and tampons. Likewise I would think you'd keep plastic drums for most stuff, and then maybe steel or stainless with an inert ceramic paint liner, and then maybe some more exotic dewar-type stuff.

Is there a fairly well-known flow chart or cascade diagram so you can quickly select the right stuff to use from a small set? Otherwise I imagine you would spend far too long choosing a solution.

[beebs]

Whatever happened to a bucket, a mop, and some elbow grease?

[/joke]

[danceswithcats]

That makes more sense to me. Do you typically have one (or two, or three) "standard" drums and sorbents around that are generally inert with most stuff? I would imagine you'd want cheap stuff like sawdust, kitty litter, or sand if possible before going to more exotic stuff like granules of that material that's in diapers and tampons. Likewise I would think you'd keep plastic drums for most stuff, and then maybe steel or stainless with an inert ceramic paint liner, and then maybe some more exotic dewar-type stuff.

Is there a fairly well-known flow chart or cascade diagram so you can quickly select the right stuff to use from a small set? Otherwise I imagine you would spend far too long choosing a solution.

You're quite correct. Most teams carry crushed clay (oil dry) and sorbent pads/rolls, often called pigs. Some may carry diatomaceous earth, along with plastic and lined drums. The drum manufacturers provide a list of approved chemicals which can be placed therein. If it's not on the list, then I'm back to the research library, or on the internet.

For larger spills, teams typically work with the local municipal works people, who can provide a dump truck, backhoe, and materials like sand in a relatively short time.

[danceswithcats]

Whatever happened to a bucket, a mop, and some elbow grease?

[/joke]

We sent a guy in with that equipment, and he became a puddle of goo, so we filed that under "Plans, Bad" :wink:

[Chimpy]

...Once the material is absorbed, then all of the sorbent would be shoveled into plastic drums for disposal by an approved handler.

Won't an oxidizer that aggressive be hypergolic with any organic plastic? Are there plastics designed to be strongly inert, or plastics that you can coat with glass or some ridiculously neutral oil?

In a related field of research, this sort of thing comes up. Synthesis of covalent compounds of the noble gases results in compounds which are fantastic fluorinating/oxidising agents. They also have the unfortunate side effect of reactivity with glass;

XeF4 + SiO2 --> XeO2F2 + SiF4 (not balanced, obviously) and so on until you get to XeO3 which goes boom (2XeO3(s) --> 2Xe(g) + 3O2(g)...).

This, for a while hindered the investigation of these compounds. The solution commonly used nowadays is that synthesise are run in either glass coated in Teflon or metal containers, which swiftly develop a protective layer of metal fluoride on the surface. Furthermore, the compounds are usually supplied in Teflon bottles. The reason for Teflon's inert nature in this case arises from the fact it's already fully fluorinated ((CF2)n).

Essentially, in answer to your question, the link provided earlier gives;

It can be kept in some of the ordinary structural metals-steel, copper, aluminium, etc.-because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal

So essentially, much of the same chemistry here, which stands to reason as the polyhalogens are isoelectronic with a range of the xenon fluorides.

[Duke]

So how would a large spill of that chemical be cleaned up?

Right after calling CHEMTREC, I'd dike and dam with something nonreactive, such as clean sand or diatomaceous earth, and then test a small quantity of the material for reactivity with crushed clay (kitty litter), or absorbent pads. Once the material is absorbed, then all of the sorbent would be shoveled into plastic drums for disposal by an approved handler.

It amuses me that kitty litter is used in the same cleanup of the two of the world's most toxic chemicals...that tert-Butyl whatever and our cat Louie's Awesome Megadumps, the latter of which releases clouds of Toxic Funk.

[flymousechiu]

I have done quite a few searches about a widely commercialized chemical that has an NFPA rating of 444, and it seemed to me that tert-butyl hydroperoxide is indeed the only one that I stumbled on with. It is an iso-butane molecule with a O-OH sticks on its central carbon instead of an H. It is actually a nicer one (i.e. not as reactive) of the extremely unstable peroxy acids. It is used in chemical reactions to add one oxygen to the molecules to oxidate it but not destroy it, as most oxidating processes requires and releases a lot of heat. Such an example is in the epoxidation process of ethene reaction to form a 3 atom ring of 1 oxygen and 2 carbon. But if you don't limit yourself strictly to 444, there are a whole bunch of 3s and 4s only out there, such as hydrazine (feel free to add an nice reactive anion to make it 444) and ethlene oxide (which happens the product of the epoxidation process of ethene). Carbon monoxide slightly less reactive and received a 442, and TNT is slightly less dangerous for your health (although i wouldn't think that would be the case, haha) to get a 444 rating, but still obtained a nice 244. there are a whole bunch more stuff that are explosive and combustible but not unhealthy (044, such as cyclopropenylidene? lacking data. acetylene with 143 is good enough i think), or explosive and unhealthy but not flammable (404 like sodium azide. such things are explosive but not flammable because after explosion there's nothing for oxygen to oxidize, so nothing really "burned"), or unhealthy and flammable but not quite reactive (hydrogen cyanide has a 441, which means it burns violently but isn't quite capable of reacting anaerobically).
Edit1: and did i mention that diborane and various metal/xenon tetraoxide/tetrafluoride got a nice 443?