The power of oxygen

Oxidation seems to be one of the unusual intersections between the needs of the laboratory organic chemist and the chemical needs of the wider world. Hydrogen peroxide is sold in big bottles in the first aid aisle, and there are always gallons of bleach in the laundry aisle. Both of these chemicals are made not on the tonne scale, but on the millions of tonnes scale, which demonstrates both their ubiquity and their low cost. I wasn’t making much as a graduate student, but I don’t think I ever asked for a reimbursement for the two dollars I might have spent buying bleach at the store.

There’s another ubiquitous stoichiometric oxidant that doesn’t cost too much – oxygen. There are countless methods to perform oxidations with molecular oxygen. I particularly admire the Wacker process, where ethene can be oxidised to acetaldehyde in the presence of a palladium(II) catalyst. Of course, the extraordinary pressures and temperatures to help this reaction proceed make this particular transformation inaccessible to the laboratory chemist.

Something more accessible to me in graduate school was a strange machine called the ‘ozonator’. I loved running ozonolysis reactions because they seemed like a trip to a Frankenstein movie, with the buzzing angry high-voltage machine making the most awful racket when you turned it on. All I was missing was the wild hair and old-fashioned welding-type safety goggles. Even though I ran it in a fume hood, I often smelled the very distinct sharp odour of ozone. (People talk about the smell of ozone after thunderstorms, but not growing up in the South or the Midwest of the US, I’m not sure I’ve ever smelled it in nature.)