Sciencemadness Discussion Board

polyvinyl azide?

RunPyroRun - 15-1-2013 at 18:35

Been having trouble finding any information about polyvinyl azide (polyvinyl alcohol with some of the hydroxyl groups replaced by azide groups)

I figured if this was possible, it would at least get some passing mention in papers or energetics books. Most of what I've seen is in PVA modified into a tri-block set up with some -OH groups, some -N3 groups, and another functional group thrown into the mix.

Could be pretty neat with the potential for a lot of azide groups for good energy release and the potential for some nice click chemistry polymerization.

Please enlighten me on the deal of azidation of polyvinyl alcohol.:D

Adas - 16-1-2013 at 08:56

I think that polyvinyl azide has been discussed on this forum. They mentioned preparation from PVC and sodium azide in a solvent (acetone) from which NaCl would crystallize and PVA would stay in solution, AFAIR.

RunPyroRun - 16-1-2013 at 10:32

Still hunting down the thread you mentioned, but I have seen some papers on PVC to PVAzide and it makes a whole lot of sense. I was just wondering if it could be synthesized from PVAlcohol straight with a similar process using NaN3. Is NaOH formation even favorable?

Hydrazoic acid may be another route, with the formation of H2O being a lot more favorable. But hyrdrazoic acid isnt the best thing to be messing around with.

Adas - 16-1-2013 at 10:36

Quote: Originally posted by RunPyroRun  
Still hunting down the thread you mentioned, but I have seen some papers on PVC to PVAzide and it makes a whole lot of sense. I was just wondering if it could be synthesized from PVAlcohol straight with a similar process using NaN3. Is NaOH formation even favorable?

Hydrazoic acid may be another route, with the formation of H2O being a lot more favorable. But hyrdrazoic acid isnt the best thing to be messing around with.


Formation of NaOH is not favorable. Neither is formation of H2O when you use HN3. PVC powder is much easier to get. NaN3 might be the problem.

RunPyroRun - 16-1-2013 at 11:38

Thinking further on the subject, would it be possible to nitrate the PVA then add azide groups with a metal azide (such as sodium azide) forming sodium nitrate.

PVA is nice in that, in addition to very high molecular weight polymer chains, its bristling with -OH groups, so that even if the polymer isnt fully nitrated or azided, the remaining OH groups can contribute mechanically with hydrogen bonding and it absorbs certain liquids extremely well.

I'm weirdly obsessed with PVA right now, I know.:D
Thanks for the help!

Adas - 16-1-2013 at 11:56

Nitration would be very difficult unless you divide the PVA into smallest particles possible. Still, it would be poorly nitrated. But removing the nitro groups to add azide groups would be a waste since you can use PVC for that.

AndersHoveland - 24-1-2013 at 13:51

Quote: Originally posted by Adas  
Nitration would be very difficult unless you divide the PVA into smallest particles possible. Still, it would be poorly nitrated.

Actually, polyvinyl alcohol is not as hydrophobic as other polymers, so the nitration acids may be able to soak further in, especially if the polymer is in a loose (non-compact) form.

If methylene chloride is used as the solvent, it may be able to saturate deeper into the polymer and allow a more complete nitration.

Quote: Originally posted by Adas  
Neither is formation of H2O when you use HN3.

Actually, this would be the formation of an ester, and can be favorable if the H2O is dehydrated out. A mix of HN3 and anhydrous HCl gas on the PVA may be enough to form the azide.

Just my opinion here, but I do not think organic azides have the best sensitivity to energy ratio. There are many other families of energetic compounds that are much less sensitive for the same power, or much more powerful at the same sensitivity. Azide esters tend to be much more sensitive than ionic azides. If you are interested in packing nitrogen into a molecule, nitrogen-rich heterocycles are a much better way to go. There was mention in another thread of a tetrazole polymer that could be made from polyacrylonitrile (synthetic wool fiber).

[Edited on 24-1-2013 by AndersHoveland]

DubaiAmateurRocketry - 3-10-2013 at 23:05


A PV-Azide polymer has been synthesised and characterized by this team.

The IS and FS is very related to RDX, they prepared it from PV-nitrate, and found it hard to fully converting it to PV-azide with around half remaining as PV-nitrate

https://www.google.ae/url?sa=t&rct=j&q=&esrc=s&a...

