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Author: Subject: White phosphorus to red?
PirateDocBrown
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[*] posted on 24-5-2017 at 14:14
White phosphorus to red?


Who has done this conversion? Any pointers?

Red P is far easier and safer to handle and store.
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elementcollector1
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[*] posted on 24-5-2017 at 15:33


I am told that heating at 250 degrees C with a small amount of iodine catalyst for a few hours will do it.



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PirateDocBrown
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[*] posted on 24-5-2017 at 23:12



What technique is used to prevent reaction with air?
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[*] posted on 25-5-2017 at 06:35


I once asked my Professor who is an expert on Phosphorus chemistry about how likely it would be that my white P turned to red P and he said even if I tried to convert it it would not be that easy.



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[*] posted on 25-5-2017 at 08:23


This may be helpful (from Ullmann's Encyclopedia of Industrial Chemistry):

"5. Production of Red Phosphorus
The conversion of white phosphorus into the
more stable red form is an exothermic reaction.
It must therefore be carried out under controlled
conditions.
The process which has been used in Germany
since 1936in Bitterfeld and since 1953 in Knapsack
is based on a Russian invention in which
the phosphorus is converted in an open reactor.
However, in Bitterfeld and Knapsack, closed reactors
with charges of ca. 6t are used (Fig. 8).
The reactor consists of a thick-walled iron
rotary furnace resting on two hollow shafts with
a driving mechanism, and surrounded by an air
bath. It contains a small charge of steel balls.
The white phosphorus in the reactor is first
heated by the gas-heated air bath to 100 – 180 ◦C
to drive off the water completely. Evaporating
phosphorus is recovered in a condenser. After
removal of the water, the reactor is sealed
and heated to 270 – 275 ◦C over a period of
ca. 24 h, whereby ca. 70% of the white phosphorus
is converted to the red form. A further
increase in temperature causes the remainder to
be converted very rapidly, with accompanying
increases in pressure and temperature. The reactor
is then cooled and filled with water, and the
phosphorus is ground to the desired fineness.
In addition to the fact that the charge is relatively
large, an important advantage of this process
is that the phosphorus is not produced in
the form of hard cakes, as in earlier autoclave
processes, but as a powder.
In a modified version of this process, the full
charge is not added to the cold reactor. Instead,
white phosphorus is pumped in small batches
into the dry reactor, which has been brought up
to the reaction temperature. A large fraction of
the phosphorus is converted directly into the red
form. The advantages of this method are higher
throughput and greater safety because the quantity
of white phosphorus present in the reactor at
any time is small [32].
The aqueous suspension of red phosphorus is
steam heated in stirred vessels, and the remaining
white phosphorus (ca. 0.1 %) is decomposed
by adding sodium hydroxide solution. The phosphorus
is filtered off and washed in rotary cellless
filters or filter presses. The phosphorus is
then continuously dried in steam-heated rotary
or shelf dryers under a slight positive pressure
of nitrogen. The nitrogen is circulated to remove
the water vapor from the drying equipment. Airentrained
dust is removed in scrubbing towers
and returned to the process.
The conversion and drying of the red phosphorus
must be precisely controlled to avoid severe
accidents. The pressure and temperature in
the reactor can rise sharply if the conversion is
uncontrolled. The oxygen content of the nitrogen
in the shelf dryer must be controlled to avoid
spontaneous explosive ignition of the red phosphorus.
The explosion limit is at 3.5% oxygen;
in practice, the concentration of oxygen in the
nitrogen is usually limited to ca. 1.5 %.
In the course of the treatment process (after
heating to remove the last of the white phosphorus
and up to the drying process), the red
phosphorus can be treated to coat the surface
of the grains with substances to perform various
functions, e.g., to stabilize the red phosphorus
(against P2O5 formation), to consolidate
or “phlegmatize” (to prevent dust formation), to
give hydrophobic properties, or to produce special
properties to enable the material to be incorporated
into plastics. The major producers of
red phosphorus have developed special grades
for the various applications in collaboration with
their customers (see Section 6.2. and Chap. 7)."





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PirateDocBrown
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[*] posted on 26-5-2017 at 16:10


I was just wondering if and forum members had made the conversion.

You see lots of people making WP, but RP would be much more useful to have.
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[*] posted on 2-6-2017 at 13:33


Seems to me, sunlight can do the trick.
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[*] posted on 2-6-2017 at 18:34


Would sunlight work entirely, or just on the surface?



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[*] posted on 7-6-2017 at 14:39


Seems to me, guys report refluxing White Phosphorus in a Non-polar solvent like Xylene Etc.
in bright sunlight. White Phosphorus melts at reflux temperature. And, dispersed in a solvent, its surface area becomes quite large.

Try the Phosphorus Thread in General Chemistry. Got 55 pages or so, about Phosphorus, in General Chemistry. Probably have a procedure there. Or possibly, on the Hive. Might take a while to dig it out.
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