Silver Azide

[Microtek]

Following my success with producing sodium azide using the FEMFEP method, I made a tiny amount of silver azide as a means of testing the whether I really had made the azide or if it was just NaOH.
This silver azide was initially pure white, but on drying it darkened a bit - this was expected.
Next I tested the initiating capacity of the SA by placing some MHN in a 2.5 mm wide plastic straw and compressing it slightly.
On top of the MHN was pressed 0.5 mm SA corresponding to 0.0125 grams at maximum density, but as the SA was very lightly compressed ( so as not to compact the MHN too much ) the actual figure was probably closer to 0.007 grams.
On top of the SA, a few granules of double salts were pressed to ensure flame sensitivity. The double salts were in a layer of between 0.1 and 0.25 mm thickness. Upon ignition, the MHN detonated with its usual ferocity.

[andreas]

Of topic but, would be interesting.
Does anybody know the exact Vdet for mhn.
I have seen stated the folowing:
<a href="http://www.url1.de/sprengchemie" target="_blank">http://www.url1.de/sprengchemie</a> (Vdet of mhn at density of 1,6 8260M/S
<a href="http://roguesci.org/megalomania/explo/mannitol_hexanitrate.html" target="_blank">http://roguesci.org/megalomania/explo/mannitol_hexanitrate.html</a>
I think at density of 1,6 7000m/s
And somewhere else I have seen stated 8000m/s at MAX dens.
Despite the fact that it doesn't really matter as it does perform uncanny for such a simple synthesis procedure, I would like to know.

[Mr Cool]

andreas: the VoD of MHN will vary, even at a constant density, if the diameter of the charge is not the same. Very narrow charges reduce the VoD IIRC. It's also conceivable that a detonator that is only just sufficient to set it off will produce a lower VoD.

Microtek: sounds good :)

[Microtek]

I've read in a reliable text ( though I can't remember which ) that MHN will detonate at ca. 7000 m/s in tubes of just 2 mm thickness. That is extraordinarily close to max VOD for such thin coloumns.

[da man]

Microtek, i read in the COPAE that silver azide can be made directly by reacting silver nitrite with hydrazine sulphate. This would be a much easier way of making it, missing out alot of steps. Though this reaction doesn't seem logical to me, i would of thought that would just make hydrazine nitrite and silver sulphate, whats your opinion?
And also, so you think that this could be done with lead (silver is BLOODY expensive for me)? If that doesn't work, I"ll either make it through hydrazine hydrate, all though i thought up a method that would probably be a bit easier and give better yields though it would be quite dangerous. I thought i'd make hydrazine nitrate, and react that with KNO2 to make dilute HN3 (yes i know how dangerous this is), but i'd keep the temperature very low with an icebath (to avoid giving off too much gas), and i'd quickly add lead hydroxide/carbonate, to convert it to lead azide. Hydrogen azide is supposed to be reasonably stable when dilute and this reaction produces about 25% HN3. Do you think this is too dangerous?
Or i suppose i could just make hydrazine hydrate and react that with lead nitrite.
I'll probably just use 5% household ammonia (with the soaps filtered out) ordinary bleach, (i just use an excess of ammonia right?) to make the hydrazine hydrochloride. I'll do this next weekend, im excited :)
Well, i hoped i've helped somewhat, and thankyou for any reply on my questions!

[Microtek]

In my experience the reaction of hydrazine and nitrite to form azide is not very fast. I don't know exactly how long it takes at different temps, but I think it's more than a few hours. I've seen refluxing mentioned in some procedures, and I don't think I would like to reflux a mixture containing either lead or silver azide.
I tried the hydrazine sulfate and silver nitrite when I was looking for a synthetic route to silver azide, but I couldn't get it to work ( though maybe I just needed to let it sit on the heat longer ).

[FrankRizzo]

Would it be possible to use silver acetate and sodium azide similarly to the procedure using lead acetate?

[Anath]

da man : Silver isn't all that expensive, go into Australia Post and ask for some 2 oz "Kookaburra Coins". 2 oz. of 99.99% pure silver for AUD$49.50

[Rosco Bodine]

The following patent describes a simplified method for azides .

GB128014 , Complete Specification ,
Improvements in and relating to the Production of Azides
application date: June 17 , 1918 No. 9952 / 18
complete accepted : June 17 , 1919

I , William Richard Hodgkinson , C.B.E. , of Ordnance College ,
Woolwich , London , S.E. 18 , Professor of Chemistry and Metallurgy ,
do hereby declare the nature of this invention and in what manner
the same is to be performed , to be particularly described and
ascertained in and by the following statement :

This invention relates to the production of azides .

