[macman104]

I've been wanting to purify my MCPBA, because I'm having to use much larger excess than I want due to the acid and water impurities, and I found a perkin transaction procedure for it.  However, I've read that it is a highly shock sensitive, and I'm wondering if anyone has used pure MCPBA before.

This was a purification, similar to the one I read.

http://tvv2008.blogspot.com/2008/04/purification-of-mcpba.html

I just can't imagine handling 17g of highly shock sensitive material...

[MissPhosgene]

I looked in my copy of Purification of Laboratory Chemicals and didn't find much else, aside from a recrystallization that was done post-washing. Maybe the washes can be skipped and recrystallization can be done from ether/ methylene chloride? You will probably have to do several. I don't know if recrystallizing it does anything to reduce the risk of explosion. J. Org. Chem., 1987, 52, 5093.

If you are really worried about an explosion, you could break up the amount you need to rotovap into portions.

Another tip: glass can catalyze the decomposition of m-CPBA, so sometimes people use plastic to store it.

[macman104]

Thanks for the thoughts MissPhosgene, I found a plastic container for it.  I am carrying out the purification today (on a very small scale to start), my hesitation is just to what degree the shock sensitivity is.  Obviously people can handle it, so it can't be that shock sensitive.  I just don't want it exploding in my hand

[MissPhosgene]

How did it go?

[macman104]

It seemed to go pretty good.  From 2g, I obtained about 1.2g of the material.  By NMR, it is certainly more pure than the stuff out of the bottle, but still a small amount of acid impurity (1:0.05 by integration).  NMR isn't totally reliable for this, but at least I didn't blow anything up and I was able to scrap the sides of the flask to get the solid material into my bottle.  Really simple to do, and ether is nice cause i could keep the MCPBA cold while removing it just with an aspirator.

I'll be using it tomorrow, hopefully with better results.

[MissPhosgene]

I'm not sure if making it is any better:

http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0276

Check out Note 2! It could be very useful in purification of purchased material.

[408]

I have not worked with pure mcpba before, but a good protocol when working with any shock sensitive material is to isolate a small amount first, and see the sensitivity to hammer impact.  If it goes off (many explosives, ex TNT, will not) you then can judge how much force you should use with your  spatula.

[macman104]

Thanks for the info 408, I may give that a shot next time I make some up.  Also, it appears the oxidation went much more smoothly this time, but it's hard to judge if that is because of the higher purity, or because I switched from a biphasic to single phase by omitting the saturated bicarb.  Either way thanks for the insight everyone!

[macman104]

I tried smashing a bit of the MCPBA, nothing happened, it seems more stable than what it was explained as.  I used a calculation of 1.5eq, assuming 90% purity, and had still a large amount left.  Moreover, I tried it without concentration to the solid, in the ether, and it seems to have also worked really well.

Thanks for all the insight and help everyone

[408]

My rule of thumb for if it goes off with a hammer hit is to be careful, use a plastic spatula body armour, etc. If it is insensitive to hammer I pretty much feel fine going to town with the scraping.

[MissPhosgene]

Did you hit it with a hammer? If you don't I will and report.

[macman104]

Well, didn't want to dig for a hammer, but I had a pretty heavy pliers on hand, so I used those.  Behind the blast shield, with the hood sash down, nothing happened, I was actually a bit disappointed lol.

I didn't quite nail down what the exact % purity is, but like I said, I used 1.5 eq based on 90% impurity, and I had almost a full 0.5 equivalent left (again by NMR), so even 95% maybe underestimating the purity.  I have MCPBA/Ether solution in a sealed culture tube, I am curious to see if the MCPBA decomposition is impacted by the fact that it is a glass culture tube (but diluted in the ether)

[Borek]

lol, when I was a kid my Dad showed me that if you put the mass from match head in the combination pliers and you hit them with the hammer on an anvil, shock is strong enough to create a small explosion. So I scaled it up... until pliers jaw broke.

Don't try it at home. If those were your Dad's favorite pliers, you are in deep ***.