N6 (Hexanitrogen) Synthesized for the First Time - Twice As Energy Dense As TNT (nature.com) 68
Slashdot reader ffkom writes: The air around you mostly consists of nitrogen [78%]. And in that air exist happy little monogamous pairs of two nitrogen atoms per molecule, also known as N2. Researchers from the University of Giessen, Germany, recently managed to synthesize N6 molecules, "the first, to our knowledge, experimentally realized neutral molecular nitrogen allotrope beyond N2 that exhibits unexpected stability."
And these appear to be pretty angry little molecules, as they detonate at more than twice the energy density than good old TNT:
A kiloton of N6 is 1.19×10**7mol, which can release an energy of 2.20×109kcal (9.21terajoules) based on the enthalpy. Considering that the standard kiloton TNT equivalent is 4.184terajoules, N6 can release 2.2 times the energy of TNT of the same weight. On the basis of the documented TNT equivalent based on weight for HMX (1.15) and RDX (1.15), N6 can release 1.9 times the energy of HMX or RDX with the same weight.
In interviews the researchers contemplated the possibility of using N6 as rocket fuel, given its superior energy density and that its reaction product is just N2, so basically air, but no smoke, no CO2 or other potentially harmful substances.
And these appear to be pretty angry little molecules, as they detonate at more than twice the energy density than good old TNT:
A kiloton of N6 is 1.19×10**7mol, which can release an energy of 2.20×109kcal (9.21terajoules) based on the enthalpy. Considering that the standard kiloton TNT equivalent is 4.184terajoules, N6 can release 2.2 times the energy of TNT of the same weight. On the basis of the documented TNT equivalent based on weight for HMX (1.15) and RDX (1.15), N6 can release 1.9 times the energy of HMX or RDX with the same weight.
In interviews the researchers contemplated the possibility of using N6 as rocket fuel, given its superior energy density and that its reaction product is just N2, so basically air, but no smoke, no CO2 or other potentially harmful substances.
Really cool, application to rockets not so much (Score:5, Informative)
People have been trying to synthesize N6 for about a hundred years. In that regard it is similar to trying to synthesize tetrahedrane https://en.wikipedia.org/wiki/Tetrahedrane [wikipedia.org]. But people also synthesized cubane a while ago https://en.wikipedia.org/wiki/Cubane [wikipedia.org] and attempts to make it large enough quantities for rockets were not successful. In the 1960s through the 1980s there was a general tendency to want to have really extreme substances and use them either as rocket fuels or rocket oxidizers. FOOF https://en.wikipedia.org/wiki/Dioxygen_difluoride [wikipedia.org] and ClF3 https://en.wikipedia.org/wiki/Chlorine_trifluoride [wikipedia.org] are the two most infamous ones, and both of those are really easy to synthesize, but just insanely dangerous.
However, one of the major insights in rocket development in the last 25 years has been that even if you can get a few percentage points more of energy out of a rocket fuel, if the fuel or oxidizer is really hard to make or really hard to safely use, then the difficulties involved just aren't worth it. Thus, the cheaper, more reusable rockets were now seeing like SpaceX's Falcon 9 and Rocket Lab's Electron use fuels like kerosene and methane. N6 seems like it would not fit in this paradigm unless someone comes up with a really efficient synthesis method.
That's all the more the case because twice as energetic as TNT isn't that energetic. Methane has a specific energy about 10 times that as TNT. TNT is really good as an explosive not as much because of its high energy but because it easily releases it all at once. So if N6 does get a use, it might be for making missiles and bombs.
Re:Really cool, application to rockets not so much (Score:5, Insightful)
Re:Really cool, application to rockets not so much (Score:4, Interesting)
Re:Really cool, application to rockets not so much (Score:4, Informative)
Re: (Score:2)
We produce a lot of things that cost more energy to make than they release on-use. It's a matter of how that energy is released and how it's delivered to the point of release.
The Manhattan Project and subsequent nuclear weapons programs demonstrated how much effort and energy we are willing to put into producing bombs. The bombs are incredibly powerful, but cost immense amounts of energy to produce, slowly, over time.
I have no doubt that an explosive twice as dense as TNT would be of interest presuming th
Re: (Score:2)
Re: (Score:3)
Respectfully I must disagree. The US military switched from the Beretta 92/M9 to the Sig Sauer P320/M17 in order to gain a few more rounds and to save a few ounces of weight. There was nothing wrong with their prior service pistol that couldn't be resolved with reordering a batch of them to replace the clapped-out ones that had seen decades of use, the M9s were compatible with NATO partners and the supply chain for them was well established. They chose to make a change for what on-paper was only margin
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
It seems like you are saying batteries are not useful. They take more energy than they produce, yet have been very useful. Power plants and others often produce more power than they need. Perhaps the creation of this could be a way to store that energy for later.
