16 ways to TNAZ synthesis.

[megalomania]

TNAZ is a new explosive first developed way back in 1983 by the Fluorochem corporation. TNAZ stands for 1,3,3-trinitroazetidine. TNAZ is worthy or mention because it is more powerful than RDX, quite stable, and insensitive. The problem is most of the routes to its synthesis are only applicable to the laboratory scale. Another downside is the best lab procedure churns the stuff out at $5 a gram. I am sure better ways will be found in time, but for now I present 16 routes to its preparation. None of these are exactly simple, so get ready for a ride :)

Here we go in no particular order or accuracy… The base catalysed reaction of nitromethane with formaldehyde produces tris(hydroxymethyl)nitromethane (#1), which reacts with more formaldehyde and tert-butylamine to give 3-tert-butyl-5-hydroxymethyl-5-nitrotetrahydro-1,3-oxazine (#2). #2 is then heated in methanol with conc. HCl to make 2-tert-butylaminomethyl-2-nitro-1,3-propanediol hydrochloride (#3), which is cyclised by adding some DEAD (diethyl azodicarboxylate, I love that acronym) and some triphenylphosphine or DIAD (diisopropyl azodicarboxylate) and triphenylphosphine, which produces 1-tert-butyl-3-hydroxymethyl-3-nitroazetidine (#4). Using some sodium nitrite mixed with potassium ferricyanide and sodium persulfate we can introduce a nitro group to #4 making 1-tert-butyl-3,3-dinitroazetidine (#5). #5 is nitrolysed to TNAZ with a mix of nitric acid, acetic anhydride, and ammonium nitrate.
Next we try to condense epichlorhydrin with tert-butylamine to make 1-tert-butyl-azetidin-3-ol (#6). This is reacted with methanesulfonyl chloride to give 1-tert-butyl-3-methanesulfonyloxyazetidine (#7). #7 can be made into #4 by reacting with formaldehyde mixed with sodium nitrite, or it can be reacted with just sodium nitrite to make 1-tert-butyl-3-nitroazetidine (#8). #8 can be transformed into #5 by oxidative nitration with a mix of silver nitrate and sodium nitrite, or with a mix of sodium nitrite, potassium ferricyanide, and sodium persulfate.
Moving on, #6 can react with acetic anhydride to give 1-acetyl-3-acetoxyazetidine (#9), which can be nitrolysed with a mix of ammonium nitrate and acetic anhydride, or with just fuming nitric acid to give 1-nitro-3-acetoxyazetidine (#10). #10 can be hydrolysed and oxidized with PCC (pyridinium chlorochromate) to give 1-nitro-azetidin-3-one (#11), which reacts with hydroxylamine to give 1-nitro-azetidin-3-one oxime (#12). #12 is made into TNAZ by reacting with either dinitrogen pentoxide in methylenedichloride, or with just fuming nitric acid.
Another way is to begin with some household 3-aminopropane-1,2-diol (#13) and react that with p-toluenesulfonyl chloride and tert-butyldimethylsilyl chloride (t-BDMSCI) to make the joy to pronounce 3-p-toluenesulfonamido-2-tert-butyldimethyl-silyloxy-1-(p-toluenesulfonyl)-oxypropane (#14). Add a pinch of lithium hydride to #14 and we get 1-(p-toluenesulfonyl)-3-tert-butyldimehylsilyloxy-azetidine (#15). #15 could also be prepared from 1,3-dibromopropan-2-ol reacted with tert-butyldimethylsilyl chloride giving 1,3-dibromo-2-tert-butyldimethylsilyloxy-propane (#16). #16 reacts with p-toluenesulfonamide to give #15. Hydrolysis of #15 with acetic acid give us some 1-(p-toluenesulfonyl)-azetidin-3-ol (#17). #17 could also be made from #9 by hydrolysis and reaction with p-toluenesulfonyl chloride. #17 can be oxidized with chromium(VI) oxide to give 1-(p-toluenesulfonyl)-azetidin-3-one (#18). #18 could also be made by reacting N-(p-toluenesulfonyl)2-aminoacetyl chloride with diazomethane and the subsequent ring closure of diazoketone (#19), the first easy to name product I have had to write for awhile! In the synthesis of 17 and 18, it is also possible to use epichlorohydrin and benzhydrylamine as the starting materials. Their condensation leads to 1-benzhydryl-azetidin-3-ol (#20). Hydrogenolysis of #20 with p-toluenesulfonyl chloride gives #17. Also, #20 can be oxidized with chromium(VI) oxide or pyridine sulphur trioxide complex to give 1-benzhydryl-azetidin-3-one (#21). Hydrogenolysis of #21 with p-toluenesulfonyl chloride gives us #18, which in reaction with hydroxylamine gives 1-(p-toluenesulfonyl)-azetidin-3-one oxime (#22). #22 can be nitrated and nitrolysed with a mix of nitric acid, ammonium nitrate, and dichloromethane, or with just nitric acid and dichloromethane to give TNAZ (at last).
If you are still following me, yet another route to TNAZ is to start with some #9 which on alkaline hydrolysis and oxidation with PCC or PDD (pyridinium dichromate) gives us 1-acetyl-azetidin-3-one (#23) which reacts with hydroxylamine to give 1-acetyl-azetidin-3-one oxime (#24). Last but not least #24 is nitrated and nitrolysed with dinitrogen pentoxide in dichloromethane, or with just nitric acid to give TNAZ.
But wait, there’s more. By using some 1-azabicyclo[1.1.0]butane (#25) we can eventually get to our goal, but first we have to make that. Take some N-chlorosuccinimide, react it with allylamine is one way, or one could brominates 2-amino-1,3-propanediol and bicyclise the intermediate 1,3-dibromopropyl-2-amine hydrobromide, or one could chlorinate 1-tert-butyl-azetidin-3-ol (#6, see how these tie in) to 1-tert-butyl-3-chloroazetidine (#26). Then we acetylate #26 to 1-acetyl-3-chloroazetidine. All of this to make #25, but there is yet another way, by hydrolysis and bicyclization of #9. Now then, #25 reacts with sodium nitrite to give 1-nitroso-3-nitroazetidine whose nitrolysis with a mix of trifluoroacetic anhydride leads to 1,3-dinitroazetidine, upon subsequent oxidative nitrative we finally get TNAZ.
Looks like there is more, by reacting tris(methylol)aminomethane by brominating in acid we get tris(bromomethyl)aminomethane hydrobromide (#27). #27 is made into TNAZ by reacting with sodium nitrate giving 1-nitroso-3-bromomethyl-3-nitroazetidine, whose nitrolysis gives 3-bromomethyl-1,3-dinitroazetidine, which is hydrolysed to 3-hydroxymethyl-1,3-dinitroazetidine, which upon oxidative nitrolysis finially gives TNAZ.

