DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
Direct Esterification of Phosphoric Acid
I read some things about this on various websites, of simply reacting a Primary Alcohol with ortho-Phosphoric Acid to obtain Alkyl Phosphates.
Sulfuric Acid is used as a catalyst during the reaction. Basically, the reaction proceeds much the same way as esterification of Carboxylic Acids.
However, I have not found any practical procedures in regard to this. Usually, obtaining Phosphoric Acid esters is done using Phosphorus Trichloride
as the main precursor. This is unfortunate, since Phosphorus Trichloride is so difficult to come by.
At the moment, my "lab" is in pitiful condition. I have plenty of chemicals, but just about no equipment, not even a heat source or scale.
As such, I am very limited in my experiments, and I cannot test this out for myself (I imagine that slight heating may be necessary). So, I am
wondering if anyone else knows a bit about the topic, especially regarding yields by this method.
[Edited on 28-2-2003 by Samosa]
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
Well, since this topic seems to be a bit dead, maybe I should bring something else to the table  .
The reaction would proceed this way ("equation" showing just part of Phosphoric Acid molecule) :
P-OH + R-OH --Drying Agent--> P-O-R + H2O
Correct? Now, am I right to assume that the more powerful the drying agent, the more efficiently the reaction is carried out?
If this is the case, if one were to make Phosphoric Acid Esters, could concentrated, fuming Sulfuric Acid be used to catalyze the reaction? I'm
sure P2O5 would be an even better choice, but that is not easily obtained by everyone.
Also, would about synthesizing Pyrophosphoric Acid? One simple way to make it is to heat Ortho-Phosphoric Acid to some 215*C (I may be wrong, but this
sounds right...). However, such high temperatures are a pain. Could this reaction be done with lower heats if catalyzed with a drying agent, such as
said concentrated Sulfuric Acid?
|
|
|
madscientist
National Hazard
Posts: 962
Registered: 19-5-2002
Location: American Midwest
Member Is Offline
Mood: pyrophoric
|
|
It probably would be possible to yield the dialkyl ester via direct esterification, but not the trialkyl ester; the third hydrogen is not very acidic.
Adding a dessicant likely would help, but also would make it more difficult to separate out the ester from the reaction mixture (depending on what you
used as the dessicant). Use of H<sub>2</sub>SO<sub>4</sub> as a catalyst certainly would be a good idea; heating would also
speed the reaction up.
It shouldn't be hard to heat H<sub>3</sub>PO<sub>4</sub> to around 215C. My heavily damaged $15 hotplate can easily top
300C when standing outside in whipping -20C winds.
I don't think that H<sub>2</sub>SO<sub>4</sub> will be of much help in the dehydration of
H<sub>3</sub>PO<sub>4</sub>. Consider the fact that H<sub>2</sub>SO<sub>4</sub> is dehydrated to
SO<sub>3</sub> by the action of P<sub>4</sub>O<sub>10</sub>. Even if it worked, it really wouldn't be
removing the water from the mixture, as H<sub>2</sub>SO<sub>4</sub> molecules dehydrate simply by coordinating water
molecules around itself. You wouldn't be able to distill out the H<sub>4</sub>P<sub>2</sub>O<sub>7</sub>,
which would circumvent that issue, because it will decompose into HPO<sub>3</sub> rather than boil.
I weep at the sight of flaming acetic anhydride.
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
H3PO4 can be dehydrated by long boiling!
Naturally at 40°C pure H3PO4 turns into H4P2O7
in the amount of arround 6% at equilibrium!
2(HO)3P=O <--> H2O + (HO)2P(O)-O-P(O)(OH)2
You thus have anydride of orthophosphoric acid forming naturally!And heating a little and taking the water off will form more and more anhydride!
The idea would be to heat it under 200°C under reflux with a dehydratant in another compartiment (at the output to force dehydration without any
contamination).
(HO)2P(O)-OH + HO-P(O)(OH)2 <--> H2O + (HO)2P(O)-O-P(O)(OH)2
(HO)2P(O)-O-P(O)(OH)2 + HO-P(O)(OH)2 <--> H2O + (HO)2P(O)-O-P(O)-O-P(O)(OH)2
...
YOU FINALY GET POLYPHOSPHORIC ACID (what is a polyanydride of acid) often used to make certain kind of nitramines aside with conc HNO3!
(HO)2P(O)-O(-P(O)-O-)n-P(O)(OH)2
This natural presence of anhydride in the acid must explain the fast esterification of alcools!
(HO)2P(O)-O-P(O)(OH)2 + 4R-OH -->
(RO)2P(O)-O-P(O)(OR)2 + 4 H2O
(HO)2P(O)-O-P(O)(OH)2 + H2O --> 2 H3PO4
(RO)2P(O)-O-P(O)(OR)2 + ROH --> (RO)3P=O + (RO)2(HO)P=O
Anyway the best way is not to use H2SO4 since in the mix you will not only have:
(RO-)P(OH)2=O, (RO-)2P(OH)=O and (RO-)3P=O
But also RO-S(OH)O2 and (RO-)2SO2 sulfuric esters that favourise the formation of ether R-O-R and alcene R=R if the heat exceeds 170°C!
Lab procedure uses not the PCl5 since reaction is too violent!
PCl5 + 5 HO-R --> P(OR)5 + 5HCl(g)
P(OR)5 --> (RO)3P=O + R-O-R
But Cl3P=O is favourised because more controlable and less risky!
