PREPARATION AND PROPERTIES OF DI-SEC-BUTYLMAGNESIUM

New synthetic procedures for obtaining dialkylmagnesium reagents are illustrated with the preparation of di-sec-butylmagnesium. The procedures, which can yield magnesium reagents with or without solvation by a Lewis base, involve either direct synthesis of the magnesium alkyl from alkyl chloride and metal under conditions causing magnesium halide to precipitate, or reaction of a magnesium halide with an alkyllithium reagent causing lithium chloride to precipitate. The latter reaction will occur in a hydrocarbon medium, free of basic solvent, if one employs an activated form of magnesium chloride. A number of characteristics of di-sec-butylmagnesium are reported, including formation of crystalline complexes (R2Mg-base) with the bicyclic bases triethylenediamine and methyltriethylenediamine. When free of basic solvation, di-sec-butylmagnesium is a mobile liquid, which is completely miscible with hydrocarbons; this property distinguishes it from all previously characterized magnesium alkyls. A dimeric structure (R4Mg2) is proposed for the sec-butylmagnesium reagent, analogous in size to tetrameric sec-butyllithium (R4Li4). © 1969, American Chemical Society. All rights reserved.