Re:Really cool, application to rockets not so much (Score:4, Interesting)
But would it really be non-polluting?
In fracturing its atomic bonds, N6 will likely release most of its energy as heat and we all know that if you heat N2 and O2 enough you end up with all types of oxides including a nasty pollutant called NItric Oxide (NO). I can't see N6 simply disassembling itself neatly into 3(N2) in an oxidative environment such as the earth's atmosphere.
Re: (Score:3)
But would it really be non-polluting?
In fracturing its atomic bonds, N6 will likely release most of its energy as heat and we all know that if you heat N2 and O2 enough you end up with all types of oxides including a nasty pollutant called Nitric Oxide (NO). I can't see N6 simply disassembling itself neatly into 3(N2) in an oxidative environment such as the earth's atmosphere.
Any sort of combustion-level heat in the presence of nitrogen and oxygen creates lots of messy NOx byproducts (that are all atmospheric pollutants), so, yeah, unlikely to be a pure N6 -> 3(N2) reaction without at least restricting its decomposition environment to exclude O2.
My father designed instruments to measure atmospheric concentrations of NOx (and I wrote much of the software for them) for one of the biggest manufacturers of things like that. He explained the chemistry to me years ago, and NOx pol
Re: (Score:2)
Any sort of combustion-level heat in the presence of nitrogen and oxygen creates lots of messy NOx byproducts (that are all atmospheric pollutants), so, yeah, unlikely to be a pure N6 -> 3(N2) reaction without at least restricting its decomposition environment to exclude O2.
Given the high detonation speed of N6 I would consider it conceivable that almost all of the N6 decomposes into N2 and expands into a not-so-hot-anymore gas before it has a chance to get into contact with the O2 of the surrounding air. But we certainly need to wait for the results of the planned detonation tests before we can really know.
Re: (Score:3)
TNT is good because not only will it release it's energy all at once, it's not super easy not insanely difficult to make it so so.
By the way, kerosene has been popular for ages, and was used in the Saturn 5 and the ill fated N1.
Re: (Score:1)
Yeah, one of the first explosives is nitroglycerine. (And yes, it's the same stuff used in blood pressure medicine).
But nitroglycerine is very unstable and just looking at it funny can make it go off. That's when Nobel (of prize fame) managed to convert it to TNT, which was far more stable. Though it isn't shelf stable - left alone especially in a hot environment and the TNT starts to decompose into nitroglycerine.
Modern explosives are far less reactive nowadays and often only explode when subject to an ele
Re:Really cool, application to rockets not so much (Score:4, Informative)
But nitroglycerine is very unstable and just looking at it funny can make it go off. That's when Nobel (of prize fame) managed to convert it to TNT, which was far more stable. Though it isn't shelf stable - left alone especially in a hot environment and the TNT starts to decompose into nitroglycerine.
I'm not an expert but I'm fairly sure dynamite, of Dynamit Nobel fame, is regular nitroglycerin that has been desensitised by mixing it with diatomaceous earth. The time to worry is when the nitroglycerine starts seeping out of the clay. AFAIK nitroglycerine and TNT are unrelated.
Re:Really cool, application to rockets not so much (Score:5, Interesting)
Various materials have been used, including Kieselgh, the "diatomaceous earth" you mention. It's probably a synthetic zeolite mineral these decades, because the natural product is more expensive. But Dynamite per se is much less popular for general explosive use in favour of various other explosives, such as AmFO and synthetic mixtures such as "PowerGel".
On this side of the Pond, we call that "sweating", as in the phrase "porridge oats are good for sweating". See "other materials" above - it's a field expedient worth knowing about for when calling the Bomb Squad isn't such a good option.
Except by both containing 3 -NO2 "nitro" groups per molecule, introduced by quite similar chemical processes. Hence the name.
Re:Really cool, application to rockets not so much (Score:5, Informative)
The measurement is presented in units of a velocity, because it is, at a very basic level, a velocity.
If you made a 1cm by 1cm by 10km long lu-shaped loop sample of TNT, and placed it near a similar length loop of (say) "AN/FO" (ammonium-nitrate/ fuel-oil) and detonated both at one end from the same detonator, the shock waves of the explosives' detonations would arrive separated by around 5 seconds. TNT has a moderately high detonation velocity - around 6900 m/s, while AN/FO maxes out a bit below 5000 m/s. Pure AN has a detonation velocity of about 2500 m/s, while gunpowder, a "low explosive" can be from 0.06 to 9 m/s (depending on the granularity).
