My first experience with truly hazardous materials was in 1981.  It was a sophomore organic lab and we were making sulfanilamide.  Using chlorosulfonic acid, we attached a ClSO2 group in the para position of acetanilide.  Pedagogically, it was a very rich experience because it validated the idea of O,P-directors, protecting groups, medicinal chemistry, and offered real experience in the handling of hazardous materials.  And, at least as corrosive materials go, they don’t get much more obnoxious than chlorosulfonic acid.

The preparation of sulfanilamide was an excellent lab experience because it brought home some fundamental truths about nature.  Namely, that physical and chemical properties of matter can be “tuned” and tweaked by people to give a desired outcome.  For students, this lab experience connects the inorganic, inanimate world of the periodic table to something closer and more personal.  It gets to the very nanomachinery of life itself.  It is a glimse of how drugs work. It gets right to the pointy end of the stick- Drugs are about selective toxicity. 

Once you have taken the time to gain some understanding of how drugs work at the molecular level, you are forever changed.  One begins to realize that biochemical “mistakes” can happen naturally and are part of the game.  Suddenly, the world is full of rogue “isosteres” and “pharmacophores“.  You can no longer accept blithe generalizations about toxicity and chemical hazards.  There is truth in the First Law of Toxicology- Dose makes the poison.  Your working definition of toxicity takes on new forms, like the notion of endocrine disrupters. 

As time goes on and my view of the natural world becomes increasingly molecular in scope, I find that my working definition of what constitutes “hazardous” has skewed a bit as well. Hazardous does not automatically equal “bad”. The modern material world is now a swirl of substances synthetic and substances natural.  Industry has given us dioxin and nature has given us aflatoxin.  But at worst nature is indifferent; human activity can be negligent or even malevolent. 

A mature view of hazardous materials must simultaneously accomodate physical/chemical reality with certain norms of conduct, with prompt and delayed biological effects of hazardous materials, and with consequences to the biosphere.  In truth, modern society must use hazardous materials to produce goods and services vital for healthy living.  But we chemists must find ways to limit the number of moles of hazardous waste we generate. Especially the persistant substances- metal salts, halogenated hydrocarbons, etc.

Synthetic chemistry relies on reactive materials in order to do bond making and bond breaking.  There really is no getting around the need for reactive materials. But we can find ways to generate reactive materials in situ.  Reactive intermediates are generated in a catalytic cycle and used on the spot.  More pervasive use of catalysis could be a contributor to lower generation of haz waste or a greener chemistry.  This is just a corollary to Trost’s Atom Efficiency concept.

Hazardous materials have a utility that is similar to a knife.  A knife is a tool that does a very useful thing- it cuts. Every single time you pick it up you have to be wary of the edge and the point.  It is a persistant hazard.  But we continue to use it because of it’s utility.  In a way, chemicals are the just like that.