Author Topic: Final Word on the HI/RP Mechanism  (Read 8843 times)

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Rhodium

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Final Word on the HI/RP Mechanism
« on: November 04, 2003, 05:47:00 PM »
Regenerative role of the red phosphorus in the couple 'Hydriodic Acid-Red Phosphorus'

J. Organomet. Chem. 529, 295-299 (1997)

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/hi-rp.mechanism.html)


halfkast

  • Guest
whoa would you look at that thats so ...
« Reply #1 on: November 04, 2003, 10:32:00 PM »
whoa would you look at that
thats so beautiful, I'm pretty sure I don't have the mind at present to appreciate it and the rationale fully.

but I do know it's beautiful and something special.

wow again.

you must bee happy with that Rh, you don't come across as someone who likes uncertainties. So have you learnt anything from this reference for yourself or is it confirming your past beliefs?

WizardX are you going to make this your wallpaper for a while?

it's a beauty. :o


WizardX

  • Guest
catalytic cycle
« Reply #2 on: November 05, 2003, 02:30:00 AM »
I disagree with the term, "catalytic cycle".

Osmium

  • Guest
Funny, no PH3 mentioned on the left, ...
« Reply #3 on: November 05, 2003, 03:17:00 AM »
Funny, no PH3 mentioned on the left, "wet" scheme.


Rhodium

  • Guest
Doesn't the catalytic cycles look like flowers?
« Reply #4 on: November 05, 2003, 05:33:00 AM »
I disagree with the term, "catalytic cycle".

Why? It is certainly a cycle for the production of hydrogen and phosphoric acid from red P and water, the cycle being catalytic in iodine.

you must bee happy with that Rh, you don't come across as someone who likes uncertainties. So have you learnt anything from this reference for yourself or is it confirming your past beliefs?

Yes, I'm very happy with finding this article, as finally I have hard data to point to whenever someone posts any misinformation again, as well as the article itself being full of useful things.

New things I've learned myself is that formation of toxic phosphine gas is unavoidable when insufficient water is present (and as phosphine self-ignites in air, this is thus the culprit of all "flask fires"), and that P2I4 can be an intermediate, rather than PI3.

BOS

  • Guest
Thats lovely and all,But what kind of pretty...
« Reply #5 on: November 05, 2003, 09:50:00 PM »
Thats lovely and all,But what kind of pretty paterns does one
get when ephedrine is bought into the equation?
What bearing would this have on how one would determine if someone is presenting misinformation ,following this scheme?

mr_pyrex

  • Guest
Well I would like to say THANKS as well, cause
« Reply #6 on: November 05, 2003, 11:53:00 PM »
Well I would like to say THANKS as well, cause it was just the last weekend I was sitting around rehashing old theories and ideas and trying to figure out the exact way by which the "dry setup" or push/pull runs its course.  Reason being is I was reading the posts from back around January or at least a recent link you had in a post that referred back to when you discussed using Phosphorus Acid in place of Red and using HI instead of using the push/pull setup and was trying to figure out if there might be a benefit in doing a push/pull setup with a condensor on top of the reaction vessel and then the push/pull setup coming off the condensor.  Reason is I figured that if push pull works good even when it is slowly but progressively dumping the HI into the tanks wouldn't it be a good idea to keep the continually being made, high concentration HI in the pot and thereby maybe have it run more efficiently and end up with a better end product.  I haven't figured out exactly the details yet but will be in the near future...and once again thanks for the very useful info Rhodium.  Pyrex out of theories


WizardX

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Re: Red Phosphorus involvement in a catalytic...
« Reply #7 on: November 06, 2003, 01:39:00 AM »

Red Phosphorus involvement in a catalytic cycle for the generation of hydriodic acid in ...




This can be interpreted that Red Phosphorus has a catalyst mechanism.

It would be better if it was written maybe like this.


Red Phosphorus involvement in a reactant cycle for the generation of hydriodic acid in ...




An iodide ion I- acts as a catalyst on the catalytic decomposition of H2O2.

H2O2 ==[ I- ]==> H2O + 1/2 O2


Rhodium

  • Guest
HI as a reducing agent
« Reply #8 on: November 06, 2003, 03:23:00 AM »
BOS: Very simplistic, one could say that the hydrogen (H2) given off in the above depicted cycle reacts with (pseudo)ephedrine forming methamphetamine and water.

More detailed:

1. (pseudo)Ephedrine + HI -> Iodoephedrine + H2O
2. Iodoephedrine + HI -> Methamphetamine + I2

Overall: (pseudo)Ephedrine + 2 HI -> Methamphetamine + I2 + H2O

Osmium

  • Guest
> Very simplistic, one could say that the...
« Reply #9 on: November 06, 2003, 05:37:00 AM »
> Very simplistic, one could say that the hydrogen (H2) given off in the above
> depicted cycle reacts with (pseudo)ephedrine forming methamphetamine and water.

