Author Topic: Initiation Of Grignard With Broken Glass  (Read 2560 times)

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Bwiti

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Initiation Of Grignard With Broken Glass
« on: December 21, 2001, 10:08:00 PM »

  I was having trouble initiating a Grignard from 4-bromoanisole, even with the use of an ultrasonicator, but I came up with an idea, and it works great! I put the 4-bromoanisole into a large amber bottle with about 1/4 its volume of THF and a few drops of shitty diethyl ether that I distilled from starting fluid. About 8 inches of Mg ribbon was scraped clean with a knife, snipped into pieces and added to the amber bottle along with 4 marbles and a bunch of lightly crushed, dry glass. I capped the bottle and shook it for about 10 minutes. I opened it, then duct-taped an smaller up side down, rubber-coated bottle to it, and left it in my basement for about 2 hours. When I checked the bottle, most of the Mg was gone, the solution was a bit cloudy, and the bottle was as cold as the basement. Didn't get hot? A few hours ago, I added several grams of Mg powder, but the solution's very cloudy and it's hard to see inside the bottle through the amber glass even when I use a flashlight. What color would the solution be if the Mg has reacted? I'm kind of color-blind, but I can have someone else check it for me. Do you think that shitty, old pyrotechnic Mg powder will work? I'll soon find out, so place your bets. Just as long as a Grignard doesn't get too hot, and only a little Mg is added at a time, could I keep the cover screwed on without it exploding? Happy cooking! 8)

  Love my country. Fear my government.

Ritter

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Re: Initiation Of Grignard With Broken Glass
« Reply #1 on: December 22, 2001, 12:20:00 AM »
Hey Bwiti!

Man, you manage to come up with some of the most effective ingenious ghetto-style cooking techniques I have ever heard of!  Well anyway, the pyro grade Mg powder is a crapshoot for a couple of reasons.  Finely divided Mg almost always has a significant oxide coating, especially the low grade material usually employed in pyrotechnics.  However, you may have lucked out as I have seen some batches of magnesium powder for sale over the years which were coated with some sort of inhibitor to prevent oxidation.  Stearic acid was commonly used to protect aluminum powders in the past so perhaps this was also used for the Mg.  I think if the Mg powder was going to work, you would know right away because the massive surface area would definitely contribute to a highly exothermic reaction.  What mesh is the Mag powder?

As a side note, since it seems like you have no trouble getting ahold of semi-exotic reagents, pick up a bottle of Red-Al (sodium bis methoxyethoxyaluminum hydride) soln.  A couple drops of this reducing agent will initiate the most difficult grignard fairly rapidly.  Combine this with the ultrasonic bath and you should have no trouble at all in the future!  Another handy technique for initiating grignards is adding a few drops of methylmagnesium iodide soln.  Many chemists keep one of those Aldrich sure-seal bottles of this stuff around just for this purpose.

Bwiti

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Re: Initiation Of Grignard With Broken Glass
« Reply #2 on: December 22, 2001, 08:24:00 AM »
"Another handy technique for initiating grignards is adding a few drops of methylmagnesium iodide"
 
  I've never laid eyes on that, but I have made the bromide, and for some reason it's alot easier to make than a grignard with a benzene ring. Sometime, I'll try your suggestion and of course post the results. In the future, when I'm not broke, I want to try making a grignard in some type of teflon-coated, strong sealed vessel. That way, I could add 1/4 the amount of Mg strips at a time and not have to worry about being burned and blinded by shattering glass and hot corrosive materials. I've had over-flows in the process of producing NaCN and bromine, and I don't want to carry on this dangerous tradition. Shit, now I have to find a place that sells Mg strips at a reasonable price. It would be a good idea to find a few places to spread my orders out on, because orders for large amounts of Mg might raise a flag. I wish there was was a chem that could consume the oxide without consuming the metal. I should find a place that sells Mg ingots, so the reaction will be safe, steady and absolutely predictable..Hmmmm, I have one of those magnesium fire starting tools. If it's mixed with a little aluminum or copper, should I still use it? That reminds me of something I've been wondering: Besides lithium, Mg, K, Na, are there any other metals that I could use to make PCP-analogues? Peace! 8)

  Love my country. Fear my government.

