posted November 08, 1999 07:52 AM            

Buy?in the store[where]?

bye!

posted November 08, 1999 08:30 AM            

Pentaerythritol is made by reacting formaldehyde with acetaldehyde,
condensing them together with the help of calcium hydroxide.

8 CH2O + 2 CH3CHO + Ca(OH)2 => 2 C(CH2OH)4 + Ca(COOH)2

Formaldehyde + Acetaldehyde + Calcium Hydroxide => Pentaerythritol

There is not too much which can go wrong with this reaction, so long as
reasonable care is taken to follow the directions. It is, however, very
stinky and potentially unhealthful if the experimenter allows himself to
breathe in the fumes of formaldehyde and acetaldehyde. This reaction is
best done outside with a steady breeze, the "cooker" keeping himself upwind
throughout the process. If the watchful eyes of neighbors preclude this, a
garage with a strong wind flow is acceptable. This may obscure the view of
civic-minded citizens, but their noses are another enemy to be remembered.
This process is best done in a secluded area.

To begin production, a clean plastic 5-gallon pail is filled with 2160
grams (2000 ml) of 37% formaldehyde solution, 210 grams (275 ml) of
acetaldehyde, and 4 quarts of water. These chemicals do not need to be of a
particularly high grade, so if money can be saved by using technical grade
chemicals instead of reagent grade, then do so. Also, the formaldehyde
solution can be replaced by 800 grams of paraformaldehyde. This solid form
of formaldehyde does not have the powerful smell of the formaldehyde
solution, but is much more expensive than regular formaldehyde. The 37%
formaldehyde solution may be sold under the name of formalin, so be aware
of this example of the proliferation of chemical synonyms.

Next, a clean wooden stick must be obtained. A section of broom handle
minus the finish is a good example of what is called for here. This wooden
stick is used to stir the solution.

First mix the ingredients already in the pail, then begin adding
powdered quicklime (CaO, calcium oxide) to the pail in small portions with
vigorous stirring. When the calcium oxide goes into solution, it first
picks up a molecule of water, becoming Ca(OH)2, and then takes part in the
reaction shown above. The CaO should be added at such a rate that the
temperature of the mixture rises to 50ø C (a little over 120ø F) within the
first half hour of adding the CaO. Then the CaO is continued to be added at
such a rate that the temperature of the mixture does not go over 55ø C
(about 130ø F). As can easily be imagined, the fumes of formaldehyde and
acetaldehyde get pretty intense as the solution gets hot. They get less
revolting as the reaction nears completion and the aldehydes get consumed.
The total amount of CaO added is 180 grams.

When all the CaO has been added, the stirring is continued at a more
leisurely pace for another three hours. This long stretch of stirring is
bound to tire even the most dedicated explosive manufacturer so an
alternative which can be used where electricity is available is to suspend
an electric drill or similar motor over the pail, and use a clean paint
stirrer attachment to stir the solution. The fumes are not especially
flammable, so fires are not the hazard they often are when dealing with
more flammable chemicals. Even so, rigging an extra long stem for the
stirrer, so the motor is elevated above the pail rim, is a wise precaution.

When the stirring is done, it is time to filter the now yellowcolored
solution. A large coffee filter fitted inside a plastic funnel will do a
good job of this. The total volume of liquid amounts to about 3 gallons.
Contained in this 3 gallons, is about 3/4 pound of pentaerythritol. Now the
real work begins as the workaholic explosives manufacturer isolates his
product from the mixture.

First, the mixture must be made slightly acid. To do this, hydrochloric
acid (the 28% strength material available from hardware stores is good
enough) is diluted 50-50 with water. Then this diluted HCI is added to the
mixture with stirring until the mixture is acid to litmus (turns blue
litmus paper red). A good way to do this is to add 100 ml of the dilute HCl
right away, and then after stirring and checking for acid reaction, add
smaller amounts of acid until an acid condition is achieved. This will
convert the calcium formate made in the reaction to formic acid and CaCl,
and also knock out left over CaO. In these forms they are more easily
gotten rid of.

Next, the yellow color can be removed by adding 30 grams of activated
charcoal powder (Norite brand is usually used in the lab) and stirring it
around for a few minutes. Then the solution is once again filtered so as to
remove the charcoal, and the filtrate is clear once all the charcoal has
been successfully filtered out. Until then it is black, and the pail is a
holy mess. Get a clean pail. This step can be omitted, but a yellow product
will result which will be more touchy to convert to PETN without the
dreaded red gas being formed. It will also not keep so well.

Now the solution must be reduced in volume so that crystals of
pentaerythritol can form. To do this the water and other assorted smelly
gunk must be boiled away under a vacuum. Formic acid and the unreacted
aldehydes will be eliminated in this process. The first step in this
adventure is to get a large enough container to hold the reaction mixture
for the boil down. 5-gallon flasks are not commonly available to the
public, but a good substitute is one of those thick glass water jugs often
seen in offices for the water cooler. This is about 5 gallons in volume,
and has a narrow opening which can be plugged with a onehole rubber
stopper, and attached to the vacuum source (either aspirator or water bed
pump).

To get this process going, put the reaction mixture into the glass jug
along with a couple small pieces of a Dr. Scholl's pumice footstone (to
ensure an even boil) and a chunk of paraffin wax the size of a small grape
(to control frothing). The jug should be heated by means of steam, which
can be supplied from a pressure cooker by filling it half full of water,
clamping a section of automotive hose to the outlet on the lid where the
weighted pressure control usually sits, and piping the steam produced from
heating the pressure cooker into a cowling surrounding the jug.

The jug should sit in a large pan and be lifted off the bottom an inch
or so by use of a few wooden blocks. The steam hose is run under the jug so
that the steam rises up around the jug to heat it. The cowling can be as
simple as a plastic garbage bag draped around the jug. A drain hose should
run from the bottom of the pan to a drain or sink to carry away the water
formed from the condensing steam.

When the jug is reasonably warm, vacuum should be applied to it and the
heating continued. The contents of the jug will begin to boil away. This
should be continued until the volume of liquid in the jug is reduced from 3
gallons to one gallon. Then the heating is stopped, and when the boiling
ceases, the vacuum is removed.

Now that the liquid has been concentrated, crystals of pentaerythritol
can form. Just let the jug cool off in the refrigerator overnight. In the
morning, the crystals can be filtered out.

The liquid that filters through contains more product. This can be
obtained by boiling away until the volume of the liquid is halved, i.e.,
reduced to 2 quarts. Upon cooling, a new crop of crystals can be filtered
out. Repeating the process again, and boiling away the liquid down to one
quart gives, upon cooling, another set of crystals. The remaining liquid
can then be flushed down the toilet.

The crude product should be purified before use in PETN production. To
do this, it is weighed, and an equal weight of distilled water is put into
a stainless steel pan, or large pyrex beaker. The volume of water will be
about a pint. The water is heated up on the stove, and the crystals are put
into the water, along with 10 ml of hydrochloric acid. Mix them around
until they dissolve, and boil just a little bit. Upon cooling, a large mass
of crystals will appear. Filter them out. The liquid should then be
concentrated down to about half its starting volume, and then cooled.
Another crop of crystals will appear. By repeating this process a couple
more times, about 350 grams of pure pentaerythritol will be obtained. It
may be somewhat yellowish, but will work for making PETN. This product
should be spread out on wax paper and allowed to dry thoroughly before use.

Ref.
Home Workshop Explosives
by Uncle Fester

posted November 09, 1999 03:00 AM            

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