That's of course VERY simplistic, since bubbling H2 through a pseudo or ephedrine solution will of course NOT produce meth. Just thought I'd say that before someone starts a new urban legend.


bloosh

  • Guest
i can totally relate to you on this!
« Reply #10 on: November 07, 2003, 05:39:00 AM »

BOS

  • Guest
Sure,But doesnt such a simplification follow...
« Reply #11 on: November 09, 2003, 08:14:00 PM »
Sure,But doesnt such a simplification follow along the lines of RP + I + H20 = HI?
And nothing else realy matters?

I find it hard to accept that all of these rxns can occur
and yet only the H and the I from the formed HI have any bearing on what happens to the ephedrine e.g forming the intermediate iodo-compounds and then the reduction itself.
If this was the case, what would be the reasoning behind such a sluggish,low yielding rxn when a only massive excess of premade HI is used (no regenerative agent) as aposed to it being formed in situ?

Are we now saying that the wet rxn and the dry rxn both
follow the same mechanism in regards to reducing ephedrine
e.g follow your statement above?
If so,what makes one better then the other,seeing as it is only a matter of HI production that counts,and that by accounting for enough reactants ,both schemes will produce HI and a full reduction should occur no matter what.

I see no mention of PI3,no mention of iodic or periodic acids and many other inorganic by-products or side rxns which I have read about in relation to these rxns.

Why do we have to accept such a simplistic version of events when it comes to using these schemes in a reduction.

I have no problem with what your find tells us,but to me it merely points out an order of rxns which have been common knowledge all along.
I feel the real issue is how such proceedings,effect the rate/degree/by-products of the halogenation and reduction of organic compounds,and that the simplistic reasoning you have used above with the old HI + Ephedrine = Water and meth quote, is how the abundance of misinformation/misinterpritation has come about.

It is obviously not so simple is it?

Rhod` Im sorry if I sound belligerent.
I dont want to seem like I know the answers.
It just frustrates me so much, when I have personally sought
a simple explination for the myriad of different results we encounter when talking about this rxn, and all I ever seem to get back is this simplification, which would be lovely if it was so simple(I simply dump my ephedrine in a bucket of hydriodic acid and be done ;) ),but if translated to real world findings leaves a whole lot more blanks than the reasoning behind the regenerative role of Phosphorus in HI production could ever dream of leaving.

Surely you have a paper or simular,depicting these rxns in as much detail as the one above.This would be nice.
All the lit` I have scanned pretty much pumps out the same chemical equations and leavs it at that.


End rant.

Rhodium

  • Guest
The current state of the art model
« Reply #12 on: November 11, 2003, 01:50:00 AM »
If this was the case, what would be the reasoning behind such a sluggish,low yielding rxn when a only massive excess of premade HI is used (no regenerative agent) as aposed to it being formed in situ?

How massive an excess of HI has been tested under controlled conditions?

The concentration is very important, if the HI concentration drops below 50% the reaction grinds to a halt (ref:

Post 344019 (missing)

(foxy2: "US Pat 5516960", Stimulants)
), and it is easily extrapolated that the higher the concentration, the faster the reaction (up to a certain point, where byproducts may form instead, due to elimination/hydrolysis to form P2P, followed by a cascade of other reactions, see the links below).

If so,what makes one better then the other,seeing as it is only a matter of HI production that counts,and that by accounting for enough reactants ,both schemes will produce HI and a full reduction should occur no matter what.

A very important factor is temperature control. Without acetic acid, water or toluene as solvent, localized hot-spots may easily form and high temp leads to byproduct formation.

Why do we have to accept such a simplistic version of events when it comes to using these schemes in a reduction.

Because beyond this, we lack hard facts and we have only idle speculation without proofs. Also, this model explains the majority of observed events pretty good, and at the moment there is no competing model.

I have no problem with what your find tells us,but to me it merely points out an order of rxns which have been common knowledge all along.

By those in the know, yes, but many people have also been refusing to accept even this simple theory, for example by claiming that RP is a catalyst rather than a reactant.

I feel the real issue is how such proceedings,effect the rate/degree/by-products of the halogenation and reduction of organic compounds

That is also a very important aspect of the reaction when applied to real-world reductions. That is however discussed in other articles, and is not the main topic of the article I posted, which is mainly focused on the interaction of Iodine, Hydriodic acid and phosphorous-based regeneration agents.

