More Ferrocene and A Bit of Spectroscopy

The first thing we did on Thursday 9-15-11 was look at the product of our acetylation reaction that had been sitting for two days. Surprisingly, the solution was no longer blue-green, but had turned completely orange and there appeared to be an orange precipitate on the bottom (along with what looked like some excess NaHCO3).

We vacuum-filtered this and below is the picture of the orange precipitate. We then let it dry in the oven for a little bit, and it turned a light brown after this.

The yield was very small, but then the amounts of reactants were small as well. We barely had enough for a sample to be dissolved in methylene chloride to run through the GC-MS. We can only know if the acetylation of ferrocene worked once we get the spectra back from the GC-MS!

The purification of our ferrocene sample by sublimation was a really neat thing to watch. We put our crude sample in a glass petri dish on top of a hot plate and turned the hot plate on. We placed a beaker full of ice on top of the petri dish.

 As the sample heated up, we began to see little bright orange crystals forming on the inside of the petri dish lid under where the ice beaker was placed.

Finally, after about 20 minutes, there were crystals all over the sides of the petri dish bottom and all over the top of the petri dish. What was left of the crude sample was a black pile of dust:

Here is a picture of the top of the petri dish, which is definitely nicer to look at than the bottom:

We had to scrape all the crystals out of the petri dish and mass them so we could calculate percent yield.

The rest of the lab period involved getting spectra to see if we actually made what we thought we made. We ran the ferrocene crystals through the Mel-temp device and got a melting point very close to that of pure ferrocene, so it's looking good so far! We also ran an IR, H-NMR, and a GC-MS on ferrocene. We left the GC-MS to run overnight, so we don't have those spectra yet but we do have the IR and NMR:

IR Spectrum of our Product

The only thing that was weird about this was the carbonyl peak that shows up at about 1750 1/cm. We ran background scans several times, but it never showed up in the background scan, just in the spectrum of our product.

H-NMR Spectrum of our Product:

The single peak at about 4 ppm is characteristic of ferrocene because of the aromatic cyclopentene rings on either side of the Fe atom in the "sandwich compound":

                        

Structure from http://chemistry.about.com/od/factsstructures/ig/Chemical-Structures---F/Ferrocene.htm

So far, we seem to have a lot of evidence in  favor of us actually making ferrocene, so we'll see if the GC-MS disputes that or supports it.