PowerLabs Lead Picrate Synthesis

Lead Picrate (2,4,6-Trinitrophenol, lead salt) Laboratory
Synthesis:

INTRODUCTION:

It is
widely known that Picric Acid should not be allowed to contact metals or their
salts due to the danger of formation of metal picrates. Metal picrates are salts
of Picric Acid formed by the addition of the metal to the 2,4,6TriNitroPhenol
ring at the first hydroxide, as seen on the example to the left
(PbO-C6H2(NO2)3 or
PbC6H2N3O7). They are all, to some
degree, explosive. Their explosive strength is lower than Picric Acid's own
(between 48 and 70% depending on the particular salt), but their sensitivity is
much greater, increasing with the weight of the particular metal ion used. For
curiosity's sake I experimented with making a few metal picrates and testing
them to evaluate their properties. The most interesting one was Lead Picrate,
which's synthesis I outline below for informational purposes
only.
Metal Picrates are sensitive explosives and as such should not be
manufactured at all!

MATERIALS:

Reactants:

Glassware:

Lead Monoxide (PbO(s))

250mL Glass beaker.

Picric Acid (saturated solution)
(C6H3N3O7(aq))

Pipette

Distilled Water (H2O(l))

Stirring Rod

Funnel/filter
paper

PROCEDURE:

C6H3N3O7(aq)
+ PbO(s) =>
PbC6H2N3O7(s).

Here all the chemicals used in the synthesis are seen, from left
to right, back to front: Picric Acid, Lead Monoxide Methanol, 50mL glass beaker,
spatula, glass rod.

The picric acid is dissolved in Methanol and heated until no solid remains. It
forms a yellow colored liquid, to which an equal amount of Lead Monoxide is
added. The methanol is heated further until boiling commences and stirring is
maintained.

Shortly after the mixture begins to boil a
reaction takes place which thickens it. Lead Picrate has thus formed. Boiling is
continued until the solution becomes a thick emulsion. It is than filtered and
washed with Methanol until the residue from the wash is colorless. The filtrate
is than allowed to dry.

Lead Picrate forms into a yellow/rust colored
powder once it has been dried. Heating at 100C for 2 hours is reported to
increase the product's stability, as it converts it from monohydrate to pure
lead picrate.

RESULTS!

The product is sensitive to shock (2cm fall from a 2 kilogram
block causes detonation in 50% of the attempts (Urbanski), flame, and friction.
On burning, it deflagrates violently with a bright yellow flame and large
amounts of lead metal vapor are released. Click on the picture to the left to
watch the 98Kb .mpg video of a small amount being burnt unconfined. Confined
deflagration transits easily into detonation (DDT) which makes this product
suitable for use in detonators and/or blasting caps.

Questions? Comments?
Suggestions? E-mail me!

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Last updated 30/01/04

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