Ok so I usually only post bad things here about my research experience so I decided to go for something good now. For those non-chemists this post will make no sense, but since it's my blog I can only write what I know.
I have been frustrated with the technique of recrystallization, as are many beginning organic chemists. I've done it plenty of times, but never achieved great success. This most recent reaction was no different: I ran it on a small scale and when I went to recrystallize, I managed to drop the flask into the ice bath (actually I left it in ice and went to write up something and when I came back the ice had melted and the flask had slipped - yes there are reasons to clamp things down). So I only recovered maybe 20% of my product. No big though, CF assured me since I was going to scale up anyway. 1H NMR confirmed structure of my compound so I went on to the scale up.
After precipitating out ~28 g of product, I went to recrystallize, but I couldn't get it to dissolve easily in the 1:1 EtOAc/Hexane mixture I used for the small scale. So I had to add lots of solvent. Too much, in fact, because I got no crystals. I rotovapped off the solvent and tried again. Unfortunately somehow my clear solution turned yellow. Some other folks in the lab are working on some highly fluorescent yellow compounds so I figured that there must have been some left on the rotovap. (This is why I always clean the rotovap before I use it, but I was frustrated and in a hurry.) This time, I added pure EtOAc and heated it with a heat gun (not my usual method, but was told it was easier to do this way) until it dissolved. I added some hexane until I saw some crystals form. Left it in the fridge overnight.
No crystals. So I decided to do what any person who isn't sure of what to do would do - look it up on the interweb! I rotovapped off all the solvent and decided to see if I could find any tips online. I actually read the description on wikipedia and ended up reminding myself of years ago at Auburn when I actually learned this technique. So I did what it said and lo an behold it worked!!! Patience and precision worked well. I added small portions of EtOAc and sonicated after each portion to try to get it to go into solution. I kept it in a hot water bath to keep it warm. After a few rounds of this, everything was dissolved. I slowly added hexane until something began to precipitate out of solution. I added more small portions until the precipitate stayed solid. I then let it cool to room temperature and then let it cool in the fridge overnight and collected 13.8 g of pure product!

