Lead Acetate for Primaries

[2,4,6-TNP]

Lead Acetate Synthesis:

Materials:

10 Grams Lead Monoxide
200 mL White Vinegar (5% Acidity)

Procedure:

In a medium suace pan place 10 grams of lead monoxide.
To this add 200 mL white vinegar (5% acidity).
Heat mixture on a stove top over medium high heat.
Maintain a constant boil. Reduce this mixture until all the vinegar has
evaporated. Then quickly remove from heat source and allow to cool.

Note: During most of the reducing process the mixture will be an
orangish color but just before all the vinegar has evaporated the solution will turn a blackish-gray color.

After cooling, a grayish powder will be left in the sauce pan.
Collect the powder and store it in an airtight container.
Lead acetate takes up carbon dioxide from the air, and therefore becomes water insoluble. Yeild is same as amount of lead monoxide used.

When this 10 grams of gray powder is added to 200 mL of water it dissolves into a cloudy white solution. When this cloudy white solution is filtered all of it goes through the filter with a little undissolved lead acetate left in the filter. If the gray powder is heated above 100 Celsius it begins to decompose into lead monoxide. Decomposition is complete above 200 Celsius.

This material is great for sythesis of lead azide, lead picrate, lead styphnate, Trinitrophloroglucinol lead salt and can even be used to synthesize lead nitrotetrazole, basic salt Pb(HO)2. Basically it's a cheap substitute for lead nitrate.

Warning: I recommend wearing a gas mask during this process to avoid lead vapors and the noxious smell of acetic acid. Lead acetate is a carcinogen so use care and take precautions: gloves, gas mask ect.

I also want to use this thread to discuss with you your experiances with lead acetate and its use in explosive manufacture.

[chemoleo]

A while back I managed to solubilse a couple of kilograms of lead with a neat little method. I didnt want to waste HNO3 for the dissolution, neither NH4NO3 etc. Neither did I have any existing lead salts, or lead oxide.

But I did have about 20 kg of solid lead metal, plus 10 kg of copper sulphate (CuSO4), obtained from a gardeners store.


I got it to work as follows:

1. Calcium carbonate is easily obtained, I neutralised a known amount with acetic acid (conc. vinegar), yielding a solution of calcium acetate.

2. I dissolved an equimolar amount of Copper sulphate CuSO4, and added to it the stoichiometric amount of calcium acetate. What you get is copper acetate and calcium sulphate

3. THe precipitating calcium sulphate is filtered off, then the filtrate is cooled to precipitate more CaSO4, and filtered off again. One is left with a fairly clean solution of copper acetate, which has a lovely dark green colour and tends to crystallise at the surface of the the liquid.

4. This is probably the longest step - to the solution of copper acetate, one adds a large excess of solid lead metal! the finer the lead pieces, the better (faster). Over the course of a week or two, the copper acetate colour (dark green) slowly disappears, and becomes completely colourless. What happened meanwhile is that solid copper deposited as thin sheaths on the solid lead. I found no stirring is needed during those two weeks, the copper deposited anyway.

5. The solid copper is scraped off the remaining lead, the lead pieces are taken out, and the solution is filtered once again to remove copper pieces and any more CaSO4

6. One is left with a clear solution of lead acetate. Made from 100% over the counter materials. Slow evaporation of the water in the solution leads to LARGE crystals of lead acetate, which are very heavy and slowly become milky/powdery on the surface at air! This way I obtained several kg of lead acetate, with minimal effort/expenses :)



PS There is another thread that partially discusses lead nitrate/acetate, it is
http://www.roguesci.org/theforum/showthread.php?t=1845&highlight=lead+acetate

[Rosco Bodine]

chemoleo ,

Good work .

That is an ingenious synthetic method for lead acetate from
OTC materials . The formation of any basic lead acetate by
hydrolysis may be avoided by keeping the solution acidic during
the evaporation / crystallization . A series of hydrates may
form dependant upon the temperature of the solution from
which crystals are forming . Above 75 C , the anhydrous
salt is formed . Below 75 C and above 22 C , is the range
where the desired trihydrate will crystallize from solution .
A decahydrate with a melting point of 22 C will crystallize
from solution below 22 C .

[Microtek]

If the lead acetate is to be used for lead azide, you should be aware that there will be traces of copper acetate mixed in with it. This will lead to a more sensitive product.

[pdb]

In my opinion, the likelihood of contamination by complex and unstable Cu azide-based salts is such that it should definitively ban the use of lead acetate obtained by the method described above for preparing lead azide. Lead azide is perfidious enough by itself for its handling not be made even more hazardous.

[chemoleo]

Good thing you pointed this out.

However, the fact that
1.) no colour remains, and
2.) that the resultant lead acetate can be recrystallised

would indicate that the resultant purity of the lead acetate is good, as recrystallisation normally has the point of removing other compounds that have a different molecular structure, i.e. copper acetate would be excluded in lead acetate crystals as it wouldn't fit into its crystal lattice.

