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Author: Subject: Metapurpurate
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[*] posted on 25-7-2008 at 23:48
Metapurpurate


While looking at an old patent (about which I might make a separate post later on), I found a refence to a compound called "metapurpurate" (by which name apparently the potassium salt of metapurpuric acid is meant.) The author of the patent seems to have experimented with combinations of it and potassium chlorate as a substitute for compressed fulminate blasting caps, which he obviously did not like or trust (the whole point of his patent is in fact to dispense with such blasting caps that rely on compressed fulminate, and instead use mixtures which can be simply packed without compression inside cardboard or metal tubes and detonated by a fuse.)

In any event, I got curious about this "metapurpurate", as I don't recall having heard of it before. A search through books and the Internet has turned up quite little on the subject, though.

Watts mentions the compound and its preparation in his Dictionary of Chemistry, Vol. 4, page 408:

http://books.google.com/books?id=jcIMAAAAYAAJ&pg=PA795&a...

He does not say anything about it being explosive, though.

Thorpe also mentions it in his Dictionary of Applied Chemistry, Vol 4, page 421:

http://books.google.com/books?id=CT63dsYHtG4C&pg=PA421&a...

Again, no reference to it being explosive.

A brief abstract published in the Journal of the Chemical Society (J. Chem. Soc., Abstr., 1904, 86, pp. 574-575) mentions it, as well as ammonium and barium metapurpurate, but again there is no reference to anything explosive about the potassium compound:

http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleFo...

Another brief abstract published in the same journal (J. Chem. Soc., Abstr., 1900, 78, page 645) again mentions the potassium compound:

http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleFo...

This time, however, reference is made to its explosive properties. If heated (suddenly, I suppose) or put in contact with concentrated sulfuric acid, it explodes.

Unfortunately, that's all the information I have been able to gather on this compound so far. Does anyone around here have more information about it? Like, for example, how sensitive to friction and shock is it? Since the chemicals to manufacture it are not easy at all to come by these days (they would have to be manufactured from raw materials, unless you have a permit to freely buy already made potassium cyanide and 2:4-dinitrophenol), before attempting to produce samples it would useful to have more data about it. If it's too sensitive to friction or shock it might not be worth the trouble.
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Axt
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[*] posted on 26-7-2008 at 01:54


Theres another compound derived from picric acid (rather then the dinitro analogue) and presumably more energetic, refered to as potassium isopurpurate.

"Potassium Isopurpurate. C8H2O6N5K, mw 303.24, N 23.10%. Brownish-red crystals; may be prepd by adding slowly, with agitation, a solution of 10g of KCN in 40rnl of H2O to 10g of PA dissolved in 170ml of alcohol. The temperature should be kept below 30°. Stirring is continued for a while after completing the addition of KCN and then the mixture is left to stand. After this, the precipitate is filtered off and crystallized from about 1.5 L of hot water. The salt is fairly sol in w and easily sol in most organic solvents. It is a violent explosive, very sensitive to impact and friction. It puffs off at 215°" PATR vol. 7, I 137.
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[*] posted on 26-7-2008 at 03:48


Quote:
Originally posted by Axt
Theres another compound derived from picric acid (rather then the dinitro analogue) and presumably more energetic, refered to as potassium isopurpurate.

"Potassium Isopurpurate. C8H2O6N5K, mw 303.24, N 23.10%. Brownish-red crystals; may be prepd by adding slowly, with agitation, a solution of 10g of KCN in 40rnl of H2O to 10g of PA dissolved in 170ml of alcohol. The temperature should be kept below 30°. Stirring is continued for a while after completing the addition of KCN and then the mixture is left to stand. After this, the precipitate is filtered off and crystallized from about 1.5 L of hot water. The salt is fairly sol in w and easily sol in most organic solvents. It is a violent explosive, very sensitive to impact and friction. It puffs off at 215°" PATR vol. 7, I 137.


Thanks for the reference. As your source says, though, that one is quite sensitive. After I read the rather "casual" manner in which potassium metapurpurate seems to be handled in the sources I referred to, with no warnings to the reader regarding its potentially explosive decomposition (except in only one paper), I am wondering just how stable is this substance. When a compound is very dangerous to handle, such chemistry books usually make note of it.
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[*] posted on 26-7-2008 at 12:46


I wouldn't read too much into the "very sensitive to impact and friction", compared to what? TNT? I'm not saying it isn't, just that you cant tell much by that.

There may be some enhanced synergy between it and chlorate as well, since it contains reducing as well as oxidising groups.
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[*] posted on 26-7-2008 at 17:41


Downloading from Google is a pain in the ass. For everyones convenience
the references are reproduced here _

Metapurpuric Ref.JPG - 647kB
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