Transcription
Welcome back to lab. In today's video, we are going to be preparing a complex of cobalt and salen, referred to as self-amine. For the synthesis, we are going to be using 2.17 grams of cobalt(II) acetate tetrahydrate. I just prepared this yesterday from cobalt carbonate and acetic acid. And we're also going to need 2.34 grams of salen. On top of this, we're gonna need 120 mls of ethanol as our solvent and for the washings, as well as water as a solvent in washes.
As you can see, I've already set up the apparatus. At the bottom, we have a 250 ml three-neck round bottom flask. Attached to that, we have a 500 ml addition funnel. You don't need something so large because we're going to have 50 mls, but it is my only addition funnel, so that's what I'm using. We have a reflux condenser, and that tubing leads to a bubbler. In that bubbler is mineral oil. The reason we have this pump works because we're gonna be passing argon through this whole apparatus to flush it. So you can see down here I have my argon tank. The reason we're gonna have to use argon is because as this complex is forming, it is sensitive to air and will decompose unless there is an inert gas within the apparatus. However, once the synthesis is completed, we can freely handle it in air.
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So now that all of the cobalt acetate solution has been added, we will allow this to reflux for an hour while maintaining a slow stream of argon through the apparatus.
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One hour has elapsed, and you can see the mixture has turned a very dark red color. It's not actually that dark in real life; the camera is making it look darker, but I'll get some good photos and pictures of it later. But for now, we're gonna turn off the heating and allow the mixture to cool down to room temperature before disconnecting the argon stream. And I'm just going to put some cool water on the flask to help it cool down faster.
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So now that I've filtered off all of the original solvent, I'm going to do three washings with distilled water and then another three washings with 95% ethanol. And now, dry thoroughly on the pump. And here is the final product. You can see it's a nice brilliant red; a light shine on it, so it's brighter—it's more of a burgundy. The camera makes it quite a vivid, but it is a little duller in person, surprisingly. Now, the final step for this would be putting it in a desiccator to fully dry out, but as it is, it's just a clumpy red powder. The final yield of the still slightly damp product is 2.4 grams.