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AndersHoveland
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I also want to emphasise that tetranitrocyclobutane (TNCB) is probably less sensitive, and more stable than HMX. Although
TNCB has been prepared, there finds not any information about its detonation velocity or sensitivity.
We can, however, probably get a good idea of these properties by looking at the properties of a structurally similar energetic compound, TNAZ, which
has been researched in much more detail. As TNAZ contains structural elements of both TNCB and RDX, one would expect that the properties of TNAZ would
lay between TNCB and RDX. In other words, if TNAZ is less sensitive than RDX, then TNCB should be even less sensitive.
For thermal stability, although 1,1,3,3-tetranitrocyclobutane contains geminal nitro groups [two nitro groups on the same carbon atom], this should
not be a problem. The strained square ring should prevent thermal instability. For example, TNAZ begins to slowly decompose, releasing small ammounts
NO2, above 180degC. Prolonged temperatures above 200degC can lead to explosion, but TNAZ can withstand a shorter duration of heating up to 240degC.
For comparison, RDX begins to decompose at 170 °C, (RDX and HMX are very similar chemically).
TNAZ is more resistant to shock and impact than HMX, but the sensitivity is highly variable depending on the crystal grain size. Smaller grains (5.5
micrometers) have a 66cm sensitivity using the drop height test, while larger grains approach the 23cm sensitivity of HMX.
So tetranitrocyclobutane should have ideal explosive properties.
also made a post about tri-nitrocyclobutane here:
http://www.sciencemadness.org/talk/viewthread.php?tid=17012&... (in the thread "Strategies in Designing Ideal Explosives")
[Edited on 25-2-2012 by AndersHoveland]
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AirCowPeaCock
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I may (attempt) synthesize this compound over spring break, when I have plenty of time on my hands (and my neighbors are at work). Any advise
(besides be careful)?
BOLD
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AndersHoveland
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The chemical synthesis of TNCB is very different from the synthesis of most other typical explosives. It would be very helpful to get advice from
someone very knowledgeable and familiar with organic chemistry. TNCB requires several precursors, and it would be important to familarise yourself
with the chemistry of these individual compounds.
Remember that nitroalkanes (such as 1,3-dinitropropane) can undergo complex reactions with water if the pH is very high or low. The salts of
nitroalkanes are only stable in the absence of water. Use pure alcohol or DMSO. For example, nitromethane mixed with pure alcohol will react
with solid NaOH to form the sodium salt of nitromethane, but as soon as water is added the solution will become brown-red colored, indicating the
formation of complex solid degredation products. Sodium 2-nitroethanaloximate (alternatively referred to as "methazonate") also forms from this
reaction.
For the reaction of nitroalkanes with acid, see:
http://en.wikipedia.org/wiki/Nef_reaction
Heating nitromethane with hydrochloric or sulfuric Acid results in the formation of formic acid and hydroxylamine salts; (Victor Meyer, Ann. (1876)
p.663)
It would also be helpful to read about the final steps in the synthesis of TNAZ.
And of course, you would need a good procedure to make methylene bromide (dibromomethane). Dibromomethane can be made by first making bromoform from
the haloform reaction (NaOH, ethanol, Br2), then reducing the bromoform using sodium arsenite Na3AsO3 and NaOH.
Alternatively, perhaps it could be made from the methylene chloride, which is a commonly available hobbyist/automotive solvent, through
copper-catalysed halogen exchange; www.sciencemadness.org/talk/files.php?pid=7109&aid=96
(reaction still takes 24 hours)
Chlorine typically substitutes off alkanes much more slowly than bromine or iodine atoms. This is the reason methylene chloride would not be
satisfactory for the TNCB synthesis, the reaction rate would be negligible (it would take several months!) Also a note of warning:
dibromoethane is an alkylating agent, giving off moderately toxic fumes. Bromomethane, for example, was used as a pesticide.
The reaction of dibromomethane with 1,3-dinitropropane would also form some other undesirable byproducts. But these should be easy to separate out
because the byproducts will generally be a gunky polymerised compound, with much less solubility. For best yeilds, use an excess of 1,2-dinitropropane
and be sure the reactants are diluted with plenty of solvent. Low reactant concentration may help favor cyclization rather than polymerization. It may
also be possible that the 1,3-dinitrocyclobutane could further react with the base and bromomethane, another reason why it would be
important to use an excess of 1,3-dinitropropane. But as can be seen from that "Synthesis of trans-1.2-Dinitrocyclopropane (DNCP)"
earlier in this thread, these types of cyclizations certainly are possible. It would probably be helpful to read about the details of the DNCP
synthesis, as it would realte to making TNCB.
I do not know the actual synthesis that was originally used to make tetranitrocyclobutane (TNCB).
I think the melting point and density values came from another source.
[Edited on 25-2-2012 by AndersHoveland]
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AndersHoveland
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Cyclopropane reacted with dinitrogen pentoxide, in methylene chloride, at reduced temperature to yield 3-nitro-1-propanol nitrate.
Golding, Honey, and Miller, US Patent Application 923 024 (1987)
O2N-O-CH2-CH2-CH2-NO2
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AndersHoveland
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Some more information about how to potentially make the 1,3-dinitropropane precursor (for the preparation of TNCB). It is already posted in another
thread, but I thought it appropriate to put it here, in case anyone wants to try my idea.
Quote: Originally posted by anomolous  | | Of the many syntheses of nitroethane discussed in this thread, one method in particular sparked my interest. UpNatom, in his posts above, mentioned
the method described in US patent 4,319,059, using 2-Bromoproprionic acid, Rhodium started a thread about this patent on the Hive too. The patent
describes a straightforward reaction of 2-bromoproprionic acid with an alkali nitrite and magnesium ion (methoxide is preferred but the sulfate,
chloride, etc. are also said to work) in DMSO. Since 2-bromoproprionic acid can be made from alanine using HBr and sodium nitrite, I thought I'd give
it a try. |
So diazotization of alanine to 2-bromoproprionic acid, then conversion to nitroethane, as according to US patent 4,319,059.
What if you did this reaction on glutamic acid (from the common food additive MSG) ? Presumably you could get 4-nitro-butyric acid.
NO2-CH2CH2CH2-COOH
Now, does anyone remember the thread about making nitromethane from 2-chloroacetic acid? I am not going to go into the details, but will quickly
summarize.
One of the possible ways to chlorinate acetic acid is to dissolve it in acetic anhydride and pass chlorine into the solution. Under the extremely
acidic conditions, acetic acid essentially reverts to its CH2=C(OH)2 tautomer, through which it can be attacked by the chlorine.
Presumably, we could selectively chlorinate 4-nitro-butyric acid under the same conditions to get 2-chloro-4-nitro-butyric acid.
NO2-CH2-CH2-CHCl-COOH
Nitromethane can be made by distilling 2-chloroacetic acid with sodium nitrite. So what would happen if we distilled 4-nitro-butyric acid with sodium
nitrite? Is it possible that 1,3-dinitropropane could result?
NO2-CH2-CH2-CH2-NO2
[Edited on 19-3-2013 by AndersHoveland]
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