deltaH
Dangerous source of unreferenced speculation
Posts: 1663
Registered: 30-9-2013
Location: South Africa
Member Is Offline
Mood: Heavily protonated
|
|
Glyoxal + hydrazine
This one's for Bert on the theme of flame retardants for DB propellants:
Safety warning
Hydrazine is very toxic, suitable precautions must be taken when working with this reagent!
Experimental
A long time ago in a galaxy far far away  I conducted an experiment where I
refluxed equimolar amounts of hydrazine hydrate and conc. glyoxal in water as a solvent under magnetic stirring with the aim of investigating
energetic properties.
After a lengthy induction period, the reaction mixture produced a thick mass of beautiful vivid yellow precipitate. The product was filtered and
washed with water in which it appeared to be completely insoluble and gently dried in a vented oven.
A mass of this powder when heated in a tube furnace flushed by inert gas suddenly decomposed at about 350°C, generating enough gas volume to shoot
out the ground glass ends of the furnace’s glass tube, but didn’t break it. It made a quick whoosh sound, but not a bang and yielded charred
granules, smoke and unreacted yellow powder (sprayed out the ends onto the counter top).
Today remembering this, I realise that this material could potentially be useful as a flame retardant for propellants so decided to report on what I
can remember. I apologise in advance that I no longer have my lab notes on it, I’m writing from my recollection of a long time ago, but I might be
able to remember additional details, so please do ask if you have questions.
Some additional observations:
The product didn’t ignite when I attempted to light it by a small flame from a lighter in the open, so the sudden and rapid decomposition in the
inert atmosphere at ~350°C was a complete surprise!
The reaction was also conducted in warm THF and proceeds very rapidly in that medium, also affording a bright yellow highly insoluble solid. The
refluxed water version has a long induction period but then converts quickly forming the mass of precipitate.
A friend had a mass spectrum drawn for me on the THF derived product, the details of which I no longer remember, but I do remember it yielded a
heaviest peak of 110amu’s and I’m certain of that figure.
Discussion
[speculations]
The hellish insolubility in everything I could throw at it and m.p higher than the decomposition temperature higher than 350°C suggests something
with strong hydrogen bonding, you know, like the behaviour of melamine cyanurate.
Now that I think about it, it could have been an extensively hydrogen bonded 1:1 adduct of hydrazine and glyoxal. According to the wiki on glyoxal, it
is a yellow coloured liquid (the glyoxal solutions in water are colourless though due to formation of hydrates).
If it was the 1:1 adduct of hydrazine and glyoxal, then the decomposition products would could have been hydrazine's, freeing the glyoxal, though I
don't recall smelling any ammonia, but rather a sweetish smell I think. Could also have been nitrogen and ethylene glycol perhaps? That would explain
the smoke that formed and set off the smoke detectors, but then again, that could also been anything else.
Finally, the reaction can in principle be carried out in any suitable inert solvent capable of solvating the reagents, not just tetrahydrofuran or
water, though water is the greenest solvent.
[/speculations]
If anyone ever makes money out of this... please remember poor deltaH 
[Edited on 4-2-2015 by deltaH]
|
|
|
franklyn
International Hazard
Posts: 3026
Registered: 30-5-2006
Location: Da Big Apple
Member Is Offline
Mood: No Mood
|
|
bisHydrazones have been known a long time. Studied as cancer drugs and route to triazine heterocyclics
http://books.google.com/books?id=xdg4AAAAMAAJ&lpg=PA393&...
http://pubs.acs.org/doi/abs/10.1021/je00028a036
Patent - 1,2,3 Triazole by N2H4 & (CHO)2 - US5478947
Glyoxal is expensive , Formaldehyde gives something as suitable.
http://www.sciencemadness.org/talk/viewthread.php?tid=3363#p...
http://www.sciencemadness.org/talk/files.php?pid=66978&a...
Patent - Tetraformaltriazine US3664131
.
|
|
|
deltaH
Dangerous source of unreferenced speculation
Posts: 1663
Registered: 30-9-2013
Location: South Africa
Member Is Offline
Mood: Heavily protonated
|
|
Thanks franklyn for the literature, I appreciate it.
I think I also tried the THF reaction at very low temperature and it was still very fast, I can't recall exactly what I used for cooling, I remember
it was a crushed ice and some organic solvent... probably acetone I would guess, anyhow, the details here are very hazy so take this paragraph with a
pinch of salt.
Why the amorphousness of the product and extreme insolubility?
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
H2N-NH2 + O=CH-CH=O --> (=N-N=CH-CH=)n + 2n H2O
(=N-N=CH-CH=)n -heat-> 2n H-C#N
H-C#N being endothermic from its elements --> H2 + C(s) + N2 (+ CxHy + CzHwNv)
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
deltaH
Dangerous source of unreferenced speculation
Posts: 1663
Registered: 30-9-2013
Location: South Africa
Member Is Offline
Mood: Heavily protonated
|
|
PHILOU, I also thought I had formed some polymeric specie, but I'm also doubting it now and can't make up my mind  There really seemed to be very extensive hydrogen bonding at work. Perhaps some
initial hydrazone formed and then strongly hydrogen bonded to itself to form the amorphous yellow stuff based on say O=CH-CH=N-NH2 'monomers'.
