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Author: Subject: Synthesis of t-nitrosobutane (w/ pictures)
numos
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[*] posted on 21-12-2016 at 00:31
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.

1.jpg - 567kB

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.

2.jpg - 578kB

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! :D

3.jpg - 769kB

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

4.jpg - 613kB

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]




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Tsjerk
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[*] posted on 21-12-2016 at 01:27


Very cool, nice write up.

Can you complex ions with this ring? Possible making a ferrocene like complex?
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[*] posted on 21-12-2016 at 01:34


Thats an amazing colour, thanks for sharing! Does the dimer dissociate on heating (without decomposition)?
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[*] posted on 21-12-2016 at 05:21


That is a beautiful blue color, I rarely see nice colors in the lab, mostly colorless and brown. Copper makes some nice blue compounds, but very few organics do.
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[*] posted on 21-12-2016 at 09:11


Brilliant blue colour! Well done.



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[*] posted on 21-12-2016 at 09:19


Superb numos !





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[*] posted on 21-12-2016 at 09:38


That’s a spectacular synthesis. I love strong colour changes its gives me confidence in the reaction and that blue is very neat.

I want to try it. I will have to risk ordering some sodium nitrite even though it’s on the UK watch list.
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[*] posted on 21-12-2016 at 10:03


Quote: Originally posted by wg48  
...

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

What for?
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[*] posted on 21-12-2016 at 10:19


Quote: Originally posted by Tsjerk  
Very cool, nice write up.

Can you complex ions with this ring? Possible making a ferrocene like complex?

Nitrite ion can act as a ligand; I wonder if this monomer would as well...

ETA: Nitrosoalkanes can act as ligands: http://pubs.acs.org/doi/abs/10.1021/ja00350a030?journalCode=...

[Edited on 21-12-2016 by DraconicAcid]




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[*] posted on 21-12-2016 at 13:20


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?


Oops I was thinking about some of the other blue compounds like smurf blue. I don't have any tungstate.

But now I think about it, I have some spare TIG rods so diy sodium tungstate should be easy.
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[*] posted on 21-12-2016 at 13:51


Quote: Originally posted by wg48  
But now I think about it, I have some spare TIG rods so diy sodium tungstate should be easy.

Cool !

Please please show us how you do that.

Glad you said it 'should be easy' so i guess we'll see some of your awesome chemistry soon !

Can't wait to see how it is done 'cos i also have some tungsten welding rods in the shed.

Exciting times !




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[*] posted on 21-12-2016 at 16:49


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 :cool:?)
(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)




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[*] posted on 21-12-2016 at 17:26


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.

t_nitrosobutane.jpeg - 49kB




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[*] posted on 21-12-2016 at 23:52


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).



nitrosbutane2.jpg - 40kB

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[*] posted on 22-12-2016 at 02:26


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.


I agree completely, especially given the following:

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.
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[*] posted on 22-12-2016 at 05:47


Incidentally, : cool prep. Where did you get t butylamine?
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[*] posted on 22-12-2016 at 10:24


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.


Following the diazo di N oxyde structure
(CH3)3C-N=O + O=N-C(CH3)3 <==> (CH3)3C-N(O)=N(O)-C(CH3)3
And as exposed into Nicodem's post picture of the trans dimer conformation, one may see that each oxygen atom onto the nitrogens comes into close vicinity to one or two hydrogen atoms from a methyl group --> 2 or 4 interractions O free doublets and H atom...might this explain you HNMR spectra with large H-O peak?

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?




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[*] posted on 22-12-2016 at 18:52


Quote: Originally posted by Nicodem  

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


I think you are correct, I saw that square structure somewhere originally, but I can't for the life of me remember where, even the paper I referenced has the R-ON=NO-R structure... Sorry about that.

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 :P




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[*] posted on 30-12-2016 at 07:06


Very nice, numos!! Always nice to read about some more chemistry - I also kind of like nitroso compounds (and S-nitrosothiols!) so it's nice to read about the weirder nitrosoalkanes (vs nitrosoaromatics)!



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[*] posted on 30-12-2016 at 07:28


Nice NMR, I agree that the two main peaks are the monomer and dimer, most likely, the peak at 7.26 is residual CHCl3. I still love the blue distillation, almost as colorful as a bromination, but looks like you are distilling a Smurf.
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