Nitro route using ultra thick foil

[tecnetium]

Hi bees
I was just wondering if anyone had tried a MM nitro using thick foil (~0.3mm thick) similiar to Osmiums variation at Rhodiums page? Reynolds does not exist where I live and a few of us bees have had trouble getting anything even close to it! I assume that everything stays the same except the reaction time- say 10-12 hours? Any one agree?

Tec

[blue]

problem with ultra thick  (ala pie plate etc) is that it doesn't turn into little nuggets in a food processor the same way as foil. this causes three problems


1. it doesn't float

2. it is more difficult to stir

3. it will run longer and not as hot (we know running it HOT increases yeild)

the 1st two can be solved by using overhead stirring, but this will complicate your reflux set-up, unless you have an airtight stirrer bearing, or are willing to run a long drill bit down your condenser.

stranger? muahahahaha

[tecnetium]

I thought that I could maybe fold the foil up myself into little nuggets and add some external heat for the duration of the reaction. Any other ideas?

[noj]

0.3mm isn't really that thick. And since swim doesn't have a coffee grinder he has success just balling them up with his hands and giving them a good squeeze. If they don't ball up, maybe try cutting them like in BS method, 1 cm squares.

An optimist thinks this is the best possible world.
A pessimist fears this is true.

[refluxx]

Balling the shit up by hand seems like a hella lot of trouble.  Why have 500 dollars worth of equipment and not spend 20 bucks for a grinder that looks just like the ones in the picture on Rhodium?  Whatever floats your foil I guess.....

did I say that?

[Osmium]

What are you guys doing there again???

[ ] I read and fully understood Osmium's Al/Hg text on Rhodium's site.
(Or didn't you?!?)

Don't crush the the Al up! I don't care in which ways you weirdos rape your ketone with ultra-thin Al, but when doing it true Os style then simply cut the sheet Al into little squares. Size doesn't matter as long as you are able to somehow stir that fucker. Even rectangular shape might work on uneven weekdays   .

When you crush the Al up it slows down amalgamation, and inhibits some of the Al surface. You DO NOT want that to happen with thick Al.

And while you guys fire up your 20 L flasks to process a mole of ketone, true believers in the way of Os do that reaction in a 2L flask, and don't care if it runs a overnight or even a whole day.  

[Lino]

When it comes to Al/Hg Os' is da man. This Bee knows Jack 'bout the nitro variation, but I had thought of a variation to Os's variation which involved pie tins cut into long strips then bent into W or even M shapes. They would be evenly spread in the flask/PP garden sprayer (hint) and so stirring may not be needed (stuff fizzes). An excess of Al would not harm the outcome because it won't all be reduced to Al oxide. And 'cause stirring may not be ness. this could be done in a sealed system (pressure). What do you think?

Lino

[wacko_reaco]

Os,
read your method on rhod's site, two quick questions,  can methanol be used? can nitromethane be used instead of aq.MeNH2 if say some of the nitro is added initially then the remainder with the ketone?
your method on paper appears to make much more sense than the thin foil route I wonder why bees don't use it??
thanks in advance

wacka wacka wacka

[Osmium]

Lino: stirring will always improve your yield. The reaction takes place at the Al surface, so you have to ensure that new unreduced imine is always present at the solid-liquid interface. Excess Al will dissolve in the reaction, so using excessive amounts is no good idea. Running this reaction under pressure in a closed vessel won't help much, sure it will take care of MeNH2 losses, but since a lot of the Al reacts with the solvent/water forming (useless) H2 you will produce a lot of gas and pressure. Flask with good condensor works fine.

wacko:
1) yes
2) yes
3) Some use it, but not many. I'm wondering the same.  
I guess the problem is that no detailed step-by-step writeup exists, and most bees need one for successful cooking.

