This May Be the Last Straw

So I bought this awesome laser pointer/pen/stylus 3-in-1 thingy for $20 from the bookstore, and the douchebag REU student who's too shy to ask to borrow it has both stolen and lost it. That I can deal with; after all, it's just a pen and my mom (via my student ID account) paid for it. But today...I walked into my office to find all my books pushed aside and the REU student's computer (courtesy of UK, the rotten bastards) on my desk.

So essentially, I have no desk. We can't isolate the PCN radical, all the parts for the matrix isolation system are in the machine shop, and now I have no desk.

And I was beginning to think not doing an REU was a good thing. Thanks for proving me wrong UK!

PDA for PDIs!

This paper caught my eye because I recalled my one regular commenter (come on dear readers...where are you? :'-( ) working with perylenes in the past. The reactant in the middle is imide-substituted perylene diimide, PDI. DMP PDI, compound 1a, has some interesting solid-state photochemical quirks, so who knows, substituting the perylene core could lead to the next big thing in photonic organics. So the author says.

The first reaction described looks less than impressive: for 1a, 26% came out a mixture of dibrominated isomers (1,6-3a and 1,7-3a), 57% came out monobrominated, and 15% remained unreacted. Restricted rotation of the bulky R groups about the C-N bond meant two isomers for each potentially brominated carbon. The author goes on to describe a reaction using a refluxing solution of bromine that gives exclusively dibrominated product overnight, with a 1,7/1,6 ratio of 3:1. The regioisomers can be separated by recrystallization from a 1:1 solution of dichloromethane and hexane.

Sonogashira coupling of 2a with TMS acetylene works, as does nucleophilic substitution by piperidine.


Bromination causes an interesting "core twist" vibration involving, well, the twisting of the perylene core. Energy barriers associated with the motion were relatively low and thus interconversion between the two "twist states" of the molecule is relatively easy.

Bromosilane go BOOM!

Well ladies and gentlemen, I've reached a milestone...I caused my first explosion in lab yesterday. I was cleaning out a flask after a cold-trap separation of the reaction products of the bromosilane synthesis reaction:

PhSiH3 + HBr --> SiH3Br + C6H6

I believed that no bromosilane (or perhaps a negligibly small amount) remained in said flask. I was wrong. Set the flask inside the hood, put a little heat on it to vaporize things, took a step back to walk away, and BAM! A huge, quick flame burst out of the flask's mouth, accompanied by a horrible noise like a gunshot. Incredibly, the flask was just fine, save for a few brown spots that 48% HF took care of right away. Nothing got burned in the hood either. It was just a really loud, scary noise and a few flames. Doesn't mean it didn't scare the pants off me, of course.

The picture, for your viewing pleasure, is the LUMO of bromosilane.