Detonation velocity is a useful thing to know if you're trying to design, say, a demolition scheme to bring the centre of a building down onto it's footprint, then collapse the walls in onto the same rubble pile. Which is why "blasting cord" is designed to have a very specific (per brand) detonation velocity.
Re: (Score:2)
Re:Really cool, application to rockets not so much (Score:4)
Re: (Score:3)
It's technically interesting, so the story does belong here on Slashdot. But, at this moment in time, any talk about potential applications is really putting the cart before the horse.
However that's the life of a university researcher nowadays. No one cares about your great scientific breakthroughs in and of themselves... from day one, you need to be talking about pathways to monetization.
Re: (Score:3)
I am somewhat skeptical about the proposed use cases, too. But at least some chemists appear really exited about the results [chemistryworld.com].
Prediction: chemists will be exited by trying to reproduce this result.
Re: (Score:2)
Hey Internet pedants, that's how you correct someone's spelling. Well played.
Re:Really cool, application to rockets not so much (Score:5, Informative)
That's all the more the case because twice as energetic as TNT isn't that energetic. Methane has a specific energy about 10 times that as TNT.
That's an apples to oranges comparison though. The specific energy of methane that you're using there is almost certainly based on a paradigm where there's free oxygen everywhere to combine with the methane. Presumably, you are comparing a specific energy of 50 to 55 MJ/kg for methane (when burned) to a specific energy of 4.184 MJ/kg for TNT (when detonated). That is, as you said, about an order of magnitude higher than methane when you compare those numbers directly. However, the difference between "when burned" and "when detonated" is significant. TNT does not require any external substances to release energy through detonation. On the other hand, the reaction for methane is CH + 2O CO + 2HO. In other words, every methane molecules requires two oxygen molecules to burn. A methane molecule masses exactly the same as an oxygen molecule (ignoring isotopic variation for simplicity) So, a realistic comparison would be 4.184 MJ/kg for TNT with 16.66 to 18.33 MJ/kg for methane. That's still around 4 times the energy, so, theoretically methane plus oxygen would still be around twice as energy dense.
As you say, it definitely might make more sense as an explosive than a rocket fuel. However, there's more to consider than just the pure energy density for use as a rocket fuel. The above shows that methane plus oxygen would be technically about twice as energy dense by mass than hexanitrogen. However, there are other practical considerations
The most obvious place to start is the fact that methane and oxygen are both gases at room temperature, whereas hexanitrogen is a solid at room temperature. That means major differences in how you handle them. You can either compress the gases, which means very heavy tanks. Typically compressed gas tanks mass something like 5X as much as the gas they hold (don't use propane tanks as a mental example, because that is actually a liquid when compressed) A lot of that mass can be shaved off for applications like rocketry through more exotic composition, and tricks like using spherical tanks (which can hold the equivalent mass of pressurized gas of a cylindrical tank with about half the mass), but those tricks and materials present their own cost and practical concerns. Even then, it is unlikely to be able to use compressed methane and oxygen without adding significant mass, negating the benefit of its high specific energy.
The alternative to compression is using cryogenic liquid. That still presents containment challenges and all sorts of tradeoffs between the mass of extra insulation vs. the structural problems inherent in containing a cryogenic liquid in tanks (not to mention some of the weird behaviors of cryogenic liquids). Plenty of rocket explosions have happened due to the compromises inherent in trying to contain such liquids while keeping the mass under control. The density of liquid oxygen is about 1.14X that of water, while the density of liquid methane is about 0.42 that of water, so the average is about 0.9X that of water. So it is reasonable in terms of volume (which relates to how heavy the rest of the rocket has to be). The density of hexanitrogen, however is about twice that, which can mean that the rest of the rocket can be a lot smaller as well as not needing to either withstand a lot of pressure or require a lot of insulation, or special structural requirements for cryogenic temperatures, or requirements for built in mixers to prevent explosive gas pockets from forming, etc.
I should also mention that you can still use non-cryogenic liquids. Obviously there's kerosene, for example. That still needs an oxidizer though, so that means you're mostly stuck with things like cryogenic oxygen or other gases like nitrous oxide (which can be prone to self-deflagration in large quantities). There are liquid oxidizers that can be used (generally fluorine compounds), but those tend to also
Re: (Score:2)
Re: (Score:2)
Ugh. Only just noticed that I forgot to reformat that chemical reaction when I copied and pasted it. The subscripts and arrow didn't copy. Should have been:
CH4 + 2O2 -> C02 + 2H2O. The part about the required oxygen having twice the mass of the methane (ignoring isotopic variation in atomic weights) obviously still stands
Re: (Score:2)
I read the article on using it for rocket fuel, and concluded the author knows a lot less than he thinks he does. Like you said, why would you choose this over methane when it's both less energy dense and much harder to work with? It does have the advantage of not needing an oxidizer, but the energy density still comes out lower even accounting for that.
