A Convenient Preparation of Pure Dialkylmagnesium from a Grignard Reagent

Dimethyl ether of acyclic polyethers, Me(OCH2CH2)nOMe, predominantly coordinated to MgX2 in an ether solution of Grignard reagent and the MgX2 adduct was removed as a precipitate. Consequently, an ethereal solution of pure R2Mg was obtained in reasonable yield. This method is more convenient than those known general.