DubaiAmateurRocketry - 3-10-2013 at 23:33

I also wonder if you can replace the Cl in those compounds with Azide groups

http://en.wikipedia.org/wiki/1,3-Dichloropropane
http://en.wikipedia.org/wiki/Dichlorobutane


[Edited on 4-10-2013 by DubaiAmateurRocketry]

AndersHoveland - 4-10-2013 at 09:15

Quote: Originally posted by DubaiAmateurRocketry  
I also wonder if you can replace the Cl in those compounds with Azide groups

Not by direct reaction, at least not under normal conditions. Chloroalkanes are very sluggish in undergoing nucleophilic substitution, in fact the reaction rate is negligible (although there are exceptions in certain situations).

One idea may be a catalyzed Finkelstein reaction to transform those Cl into Br, and then displacement with NaN3. Choice of solvent is important here, there several things that need to be considered, it is not a straightforward reaction.

Dany - 4-10-2013 at 10:49

@AndersHoveland

what do you mean by "normal conditions"?

the answer is yes. You can prepare PolyVinyl Azide (PVA) by direct SN2 reaction of PolyVinyl Chloride (PVC) with NaN3 in dimethylformamide (DMF) by heating the mixture @ 55°C for 96h (4 days). below is the procedure copied from [1] (see page 233 in [1]:

Synthesis of Polyvinyl Azide 2:

Polyvinyl chloride (6.0 g) and sodium azide (31.2 g, 480 mmol) were suspended in DMF (150 mL) and stirred for 96 h at 55 °C. After cooling to ambient temperature, the reaction mixture was poured on water (500 mL) and stirred for 24 h. The precipitate was filtered off and washed with water and methanol. The solid was stirred in a 1:1 acetone/water mixture for 12 h, filtered off and dried under reduced pressure. 2 was obtained as dark, rubber-like solid (5.1 g).

dec.: 189 °C.

also PVA can be prepared from Polyvinyl Nitrate (PVN) also by reaction with NaN3 in DMF (see [2] and the reference therein).

References:

[1] Stefan Sproll, Investigation of Nitrogen-Rich Polymers Based on Tetrazoles and Triazoles (PhD thesis, 2009)
[2] S.C. Mishra, Jyotsna Pant, P.K. Dutta and U.C. Durgapal, Def. Sci. J., 47(2), (1997), 131-137

link for reference [1]:

http://edoc.ub.uni-muenchen.de/11959/1/Sproll_Stefan_M.pdf

for reference [2] see attached file.

Dany.

Attachment: [2].pdf (746kB)
This file has been downloaded 407 times

[Edited on 4-10-2013 by Dany]

madscientist - 14-5-2014 at 00:54

Quote: Originally posted by AndersHoveland  
Quote: Originally posted by DubaiAmateurRocketry  
I also wonder if you can replace the Cl in those compounds with Azide groups

Not by direct reaction, at least not under normal conditions. Chloroalkanes are very sluggish in undergoing nucleophilic substitution, in fact the reaction rate is negligible (although there are exceptions in certain situations).

One idea may be a catalyzed Finkelstein reaction to transform those Cl into Br, and then displacement with NaN3. Choice of solvent is important here, there several things that need to be considered, it is not a straightforward reaction.


Nucleophilic Substitution under Normal Conditions with Exceptions in Certain Situations - Deoptimization of Early 20th Century Chemistry.

Sometimes a show opens with a stroke. Beer spills at the mic. Chunks spew across the drum kit. Guitarist tumbles dead off the stage - bad cocaine. It happens.

Just don't encore with excrement striptease. At least not again.

The Finkelstein Reaction in the 21st Century: Novel Application of Sodium Bromide in Refluxing Naphtha. Why Not? Rasputin* et al., JACS 2014, Accepted.

PHILOU Zrealone - 16-6-2014 at 08:03

Quote: Originally posted by DubaiAmateurRocketry  
I also wonder if you can replace the Cl in those compounds with Azide groups

http://en.wikipedia.org/wiki/1,3-Dichloropropane
http://en.wikipedia.org/wiki/Dichlorobutane


[Edited on 4-10-2013 by DubaiAmateurRocketry]

Possible just as it is possible to do 1,2-diazido-ethane from 1,2-dichloroethane, 1,2-dibromoethane or 1,2-diiodoethane and NaN3 in DMF or DMSO.
Terminal "primary" X-CH2- are required for this to occure easily...secondary -CHX- will be much harder for substitution.

Electro withdrawing group will increase the ease of substitution by leading to a more labile halogen...expect thus the compound to be lacrymatory and toxic (related to war gasses)... X-CH2-EWG
EWG can be -CH=CH-, -C#C-, -CO-, -CO2-R, -Ar, -C#N, -NO2, ...