Al/Hg Basic question

Friendlycat · Thu May 19, 2005 10:18 am

Swim did a Al/Hg on 50g P2P the other day using Sheet aluminium ala Osmium style. The Al sheet was put through a paper shredder you know the one's that shred and cut so you end up with curled strips about 20mm X 5mm. Anyway this was refluxed for 8 hours and stirred for total of 20 Hrs from start of reflux.

Just about all of the Al was reduced and the liquid was almost clear/slightly yellow. Looked nice, decanted that, hit the junk with 40% NaOH, extracted with IPA X3 filtered then began to distill. Thats when colour went from almost clear to dark orange, and yield was shocking. 22%

WHY? When the IPA was pooled together, it was only filtered and not dried, also it wasn't filtered very well because it still looked a little frosty. When distilling, a solid was caked on the flask wall. So did swims freebase react with the NaOH thet was still there from not drying? Does that happen?

Thanks,
FC

brain · Linguist Extraordinaire

IndoleAmine · Dreamreader Deluxe

If the color is/was colorless, everything was reduced. The imine between p2p and methylamine would be coffee/brown in color, methylamine itself has a greenish tint to it, and so has p2p. If the color was yellow, it sounds to me as if it was successful (methedrine fb is light yellow).

I guess the problem was trying to extract with a slightly polar water-miscible substance (IPA isn't miscible very well with conc. NaOH/KOH solutions and conc. salt solns., but nevertheless its a shitty extraction solvent. Better use toluene (same volume as rxn liquid) and partition this into three aliquots (like 3x200ml for extracting a 600ml rxn mixture), then mix each portion with the AL/Hg soup thoroughly by mechanical stirring for 10 minutes (mag.stirrer set on max), then let settle to the top (takes some minutes, be patient), then pour into giant funnel with improvised stopcock on bottom (or huge sep.funnel if you have), drain the lower ugly grey Al sludge/water layer, and decant the upper tolunene layer into a clean vessel. Repeat this extraction 2x, and you will get out everything, without any doubt.

Sandmeyer · Thu May 19, 2005 11:00 pm

IndoleAmine · Dreamreader Deluxe

IndoleAmine · Dreamreader Deluxe

FriendlyCat: Just ignore him, he obviously hates me for some reason and tries routinely to disturb the peace here.

My point was and is that you didn't neutralize the excess NaOH you used for basifying, which is recommended. If you use IPA, you can not really wash the combined organic layers with brine and bicarb solution, since IPA isn't completely immiscible with those liquids and would carry over some product into the aequous phase.

If you use toluene on the other hand, you can shake your combined extracts thoroughly with saturated NaHCO3 and NaCl solution to remove all inorganic impurities effectively WITHOUT any losses to the aequous layer (this also is very effective for removing mercury contaminants!! One more reason to use a nonpolar solvent! Or would you like Hg contamination in your final product??)

Think this is enough clarification, even for dumbass Sandmueller.

Friendlycat · Sat May 21, 2005 2:08 pm

WOW! A cyber bar brawl!

Just to see if I understand, you are saying still do the reaction with IPA but when that is decanted, extract the basified muck with toluene then pool with the IPA and distill. Right? How does NaHCO3 get rid of HaOH?

I thought that even if the Hg made it through the extraction, that it wouldn't make it through an acid/ base clean up.

Thanks,
FC

Friendlycat · Wed May 25, 2005 3:23 pm

Thanks for your advice! and please disregard my previous post. My brain was not working this week. In fact swim did this reaction 2 years ago perfectly but made a clerical error writing IPA instead of toluene etc, and copied this into my book of synths (like Michael Valentine Smith did) and followed this blindly without thinking or refering to the original writeup!! What a fucked up week and fucked up thread!

But thanks alot anyway,

King regards,
FC.

IndoleAmine · Dreamreader Deluxe

Actually IPA does partially separate when the water it is mixed with is basified to a rather great extent..

(but toluene does this much better Wink

)

Oh, and: NaOH + NaHCO3 -> Na2CO3 + H2O, thus washing repeatedly with a saturated NaHCO3 solution will convert all hydroxide traces to Na2CO3 - which has a far higher solubility in H2O than NaHCO3, thus the thing really works.
(don't forget the brine wash(es) to remove the NaHCO3 though..)

greets

indole

2spun · The Resistor

Swiy ,

was think'n somewhere around the lines of basic questions for the Al/Hg as well.
that question bee'n.
Can Denatured Alcohol be a good replacement for MeOH in this reaction?
if so would it harm ones yelds?
Much thanks

IndoleAmine · Dreamreader Deluxe

If denatured with ketones like MEK and/or acetone, most likely yes since they form schiff bases with methylamine too, and cause minor n-methyl-isopropyl/-isobutylamine side products...

(in fact not really an issue as long as you reXtalize properly..)

You can also add some bisulfite to the alcohol to remove the ketones, or (I think) boil them with Ba(OH)2 to destroy the ketones into tarry substances, which are left behind upon distillation...

2spun · The Resistor

ok swiy,
understands. What if swiy is going to use nitromethane?
swiy belives he read somewhere if swiy use's nitromethane he don't have to have methylamine.

hAzzBEEn · Wed May 25, 2005 10:06 pm

2spun · The Resistor

ok,
cool cool. on the lear'n faze
Much thanks