Synthesis
Several general methods exist for the generation of organozinc compounds.
- Oxidative addition. The original diethylzinc synthesis by Frankland was an oxidative addition of iodoethane to zinc metal with hydrogen gas as a "protective" blanket (this reaction is called the Frankland synthesis). The reactivity of zinc metal is increased in so-called Rieke zinc obtained by reduction of zinc chloride by potassium metal.
- 2RI + 2Zn → ZnR2 + ZnI2
- Halogen zinc exchange. Two main halogen zinc exchange reactions are iodine zinc exchange and boron zinc exchange. The first step in the second procedure is hydroboration of an alkene:
- Transmetalation. In a typical transmetalation, diphenylmercury reacts with zinc metal to diphenylzinc and metallic mercury in diethyl ether. Unfortunately, this reaction is slow, taking two weeks.
- Organozinc compounds can be obtained directly from zinc metal:
- In this method zinc is activated by the action of 1,2-dibromoethane and trimethylsilyl chloride. A key ingredient is lithium chloride which quickly forms a soluble adduct with the organozinc compound thus removing it from the metal surface.
Read more about this topic: Organozinc Compound
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