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Author Topic: synthesis of cubane  (Read 11635 times)

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Enthalpy

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Re: synthesis of cubane
« Reply #30 on: February 23, 2011, 01:19:52 PM »

Thank you all!

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Oxidisers... We would need some, but oxidisers better than liquid oxygen are extremely difficult. They shall be safe enough to use 500t in a rocket, and such a propellant still hasn't been discovered.

Though some niche uses exist. To land on Mars and lift-off, I'd prefer propellants liquid on Earth and Mars, and for this bizarre but very seducing cycle
http://saposjoint.net/Forum/viewtopic.php?f=66&t=2272&start=40#p30642
I've found only a composition of 33% NO dissolved into 67% N2O4.
Liquid down to -107°C, and exothermic decomposition making my nice pumping scheme possible, BUT the pressure of dissolved NO is 23b at +55°C, yuk cough cough. A replacement that depresses the melting point of N2O4 and brings energy, as NO does, would be welcome. Hence even if N(NO2)3 is solid, it could be useful in this scheme.

If you liked the wishful tetraaminoethane, its use is in the following post at the address linked above.

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Well, if three nitrogen neighbours are too much for a carbon, diaza-Cubane would be just perfect! Very exposed tertiary amines, this is believed to provide hypergolic ignition with N2O4.

Any hope that it lasts long enough to observe its colour? And be reasonably produced in ton amounts?

[Seen that in a big table with compounds properties. From time to time, it put decomp or expl instead of a melting or boiling point. One compound had expl instead of its crystal form and colour. I took it for chemist's humour.]
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AndersHoveland

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Re: synthesis of cubane
« Reply #31 on: February 23, 2011, 02:05:22 PM »

I am fairly certain that a cubane structure with only two nitrogen atoms would be completely stable, and would not be very difficult to synthesize.

Entropy, can I suggest using liquid nitrogen instead of helium to cool your oxidizer? While liquid helium is actually colder, liquid nitrogen has a much higher heat capacity and can absorb much more heat per a given volume of coolent. It takes more heat to boil a given quantity of liquid N2 than liquid He.

As for a suitable oxidizer, consider chlorine pentafluoride for use lifting off from Mars on the return trip back to earth. With a melting point of (minus) -103degC and a boiling point of (minus) -13degC, it has a wide liquid range.
Since there are no inhabitants on Mars, no exhaust toxicity worries. There is also Chloryl fluoride (ClO2F) but it has a very narrow liquid range that would be problematic (-15 to -6 degC). Interestingly ClO2F far more stable than ClO2. NO2F, if you where wondering, boils at only -72 degC. BrO2F probably has a high boiling point since BrF boils at +20degC. Iodine pentafluoride has a melting and boiling point of 9.5 and 98 degC, respectively, but is a far less energetic oxidizer than the other halogen fluorides (elemental iodine can actually be oxidized to I2O5 by concentrated nitric acid).


Nitric oxide is not a good oxidizer, and furthermore it is not even chemically stable. It slowly disproportionates to nitrogen dioxide and nitric oxide. An online search failed to reveal any information about pressurized tanks of nitric oxide, except tanks that contained only small traces of NO only in a concentration of several parts per million. I thought that NO, in the absence of O2, breaks down after several minutes, depending on its concentration, and I would think that the molecule would decay at a much faster rate in the liquid phase. Is there a reference which provides detail about cyrogenic nitric oxide?


BUT the pressure of dissolved NO is 23b at +55°C, yuk cough cough.

There is a myth that if copious ammounts of nitric oxide are produced in a reaction without adequate ventilation it will give all the chemists in the room erections.
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