• Question: whats the worst chemical you have worked with?

    Asked by the wheeler dealer to Angela, Claire, Ian, Robert, Sarah on 14 Nov 2014. This question was also asked by Ian21.
    • Photo: Ian Cade

      Ian Cade answered on 14 Nov 2014:

      It depends what you mean by worst… but here’s one that comes to mind:

      This year, I have been working with a carbene (tetramethyl NHC – a compound with a carbon atom in oxidation state II and a lone pair… so it behaves as a ligand, like water, amine or a phosphine etc.).

      The carbene itself is not bad to use, but to make it I need to heat half a gram of potassium metal with a sulphur compound in a hexanol… This is annoying for the following reasons:

      1) potassium metal is quite dangerous and reacts spontaneously with air and water… so I cut it up in a glovebox filled with argon… this is made more troublesome by the fact that potassium is also very sticky, a little bit like toffee.

      2) The sulphur compound reacts with potassium to give a fine sticky powder (of potassium sulphide and a small amount of fine potassium powder). Potassium sulphide can react with water to give off extremely poisonous H2S, the powdered potassium is even more flammable than lumps of potassium and the whole lot tends to gum up the filters I use to try to separate my product from this residue.

      3) The hexanol solvent has to be distilled off at one stage, and since it has such a high boiling point this takes quite a while.

      4) … and the product is very sensitive to air… so if I make a mistake I have to start all over again…

      so, worst? maybe…. most annoying? probably…

      As for most dangerous… it was probably the 5-10 litres of TMS-azide I used in 2006… This, when it reacts with water, such as present in your lungs makes hydrazoic acid which is both explosive and has the properties of hydrogen cyanide. (my survival being clear testament to my competence… or luck in the lab!)

    • Photo: Angela Stokes

      Angela Stokes answered on 16 Nov 2014:

      I worked with a chemical once that smelt like fish and the smell stayed with you for days – it was in the air, in my car, at home, it was truly awful. The worst thing was I went to a supermarket on the way home one day and as I put my shopping on the conveyer the assistant apologised for the smell – as she thought someone before me had bought fish!! I didn’t tell her it was probably me, but did laugh afterwards!

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