Reaction modes ofn-butylmagnesium bromide with α,β-unsaturated esters, ketones, and nitriles were investigated in ether under anionic polymerization conditions.n-Butane and conjugate addition products observed were with all the monomers examined, but carbonyl addition products were not detected except with the unsaturated esters. Product distribution depends mainly upon reaction temperature and the concentration of the Grignard reagent, not upon the concentration of the unsaturated compounds.n-Butyl-magnesium bromide etherate in toluene gave similar results.