And that, my friends, is every method of TNAZ synthesis in a nutshell. Supposedly this covers every published method in existence period. From these many ways of getting to TNAZ you would think one would be better than another. Perhaps, but I leave that up to you, dear members, to decide based on what chemicals are in your arsenals. Was that 16 ways? Who cares, close enough. I hope I spelled all those chemical names right.

Apparently the most economical procedure thus far is the one using nitromethane and formaldehyde. This also happens to be the one referenced procedure that has a patent, hurrah. There are other patents of course, and many many journal references. See US patents 5,336,784; 5,580,988; and WO patent 96 36,602. I hope everyone finds those patents helpful. Sometime soon I will summarize them and stick them on my website. At a later date some of the other journals will arrive and I can go into detail about them.

I am sure everyone wants to know why this explosive is so important. I don’t know, it just crossed my desk so to speak as a new explosive. Mr Cool should be able to tell you more than I what its significance is. I do know that it gives the best explosives we all know and love a run for their money. Lets see, 96% the energy of HMX and 150% of TNT, and slightly more powerful than RDX. It is melt castable, and actually improves all of the top explosives making them better than either component would be alone. It has been suggested for use in propellants and is compared to HNIW in that respect. Apparently TNAZ runs a little hot when it blows which is considered to be a valuable characteristic in composite explosives. I can’t tell you what the explosive velocity actually is because the table with comparisons to bunches of other explosives is not where it should be… The original must be referenced in a Laewrence Livermore Lab report “Characterization of TNAZ Rep. UCRL-ID-119572” Can anybody scare that up?

Some mixes with TNAZ include (all %’s in moles):
35.3%/64.7% TNAZ/TNT
63.3-65%/36.7-35% TNAZ/Tetryl
97.87%/2.13% TNAZ/HMX
97.67%/2.33% TNAZ/2,4-dinitroimidazole
61.7-66.0%/38.3-34% TNAZ/N-acetyl-3,3-dinitro-azetidine
87.5%/12.5% TNAZ/1,3-dinitro-3-(1,3-dinitroazetidin-3-yl)-azetidin
For more mixtures of TNAZ check out US patent 5,997,668.

[nbk2000]

Anyone care to count the number of controled/reported drug precursors that happen to be needed for making TNAZ?

More than there are ways to make it. <img border="0" title="" alt="[Wink]" src="wink.gif" />

(DEA kicking down door to Mega's lab)

DEA:
"Freeze dirtbag!"

Mega turning around with condensor in his hand:
"I'm in the middle..."