[wacko_reaco]

the pro's as far as i can see it for Os's route
-less solvent
-less Al, therefore less Hg
-lot less fuss
-bigger scale-up's as flask size less critical
con's
-longer reaction time (do you really think the fed's will miss you by four hours?)
-not much else
it all seems quite simple, but the lack of detailed writeup rationale seems to make sense
also you need overhead stirring, whereas with thin foil and small scale a stirrer bar can suffice so there you go
I am definetely very far from chaining myself to the next old-growth tree Bush wants to cut down but also I am not oblivious to the cause and effect cycle. From a look after it, it will look after you perspective this thick route is uncomparably better

wacka wacka wacka

[tecnetium]

Here's what Swim performed with what she thinks was pure distilled P2P. In a 1 litre vessel:

24g Al foil (approx 150 microns)
550 ml MeOH/IPA (50/50)
28mg HgCl2

11.5ml nitro
10g phenylacetone
15ml MeOH

Added HgCl2 to MeOH/IPA and Al. After 20 mins the Al was fizzing and the solution started to trun grey although there was still a lot of shiny surface area. Started adding ketone/nitro mix over a 45 minute period. Mild heat was applied to a gentle reflux. Swim could not get the bastard to stir but the refluxing did give the solution a good mix. Let the mix reflux for 16 hours. Basified with 130 g NaOH and 350 mL water (there was still quite a bit of unreacted Al). Extracted 2 x 200 mL toluene. At this stage the toluene looked orange. Washed 2 x bicarb, 2 x NaCl solution and once with dH2O. Extracted with 1M HCl- toluene went very red. Basified with NaOH- No freebase except about 0.2 ml of floating red oil. = Failure?!
 
Any suggestions? Other than perhaps overhead stirring and maybe less Al- perhaps a bit more HgCl2 may help but Swim thinks she needs to alter the reaction parameters. Osmium do think that your variation at Rhodium's page will work as described with P2P as it does with MD-P2P?

Tec

[Osmium]

> do think that your variation at Rhodium's page will work as
> described with P2P as it does with MD-P2P?

Absolutely. No doubt about that. Maybe your ketone wasn't ketone?
BTW, you used way too much Al. Here are numbers for the theoretically needed amounts:

CH3NO2 + 2 Al + 4 H2O --------> CH3NH2 + 2 Al(OH)3
Two moles of Al for every mole of nitromethane

3 imine + 2 Al + 6 H2O --------> 3 amine + 2 Al(OH)3
0.67 moles of Al per mole of ketone

These are the theoretical amounts. Since some Al is lost, you will definitely need more. 1:2:6 molar amounts of ketone:nitro:Al sound like a good starting point. Also have a look at the required amounts of water. Even when the Al sludge is considered to be Al2O3 instead of Al(OH)3, you will need lots of water. Don't run that reaction completely anhydrous! It needs that water!

[tecnetium]

Ah Shit! Swim did not add any water! MM, Gonz and Baal's methods did not have any water added- could this be the source of swim's failure?

[Osmium]

Well apparently it worked for them without adding any. Os always had water present, and it worked very well for him.
Try to add some next time and see if yields will be better. Don't add too much, go up slowly. And you can always try to add more later during the reaction and see if it makes any difference (like temp going up a little or so).
Another trick for thick Al reductions: Adding a little solid NaOH will speed up Al consumption in case that shit takes too long for your taste.

[blue]

i was under the impression that the nitro >> methylamine produced H2O as a by product. eliminating the need for additional H2O.

that's a pretty bald choice there Os beleiver or unbeleiver . actually i think both routes have their merit, yours definately scales better, but it isn't as much fun .

is it soup yet?

[hypo]

Hm... If i get this right, 1 mol Al can (in theory) introduce 3 mol H⁺. So for the reduction of 1 mol oxime, one would need (in theory) 4/3 mol Al and use around 2 mol.

>CNOH + 4H⁺ + 4e^- -> >CH-NH2 + H2O

Yep??

[weasil]

What is wrong with these junk-yard synthesise; howcome they yield nothing?

[baalchemist]

"And while you guys fire up your 20 L flasks to process a mole of ketone, true believers in the way of Os do that reaction in a 2L flask, and don't care if it runs a overnight or even a whole day."
 
That may be true, but by the time one makes enough MeAm to process that mole of ketone, Nitro users will be processing their second mole of ketone by then. As for thinner foil, make 5x5 or larger squares intead of 2x2, and wad them up, then do the coffee grinder bit to compress them wads tighter.  Also decreasing the HgCl2 amount helps immensely.

[Chromic]

You can make 250g of methylamine in a 2L flask, more than enough for 1 mol of ketone. Just wash with acetone or dcm to remove the dimethylamine, and filter out the ammonium chloride when it won't dissolve in the 91% IPA (or MeOH, whatever you guys are using).

[Osmium]

I never even considered doing that reaction without a condenser!
In my opinion a condenser is always a good idea, even with small scale reactions. I don't know exactly how much methylamine will be lost when you don't use one, but I guess it could easily be 50% or so.