Then he had this sentence:
Anything that begins with "According to CCSD(T)/cc-pVTZ (H0) computations" falls under the umbrella of physical chemistry, specifically thermodynamics, a subspecialty so
beyond comprehension that it makes organic chemistry seem like playing with Legos.
That's wrong on every point. It has nothing to do with physical chemistry and nothing to do with thermodynamics. It's actually
Re: (Score:3)
You're right that "easy to handle" is actually a pretty big concern for rockets, which is why we're moving away from hydrogen and more towards methane.
Methane doesn't require anywhere near as cold of a temperature as hydrogen, meaning that a lot of concerns about things like freezing the oxygen goes away, such that while theoretically a hydrogen engine would have more energy and thus thrust by mass, in practical terms, methane often beats it because the rocket itself can be simpler and lighter.
As far as N6
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
But methane requires an oxidizer; this would not. This is also why fuels like hydrazine are still used.
surprisingly stable? (Score:5, Informative)
I mean given I'd maybe expect it to be marginally stable at LN2 temperatures, that doesn't imply it's particularly stable. More stable than expected is more like survived long enough when treated with extreme delicacy to take a few measurements.
And for rocket fuel you don't generally want something that will happily donate the entire fuel supply with the slightest provocation.
Really this sounds like it would make another fun article in the "things I won't work with" blog under the category of lunatics destroying lab equipment with hilariously unstable compounds consisting of far too much nitrogen.
Props to those lunatics for making it!
Re: (Score:2)
Derek Lowe, currently hosted at Science Mag, for example https://www.science.org/conten... [science.org]
For people of a certain sense of humour, it is utterly, eye-wateringly funny. Otherwise, your kilometrage may vary.
Without RTFA, would I be right in thinking it's the Munich Group of happy laughing pyromaniacs with the leather aprons, armour plate, and light roof?
Re: (Score:2)
Read Ignition!, an excellent and entertaining history of the development of liquid rocket fuel by John D. Clark (one of the main protagonists of the field), with the truly excellent forward by Isaac Asimov that includes the following excerpt:
Now it is clear that anyone working with rocket fuels is outstand-
ingly mad. I don't mean garden-variety crazy or a merely raving luna-
tic. I mean a record-shattering exponent of far-out insanity.
There are, after all, some chemicals that explode shatteringly, some
that flame ravenously, some that corrode hellishly, some that poison
sneakily, and some that stink stenchily. As far as I know, though, only
liquid rocket fuels have all these delightful properties combined into
one delectable whole.
Search for a PDF, and you'll find it. I've had the fortune to meet a number of scientists cut from the same cloth as Dr. Clark, and they are among my favorite people. I'm sorry I never had a chance to meet him.
Re: (Score:1)
Re: (Score:2)
And for rocket fuel you don't generally want something that will happily donate the entire fuel supply with the slightest provocation.
True, but rockets being filled with stuff that needs cooling to very low temperatures in order to not make the rocket go kaboom in a second are not quite seldom, when you think of the ones that require liquid oxygen or hydrogen.
Really this sounds like it would make another fun article in the "things I won't work with" blog
The author of that blog has already commented on N6 [science.org].
Nitric acid (Score:2)
I wonder which of the crazy Youtubers... (Score:3)
Re: (Score:2)
My vote is on Nile. He also has a Blue channel:
https://www.youtube.com/watch?... [youtube.com]
In case you want someone to make pop rocks out of N6.
Re: (Score:2)
My vote is on Nile. He also has a Blue channel:
No I don't think so. Sorry. Nile makes some very good videos but I don't think I've seen him do much in the way of explosives or really complicated chemistry. I'm not saying he couldn't, just that that's not what Nile's channel is about.
Tom of Explosions&Fire [youtube.com] would probably want to but couldn't do it in his shed or on his budget. It would also take two years.
Chemiolis [youtube.com] probably could make it but has far too much sense to try.
PrussianBlue [youtube.com] seems just mad enough to have a go, but I think it's best for all
Re: (Score:2)
Nile has the budget, you've got to admit. Plus if he wanted to do a collab with the The Slo Mo Guys, they'd probably agree to it. Yeah he'd probably do something stupid with N6 (like make Pop Rocks out of it).
