MrSamosa
August 13th, 2003, 02:03 PM
Well, seeing as regular Orthophosphoric Acid is not going to be a suitable Nerve Agent precursor on its own, I've researched it's uses in making other variants of Phosphoric Acid, and the use of these variants as precursors for Nerve Agents. Pyrophosphoric Acid is a great example, and can easily be prepared by heating Phosphoric Acid to 217*C (correct me if I'm wrong on the temperature). However, the two variants of Phosphoric Acid that have interested me the most are Hypophosphoric Acid (Phosphonic Acid) and Metaphosphoric Acid (Phosphorous Acid). Both of these compounds have uses in the synthesis of pesticides.
Hypophosphoric Acid has the following structure: O=PH2(OH). As you see, there is one "acidic" Hydrogen while the other two are bonded directly to the Phosphorus. I imagine that the acidic Hydrogen- the one bonded to the Oxygen- could easily be replaced by an alkyl group by a reaction between an Alkyl Iodide and the Silver Salt of the Acid, or perhaps by a reaction between Dimethyl Sulfate (which has proven itself a very strong methylating agent) should you want to insert a Methyl group there (as for Sarin or Soman).
Metaphosphoric Acid has the structure: O=PH(OH2). There are two "acidic" Hydrogens and just one bonded directly to the Phosphorus atom. I see this is a potential precursor for Dialkyl Halophosphates, such as DFP. The esterification of the acid doesn't seem too difficult...according to Polverone's book "Some Aspects of the Toxicity of Compounds Containing Fluorine and Phosphorus" (did I get this title right?), there seem to be a few "generic" reactions to esterify Phosphoric Acids. So, in line with that, once again we could use the Silver salt of the Acid and Methyl Iodide.
However, the key to making an effective Nerve Agent is the leaving group... And this is where a big question comes in: Would it be possible to substitute the non-acidic Hydrogens in these acids with a more reactive group, such as -CN, -Cl, or -F ??
Then again, the goal with using Hypo- or Metaphosphoric Acid as precursors may simply be to find an alternative to Phosphorus Trichloride/Oxychloride. I see them mostly for this use...the conventional synthesis for the Nerve Agents would remain the same, but we would find an alternative to PCl3 :D.
Another concern is obtaining these acids. On the "Household Products Database," they stated that Metaphosphoric (Phosphorous) Acid is used in some limescale/metal removers in Garden/Pool stores... However, it is mixed with a few other acids, including Hydrofluoric Acid.
Alternately, would it be possible to reduce Orthophosphoric Acid into these variants? I know it is possible to reduce H3PO4 to pure Phosphorus, as I have read about several times. But, could we somehow "stop" this reaction, so instead of pure Phosphorus, we get H3PO3 or H3PO2 ??
Hypophosphoric Acid has the following structure: O=PH2(OH). As you see, there is one "acidic" Hydrogen while the other two are bonded directly to the Phosphorus. I imagine that the acidic Hydrogen- the one bonded to the Oxygen- could easily be replaced by an alkyl group by a reaction between an Alkyl Iodide and the Silver Salt of the Acid, or perhaps by a reaction between Dimethyl Sulfate (which has proven itself a very strong methylating agent) should you want to insert a Methyl group there (as for Sarin or Soman).
Metaphosphoric Acid has the structure: O=PH(OH2). There are two "acidic" Hydrogens and just one bonded directly to the Phosphorus atom. I see this is a potential precursor for Dialkyl Halophosphates, such as DFP. The esterification of the acid doesn't seem too difficult...according to Polverone's book "Some Aspects of the Toxicity of Compounds Containing Fluorine and Phosphorus" (did I get this title right?), there seem to be a few "generic" reactions to esterify Phosphoric Acids. So, in line with that, once again we could use the Silver salt of the Acid and Methyl Iodide.
However, the key to making an effective Nerve Agent is the leaving group... And this is where a big question comes in: Would it be possible to substitute the non-acidic Hydrogens in these acids with a more reactive group, such as -CN, -Cl, or -F ??
Then again, the goal with using Hypo- or Metaphosphoric Acid as precursors may simply be to find an alternative to Phosphorus Trichloride/Oxychloride. I see them mostly for this use...the conventional synthesis for the Nerve Agents would remain the same, but we would find an alternative to PCl3 :D.
Another concern is obtaining these acids. On the "Household Products Database," they stated that Metaphosphoric (Phosphorous) Acid is used in some limescale/metal removers in Garden/Pool stores... However, it is mixed with a few other acids, including Hydrofluoric Acid.
Alternately, would it be possible to reduce Orthophosphoric Acid into these variants? I know it is possible to reduce H3PO4 to pure Phosphorus, as I have read about several times. But, could we somehow "stop" this reaction, so instead of pure Phosphorus, we get H3PO3 or H3PO2 ??