hypophosphoric convertion - Powered by XMB 1.9.11

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Author: Subject: hypophosphoric convertion hypophosphoric convertion


Can phosphoric acid be converted into hypophosphoric -and if so how?

No.

There are several oxyacids of phosphorus. I think the useful ones are phosphorous acid and hypophosphorous acid (phosphinic acid). You can make the acid from the phosphite salt, used as a foliar fertilizer.

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solo

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Mood: ....getting old and drowning in a sea of knowledge International HazardPosts: 3967Registered: 9-12-2002Location: Estados Unidos de La Republica MexicanaMember Is Offline....getting old and drowning in a sea of knowledge
posted on 25-12-2004 at 17:21

This is the synthesis of the hypophosphorous acid, you will see that the acid you want to use is nowhere in the method involved.....solo

HYPOPHOSPHOROUS ACID
[6303-21-5]
Formula: H3PO2; MW 65.997
Structure: H
|
H—P—OH
||
O
Synonym: phosphinic acid
Uses
Hypophosphorous acid is used to prepare hypophosphite salts and in electroplating
baths.
Physical Properties
Colorless deliquescent crystals or oily liquid; sour odor; density 1.493 g/cm3;
melts at 26.5°C; boils at 130°C; very soluble in water, alcohol and ether; density
of a 50% aqueous solution is 1.13 g/mL.
Thermochemical Properties
?Hf° (cry) –144,50 kcal/mol
?Hf° (liq) –142.30 kcal/mol
?Hfus 2.32 kcal/mol
Preparation
Hypophosphorous acid may be prepared by various methods:
1. Boiling white phosphorus with calcium hydroxide:
P4 + 4Ca(OH)2 + 8H2O ? 4Ca(H2PO2)2 + 4H2
The calcium salt is soluble in water. Treatment with sulfuric acid yields the
hypophosphorous acid:
(H2PO2)2Ca + H2SO4 ? 2H3PO2 + CaSO4
The product mixture is filtered to remove insoluble CaSO4. The aqueous solution
of hypophosphorous acid is concentrated under reduced pressure.
Concentrated baryta water may be used instead of calcium hydroxide.
2. By treating sodium hypophosphite, NaH2PO2 with an ion-exchange resin.
The sodium salt may be produced by boiling white phosphorus with a solution
of sodium hydroxide, a reaction similar to (1) above.

3. By oxidation of phosphine with an aqueous iodine solution: PH3 + 2I2 + 2H2O ? H3PO2 + 4HI The above method may be considered safer than that involving heating white phosphorus with an alkali. Hypophosphorous acid must be stored below 50°C. It is sold commercially as an aqueous solution at various concentrations. Reactions Pure hypophosphorous acid is a monobasic acid, pKa=1.2. It reacts withbases forming the corresponding salts: H3PO2 + NaOH ? NaH2PO2 + H2O It decomposes rapidly on heating above 100°C to orthophosphoric acid and phosphine: 100o C2H3PO2 ??? H3PO4 + PH3? The phosphorus atom in hypophosphorus acid is in the lowest oxidation state,+1. The compound is, therefore, a powerful reducing agent. It combines readily
and often explosively with oxidizing agents. For example, the acid reduces mercury(II) nitrate or mercury(II) oxide into mercury metal violently. Analysis Elemental composition: H 4.58%, P 46.94%, O 48.49%. The hypophosphite ion may be oxidized to orthophosphate by careful oxidation. The orthophophate, PO43¯ ion, may be measured by colorimetry either by using ammonium molybdate and vanadium (yellow color), ammonium molybdate and stannous chloride (blue color), or ammonium molybdate, potassium antimonyl tartrate and asorbic acid (an intense blue color). Absorbances of the solution are read at 400 (or 470), 650 (or 690) and 880 nm, respectively. Hypophosphite ion alternatively may be identified by ion chromatography. Hazard The compound is a very powerful reducing agent. Reactions with oxidizing agents may progress to explosive violence (See Reactions). Also, heating this compound above 100°C can produce toxic phosphine, which also may explode in air.

....as read in Handbook of Inorganic Chemicals
Pradyot Patnaik, Ph.D.

[Edited on 26-12-2004 by solo]

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@white shirt/black tie (previous username: white shrit/black tie, probably changed because of spelling error ): You seem to have much interest in phosphorus, what plans do you have for it? I'm just curious

\"It is dangerous to be right, when your government is wrong.\" - Voltaire

As stated above, Hypophosphorus Acid can be synthesised from Elemental Phosporus (aka White Phos) but still this leaves me wondering... Is it possible to get rid of that annoying double bonded oxygen in phosphoric acid (H3PO4) to form Phosphorus acid (H3PO3)?

Any help would be greatly appreciated

Would it be possible to roast with carbon, or would that only go right to P as is industrial process?

Tim




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Seven Transistor Labs LLC http://seventransistorlabs.com/ Electronic Design, from Concept to Layout.Need engineering assistance? Drop me a message!

Although the phosphate anion is reluctant to be reduced I am sure there is some combination of dry phosphate and a reducing agent such as a metal powder that could be taken advantage of that, upon heating, would give appreciable amounts of the reduced anion, vaguely smiliar to the methods to make nitrite from nitrate using lead as the reducing agent. The key of course finding the best combination of reactants and in doing so determining the relative amounts of your desired product being produced. Separation would be somewhat easy, if for example zinc or aluminum used then dissolution in water, basification to give the precipiated hydroxide followed by filtering, leaving you with the salt of whatever salt you origionally threw in the mix.

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So there is no patented writeups related to this topic it would be shear exerimental chemistry at it's finest? Handbook of inorganic chemicals available for download !


Quote:Originally posted by solo 26-12-2004
....as read in Handbook of Inorganic Chemicals
Pradyot Patnaik, Ph.D.

Handbook of inorganic chemicals available for download !.

Patnaik P. Handbook of inorganic chemicals (3.72 mb)
http://rapidshare.de/files/2487499/Patnaik_P._Handbook_of_in...
Quote:All good things come to those who wait patiently.

Hmm interesting read... Was reading with Carbon and alot of heat you can take Phosphoric acid back to "Elemental Phosphorus" (As stated by Tim above) for which you could synth either Hypo or Ortho Phosphorus Acid... I didn't really want to have t