Mechanical Activation of Magnesium Turnings for the Preparation of Reactive Grignard Reagents

Article abstract of DOI:10.1021/jo00002a039

Preactivation of magnesium by dry stirring in an inert atmosphere is highly beneficial for the clean synthesis of reactive allylic or benzylic organomagnesium chlorides.This procedure routinely produces 0.4 M solutions of the Grignard reagent in diethyl ether free from coupling products.The purity may be directly assayed by 13C spectroscopy.Using spin saturation transfer techniques, the rate constant for interconversion of the enantiomers of (1-phenyl-2-methylpropyl)magnesium chloride in Et2O at 25 deg C was shown to be < 0.2 s^-1.Electron microscopy has been used to define the surface changes occurring during the dry stirring of magnesium turnings.