DEA:
"GUN!"

BWAMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM*plink*(stray bullet hitting flask of boiling TNAZ)BBBBBOOOOOOOOOMMMMMMMM!!

(scene of total devastation, ruin, and death)

Mega, well-done:
"science...*gasp*..is..avenge...*death rattle*"

Just be careful you don't draw the wrong kind of attention getting the chemicals to make this.

[Mr Cool]

I'm surprised you can't get to it from a 2,2-disubstituted-3-aminopropan-1-ol, by reaction with H2SO4 and then NaOH to get a 3,3-disubstituted azetidine, followed by treating it with some crazy nitrating agents.
If you started with a 2,2-disubstituted-3-tertbutylaminopropan-1-ol, then you'd end up with a 3,3-disubstituted-N-tertbutylazetidine, and then the N-nitro could be introduced with ~90% HNO3 as with DNNC or K-RDX (other cyclic nitramines). I'm not sure what would be best to have as the mystery substituant though.

I don't know much about this compound really, but it's five of the military's six favourite things. It's melt castable, stable, powerful, insensitive and inert. But not economical! Also I believe that it's like hexanitrostilbene in that small amounts added to TNT or other castable explosives help to prevent cracking and gives a uniform crystal size in the finished product after casting. If a good method of production is found then I expect it to get some extremely heavy usage in the future.

[cutefix]

TNAZ indeed is one of the new explosives in the block.
It has been proposed as a replacement for TNT in melt-castable explosives to produce products in the same line as pentolite and composition B because it has a melting point of about 100 deg C.
Now as PETN is sensitive and TNAZ is sensitive as well, then the stable and practical binary melt-castable will be using RDX and TNAZ.
Binary mixtures of it such as TNAZ/RDX is more powerful than composition B:
Have a look at its performance (e.g.,VOD)
60/40 TNAZ/RDX 8660 M/S
60/40 COMP B 7800 M/S
The stability of this composition as observed in the Australian study (Defence Science & Technology Organization) was below that of composition B.
It was observed to form shrinkage voids on RDX particles increasing its sensitivity and hazard of stored munitions.
It does not belong to the IHE category like NTO and TATB based binaries.Therefore it was set aside for further study by the DSTO.
But it does not prevent the US special forces in using it in certain application as booster explosive in special demolition devices in the form of PBX by the Delta Forces.
It means the US has licked the TNAZ peculiarity of forming void spaces on cooling with melt cast binaries by instead using as a plastic bonded explosive.
Therefore they were able to manufacture it in production scale(or pilot scale? ) to be able to use for military devices of the Delta Force. :p

<small>[ December 25, 2002, 12:34 AM: Message edited by: cutefix ]</small>

[megalomania]

Oh, they can manufacture the stuff all right. My documents here mention something about two processes being developed for high production, however it is still damn expensive. Cost dosn't seem to be an object for special forces operations, of course they don't go through tons. There are actually several military bases that specialize in pilot production of explosives all of which escape my mind at the moment.

I didn't mention the cavities part because didn't think it is relevant to synthesis, but since you bring it up TNAZ has been reported as forming shrinkage cavities and volume contraction in the solidification of its melts which is seen as its only real disadvantage from the militaries perspective (besides the low yields of its synthesis). A high vapor pressure can also be a problem. A solution to minimize these problems has been suggested in the form of adding nitro aromatic amines to melt mixes of TNAZ.

I predict TNAZ will find its greatest use as a minor component in mixtures of other explosives and propellents in the years ahead.

Ah, here we go, "Scale-up and Waste-minimization of the Los Alamos Process for 1,3,3-Trinitroazetidine (TNAZ)" from the journal Waste Management is one route that reports a 57% yield although there is some doubt on that.

[nbk2000]

I remember reading a PDF from the FTP about one of the new insensitive explosives that had similar problems. It was a guanidine derivitave like TNGU, TNG, or something like that (hard to keep track of all these abbreviations :) ).

Anyways, the explosive would form voids from gas generation as trace impurities decomposed. It would also contract quite a bit, leaving a foamy core running a 1/3rd or more of the length of the charge.

Problem with the explosive was that it decomposed on prolonged heating, yet had a very high latent heat, requiring extended heating to melt even a little of it.

The way they got around that was zone heating.

A heating element was placed around a cylinder filled with compacted powder (whatever), and slowly raised from bottom to top.

This produced a thin melt zone that would travel to the top, melting the minimum amount necessary, while carrying all the gas bubbles with it, leaving a solid charge of explosive with only the top couple of inches needing to be removed.

