Finally...Ferrocene!

This Tuesday (9-13-11) we tried the ferrocene lab again, but this time we used a different procedure. The reaction stayed the same except for the solvent and the amount of reactants. In the last one, we used ethylene glycol but in the new procedure we used 1,2-dimethoxyethane (also known as "Glyme") as the solvent. This reaction was scaled up considerably--in the last one, we used 2 g of KOH and in this one we had to use 7 g of KOH (which is a lot more than is pictured below!). We were worried that the large amount of KOH might not dissolve and the reaction would fail, but it seemed to dissolve quickly.

The whole setup of the reaction went the same as the last one, so we had some practice and the step where we put the flask under a vacuum and inert argon atmosphere went a lot faster this time.

We didn't really notice anything changing from the last reaction to this reaction until we added the FeCl2/DMSO solution using the cannula. The last time, it was a very pretty dark red color but this time it was more of a dark brown color. The biggest change we noticed is when the HCl and ice was added at the end. The last time, the solution immediately turned a bright lime green (and was almost completely clear) but this time, it turned a murky dark blue-green color. The reason it was murky? The bunch of orange solid that precipitated out, AKA ferrocene!!!! At least, we really hoped that our spectroscopic evidence would tell us that it was actually ferrocene. What the heck, we were just excited that the reaction had produced SOMETHING! We vacuum filtered the solid, dried it in the oven, and massed the chunky reddish-brown solid that it had become.

That same day, we tried the acetylation of ferrocene reaction with commercial ferrocene that was available in the lab (we were trying to save time since we lost a day with the first ferrocene experiment). The only reactants that went into this reaction were ferrocene, phosphoric acid, and acetic anhydride. This stirred at 100 degrees celsius for 10 minutes under an air cooled condenser. The mixture changed from a light orange to a dark brown color at the end of the heating. After this, NaHCO3 was added in small increments, the key word here being "small" because each time we added some, the mixture bubbled very high in the flask and expelled CO2 gas. After the mixture stopped bubbling, it had turned a strange blue-green color but we didn't see any evidence of the brown solid we were supposed to be making. We set it in an ice bath, and then let it sit at room temperature until Thursday since we were out of time. We weren't feeling too confident about this reaction, but we would have to wait and see what happened with it!