Sciencemadness Discussion Board

Reductions using Ca metal

chemrox - 21-11-2014 at 13:30

I'm dehalogenating a heterocyclic aromatic amine that has a Cl atom on one of the phenyls. I put the free base form of the amine in ethanol with equimolar (actually slight excess) of Ca metal. The paper calls for granular metal which I don't have. Rather I have chunks of Ca as it was supplied. I tried breaking these up in an N2 filled plastic bag but the bag was broken through before any Ca broke.

Attachment: Dehalogenation of Aromatic Halides Using Metallic Calcium in Ethanol.pdf (68kB)
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WGTR - 21-11-2014 at 16:15

Depending on how big your chunks are, perhaps clamping them into a small vise under oil, and drilling them slowly with a sharp bit. I couldn't say how to wash the shavings afterwards, though.

chemrox - 22-11-2014 at 02:23

I was stirring the mixture with a flea in a small Erlenmeyer. I changed stir bars in favor of a larger (1.25") one and the Ca started breaking up. I'm hopeful.

zed - 24-11-2014 at 19:49

Again....Ball milling. Sponenberg has plans for a machine, in his book. Or, Harbor Freight offers a fairly inexpensive "Rock Tumbler". With a little tweaking, it should be able to do the job.

phlogiston - 25-11-2014 at 06:01

Dan Vizine in his 'thorium thread' used a file:

http://www.sciencemadness.org/talk/viewthread.php?tid=29927#...

If you need larger amounts, ball milling seems a good method to try, but you should be extremely cautious then because the calcium will presumably become pyrophoric.

chemrox - 25-11-2014 at 16:16

I have harbor freight ball mill. I need better balls for it. The chrome plated one get de-plated too quickly.

dermolotov - 14-12-2014 at 14:47

Quote: Originally posted by WGTR  
Depending on how big your chunks are, perhaps clamping them into a small vise under oil

This is what I did to make Potassium powder. Then I flushed out moisture in a vacuum flask and mixed it with hexanes. Then poured the solution through a funnel and put it in a vacuum dessicator for an hour.

Okay potassium powder. Don't see why it shouldn't work with calcium. Of course, if you can get calcium, just get calcium turnings to make things easier.

phlogiston - 14-12-2014 at 15:53

You must not have handled calcium metal before then.
It is a lot harder than potassium. Probably you can deform it, but don't expect to be able to flatten or extrude it with a vise like you can with sodium or potassium.
I once had great trouble cutting slivers of it of a larger piece with a knife. A saw is a more appropriate tool.

[Edited on 14-12-2014 by phlogiston]

dermolotov - 14-12-2014 at 22:50

Quote: Originally posted by phlogiston  
You must not have handled calcium metal before then.
It is a lot harder than potassium. Probably you can deform it, but don't expect to be able to flatten or extrude it with a vise like you can with sodium or potassium.
I once had great trouble cutting slivers of it of a larger piece with a knife. A saw is a more appropriate tool.

I have - but only in powdered form.

Couldn't he just vice grip it in oil and file it down in oil as well?

phlogiston - 15-12-2014 at 01:13

Yes, that should work. Ca also does not oxidase as quickly as the alkali metals, which helps too.

dermolotov - 15-12-2014 at 14:58

Quote: Originally posted by phlogiston  
Yes, that should work. Ca also does not oxidase as quickly as the alkali metals, which helps too.

What would be the quickest way of removing the layer of oxidation on calcium powder/turnings?

zed - 5-1-2015 at 14:38

Not Calcium Hydride? Used to be cheap, cheap, cheap. Now, surplus cans of CaH, seem to be gone, gone, gone.

chemrox - 5-1-2015 at 16:36

Using big chunks took longer but it worked; just stirring the mixture for a couple of days