:)

TNAZ is going to stay a very minor explosive for years to come, at least till they get it as cheap as RDX. Certainly it'd be impractical (though not impossible), and very expensive, for the home experimenter to try making it till the Big Boys figure out a more practical process than $5/gram (and that's at tanker car bulk prices! <img border="0" title="" alt="[Eek!]" src="eek.gif" /> ).

<small>[ December 25, 2002, 08:58 AM: Message edited by: nbk2000 ]</small>

[cutefix]

I have been reading these 16 TNAZ procedures and mega is right; the interesting and practical part is the use of the precursors formaldehyde and NM.
In some commonwealth countries the method using the paraformaldehyde and nitromethane as the reactant ; was found to be practical, although it is still a lengthy process.
As the topic on detailed preparation was not discussed then it look as interesting just how this unique explosive is made actually in the laboratory .
It is done this way:
1)A solution of 405 gram paraformaldehyde in 1.5liter of water at 40 deg C (with NaOH as catalyst)was slowly added 162 gram of nitromethane over a 1 hour period.The solution was heated to 60 deg C and 318 gram tert-butylamine added dropwise over 1 hour period.The mixture was then stirred for a further hour,cooled (ambient temperature) and stirred for 16 hours.The precipitate was collected by vacuum filtration and freeze dried to constant mass to give 3-tert-butyl –5- hydroxymethyl-5-nitrotetrahydro-1,3-oxazine. At 682 gram/98% yield.

2) To an aqueous solution of concentrated 83 ml HCl dissolved in water was added 281 gram of 3-tert-butyl –5-hydroxymethyl-5-nitrotetrahydro-1,3,oxazine. And the mixture was heated to 40 deg C to affect dissolution. A 110 ml of 30% H2O2 solution was added and the mixture stirred at 60 deg C for 1 hour, followed by 16 hours at ambient temperature. The solvent was removed in vacuo the residue dried azeotropically with isopropanol,filtered , washed with cold isopropanol and dried to give (2-tert-butylaminomethyl-2-nitro-1,3-propanediol hydrochloride. 199 gram/82% yield),mp at 172-173 deg C)

3)To a vigorously stirred mixture of 30 gram of 2 -tert-butylaminomethyl-2-nitro-1,3-propanediol HCl and 45.5 gram of diisopropylazodicarboxylate in 80 ml butanone at 50 deg C was added dropwise a solution or 59 gram triphenylphosphine in minimum butanone over a 1 hour maintaining a solution temperature of 50-55 deg C.The mixture stirred at 50 deg C for 3 hours ,filtered , washed with cold 30 ml butanone and dried to give 31 gram of:
1-tert-butyl-3-hydroxymethyl-3-nitroazetidine hydrochloride.

4)To a solution of 11.3 gram of 1- tert butyl-3 hydroxymethyl-3- nitrozetidine HCl dissolved in 25 ml water and the resulting light yellow solution stirred at ambient temperature for 3 hours,The reaction was cooled to 10 deg C and a chilled solution of 13.8 gram sodium nitrite and 0.165 gram of potassium ferricyanide in 38 ml water slowly added. 15 gram of solid sodium persulfate was added in a single portion and the yellow solution warmed to ambient temperature for 1 hour and extracted three times with 40 ml of dichloromethane.The organic phase was dried over magnesium sulfate and reduced under vacuum it give 8.65 gram/85% yield of a yellow oil which solidified on standing:
1-tert-butyl-3,3-dinitrozetidine.

5)To a vigorously stirred solution of 8.65 gram of 1-tert-butyl-3,3-dinitroazetidine dissolved in 35.7 ml of acetic anhydride was added 5.14 gram ammonium nitrate over a 5 minute period.The suspension was heated to 75 deg C to complete dissolution, stirred for 4 hours cooled (at ambient temperature) and stirred for further 16 hours.The resulting mixture was then vacuum filtered to give 7.11 gram of crude TNAZ( 87% yield).The solid was dissolved in hot ethanol and poured into water-ice mixture to give 6.54 gram/ 80% yield of pure
1,3,3-Trinitroazetidine
as an off white needles.
It still looks more complicated than making DADNE or FOX-7.

Although the TNAZ is rather an elite explosive being used only by Delta Forces in their special shape charge boosters,it has more broader use than FOX-7 being applicable to propellants as well.
Meanwhile the latter is of value directly as the direct replacement of RDX in insensitive High Explosive applications as it has better power than TATB and NTO.
It would be interesting if the FOX-7 and TNAZ will be combined as a melt cast explosive which will then be better in terms of explosive performance and safety (if the crystallization peculiarity of TNAZ is tamed by being bound by MNA as discussed in the patent ).

<small>[ December 30, 2002, 11:42 PM: Message edited by: cutefix ]</small>