The object of the invention is to provide a process of producing
azides from salts of hydrazine without the employment of
ethyl benzoate or the like , and the formation of benzoyl hydrazine .
According to the invention , salts of hydrazine are diazotised
by means of a suitable nitrite under such conditions that the
reaction mass is at no time so distinctly acid as to redden
litmus paper , but appears on the border line of acidity and alkalinity .
The conditions of acidity under which the reaction is carried out
according to the invention , are preferably comparable with the
conditions of acidity as indicated by litmus paper , of ,
for instance a solution of boric acid . Thus in accordance with
the invention , the nitrite solution is brought together with a
salt of hydrazine in approximately the proportions required on the
basis of theory to diazotise the hydrazine , under such conditions
that the acidity never exceeds the degree of acidity indicated above ,
and an acidified salt of the metal of which the azide is required ,
is introduced into the mixture , or alternatively the mixture
is added to the solution of the salt of the metal .

For example , silver azide is formed by adding a neutral solution
of hydrazine sulphate and sodium nitrite in molecular proportions
to a solution of silver nitrate of a degree of acidity with nitric acid
enabling the conditions in regard to acidity set forth above to
be realised , while avoiding the precipitation of silver sulphate .
Thus , for example 130 grams of hydrazine sulphate is converted
to the neutral hydrazine ammonium sulphate , which is more soluble
in water than is the simple hydrazine sulphate , by the addition of
ammonia solution , the mixture being made up to about 500 ccs .
To this solution contained in a vessel in which it can be violently
agitated , the calculated amount of sodium nitrite dissolved in
500 ccs. of water is added slowly so that the temperature does not
rise much above 30 degrees Centigrade .

The reaction resulting in the formation of sodium azide may be
represented by the following equation :

N2H4 -H-NH3-H-SO4 + NaNO2 ------> NH4HSO4 + NaN3 + 2 H2O

From this equation it will be seen that the solution would become acid
as the result of the reaction were it not for the fact that sodium nitrite
is never pure but is alkaline , the alkali in the nitrite ordinarily
being sufficient to maintain the solution on the border line of
acidity and alkalinity , and addition of a small quantity of alkali
being made should such not be the case . The solution thus made
contains sodium azide , some unchanged reagents , and the
by-products of the reaction .

The sodium sulphate and sodium azide contained in the solution
may be separated by crystallisation but preferably the solution
is added gradually to an acidified solution of silver nitrate produced
by adding 1. 0 cc. of 70% of nitric acid to 1000 ccs. of a
normal solution of silver nitrate which is violently agitated
during such adding , the temperature of the reaction mass being
prevented from rising much higher than 30 - 40 degrees Centigrade .
With adequate cooling and agitation the yield of silver azide may
be obtained equivalent to 85 % of the calculated possible amount .
Instead of adding the diazotised solution to the acidifed silver nitrate
solution , the latter may be added to the former .

When starting from hydrazine nitrate which is also an acid salt ,
a solution of ammonia should be added in order to form the
neutral hydrazine ammonium salt or , if desired , the neutral
hydrazine sodium salt may be produced , the remaining steps
of the process being then carried out as above described .

In producing lead azide , a solution of a hydrazine salt
of an acid which will not result in the precipitation of
an insoluble lead salt of the acid in question , for instance
hydrazine nitrate , is employed , and the reaction mass
in this case should be only just acid , as lead azide is
particularly easily acted on by acids , while in producing
silver azide the acidity of the reaction mass may be greater
in order to avoid the precipitation of silver sulphate
and agitation indicated in the foregoing example .

The azides produced in accordance with the invention
are usually amorphous , and in this state they are
safer to handle than when crystalline .

Having now particularly described and ascertained the nature
of my said invention and in what manner the same is to be
performed , I declare that what I claim is :

1. The process of producing azides from salts of hydrazine
in which salts of hydrazine are diazotised by means of
a suitable nitrite under such conditions that the reaction mass
is at no time so distinctly acid as to redden litmus paper ,
but appears on the border line of acidity and alkalinity .

2. The process as claimed in Claim 1 in which the conditions
of acidity under which the reaction is carried out according
to the invention are preferably comparable with conditions
of acidity as indicated by litmus paper , of , for instance ,
a solution of boric acid .

3. The process of producing azides from salts of hydrazine ,
substantially as hereinbefore described .

Dated this 10th day of December , 1918