Grignard reagents in toluene solutions

Abstract

Grignard reagents were prepared from chloroalkanes and chlorobenzene in toluene in the presence of one or 0.5 equivalents of various organic bases (ethers and amines). Reagents with an average monosolvation can be obtained in high yields from primary or secondary alkyl chlorides and chlorobenzene. Diethyl ether is the most effective donor, in that it affords the reagents with a very small content of base. The kinetics of the reactions of n-butylmagnesium chloride in diethyl ether, and of this Grignard reagent monosolvated with the ether in toluene, with alkylalkoxysilanes were investigated. Reactivity of the partially solvated reagent greatly exceeds that of the conventional Grignard reagent. Yields of addition and reduction reactions of mono- and semi-solvated n-butylmagnesium chlorides in toluene with a ketone, an aldehyde, and two esters were determined. The partially solvated reagents afford the addition products (tertiary alcohols) in yields better than, or at least comparable to, those obtained with the conventional Grignard reagents. Copyright © 2002 John Wiley & Sons, Ltd.