I2

[Dragan]

If swim do rp/I2/e reflux.He often have rp and I2 left in his rxn fluid.wouldn't RP reduce the access of I2.

[geezmeister]

The I2 is not consumed by the reaction. It is all still there in the flask. You can recover most of it.

[fierceness]

Yea, but if you have a lot of I2 and RP left in the post reaction fluid, you most likely did not have a successful reaction.  Assuming you have enough water, either your I2 or RP sucks, or you didn't get it hot enough.

Make sure you clean your post rxn fluid with toluene to get rid of the I2.

[geezmeister]

Free iodine is not a problem in the post reaction workup. You base the reaction fluid heavily enough to turn any free iodine present into sodium iodide, from which the iodine can be recovered after extracting the meth.

[Organikum]

Huh?
RP reacts with iodine to HI, there should be no I2 AND RP together present or something is wrong. Probably what you think to be RP is no RP but scrap or it is covered with scrap and unreactive. In the latter case one might try to add finely crushed glass to the reaction and to stirr/swirl from time to time.

At the end of the reaction whilst adding the base, the NaOH reacts with the remaining HI to form NaI not with I2.

Try the crushed glass. It rips the gakk from the RP and voila!

[fierceness]

Huh?
RP reacts with iodine to HI, there should be no I2 AND RP together present or something is wrong

^^^^ what i was trying to say.  If the ratios were right, and your reagents were good, you should not have RP and I2 together because they form HI.  Small amounts may be possible, since the reaction occurs on the surface of the solid molecules, but a large amount usually indicates failure.

[WizardX]

If the ratios were right, and your reagents were good, you should not have RP and I2 together because they form HI.

P + I2 will synthesis PI3 if NO WATER is present. PI3 will react with water quantitatively to make HI

I2 will form due to dissociation (2HI ==> H2 + I2) during heating (refluxing) of 47-57% HI solution.

[Organikum]

WizardX, thus is wrong:

I2 will form due to dissociation (2HI ==> H2 + I2) during heating (refluxing) of 47-57% HI solution.

Dissoziation wont form H2 and I2 but it forms the correspondending H and I ions. The HI partially decomposes to I2 and H2 whilst heating (just heat, no refluxing necessary) by oxygen present in the air and dissolved in the water. Thats one reason why the use of a baloon is so favorable - it hinders further air (oxygen) entering the flask.

[geezmeister]

If there is no I2 in the post reaction mixture, why bother with nonpolar washes to remove it? Why boil the mix to rid the solution of it? Why use sodium thiosulfate? Why will a nonpolar solvent contain iodine if you wash the reaction fluid with it? why will it stain you fingers just like I2 crystals will? Why will the coloration disappear with a NaOH wash? Some I2 is available at any given moment in a PIE reaction, at least if it is proceeding properly. The iodine is being reformed and reconverted to HI. some iodine should be available in that reaction at any given moment. I never expect to see crystals form, given the acidic nature of the reaction and the presence of some active phosphorous compounds.  If you use red phosphorous or phosphorous acid in molar ratios or just above them, Once the feedstock has been completely reduced, you should have iodine in the reaction that has no phosphorous acid or red phosphorous in the flask to recycle it to HI. It will remain iodine. Use an excess of red phosphorous and this won't happen. Use only phosphorous acid in a molar amount and when the reaction completes you should have iodine present as the phos acid is used up and oxidized in the reaction.

I have noted in particular in phosphorous acid reactions which were very complete and gave high yields of good quality methamphetamine that the reaction fluid itself would readily impart an iodine stain until based. I took this as a sign of the reaction's completeness in an off hand way, as it at least signalled that the phosphorous acid was no longer present to recycle the iodine. That could be the result of oxidization, or of complete reduction using up the phosphorous acid I added for recycling.

Perhaps I am wrong, but these observations suggest to me that one should expect some I2 present in a PIE reaction after it completes. Am I that far wrong?

[Organikum]

Use an excess of red phosphorous and this won't happen

And thats the point. The question was asked on a reaction done with excess RP - enough that there is some left unreacted after the reaction. And as you write Geez, if done this way there should be no iodine in the post reaction mix, agreed?

[geezmeister]

You are quite correct, and with such excess you will have a reaction from which one should distill the HI before basing, most likely.

[fierceness]

If there is no I2 in the post reaction mixture, why bother with nonpolar washes to remove it? Why boil the mix to rid the solution of it? Why use sodium thiosulfate? Why will a nonpolar solvent contain iodine if you wash the reaction fluid with it? why will it stain you fingers just like I2 crystals will? Why will the coloration disappear with a NaOH wash? Some I2 is available at any given moment in a PIE reaction, at least if it is proceeding properly. The iodine is being reformed and reconverted to HI. some iodine should be available in that reaction at any given moment. I never expect to see crystals form, given the acidic nature of the reaction and the presence of some active phosphorous compounds.

We do a nonpolar wash to get rid of I2 because the reaction between RP and I2 occurs at the surface of the RP molecule.  This is not an (aq) reaction since I2 is practically insoluble in water and so is RP. 

Basically all i'm saying is that if there is a LARGE amount of I2 and RP present after the reaction, you most likely have a failed synth.  Expect some, of course, especially if you used an excess of I2 and/or a short reaction period.

[Osmium]

> We do a nonpolar wash to get rid of I2

WRONG! SHEESH!
We do a NP wash to get rid of organic side products of this reaction! How often do we need to repeat this?! The I2 would be taken care of during basification anyway, since no known halogen survives contact with aq. NaOH. The NP wash is done to remove the smelly, toxic organic shit that is produced!

> because the reaction between RP and I2 occurs at the surface of
> the RP molecule.

Correct.

> This is not an (aq) reaction since I2 is practically insoluble in
> water and so is RP.

Wrong again. I3(-) is soluble in water, much more than I2 is.

[WizardX]

http://www.jtbaker.com/msds/englishhtml/h3728.htm

10. Stability and Reactivity
Stability:
Stable under ordinary conditions of use and storage. Darkens on exposure to air or light.
Hazardous Decomposition Products:
Burning may produce toxic iodine vapors. heat (thermal dissociation/decomposition)
Hazardous Polymerization:
Will not occur.
Incompatibilities:
Strong oxidizers, alkalis, fluorine, potassium, nitric acid, some metals, water, and steam. Attacks natural rubber.
Conditions to Avoid:
Light (photodissociation/decomposition), heat (thermal dissociation/decomposition), incompatibles.

http://cc.pima.edu/classes/chm080/nomen1.htm

When solid ionic compounds separate into ions in a water solution, they are said to Dissociate. Many ionic solids dissociate in water. Also, compounds that aren't primarily ionic in nature form ions in solution. For example, HCl (Hydrochloric Acid).

This is the way chemists say, "HCl gas separates into Hydrogen ions and Chloride ions in water". When molecular compounds separate into ions in solution, it is called Ionization.) Notice the difference in electronegativity is only 0.9 so the bond is classed as mostly covalent. (there is some confusion here about the terms Dissociation and Ionization. Sometimes all of these processes that lead to ion formation in solution are called dissociation. Technically, only those solids that were already ionically bonded are said to dissociate).

Theory of electronic branching in the photodissociation of HI and DI

http://content.aip.org/JCPSA6/v89/i5/2900_1.html