Osmium

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Re: Initiation Of Grignard With Broken Glass
« Reply #3 on: December 22, 2001, 04:02:00 PM »
> pyro grade Mg powder is a crapshoot for a couple of
> reasons.  Finely divided Mg almost always has a
> significant oxide coating

The ultrasonic method shouldt be able to overcome the oxides.
Zn dust/powder consists of up to 10% ZnO. I'd expect fine Mg to have a similar oxide content.

> I have seen some batches of magnesium powder for sale
> over the years which were coated with some sort of
> inhibitor to prevent oxidation.  Stearic acid was
> commonly used to protect aluminum powders in the past so
> perhaps this was also used for the Mg

Pyro Mg was (or maybe still is?) soaked in chromate solution to passivate it and make it compatible with other chems. That means even more oxides.

> if the Mg powder was going to work, you would know right
> away because the massive surface area would definitely
> contribute to a highly exothermic reaction.

I think so too.

> I should find a place that sells Mg ingots, so the
> reaction will be safe, steady and absolutely predictable

Easy to find them. Think corrosion protection. Boats. Boilers. Sacrificial anodes are often made from Mg.

Bwiti

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Re: Initiation Of Grignard With Broken Glass
« Reply #4 on: December 22, 2001, 10:26:00 PM »
"Easy to find them. Think corrosion protection. Boats. Boilers. Sacrificial anodes are often made from Mg."

  Thanks for pointing me in the right direction. Yup, the Mg powder would have made better use in the production of fireworks. Several hours ago, I brought shine to my fire-starting block of Mg(about 40g) with a file, and dropped it into the bottle of bromoanisole. Now, it's red and transparent. Dropped half a teaspoon into a bowl of water and got a violent reaction.
  If a thick layer of oxide is on the powder, then why not break it up by melting it; homemade ingots? What could I melt it in? An iron pot is all I can think of. I could heat it from the bottom with a torch. I don't think propane would work, but maybe oxy-fuel will. Peace! 8)

  Love my country. Fear my government.

Bwiti

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Re: Initiation Of Grignard With Broken Glass
« Reply #5 on: December 24, 2001, 08:18:00 AM »
"Yup, the Mg powder would have made better use in the production of fireworks."

  I take that back..I added a little more Mg powder along with 4 more marbles and a little glass, shook it for about 45 minutes. An hour after this, it's very hot! If you're willing to risk breaking the bottle while you shake, then go for it! Even if it did break and burn me, I'd still be happy, because I've pretty much mastered the initiation of Grignards!! 8)
 
  But still, when I take a welding class, I'll try to melt it into an ingot. Peace! 8)

  Love my country. Fear my government.

menthol_man

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Re: Initiation Of Grignard With Broken Glass
« Reply #6 on: December 30, 2001, 09:18:00 PM »
Dam I wanted to make the suggestion of using fire starter
Mg blocks  >:(   But thats cool though  8)   ;)
A rotary tool is top notch.  A little spinning sander
to make it all nice and oxide free!!!  Mine has no foreign
materials in it.

As far as being worried about explosions and all...
Get a $40 US Army Flak jacket and wear a $30 US Army
Chemical Suit over it.  Or be a big spender and go to your
fire dept and get an old crappy jacket of theirs for
40 or 50 Bucks.  That would bee even better.

I remember a buddy of mine was "skeptical" about kevlar
armor.  He was a whimp when it came to getting injured
by something.  I had him try the vest on.  I told him to
to move and to look "over there" I stabbed the jacket
with a very sharp kitchen knife VERY hard.  Diddent even
come close to scratching it (Yes Yes I tried it when no one
was wearing it first.... but he diddnet know that).
It scared the shit out of him when he saw that I tried to
stab him but it was like a little puch.  That is WONDERFUL
stuff folks BUY IT.  (Cover it with a chem suit because
its chem resistance is really lacking)

STAY SAFE!!! ;D  ;D  ;D  ;D  ;D

Gott Mit Uns!

lugh

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Re: Initiation Of Grignard With Broken Glass
« Reply #7 on: December 31, 2001, 03:15:00 AM »

Dam I wanted to make the suggestion of using fire starter Mg blocks




Not as good of an idea as you might think, impure Mg doesn't work very well  :(