Also, in electrochemical reactions such as this, the equilibrium lies very very far to the product side, leaving indeed very tiny amounts of copper ions in solution (the reason why it lies to the right is that copper metal is totally insoluble in water, and effectively removed 100% out of the system, thus shifting the equilibrium to the right..
Plus, copper being visible at extremely low concentrations due to its colour, gives a good indication as to purity. One could always add some ammonia to the recrystallised lead acetate, and see whether one'd get a blue colour due to the formation of a copper tetraamine complex (this is a more sensitive test)

Actually, I think a much greater 'danger' of impurities, if anything, resides in the purity of the lead used - lead may contain a number of other trace metals, such as Cadmium, tin, bismuth, anitmony, et cetera. In addition, maybe you'd like to check the purity of the PbO you use for dissolving it in acetic acid/HNO3- I'd bet it contains > 0.0001% of copper. Just about any lead product will have some copper in it.

For those really worried, you can always precipitate the the lead acetate with HCl, yielding PbCl2, while any potential CuCl2 (which would be similarly produced) remains in solution.

The PbCl2 could be solubilsed again, by mixing it with Naacetate in hot water. Recrystallisation as before. That will be about the cleanest lead acetate you can possibly get, homemade.

I do have commercial PbO, so eventually I will test this. Personally I have not many doubts as to the purity of the acetate - no more doubts as I would have with an industrial product (note, industrial, not analytical ;))

[Marvin]

Cunning method, but I bet filtering the calcium sulphate was a pain and a half.
I would think if you added ammonia to test for copper, this would mostly ppt basic lead compounds and probably take most of the copper out of solution anyway as a coprecipitant, no?

I dont follow the conversion of lead chloride back to acetate, is this a known method Ive missed? I understood lead chloride was virtually insoluable.

[chemoleo]

Cunning method, but I bet filtering the calcium sulphate was a pain and a half.
Actually, it wasn't too bad at all. CaSO4 is by far not as bad as filtering something like Cu(OH)2, or similar. In addition, I used a large total volume (>5 litres), and big coffee filters, and I got the job done in 20 minutes. Of course the filtered CaSO4 was still turquoise coloured, but the filtrate was an intense dark green solution.
Besides, the first time I tried this, I used sodium acetate instead of calcium acetate. Of course, I will have Na2SO4 in the final solution, once all of the acetate has reacted, but even then, lead acetate crystals could be picked out easily. Due to its ease, I prefer the Ca-acetate method, one doesn't have to be careful as to which crystals to pick.


I would think if you added ammonia to test for copper, this would mostly ppt basic lead compounds and probably take most of the copper out of solution anyway as a coprecipitant, no?

I guess you are right on this one, I overlooked that. In the case of the copper, it wouldn't precipitate I believe as long as an excess of ammonia is added - again, the copper tetraamine hydroxide is formed, which is dark blue once again. So, if you added ammonia to the final solution, and if it still contained significant amounts of copper, a white precipate (Pb(OH)2) should occur, while the colour goes slightly turquoise.
If you are really desperate to test this without precipitation, one could use acetic acid-acidified ammonium acetate and add that in excess to a small batch of the final solution. In this case copper tetraamine acetate should form (intensely coloured just as well), while the lead acetate remains in solution.

I dont follow the conversion of lead chloride back to acetate, is this a known method Ive missed? I understood lead chloride was virtually insoluable.
The point here is to further purify lead acetate, if it is felt necessary.
Once you precipiate the lead acetate by converting it to the chloride, the sparkling white precipitate (done that) is washed with cold water, and any copper/cadmium etc impurities are washed through (as those chlorides are soluble).
Then, the washed lead chloride is added to hot distilled water and stirred continuously, to bring as much into solution as possible (lead chloride is slightly soluble, so a few grams will dissolve). It doesnt matter if not all dissolves, as the following should happen: lead chloride in solution, in the presence of sodium acetate, will be converted to Pb acetate and NaCl. More PbCl2 can dissolve, as we just removed some... and so it proceeds. Eventually all PbCl2 has dissolved and is converted to Pb-acetate.
Then recrystallisation as before, shouldnt be a a problem (see above) to distinguish the crystals. Does that make sense?


Phew... at last:

Rosco Bodine - what you said about the basic lead acetates- it reminded me of what I had initially: when the Ca acetate started reacting over the course of a week or two, I noticed that an insoluble yellowish substance accumulated at the side of the reaction vessel.
Thinking, oh, this must be because the HAc evaporates (which is, as I found out later, because the double salt of the hydroxid/acetate forms), I added 500 ml of 20% HAc to the 5 litres in the reaction vessel - and promptly, the yellowish stuff disappeared, and it was a clear green (later clear altogehter) solution again.
From that point onwards, I always made sure I keep the solution acidic, with excess acetic acid!

The lead acetate crystals that I have (between 5- 8 cm in size ) are now all milky unfortunately (2 years later), as I kept them on air. However, what is inside of those crystals is still pure lead (II) acetate :D