Now, I've worked with light-sensitive reagents (like the iodomethane and methallyl iodide) before, so I'm comfortable turning off the light and covering the reaction with foil to keep out extraneous photons.  That's not so bad, because when the reaction's done, you can flip on the light to work up the reaction.

Not so when the product is light sensitive.  Gotta keep the light off.  Gotta extract in the dark.  Gotta dry the organic layer with foil around the flask.  Gotta rotovap in the dark with foil around the flask.  Worst of all, gotta run a column in the dark.  For that, I cut off some of the sides of a cardboard box and used them as a shield to block the light and holed myself up in the dark corner of my hood to run the column.  Then gotta rotovap the fractions corresponding to product in the dark in foil.  Take the mass in the dark...  Ugg.  Pain all around.  Oh yeah, I forgot I gotta keep the NMR samples in the dark while I acquire the spectra, too.

Plus, gotta keep the product away from light until I set up the next reaction (which is going on right now)... and that's gotta be in the dark.  At least when this reaction's done, I can turn the lights back on.

Fortunately, the first reaction worked quite well.  I ran two multi-gram reactions side by side in the dark and got quantitative yield on both.

So while I run off to find some vitamin D supplements, tell me what the most operationally painful experiment you've set up is.  I'm sure many of you have stories that make mine seem trivial.  What experiment's the biggest pain to run?  I think any reaction involving FOOF (the most awesome, most onomatopoeic molecular formula evah) has to be up there.