Also, I didn't smell an almond smell upon the decomposition indicative of cyanide, some sweet smell, but maybe you're right.
As for the cost, franklyn, I was wondering if it might be prepared from ammonia, bleach and ethylene glycol? That would make it very
cheap. However, according to Alibaba.com, bulk glyoxal 40% solution sells for a mere $1200/ton, so that's pretty affordable on an industrial scale.
Anyhow, I'm not inclined to experiment with bleach, ammonia and ethylene glycol solutions as I don't have a fume cupboard and this is a very dangerous
reaction because of the exothermicity of glycol oxidation and toxicity of hydrazine 
As an aside and warning, I've attached a paper below describing the spectacular fireball that is evolved by reacting pool chlorine with brake fluid as
an example of the dangers of combining hypochlorite and organics Don't do this
in all but the smallest quantities and with all the necessary precautions described therein!
Attachment: pool chlorine and brake fluid.pdf (313kB)
This file has been downloaded 19307 times
[Edited on 5-2-2015 by deltaH]
|
|
|
franklyn
International Hazard
Posts: 3026
Registered: 30-5-2006
Location: Da Big Apple
Member Is Offline
Mood: No Mood
|
|
http://www.sciencemadness.org/talk/viewthread.php?tid=1987&a...
http://www.sciencemadness.org/talk/viewthread.php?tid=6575
.
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
@DeltaH,
The field of molecular reactions between amines and aldehydes is very dependant on conditions:
-Heat
-Proportion of reactants
-pH
-solvent
In this case you can go through an hydrated transition state that would explain the observed "H-bonding effect":
H2N-NH2 + O=CH-CH=O --> (-NH-NH-CHOH-CHOH-)n --> (=N-N=CH-CH=)n + 2n H2O
Polyolic-poly-sym-hydrazine would display a lot of H-bondings, dehydration may be partial and not involve all hydroxy groups and hydrogen from amine.
Note that the fully dehydrated compound is fully aromatic polymeric chain and must display a large molecular orbital --> must be yellow orange red
brown of even black while "dehydration" goes further.
Just as a parallel see formazin used for turbidimetric standardization (normalized turbidimetric concentrations) made from reaction between
formaldehyde and hydrazine... this makes a polymer like (-CH2-N(-)-N(-)-CH2-)n (*) a kind of lather of tetrazacylohexane (with methylene on the sides
and N-N steps)
--> formazine
(*) the N(-) is a nitrogen atom with an open pending bond for further connection and not a negatively charged N atom .
[Edited on 7-2-2015 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
deltaH
Dangerous source of unreferenced speculation
Posts: 1663
Registered: 30-9-2013
Location: South Africa
Member Is Offline
Mood: Heavily protonated
|
|
Ah I see, thanks PHILOU Zrealone. What you say feels right. I think the matter ejected from the heated tube resembled what you
describe in colours and so was increasing in degrees of dehydration and conjugation. I think the reason the starting material would not ignite or
decompose on simple tests with a small flame is because it needed to be heated for some time to dehydrate it fully... I think perhaps it is the
finally conjugated product that deflagrates to N2 more easily because the bond between the nitrogen is then 1.5 and so easier to break to form N2?
This could be a useful property for a flame retardant because (1)it is inherently safe in its 'virgin form', (2) probably has an strong endothermic
peak in heating with dehydration before converting to gaseous products.
Franklin has mentioned the formaldehyde derivatives as well... if these compounds show similar behaviour, then they are flash
retardants candidates as well.
Ok, so that allows me to form a hypothetical and idealised reaction sequence that summarises:
H2N-NH2 + O=CH-CH=O + heat => -(NH-CHOH-)n-(N=CH-)m (yellow precipitate) + mH2O + heat => -(N=CH-)(n+m) + (n+m)H2O (dark stuff) + heat =>
N2(g) + CH#CH(g)
So then its acetylene and nitrogen that's produced in the final decomposition in this scheme, interesting if correct. Interesting because pure
acetylene is described as having a light and sweet smell, which I think is what I smelled, as stated earlier.
Per unit of mass, if we assume that n~m for the yellow precipitate, then overall:
-(NH-CHOH-)n-(N=CH-)m => N2(g) + CH#CH(g) + H2O(g)
during under strongly anaerobic conditions.
That gives a gas volume generation of 933sccm/g of yellow material, which is close to nitroguanidine's 1067sccm/g (sccm=standard cubic centimetre).
If you assume the acetylene formed goes on to form three moles of gas by scavenging two oxygen atoms from somewhere, then you generate much higher gas
volumes and exceed that of nitroguanidine.
As for preparing propellants, the question is how does one incorporate/formulate using this amorphous powder. If it's porous, perhaps some NG can be
absorbed into it by capillary action? Don't know how you would 'marry' this to the nitrocellulose + NG though.
One thing though, you'd probably go for a much higher NG to nitrocellulose ratio overall to make it work well.
[Edited on 8-2-2015 by deltaH]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
