• Question: How do you find a new cheaper and quicker chemical building block of compounds?

    Asked by smiley face to Ian on 13 Nov 2014.
    • Photo: Ian Cade

      Ian Cade answered on 13 Nov 2014:

      I suppose two ways:

      1) Either see what has been done before and think up an analogous compound maybe using a similar element (an obvious example of this is the chemistry of the Suzuki-Miyaura (SM) cross coupling. There are a huge number of very similar reactions, developed by different groups, that all basically do the same thing – couple R-M with R’-X to make R-R’ (where R and R’ are unsaturated, M is ‘a metal’ and X is ‘a halide’)

      Very roughly: (square brackets indicate there are other bits on the metals)

      SM uses R-B(OH)2 and R’-X
      Sonogashira uses R-[Cu] and R-X
      Stille uses R-[Sn] and R-X
      Negishi uses R-[Zn] and R-X
      etc. etc…

      And all work well in particular cases, or are less poisonous, or are cheaper, or easier to make.

      2) Alternatively, you can notice your reaction does something strange, and rather than binning it, you have a look to see what actually happened. Usually its because you let air or moisture in, or the starting materials weren’t very clean… but sometimes the reaction didn’t work properly because there was some other new unexpected chemistry that happened… and although it was bad for *your* reaction it could be useful in other circumstances.

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