What Reagents Will You Never Forget?

I've had the chance to use good old elemental bromine this morning, for the first time in several years. I can never see the stuff without thinking of this incident, a memorable part of the first synthetic scheme I ever tried that involved bromine. In the same way, every time I come across thiophenol - which isn't often, fortunately - I'm immediately taken back to this chemistry, which is a reaction I'll never forget either, despite numerous attempts to expunge it from my memory.

So here's a good question for a Monday: what reagents immediately recall something from your chemical past, and why? I'd assume that most working organic chemists have a few of these in their past. The common reagents all tend to blur together, but there will always be a few that have shown up only in one or two memorable instances. So what are yours?

Source: In the Pipeline - December 9, 2013 Category: Chemists Tags: Life in the Drug Labs Source Type: blogs