Synthesis of t-nitrosobutane (w/ pictures)

I was interested in this compound because it is described as a "deep blue liquid" which I found I had to witness, as there are few low weight organics with such vivid colors. The preparation is very straightforward, and the dimer seems to be stable and can be stored. I ran this reaction on a 95mmol scale based on t-Butylamine.

Another topic that mentions nitroso compounds, but I believe they were working with an entirely different reaction: link

Reagents:
-20% H₂O₂, diluted from 27% chlorine free pool shock
-Sodium tungstate, hydrate, used from bottle as is
-t-Butylamine, distilled from CaH₂ the day before to a perfectly clear liquid

Procedure:
1eq t-butylamine is added to an equal volume of water, and 0.035eq Sodium tungstate is dissolved in this, a small amount stayed undissolved, but this cleared up later on. This is chilled in an ice bath, and 2eq of Hydrogen peroxide as a 20% solution in water are dripped in over an hour, keeping the temperature between 15-20oC. The first few drops only resulted in a cloudy solution. The solution was stirred for another hour without the ice bath, and here is what I came back to.



The procedure states salt can be added to clear the "emulsion", but separation was already great, so I didn't bother. The blue liquid was separated, washed with very dilute HCL, and dried with MgSO₄. It should be noted that at this point the dimerization to the clear solid is significant, and I would recommend working with haste.



This was transferred to a RBF with a stir bar and a boiling chip. It distills at about 60oC and the blue liquid started crystalizing halfway through. If you do distill it,disassemble as soon as finished, otherwise the material will dimerize in the joints, freezing them. One of the quickest distillations I've done, this is about 5 minutes in - and if you look, I got it mid drop!



The product with it's dimer, I imagine it will all be dimerized by morning.



I will take it to the lab for NMR tomorrow, and let you guys know how pure it is.

This procedure was referenced from ACS Journal of Organic Chemistry, 1971, Volume 36, no.20

[Edited on 12-21-2016 by numos]

Quote: Originally posted by wg48

... I want to try it. I will have to risk ordering some sodium nitrite...

Quote: Originally posted by Tsjerk

Very cool, nice write up. Can you complex ions with this ring? Possible making a ferrocene like complex?

Quote: Originally posted by unionised

Quote: Originally posted by wg48   ... I want to try it. I will have to risk ordering some sodium nitrite... What for?

Quote: Originally posted by wg48

But now I think about it, I have some spare TIG rods so diy sodium tungstate should be easy.

I wonder if... this procedure would work for TRIS (trishydroxymethylaminomethane or 2-amino-2-hydroxymethyl-1,3-propanediol) (HO-CH2-)3C-NH2.

This compound is pretty OTC if made from nitromethane and formaldehyde polycondensation
CH3-NO2 + 3 CH2=O -base-> (HOCH2)3C-NO2
(HOCH2)3C-NO2 -reduction-> (HOCH2)3C-NH2

Then maybe
(HOCH2)3C-NH2 + H2O2 + Na Tungstate --> (HOCH2)3C-N=O
(HOCH2)3C-N=O + (HOCH2)3C-N=O --> (HOCH2)3C-N(O)=N(O)-C(CH2OH)3
or
(HOCH2)3C-N=O + H2N-C(CH2OH)3 --> (HOCH2)3C-N=N-C(CH2OH)3 + H2O

Upon reaction with HNO3 or N2O5 those two will:
1°) simply be oxydised back to the wel known explosive liquid nitroisobutylglycerol trinitrate ester (O2NO-CH2-)3C-NO2
2°) be nitrated to potentially novel energetic materials
(HOCH2)3C-N(O)=N(O)-C(CH2OH)3 + 6 HNO3 --> (O2NOCH2)3C-N(O)=N(O)-C(CH2ONO2)3 (A blue explosive ?)
(HOCH2)3C-N=N-C(CH2OH)3 + 6 HNO3 --> (O2NOCH2)3C-N=N-C(CH2ONO2)3
Those two would likely be solid and more powerfull than PETN (pentaerythritol tetranitrate = C(-CH2ONO2)4)

I ran an NMR (1H, CDCl₃) and it's quite interesting. The right most peak seems to be from the dimer. The second right most I believe is the water peak, but it's abnormally large (integration ratios of three main peaks, from left to right: 0.24@7.26ppm, 3.25@1.58ppm, 1@1.26ppm) The spectrum provided by Sigma for the dimer also has a large water peak. Anyone have any idea of what causes this? Chemdraw predicts a sole peak at 1.22ppm which corresponds to the right most one... But I still am at a loss for why the 1.58ppm peak is so large... there's no way there was that much water in the sample.

Tsjerk: I hadn't thought of that, I'll get back to you if I discover anything experimentally.

DJF90: so I know that dissolving the dimer in solvent causes it to revert to the monomer, the nmr tube was clear when I ran it, but was blue, maybe half an hour later when I checked back. The paper does mention that the monomer is favored at higher temperatures, and that redistilling the dimer will yield t-nitrobutane. I can try heating some later and see what happens.