Cl3P=O + 3 R-OH --> (RO)3P=O + 3HCl(g)
  
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
According to that wonderful Phosphorus-Fluorine book that Polverone uploaded, Secondary Alcohols influence an Organophosphate molecule by making more
toxic... Quite a common Secondary Alcohol is Isopropanol.
If I recall correctly, TEPP reacts with the enzyme Cholinesterase by splitting in the center of the molecule, and one half of the TEPP bonds to the
Cholinesterase Molecule. Therefore, you have Diethyl Phosphate bonded to the Enzyme...
Also, if I recall correctly, Ethyl-Phosphates are degraded quickly in the body, thus making their effects somewhat short-lived. On the other hand,
Isopropyl-Phosphates last rather long in the body...
Where is this all leading? I theorize that the compound Tetra-Isopropyl Pyrophosphate will be a cheap, easily manufactured compound, with toxicity
comparable to DFP. When this theoretical molecule (Which I cannot find any information on; perhaps I'm not searching properly) reacts with
Cholinesterase, Diisopropyl Phosphate will be what bonds do it... This is similar to when DFP reacts with Cholinesterase, and the F reacts with the OH
in Cholinesterase, forming HF and Diisopropyl Phosphate bonded to Cholinesterase.
I do not expect a Phosphate molecule to be as reactive as straight Fluorine, but that is why I said the toxicity would be "comparable" to
DFP . Does my reasoning seem sound?
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
To get a potent nerve gas...you need it volatilised!
Pyrophospahte ester will be rater less volatile than phosphoric ester!
The fluoro part also enhance volatility, while the ester link increase molecular attraction!
PH Z
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
I imagine that the problem of volatility could easily be solved through suitable weaponization and dispersal, so that should not be much of a
concern...
Other than that, though, the big problem with Pyrophosphate Esters is that they like to hydrolyze...but last I checked, it takes about 12 hours for
TEPP to hydrolyze completely.
The big advantage I see with Pyrophosphates over Phosphate Esters is that they are significantly cheaper to manufacture, thus allowing much more
experimentation. Furthermore, their precursors are not watched at all (Who is going to watch Rust Remover and Rubbing Alcohol? ).
Also, if I recall correctly, Pyrophosphate Esters are more of a hazard through skin contact... I may be wrong.
But, just assuming that everything goes well and enters the test subject's body...How do you expect "Tetra-Isopropyl Pyrophosphate" to
react with Cholinesterase? Would you imagine it being as I said?
|
|
|
Polverone
Now celebrating 21 years of madness
Posts: 3186
Registered: 19-5-2002
Location: The Sunny Pacific Northwest
Member Is Offline
Mood: Waiting for spring
|
|
tsk tsk
What is this "weaponization" you speak of? This isn't Amateur Night at Edgewood Arsenal.
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
Hehe, sorry mate... still used to the E&W ways .
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
I was thinking... would HF react with Phosphoric Acid?
I was imagining that the Fluorine would displace the OH group, which would then react with Hydrogen to form water...sort of like a reaction between
an Acid and a Base. The reason I was thinking this is because Fluorine is far more reactive than Oxygen, and as such would displace the Oxygen rather
than simply displace the Hydrogen.
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
To my knowledge the F is important to get a very toxic stuff; thus the normal ester (pyrophosphate of phosphate will be much less toxics except maybe
via injection!).
The fact secundary alcohols enhance stability towards hydrolysis is due to steric hindrance...it should be even better with tertiary alcohols.
About the toxicity:
Methyl = isoproply > ethyl is always true for all organics...our body have developped a certain resistance towards ethyl moiety!
Maybe the toxicity is increased in this case owing to electrogiving effect of the alkylic part; but I doubt it since they are esters and the oxygen
(separating R from P) stops that effect quite fast.
Samosa:
If:
F2 + H2 --> HF + hell lot of energy
It reacts explosively at -200°C!
and if
F2 + O2 is stable mix and slowly turns via HOF into stable F2O.
O2 + HF is stable and gives nothing!
HF + HO-R gives no R-F
HF + HO-NO2 gives nothing!
F2 + HO-NO2 --> HF + FO-NO2
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
"F2 + O2 is stable mix and * slowly turns via HOF into stable F2O."
I forgot this:
* water
F2 + H2O --> HOF + HF
HOF + F2 --> F2O + HF
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
Tetra-Isopropyl Pyrophosphate to Diisopropyl Fluorophosphate?
Back on the idea of Tetra-Isopropyl Pyrophosphate...
Would it be possible to convert it to Diisopropyl Fluorophosphate (DFP) through a reaction with Hydrofluoric Acid? I am theorizing it would proceed
as follows...
[B](Iso)P=O(Iso)-O-(Iso)P=O(Iso) + HF --> (Iso)P=O(Iso)-F + HO-(Iso)P=O(Iso) [B]
I'm guessing it would work similarly to the Fluorination step in many Organophosphates, where HF is reacted with a Chlorophosphate to produce
Hydrochloric Acid and the Fluorophosphate. However, in place of the Chlorophosphate, here we have the Diisopropyl Phosphate . Basically, a reaction where a more reactive ion replaces a less reactive ion.
|
|
|
Iv4
Hazard to Others
Posts: 312
Registered: 28-5-2003
Member Is Offline
Mood: No Mood
|
|
It could work but I think flourinating the phosphorous before should be better(drunk and probably wont remember any of this).
Diispropylphosphono-sulfer(real drunk)is probably worth looking into.My guess is that this could be done readely from polysulfides.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