Suggested reading:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/meth.hi-p.impurities.html


https://www.thevespiary.org/rhodium/Rhodium/chemistry/meth.forensic.html


https://www.thevespiary.org/rhodium/Rhodium/chemistry/phenylacetone.html#ephedrine


Chewbacca

  • Guest
H2
« Reply #13 on: November 11, 2003, 03:21:00 AM »
"the hydrogen (H2) given off in the above depicted cycle reacts with (pseudo)ephedrine forming methamphetamine and water"

"bubbling H2 through a pseudo or ephedrine solution will of course NOT produce meth"

why is it that the H2 produced from the reaction b/w I2 and P4 in the HI reaction mechanism will reduce (pseudo)ephedrine to methamphetamine whilst exposing the same (pseudo)ephedrine to the same H2 molecules will not? is it that the (pseudo)ephedrine must be converted to an iodo intermediate before the H2 will reduce it?


Rhodium

  • Guest
It's an illustrative simplification
« Reply #14 on: November 11, 2003, 04:35:00 AM »
why is it that the H2 produced from the reaction b/w I2 and P4 in the HI reaction mechanism will reduce (pseudo)ephedrine to methamphetamine whilst exposing the same (pseudo)ephedrine to the same H2 molecules will not?

The H2 shown in the mechanistic schemes above is only evolved as hydrogen gas at higher temperatures without any reducible substrate present (like iodoephedrine). When there is, the mechanism is slightly different, the HI and iodoephedrine more or less reacting directly with each other (possibly by a radical mechanism) forming I2 and methamphetamine.

Therefore, the H2 is not to be taken literally, but rather seen as an entity available for reducing a substrate (this is obvious if you bother to read the entire article).

Organikum

  • Guest
read this!
« Reply #15 on: November 12, 2003, 08:42:00 AM »
"impurities through higher HI concentrations" - thats nowhere in the references and plain nonsense.
Impurities by free I2 - yes.


The whole thread is just not on the point as it answers no open questions on the reaction. WHY must the concentration be higher as XXX? (the answer is in the hydrates of HI -> Gmelin) Why takes HI so much longer as PI3 to halogenate a benyzlic alcohol? (HI halogenation is reversible - a equilibrium forms similar to esterifications -> Gattermann Wieland).

The industry in the old times used fuming HI plus some phosphorus in pressure vessels. They did this for sure not to maximise byproducts and impurities.

Fuming HI and pressure vessels are not appropriate now and here.

But in the days of safrole bromination Uncle Fester presented a way how to make 48%HBr aqueous work. By dehydrating the HBr with HCl-gas bubbled into the reaction. (confirmed by Ritter)
This works perfect with HI also.
(confirmed by me)
Dehydrate the HI by HCl - fast and complete iodination takes place - the reduction is cake, this is well known. HI reduces iodoephedrine quick and complete in (almost)any concentration. The reduction is well known to be far predominant.(Skinner)


hey, some real answers and an advice how to bring this to real world!




I accept any rating except the insulting "Good Idea"
delete the post instead.

ORG


PS: the ratios from the synths from Rhodiums page where the authors boast with 100% yield PRODUCE ALL AN HI SPITTING VOLCANO! Read it. Try it. Enjoy.


Rhodium

  • Guest
Side-reactions depends on the substrate
« Reply #16 on: November 13, 2003, 07:19:00 AM »
"impurities through higher HI concentrations" - thats nowhere in the references and plain nonsense.

It is because that article did not deal with vicinal amino alcohols as substrates. My references are these:

Acid Hydrolysis of Ephedrine Derivatives to P2P

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/phenylacetone.html#ephedrine)

Profiling of impurities in illicit methamphetamine by HPLC

(https://www.thevespiary.org/rhodium/Rhodium/pdf/meth.impurity.profiling.pdf)

Investigations of the Impurities Found in Methamphetamine Synthesized from Pseudoephedrine by Reduction with Hydriodic Acid and Red Phosphorus

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/meth.hi-p.impurities.html)

Impurities by free I2 - yes.

Refs please (out of interest, not disbelief).

The industry in the old times used fuming HI plus some phosphorus in pressure vessels.

For the reduction of vicinal amino alcohols?

the ratios from the synths from Rhodiums page where the authors boast with 100% yield PRODUCE ALL AN HI SPITTING VOLCANO! Read it. Try it.

Could you specify where this is written so that I can re-evaluate it? This synth will never be quantitative.

Organikum

  • Guest
and no word on the HCl dehydration of HI? Phhhh...
« Reply #17 on: November 18, 2003, 06:57:00 AM »
Old days industry reduced with fuming pressurized HI everything with a HO group and most with an oxygene including ether cleavage.
Was for some time the universal hammer of some kind....