Congratulations on the nice synthesis.

The two singlets are probably the two different t-Bu groups, one from the monomer and the other from the dimer. You can see if their ratio changes by taking the 1H NMR again a day later. If you pay attention to the 13C NMR from Sigma, you will notice there are also two sets of signals. Water is probably a small peak partially overlapping with the one at 1.58 ppm (the picture cannot be zoomed that well, but it appears there). There might be hidden somewhere also a tiny peak of the cis-dimer, if present at all.

By the way, I don't think you got the molecular structure of the dimer correctly. A 4-membered all-single bond cycle is unlikely. At the first glance it appears to have a higher energy than the monomer. Nitroso compounds generally dimerize by the formation of -NO=NO- groups. See the structure from XRD as reported in J. Chem. Soc., Perkin Trans. 2, 1988, 701-703 (DOI: 10.1039/P29880000701).





Attachment: Structure of the trans-Dimer of 2-Methyl-2-nitrosopropane.pdf (337kB)
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Quote: Originally posted by Nicodem

The two singlets are probably the two different t-Bu groups, one from the monomer and the other from the dimer. You can see if their ratio changes by taking the 1H NMR again a day later.

Quote: Originally posted by numos

...the nmr tube was clear when I ran it, but was blue, maybe half an hour later when I checked back.

Quote: Originally posted by numos

I ran an NMR (1H, CDCl3) and it's quite interesting. The right most peak seems to be from the dimer. The second right most I believe is the water peak, but it's abnormally large (integration ratios of three main peaks, from left to right: 0.24@7.26ppm, 3.25@1.58ppm, 1@1.26ppm) The spectrum provided by Sigma for the dimer also has a large water peak. Anyone have any idea of what causes this? Chemdraw predicts a sole peak at 1.22ppm which corresponds to the right most one... But I still am at a loss for why the 1.58ppm peak is so large... there's no way there was that much water in the sample. Tsjerk: I hadn't thought of that, I'll get back to you if I discover anything experimentally. DJF90: so I know that dissolving the dimer in solvent causes it to revert to the monomer, the nmr tube was clear when I ran it, but was blue, maybe half an hour later when I checked back. The paper does mention that the monomer is favored at higher temperatures, and that redistilling the dimer will yield t-nitrobutane. I can try heating some later and see what happens.

Quote: Originally posted by Nicodem

By the way, I don't think you got the molecular structure of the dimer correctly.

Quote: Originally posted by PHILOU Zrealone

Here also I wonder, If by heating/distilling (CH3)3C-N=O you get oxydation to (CH3)3C-NO2...then what would the other molecule entering the disproportionation (CH3)3C-N=O be reduced into? --> Azo t-butane (CH3)3C-N=N-C(CH3)3? --> hexamethyl-ethane (2,2,3,3-tetramethyl-butane) (CH3)3C-C(CH3)3 and N2(g)? This would also be interesting for the nitroso-TRIS and dimer I was wondering about a few post ago. Or do you mean that O2 from air is oxydizing the nitrosocompound/dimer to the nitro compound?

When I did the distillation, there was originally only the dark blue monomer in the distilling flask, by the end of it, there was a clear liquid with a greenish tint in the flask with a much higher boiling point. I imagine some of this oxidation was taking place there. I'm speculating but I do believe it is just air oxidizing it. The paper isn't very clear on the actual oxidation, Tell ya what, I'm busy until after Christmas, but I'll run two distillations with the stuff, one under Argon, if oxidation occurs in that run then you might be correct and I'd be interested in making a larger batch and running more tests. I want to steer clear or energetic materials because they become difficult to store/dispose of safely, if you have the means to safely try this with the Tris(hydroxymethyl)aminomethane, I would love to see it!

Also, unionised, this was an old bottle from sigma, the liquid was black before I distilled it. There's also a ton of amines at my work, but that defeats the purpose of home chemistry... although I suppose nmr does too

I tried this synthesis and here is my report.

I dissolved 0,57 g of Na2WO4.2H2O in 5 ml of water and added 5 ml of t-BuNH2. I also prepared 30 ml of 20% H2O2 and 1+10 HCl for washing. Everything was cooled in the fride before starting the reaction. t-BuNH2 solution was stirred in a cold EtOH bath and from seperatory funnel 20% H2O2 was slowly dripping in to the reaction mixture. Reaction mixture quickly turned green a later blue. Blue organic layer started to form pretty quickly. I let reaction run for 2 hours and than put everything in to a separatory funnel. I discarded aqueous layer and washed organic layer with HCl. After that organic layer turned in to weird blue gel. I shake it with some water and compound turned in to the blue liquid again. I dried organic layer with anhydrous Na2SO4 and filtered it in to the clean vial. I didn't measured yield, but it obviously isn't great. I'll repeat this experiment again, this time on bigger scale.

[Edited on 12-6-2023 by Bedlasky]