Wild Card (again) and A New Arene

The next lab day, Thurday 11-10-11, we decided that Purple Chrome needed to divide and conquer. Elom and Allen worked on redoing the Wild Card (both parts in one day...ambitious!) while I (Emily) set up a new Cr Arene reaction. First up: the Wild Card.

The procedure we followed was the same as the one that we followed for the previous experiment with a little bit of creative tweaking. The masses of ruthenium chloride, diazald, and triphenyl phosphine were all the same as we used before. The Diazald from Part A was not dissolving, so an extra 6 ml of ethanol was added to the solution. Part A went very quickly and we ended up getting the same green precipitate as we did the last time once we cooled the flask down to room temperature. Here it is, just filtered out of the solution:

We took this as a good sign that this was actually what we were supposed to get, because we reproduced the same result as we had the last time we did it!

Extra ethanol was also added to the solutions of ruthenium chloride and Diazald in Part B of the experiment to get them to dissolve, so we had a lot more solution than we did the last time. Everything went well until we got to the part where we had to add the triethylamine to the solution until it turned a deep purple color. This was REALLY hard to see the last time, and this time was no different. We added the 1 ml that it said in the book, but the color that it turned did not look that purple. It looked more reddish-brown than anything.

How are we supposed to see a change from dark brown to deep purple? We thought that maybe this time we needed to add more triethylamine, so we added 4.5 ml total this time, which was 3.5 ml more than we added the last time. We also gave it an extra 5 minutes of reflux time because of all the extra solvent in the flask. When we let it cool to room temperature, we had hardly any precipitate at all! We had a couple flecks of the same coppery solid as we did the last time, as well as an unknown lump of black (possibly burned) solid. Thank goodness we still had a lot of the precipitate left from the first time we did it, so we can use that. We will have to do IRs on these to see what we got, and hopefully we get better results than we did the last time!

Now for the Cr Arene reaction:
The next arene we decided to do was 4-trifluoromethylaniline. The reaction hints for our project indicated that this one might take 2-4 days to react, so we set it up on a Thursday so it could run all weekend. We set up the flask and did the vacuum/argon-fill as usual. We added 8 ml of dibutyl ether and 1 ml of THF to the flask. Then we added 0.4 ml of the arene and 1.079 g of the chromium hexacarbonyl. We started stirring and heating that day, and it turned a light yellow color:

Overnight, there was a collection of yellow in the condenser and it looked like the reaction might be losing some solvent from the level of liquid in the flask. We shut it off over the weekend, and then the next Monday we added 2 ml more of solvent and regreased the connections in the setup. The reaction then was heated non-stop until Thursday afternoon (11-17-11).