By dehydrating the HI with HCl-gas, the HI can be hold in a hydrated stage of the 1,71 density acid or preferable slightly above this point (this would be nearly fuming so no HCl would fume anyways) with ease and almost only HCl will escape. Temperatures may as low as 50°C to 60°C (so in advance prepared HI is used) the HCl also provides the agitation. Reaction time 4 to 6 hours. Yields up to quantitative.
This say I.
 
Are ya all blind methcooks or has Geezmeister first to certify this in not less than 4000 words? (hey Geez, peace, a joke a joke this is!)

Rhodium the ratios I refered to by the fuming volcano werer taken from the two H3PO2 pdfs on your page (from memory: 4mmol substrate, 4mmol iodine, called catalyst, shit, 16 or more mol 50percnt H3PO2 all in GAA - 100percent yield - ho! try! fumes! and not only a lil fuming - no.)

I am still onlinecrippeled, I beg for excuse not to link this stuff.
I will reread the refs posted by you Rhodium but I stand to my post before in principle. Of course can you get overreduction by fuming 1,96 density HI pressurized at high temps for example.
You can also lower temperatures and stop after 10minutes.
The time factor was important in those days long gone as such a fast reaction made it possible to run one complete reaction including prep and workup on one working-day 12 to 14 hours.
Not being pressed by such economic forces the pressure may stay history as HCl dehydration does the same in just a lil. more time.

REMARK:
if you are new to chemical engineering - I talk engineering not chemistry - dont think on using density 1,96 fuming HI under pressure. First you wont be able to prepare it and second you will hurt - hopefully yourself and nobody else.
No, thats not exactly what a pressurecooker was made for.


Hey Rhodium! Dont get dogmatic in your young days already, there is enough time left when you get older!
Realy, you want: low temperature, high HI concentration and aa not to long reaction time over all.
The last simply, because if I heat almost any organic compound long enough in the presence of strong HI I will get some uncalculable reactions, thats in the nature of HI I guess, we shouldnt blame it for being this way, ok?

Somebody starts thinking and talking on the hydrates of HI and the salt formed with the amine (what I forgot to mention before) and the influence of this on the reaction, and ratios to use - or why stochiometry is not exactly what we want and need here - some call iodine a catalyst only - heresy?


Rhodium

  • Guest
People want more than unproven good ideas
« Reply #18 on: November 18, 2003, 09:19:00 AM »
Yields up to quantitative. This say I.
 
Are ya all blind methcooks or has Geezmeister first to certify this in not less than 4000 words?


Well, it has probably a lot to do with a general cynism against novel ideas which has not been backed up by references, or at least a credible-looking writeup from the person advertising it. There has been too many instances in the past where people have gotten "great ideas" which did not work at all in practice, so due to too many failures people nowadays demand some kind of proof that it really works, and that one person simply say it does is not enough.

Rhodium the ratios I refered to by the fuming volcano werer taken from the two H3PO2 pdfs on your page (from memory: 4mmol substrate, 4mmol iodine, called catalyst, shit, 16 or more mol 50percnt H3PO2 all in GAA - 100percent yield - ho! try! fumes! and not only a lil fuming - no.)

You are probably talking about

https://www.thevespiary.org/rhodium/Rhodium/excellent.ideas/



The volcano effect, did it occur at the scale used by the original authors (4 mmol) or the one in my suggestion (20 mmol)? In any way, this should be possible to eliminate by the use of more solvent, slower hypo addition, or more efficient stirring.

Organikum

  • Guest
no Rhodium - H3PO2 not H3PO3
« Reply #19 on: November 21, 2003, 07:47:00 AM »
I wasnt referring to your "...ideas" but to the two pdfs you have on your server which talk on H3PO2 reactions. I am no coward - if I mean you I tell this, ok?

Actually I cannot find the information on impurities by high HI concentration in the references you provided - the forensic ones are also suspicious per se - or do you you think they provide correct ratios for cookie cookie?

I have provided refs to every point.
I wont provide an US-childrensbedroom methmaking writeup for 8 years old. (thats not addressed to you Geez ok?) Tell me what information you need to be able to bubble HCl into a reaction at 60°C. And I will tell you why I wont give this information to you.

Try it or leave it, but dont fuck around with me.
This is no idea of mine but basic chemistry. Answer with chemistry and not with throwing dirt and cheapo tricks. Of course ppl must be careful - at least when trying your stuff from TSII. But I am not you.

Obviously I am really the only one who has read the references.

Anotherone:
Hydriodic acid may be prepared by the action of iodine on stannic or stannous salts.
Huh?
Tin + conc. HCl(excess) + iodine = HI
says Gmelin.


I apologize for the harsh tone - but could anyone come over with FACTS?