It's kinda fun to read all that poetic waxing about "potency" and stuff, but that doesn't explain it clearly enough to the next moron who will read it and start some new urban myths in his area which will without a doubt spread and end up here again.
What we have is a reaction converting A (precursor) and B (HI) into an intermediate C (iodometh) and finally into the desired end product D (meth) and a whole lot of different side products and contaminants(e, f, g, h... etc):
A + B ------> [C] ------> D (A + C + e + f + g + h...)
A + C being mentioned on the product side of the equation means there will also be some unconverted precursor and intermediate present.
Amounts and distribution patterns of D and (A, C, e, f, g, h...) in your end product depend on a whole lot of factors, mainly reaction conditions, but also on the workup procedure, method of crystallization and method of recrystallization. Needless to say, if A isn't pure and contains other chemicals the product distribution will be even more complicated.
As every chemist knows, chemical reactions take TIME to go to completion. While there are a few incredibly fast reactions which take only milliseconds or less to finish, the HI reduction is unfortunately not among them!
And every chemist will tell you, that stoichometry is also very important. When one of reactands is present in excess then it will be left over afterwards, and the conversion of the reactand which was not in excess will undergo a more complete conversion. This also means that if there is an insufficient amount of a chemical present the reaction CANNOT be completed for the other reactand being present in excess!
A good example for that last case is the 'dry' fast rP/I2 reaction. There isn't sufficient H2O present to convert all the I2 into HI, so it is absolutely impossible that this one converts all precursor A into product D. The result will be a wild ass mixture of a little D plus a shitload of unconverted A, intermediate C, and the usual e, f, g, h... crap. Since the purification methods used by garage chemists are usually insufficient to properly separate the components that wild ass ugly mixture is what you will end up with. Proof: ref. on Rhodium's claiming 50 impurities present in such meth. Shitty taste. Peanut butter appearance.
Since it is close to impossible to completely separate desired product mixture containing D (meth ) from all the other shit in a garage setting, especially A and C (which happen to have very similar solubilities as D!), the amount of pure D in the end product will be rather low, and the amount of toxic side products rather high.
I guess most of you would call that stuff 'low potency' meth. Some morons will call that 'good' meth, because the taste and toxic action is what they expect meth to be like.
I call it impure, dirty, toxic and lots of unconverted precursor present.
So what to do to get a better end product?
I) make sure that there's enough B (HI) present to convert all the A (precursor) into D (meth)
II) for condition I to be fulfilled, you have to add enough water to the reaction! Because if there's not enough water around your I2 will not be converted into HI! Also: gaseous HI which is not in solution will not contribute to the reaction. Make sure that the HI has water to dissolve in! Common sense!
III) give the reaction enough time to complete! Fulfilling conditions I and II will still be useless if you don't give A, B and C enough time to complete their reaction to yield D!
IV) Since the cleanup methods available to most bees are rather limited in separation efficiency and since a high yield is desired make sure that the amounts and number of side products (e, f, g, h...) are as small as possible to begin with. Meaning: no flask fires! No excessive reaction conditions!
There is a reason why some of the old timers and bees with a chemical background have always been telling you to do it one way and not the other! It's inevitable that a bunch of wild and reckless youngins will keep challenging the status quo and come up with new ways and 'improvements', that's how progress is made. But not all 'improvements' are really what they claim they are, and all it takes is to start some group dynamics and the whole herd will stampede towards the abyss. Like someone claiming having done a dry reaction in 30 mins and the end product was "way potent dude!" Some wannabees repeating it, failing, and not wanting to admit to themselves and their bee-friends who they bragged about their mad chemi skillz that they fucked up the reaction so they confirm the results. Then a bunch of inexperienced bees who read all that, try it out themselves, produce some weak ass mmmeth!, and publicly confirming the result that "this indeed works!!!"
Next comes a charismatic dude who loves to be the center of attention, talks shit about those who know some chemistry backgrounds and publicly claims that "tweakers don't need any of that scientific hoopla to cook some potent chili! Fuck yeah!". Add some easy to follow writeup for the morons and soon everyone is following the new shitty procedure, totally rejecting and forgetting what were once established (and working!) procedures. That's what happened to the A/B at the end of the reaction which once used to be standard procedure, and that's what happened to long reflux.
That's how rumours and urban legends are started. Offer an easy solution and everyone will love you for it. Doesn't matter if the easy solution will not work, it is what the people want to hear and want to believe! Works in politics, and apparently works among bees too. Sad but true.
I say: gently boil that reaction for as long as you can.
Boil for not long enough: you will end up with unconverted precursor and intermediate in your end product. Which you CANNOT separate from your end product easily. And those who manage that will bitch about low yield.
Boil for too long: nothing bad will happen. All precursor is converted. No intermediate is left over. Meth is pretty stable under these conditions and will not decompose. Yield of end product (*potency*
) is maximised.
I'm not fat just horizontally disproportionate.