Angry? (Score:2)
What have they got to be angry about? They do not even have to be monogamous.
Re: (Score:2)
For them, a six-way is simply not enough!
Re: (Score:3)
Re: (Score:2)
Do you really think "AI"s can tell you about a substance that has never been synthesized before?
And, right there, you've hit on the fundamental problem with "AI" - what it us actually useful for versus what the wider population (and especially PHBs) think it can do.
Re: (Score:2)
Do you really think "AI"s can tell you about a substance that has never been synthesized before?
That is a good point. However, most likely, the AI is just regurgitating a summary of conversations that others have had on the subject. One thing lacking from most current AIs is an up front analysis on the likelihood that the information it is presenting is valid. It could be coming from actual rocket scientists and chemists discussing it somewhere, or from random Joe Schmoes. The standards for academic papers are fairly easily followed by even first year university students and high schoolers (even if wr
Re: (Score:2)
Anything which burns very energetically in air will turn some of the air into (various) oxides of nitrogen.
Most of which are likely to be GHGs to some degree. They have IR-absorption features so they're likely to reduce the IR transmission from Earth's surface to the rest of the universe.
Re: (Score:2)
Anything which burns very energetically in air will turn some of the air into (various) oxides of nitrogen.
Therefore it may be good that N6 does not need to get in contact with air to detonate, and does not need to "burn" (oxidize) to set free its energy.
Wikipedia (Score:2)
I can't vouch for it, but at the moment nobody has updated it with the news and it is stated to be "hypothetical." Woohoo! First time I ever beat wikipedia to the punch on anything!
Wrong compound (Score:2)
The Wikipedia article refers to a different compound. The one synthesized here is a chain, essentially two N3 azide groups coupled via a slightly bent bond.
So much better than liquid hydrogen... not (Score:3)
So... 9.21 terajoules per kiloton.(Interesting restatement of the more common MJ/kg which is the same numeric value...)
Liquid hydrogen is "only" 13x more energy-dense at 120 MJ/kg, but whereas N6 combusts to N2 which is is plain old air (unless of course it's 100% N2 in which case it's a very up-to-date gas chamber) nasty old hydrogen combusts to dangerous DHMO [dhmo.org] so best to get rid of it.
Re: (Score:2)
So... 9.21 terajoules per kiloton.
As long as we're having fun with units, that would be 2.2 kilotons per kiloton! Note that this is a joke and kilotons and kilotons are different units (depending on context).
Re: (Score:2)
N6 doesn't combust. It detonates and reforms into N2. No oxygen source required. The real question is how sensitive is it to vibration and temperature changes.
Re: (Score:2)
You seem to be leaving oxygen out of that equation. Unless you found a way to make an air-breathing rocket, divide that by 1 + 16.
> nasty old hydrogen combusts to dangerous DHMO [dhmo.org] so best to get rid of it.
Yeah, it's like, part of some liberal conspiracy.
re: stability of N6 (Score:1)
Re: (Score:3)
Re: (Score:2)
In military terms, that would be "insensitive munitions". Generally speaking, you want stable explosives for most practical uses. You generally don't want explosives that blow up too easily by dropping, rattling, being heated, being hit with bullets or shrapnel, etc. There's an old french movie: "The wages of fear" ("La saliere de la peur" an adaptation of the french novel of the same name with the novel later being remade as the file "sorcerer") about four truck drivers, desperate for money, driving 2 tru
Re: (Score:1)
If it can be mass-produced... (Score:1)
Someone page Derke Lowe! (Score:2)
This seems vaguely relevant https://www.science.org/conten... [science.org]
He has long since posted about this. (Score:2)
He already commented twice about this compound, the last one is https://www.science.org/content/blog-post/hexanitrogen-energies
The first post is from June 23. Regardless of this topic popping up on Slashdot now, of course with a sensationalistic slant, it is still yesterdays news for professionals. The paper made a few waves two months ago.
Yay! Finally: sustainable warfare! (Score:1)
Nuff said.
What about other vehicles? (Score:2)
Hydrogen does not make a good fuel, tor a tonne of reasons, but nitrogen fuel would be less prone to nasty reactions and fewer problems. Could N6 combustion be controlled at levels suitable for heavy road vehicles or trains?
(Electric trains have their own problems, due to the fact that the junction needs to be poor and the cost of copper is so great that lines need to use far worse conductors to reduce theft.)
Re: (Score:2)
So what? (Score:2)
Useless unless it can be stably stored. Nobel's whole family blew themselves up with nitroglycerine.